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Showing posts with label Alzheimer's. Show all posts
Showing posts with label Alzheimer's. Show all posts

Wednesday 19 September 2018

Ketones and Autism Part 5 - BHB, Histone Acetylation Modification, BDNF Expression, PKA, PKB/Akt, Microglial Ramification, Depression and Kabuki Syndrome















Child displaying elongated eyelids typical of Kabuki syndrome
Source: Given by Parents of children pictured with purpose of representing children with kabuki on Wikipedia. 

The syndrome is named after its resemblance to Japanese Kabuki makeup.

As we have discovered in this blog, autism is just a condition where certain genes are over-expressed and other genes are under-expressed. Put like that makes it sound quite simple.

Methylation of histones can either increase or decrease transcription of genes. The subject is highly complex, but we can keep things simple.

The child in the photo above has Kabuki syndrome and is likely to exhibit features of autism.  In most cases this is the result of a lack of expression of the KMT2D/MLL2 gene which encodes a protein called Histone-lysine N-methyltransferase.  Unfortunately, this is quite an important protein, because it promotes the “opening of chromatin”.  It adds a “trimethylation mark to H3K4”, just think of it as a pink post-it on your DNA. 
We get H3K4me3, which is an epigenetic marker (me3, because it is trimethylation). H3K4me3 promotes gene activation and it can cause a relative imbalance between open and closed chromatin states for critical genes. It has been suggested that it may be possible to restore this balance with drugs that promote open chromatin states, such as histone deacetylase inhibitors (HDACi).
What all this means is that people with Kabuki start with under-expression of just one gene, but this leads to the miss-expression of numerous other genes. Because science has figured out what the KMT2D/MLL2 gene does, we can find ways of treating this syndrome.

BHB as an HDAC inhibitor and a treatment for Kabuki syndrome

HDAC inhibitors (HDACi) are also suggested as therapies for other single gene syndromes. We saw in an earlier post that in Pitt Hopkins syndrome people lack Transcription Factor 4 (TCF4). Too little TC4 is not good, but too much TC4 is one feature of schizophrenia.
We saw in the research that we can increase expression of TCF4 using a class 1 HDAC inhibitor and we can also activate the Wnt pathway, which can also be achieved by inhibiting GSK3 (all themes covered in this blog).
So, Pitt Hopkins therapies include: -
·        Wnt activation (covered extensively in this blog) this includes statins and GSK3 inhibitors like Lithium

·        HDAC inhibitors like valproic acid, some cancer drugs, sodium butyrate and indeed the ketone BHB
This also means that people with schizophrenia, and likely too much TCF4, might benefit from the opposite gene expression modification, so a Wnt inhibitor, these include some cheap, safe, drugs used to treat children with parasites (Mebendazole/ Niclosamide etc) and of course GSK3 activators.
It is interesting that after 500 posts of this amateur blog you can start to fit the science together and identify rational therapies for complex disorders and  note that these therapies have much wider application, either to milder conditions or discovering avenues to treat the opposite genetic variation.  The underlying biological themes are all reoccurring in different types of autism/schizophrenia/ bipolar and you do wonder why more has not been done by professionals to apply this knowledge. 500 posts may sound a lot, but for autism researchers this is their paid, full-time job, not just a hobby pastime.

But then again, Simon Baron-Cohen, Head of Cambridge University's Autism Research Centre, recently published an article in which he wrote:

"We at the Autism Research Centre have no desire to cure, prevent or eradicate autism ... As scientists, our agenda is simply to understand the causes of autism." 

Whose team is he playing for?

My conclusion is that perhaps Baron-Cohen has Asperger's himself, because he does not realize that a disorder, severe enough for a medical/psychiatric diagnosis, is a bad thing that should be minimized and ideally prevented, just like any other brain disorder. His cousin the actor Sacha gives a very good impression of someone with bipolar, so perhaps they both need a Wnt activator?

Would a mother with Multiple Sclerosis (MS) want her daughter to also develop MS to share the experience? I think not. If it is just "quirky autism", it does not warrant a medical diagnosis, because it is perfectly okay to be quirky. 

This blog does have many Aspie readers who do want pharmacological therapy and that is their choice; I am fully supportive of them and wish them well.

Back to Kabuki
There is more than one type of HDAC and so there are different types of HDACi.  There are actually 18 HDAC enzymes divided into four classes
The ketone BHB inhibits HDAC class I enzymes called HDAC2 and HDAC3
The good news is that the ketogenic diet, which produces BHB, does indeed show merit as a therapy for Kabuki.

Kabuki syndrome is caused by haploinsufficiency for either of two genes that promote the opening of chromatin. If an imbalance between open and closed chromatin is central to the pathogenesis of Kabuki syndrome, agents that promote chromatin opening might have therapeutic potential. We have characterized a mouse model of Kabuki syndrome with a heterozygous deletion in the gene encoding the lysine-specific methyltransferase 2D (Kmt2d), leading to impairment of methyltransferase function. In vitro reporter alleles demonstrated a reduction in histone 4 acetylation and histone 3 lysine 4 trimethylation (H3K4me3) activity in mouse embryonic fibroblasts from Kmt2d+/βGeo mice. These activities were normalized in response to AR-42, a histone deacetylase inhibitor. In vivo, deficiency of H3K4me3 in the dentate gyrus granule cell layer of Kmt2d+/βGeo mice correlated with reduced neurogenesis and hippocampal memory defects. These abnormalities improved upon postnatal treatment with AR-42. Our work suggests that a reversible deficiency in postnatal neurogenesis underlies intellectual disability in Kabuki syndrome.

Intellectual disability is a common clinical entity with few therapeutic options. Kabuki syndrome is a genetically determined cause of intellectual disability resulting from mutations in either of two components of the histone machinery, both of which play a role in chromatin opening. Previously, in a mouse model, we showed that agents that favor chromatin opening, such as the histone deacetylase inhibitors (HDACis), can rescue aspects of the phenotype. Here we demonstrate rescue of hippocampal memory defects and deficiency of adult neurogenesis in a mouse model of Kabuki syndrome by imposing a ketogenic diet, a strategy that raises the level of the ketone beta-hydroxybutyrate, an endogenous HDACi. This work suggests that dietary manipulation may be a feasible treatment for Kabuki syndrome.
 Although BHB has previously been shown to have HDACi activity (7, 21), the potential for therapeutic application remains speculative. Here, we show that therapeutically relevant levels of BHB are achieved with a KD modeled on protocols that are used and sustainable in humans (22, 23). In addition, we demonstrate a therapeutic rescue of disease markers in a genetic disorder by taking advantage of the BHB elevation that accompanies the KD.
Our findings that exogenous BHB treatment lead to similar effects on neurogenesis as the KD support the hypothesis that BHB contributes significantly to the therapeutic effect. In our previous study (6), the HDACi AR-42 led to improved performance in the probe trial of the MWM for both Kmt2d+/βGeo and Kmt2d+/+ mice (genotype-independent improvement). In contrast, KD treatment only led to improvement in Kmt2d+/βGeo mice (genotype-dependent improvement). This discrepancy may relate to the fact that AR-42 acts as an HDACi but also affects the expression of histone demethylases (24), resulting in increased potency but less specificity. Alternatively, because the levels of BHB appear to be higher in Kmt2d+/βGeo mice on the KD, the physiological levels of BHB might be unable to reach levels in Kmt2d+/+ mice high enough to make drastic changes on chromatin.
In addition to the effects seen on hippocampal function and morphology, we also uncovered a metabolic phenotype in Kmt2d+/βGeo mice, which leads to both increased BHB/AcAc and lactate/pyruvate ratios during ketosis; an increased NADH/NAD+ ratio could explain both observations. This increased NADH/NAD+ ratio may relate to a previously described propensity of Kmt2d+/βGeo mice toward biochemical processes predicted to produce NADH, including beta-oxidation, and a resistance to high-fat-diet–induced obesity (27). If this exaggerated BHB elevation holds true in patients with KS, the KD may be a particularly effective treatment strategy for this patient population; however, this remains to be demonstrated. Alterations of the NADH/NAD+ ratio could also affect chromatin structure through the action of sirtuins, a class of HDACs that are known to be NAD+ dependent (28). Advocates of individualized medicine have predicted therapeutic benefit of targeted dietary interventions, although currently there are few robust examples (2931). This work serves as a proof-of-principle that dietary manipulation may be a feasible strategy for KS and suggests a possible mechanism of action of the previously observed therapeutic benefits of the KD for intractable seizure disorder (22, 23).                   
Kabuki syndrome (KS) (Kabuki make-up syndrome, Niikawa-Kuroki syndrome) is a rare genetic disorder first diagnosed in 1981. Kabuki make-up syndrome (KMS) is a multiple malformation/intellectual disability syndrome that was first described in Japan but is now reported in many other ethnic groups. KMS is characterized by multiple congenital abnormalities: craniofacial, skeletal, and dermatoglyphic abnormalities; intellectual disability; and short stature. Other findings may include: congenital heart defects, genitourinary anomalies, cleft lip and/or palate, gastrointestinal anomalies including anal atresia, ptosis and strabismus, and widely spaced teeth and hypodontia. The KS is associated with mutations in the MLL2 gene in some cases were also observed deletions of KDM6A. This study describes three children with autism spectrum disorders (ASDs) and KS and rehabilitative intervention that must be implemented.

So what?
Unless you know someone with Kabuki syndrome, you might be wondering what does this matter to autism.
What is shows is that BHB/KD is sufficiently potent to be a viable HDAC inhibitor. 
We know that some cancer drug HDAC inhibitors are effective in some mouse models of autism. But these drugs usually have side effects. 

HDAC Inhibitors for which Cancer/Autism? 

BHB is safe endogenous substance, so it is a “natural” HDACi. 

The effect of HDAC2 and HDAC3 on BDNF 
Brain derived neurotropic factor (BDNF) is like brain fertilizer. In some types of autism, you would like more BDNF.
When you exercise you produce BHB and that goes on to trigger the release of BDNF. This process also involves NF-kB activation

Exercise induces beneficial responses in the brain, which is accompanied by an increase in BDNF, a trophic factor associated with cognitive improvement and the alleviation of depression and anxiety. However, the exact mechanisms whereby physical exercise produces an induction in brain Bdnf gene expression are not well understood. While pharmacological doses of HDAC inhibitors exert positive effects on Bdnf gene transcription, the inhibitors represent small molecules that do not occur in vivo. Here, we report that an endogenous molecule released after exercise is capable of inducing key promoters of the Mus musculus Bdnf gene. The metabolite β-hydroxybutyrate, which increases after prolonged exercise, induces the activities of Bdnf promoters, particularly promoter I, which is activity-dependent. We have discovered that the action of β-hydroxybutyrate is specifically upon HDAC2 and HDAC3, which act upon selective Bdnf promoters. Moreover, the effects upon hippocampal Bdnf expression were observed after direct ventricular application of β-hydroxybutyrate. Electrophysiological measurements indicate that β-hydroxybutyrate causes an increase in neurotransmitter release, which is dependent upon the TrkB receptor. These results reveal an endogenous mechanism to explain how physical exercise leads to the induction of BDNF.

Results: ROS was significantly increased in neurons after 6 hours of ketone incubation. However, after 24 hours, neurons show improved efficiency in ATP productions, upregulated expressions of antioxidant enzyme SOD2, and enhanced resistance to excitotoxicity. These effects were significantly abolished in neurons after treatment with TrkB inhibitor. More interestingly, ROS scavengers or blocking ROS-dependent NF-kB activation significantly decreased ketone-dependent BDNF-upregulation in neurons, suggesting that ROS may have increased BDNF expressions to improve mitochondrial respiration as adaptive responses.
Conclusions: 3OHB initially generates ROS and poses oxidative stress. However, ROS appears to trigger adaptive responses against oxidative stress by upregulating BDNF through NF-kB activation, which can improve mitochondrial oxidative capacity and ultimately enhance neuroprotection
BHB/KD promotes PKA/CREB activation 
Another clever way to change the function/expression of multiple genes in one single step is to use a protein kinase.  Up to 30% of all human proteins may be modified by kinase activity.  
A protein kinase is an enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). Phosphorylation usually results in a functional change of the target protein.
In the autism research you may well have come across PKA, PKB (Akt) and PKC. They clearly are disturbed in much autism.
The research shows that BHB activates PKA.
If you want good myelination you need PKA.
This might be another reason why BHB/KD is helpful in people with Multiple Sclerosis.
In much autism the myelin coating is found to be abnormally thin. 

BHB, Microglial Ramification and Depression (yes, depression)
I am increasingly impressed by research from China. The paper below by Chao Huang et al is excellent and I think we need a Chinese on the Dean’s List of this blog, it looks like he is the first.
Nantong, China on the Yangtze River and home to Chao Huang and more than 7 million other people 
Source: Wikipedia Dolly 442

The ketone body metabolite β-hydroxybutyrate induces an antidepression-associated ramification of microglia via HDACs inhibition-triggered Akt-small RhoGTPase activation. 


Abstract


Direct induction of macrophage ramification has been shown to promote an alternative (M2) polarization, suggesting that the ramified morphology may determine the function of immune cells. The ketone body metabolite β-hydroxybutyrate (BHB) elevated in conditions including fasting and low-carbohydrate ketogenic diet (KD) can reduce neuroinflammation. However, how exactly BHB impacts microglia remains unclear. We report that BHB as well as its producing stimuli fasting and KD induced obvious ramifications of murine microglia in basal and inflammatory conditions in a reversible manner, and these ramifications were accompanied with microglial profile toward M2 polarization and phagocytosis. The protein kinase B (Akt)-small RhoGTPase axis was found to mediate the effect of BHB on microglial shape change, as (i) BHB activated the microglial small RhoGTPase (Rac1, Cdc42) and Akt; (ii) Akt and Rac1-Cdc42 inhibition abolished the pro-ramification effect of BHB; (iii) Akt inhibition prevented the activation of Rac1-Cdc42 induced by BHB treatment. Incubation of microglia with other classical histone deacetylases (HDACs) inhibitors, but not G protein-coupled receptor 109a (GPR109a) activators, also induced microglial ramification and Akt activation, suggesting that the BHB-induced ramification of microglia may be triggered by HDACs inhibition. Functionally, Akt inhibition was found to abrogate the effects of BHB on microglial polarization and phagocytosis. In neuroinflammatory models induced by lipopolysaccharide (LPS) or chronic unpredictable stress (CUS), BHB prevented the microglial process retraction and depressive-like behaviors, and these effects were abolished by Akt inhibition. Our findings for the first time showed that BHB exerts anti-inflammatory actions via promotion of microglial ramification. 



NOTE:  Ramified Microglia = Resting Microglia


The brain microglia play important roles in sensing even subtle variations of their milieu. Upon moderate activation, they control brain activity via phagocytosis of cell debris and production of pro-inflammatory mediators and reactive oxygen species. However, a persistent activation would make the microglia transfer into a status with an amoeboid morphology tightly associated with neuronal damage and pro-inflammatory cytokine overproduction.

Unlike the activated microglia, the un-stimulated microglia are in a ramified status with extensively branched processes, an contribute to brain homeostasis via regulation of synaptic remodeling and neurotransmission. The ramified microglia has been shown to be associated with the induction of M2 polarization. A study by McWhorter et al. showed that elongation of macrophage by control of cell shape directly increases the expression of M2 markers and reduces the secretion of proinflammatory cytokines, suggesting that induction of microglial ramification may be a mechanism for regulation of microglial function. Methods that trigger microglial ramification may help treat brain disorders associated with neuroinflammation.
In this study, we found that BHB induces a functional ramification of murine microglia in both basal and inflammatory conditions in vitro and in vivo. The pro-ramification effects of BHB are associated with the change in microglial polarization and phagocytosis as well as the antidepressant-like effects of BHB in LPS- or chronic unpredictable stress (CUS)-stimulated mice. The ramified morphology in microglia is also induced by two BHB-producing stimuli fasting and KD, as well as two other HDACs inhibitors valproic acid (VPA) and trichostatin A (TSA). Given that microglial overactivation can mediate the pathogenesis of depression, induction of microglial ramification by BHB may have therapeutic significance in depression. 

These data confirm that BHB has an ability to transform the activated microglia back to their ramified and resting status in inflammatory conditions.

Recall the recent post about BHB and the Niacin Receptor HCA2/GPR109A in Autism:

The Chinese paper continues:

It is HDACs inhibition but not GPR109A activation that mediates the pro-ramification effect of BHB in microglia Akt inhibition abrogates the effects of BHB on microglial ramification, polarization, and phagocytosis
Akt inhibition prevents the antidepressant-like effects of BHB in acute and chronic depression models

Note that Akt is another name for Protein Kinase B (PKB)

One of the major findings in the present study is that the ketone body metabolite BHB as well as its producing stimuli fasting and KD induced reversible ramifications of murine microglia in vitro and in vivo, and these ramifications were not altered by pro-inflammatory stimuli. The ramified morphology induced by BHB seems to be a signal upstream of microglial polarization, and may mediate the antidepressant-like effect of BHB in depression induced by neuroinflammatory stimuli. Since the regulating effect of BHB in disorders associated with neuroinflammation has been well-documented, our findings provide a novel mechanism for the explanation of the neuroprotective effect of BHB in neurodegenerative and neuropsychiatric disorders from the aspect of the feedback regulation of microglial function by microglial ramification.
Induction of microglial ramification, a strategy neglected by most scientists for a long time, may have more important therapeutic significance than that of regulation of microglial polarization alone at the molecular level.

In experiments in vivo, we showed that BHB ameliorated the depressive-like behaviors induced by two neuroinflammatory stimuli LPS and CUS. These results are in accordance with previous reports, which showed that the BHB-producing stimuli, caloric restriction and fasting, produce potential antidepressant-like activities in both animals and humans. Thus, together with the pro-ramification effect of BHB in microglia in vitro, we speculate that the microglial shape change may be an independent signal that determines microglial function.

Our further analysis showed that the BHB-induced microglial ramification was mediated by the Rac1-Cdc42 signal, as BHB markedly increased the activity of Rac1 and Cdc42, and Rac1/Cdc42 inhibition attenuated the pro-ramification effect of BHB. The PI3K-Akt signal has been shown to mediate the activation of Rac1/Cdc42, and once accepting the signal from Akt, the Rac1-Cdc42 will be mobilized to promote lamellipodia/filopodia formation and cell shape change (Huang et al., 2016a). We showed that the BHB-induced microglial ramification was mediated by the Akt signal, as Akt inhibition suppressed the induction of microglial ramification by BHB. As a functional evidence for the involvement of Akt in the pro-ramification effect of BHB, Akt inhibition was found to block the functional changes in BHB-treated microglia in vitro and in vivo, including blockage of the anti-inflammatory and prophagocytic activity of BHB and abrogation of the antidepressant-like effects of BHB. Since the ramified morphology determines the anti-inflammatory phenotype in macrophages (McWhorter et al., 2013), our data suggest that there may exist a causal relationship between the ramified morphology and microglial function after BHB treatment, and this relationship may evidence the clinical significance of our findings, as the microglial process retraction has been shown to mediate the development of neurodegenerative and neuropsychiatric disorders.

Furthermore, considering the serum level of BHB in humans begin to rise to 6 to 8 mM with prolonged fasting (Cahill, 2006), investigation of whether the pro-ramification effect of BHB exists in human individuals should be of great value for the application of BHB in disease therapy. 


 Exposure to hypobaric hypoxia causes neuron cell damage, resulting in impaired cognitive function. Effective interventions to antagonize hypobaric hypoxia-induced memory impairment are in urgent need. Ketogenic diet (KD) has been successfully used to treat drug-resistant epilepsy and improves cognitive behaviors in epilepsy patients and other pathophysiological animal models. In the present study, we aimed to explore the potential beneficial effects of a KD on memory impairment caused by hypobaric hypoxia and the underlying possible mechanisms. We showed that the KD recipe used was ketogenic and increased plasma levels of ketone bodies, especially β-hydroxybutyrate. The results of the behavior tests showed that the KD did not affect general locomotor activity but obviously promoted spatial learning. Moreover, the KD significantly improved the spatial memory impairment caused by hypobaric hypoxia (simulated altitude of 6000 m, 24 h). In addition, the improving-effect of KD was mimicked by intraperitoneal injection of BHB. The western blot and immunohistochemistry results showed that KD treatment not only increased the acetylated levels of histone H3 and histone H4 compared to that of the control group but also antagonized the decrease in the acetylated histone H3 and H4 when exposed to hypobaric hypoxia. Furthermore, KD-hypoxia treatment also promoted PKA/CREB activation and BDNF protein expression compared to the effects of hypoxia alone. These results demonstrated that KD is a promising strategy to improve spatial memory impairment caused by hypobaric hypoxia, in which increased modification of histone acetylation plays an important role

Exogenous BHB prevents spatial memory impairment induced by hypobaric hypoxia

To further verify whether ketone body, a product of KD, has direct improving effect, we chose the most stable physiologic ketone body, BHB, for the subsequent experiment. In order to mimic the effect of KD as above described, the rats were pre-treated with BHB (at a dose of 200mg/kg/day) for 2 weeks and then submitted to Morris water maze test. Since intraperitoneal injection would allow substances to be absorbed at a slower rate and intraperitoneal injection would produce marginal effect during behavioral tests [16], we used the intraperitoneal injection of BHB, which has been applied in published reports [17, 18]. Although the rats in the control and BHB groups learned to find the platform with the same pattern during 5 days of acquisition training (Fig 4B), BHB could significantly improve the memory impairment induced by hypobaric hypoxia, represented by more crossing number, more time in the target quadrant, and decreased latency to first entry to platform compared to hypobaric hypoxia treatment alone (Fig 4C–4F). These results demonstrated that BHB has a direct memory-improving effect and served as the main executor of KD beneficial effects.

KD increases histone acetylation modification in the hippocampus

A previous study found that BHB is an endogenous HDAC inhibitor, and the KD recipe in our study substantially increased plasma levels of BHB. Then, we detected the effect of KD on histone acetylation in the hippocampus, which is responsible for learning and memory. As shown in Fig 5, the acetylated histone H3 (K9/K14), acetylated histone H3 (K14), and acetylated histone H4 (K12), were all increased in the hippocampus of the KD rats. Although the histone acetylation modifications listed above are decreased in hypoxia-treated rats, KD treatment could reverse the decreased levels of histone acetylation. The same pattern was displayed in the immunohistochemical staining, in which the hypoxia-induced decrease in acetylated histone H3 and acetylated histone H4 in the CA1 region of the hippocampus was reversed by KD treatment  

KD activates PKA/CREB signaling in the hippocampus

To explore a possible underlying mechanism of the beneficial effect of KD treatment on cognition, the activity of the PKA/CREB pathway in the four groups was also evaluated by western blot (Fig 7A). KD treatment was shown to not only increase the levels of PKA substrates and p-CREB (KD vs STD) but also reverse the decline in PKA substrates, p-CREB and CREB (KD-Hy vs STD-Hy). Although KD pre-treatment produced a partial restoration of PKA activity, p-CREB is nearly completely restore to its basic levels, which is may be account for its other upstream kinases, like calmodulin-dependent kinases [19]. Interestingly, the hypoxia-induced down-regulation of BDNF, a well-known neurotrophic factor involved in learning and memory formation processes, was also up-reregulated by KD treatment. These results demonstrated that KD treatment promoted PKA/CREB activation and BDNF protein expression. In order to detect whether KD promoted BDNF expression at mRNA levels, qRT-PCR assays were performed using BDNF specific primers. We found that KD-pretreatment significantly increased mRNA levels compared with that in hypobaric hypoxia group (Fig 7B). Next, we used ChIP-PCR to test if there might be increased enrichment of acetylated histones on the promoter of BDNF gene. We focused on the promoter I of BDNF gene, which response to neuronal activity [20). ]. The results showed that there is increased binding of acetylated histone H3 to the promoter I of BDNF gene (Fig 7C   

Concentrations of acetyl–coenzyme A and nicotinamide adenine dinucleotide (NAD+) affect histone acetylation and thereby couple cellular metabolic status and transcriptional regulation. We report that the ketone body d-β-hydroxybutyrate (βOHB) is an endogenous and specific inhibitor of class I histone deacetylases (HDACs). Administration of exogenous βOHB, or fasting or calorie restriction, two conditions associated with increased βOHB abundance, all increased global histone acetylation in mouse tissues. Inhibition of HDAC by βOHB was correlated with global changes in transcription, including that of the genes encoding oxidative stress resistance factors FOXO3A and MT2. Treatment of cells with βOHB increased histone acetylation at the Foxo3a and Mt2 promoters, and both genes were activated by selective depletion of HDAC1 and HDAC2. Consistent with increased FOXO3A and MT2 activity, treatment of mice with βOHB conferred substantial protection against oxidative stress. 
Abnormalities in mitochondrial function and epigenetic regulation are thought to be instrumental in Huntington's disease (HD), a fatal genetic disorder caused by an expanded polyglutamine track in the protein huntingtin. Given the lack of effective therapies for HD, we sought to assess the neuroprotective properties of the mitochondrial energizing ketone body, D-β-hydroxybutyrate (DβHB), in the 3-nitropropionic acid (3-NP) toxic and the R6/2 genetic model of HD. In mice treated with 3-NP, a complex II inhibitor, infusion of DβHB attenuates motor deficits, striatal lesions, and microgliosis in this model of toxin induced-striatal neurodegeneration. In transgenic R6/2 mice, infusion of DβHB extends life span, attenuates motor deficits, and prevents striatal histone deacetylation. In PC12 cells with inducible expression of mutant huntingtin protein, we further demonstrate that DβHB prevents histone deacetylation via a mechanism independent of its mitochondrial effects and independent of histone deacetylase inhibition. These pre-clinical findings suggest that by simultaneously targeting the mitochondrial and the epigenetic abnormalities associated with mutant huntingtin, DβHB may be a valuable therapeutic agent for HD.  

Conclusion
At the end of this fifth post on ketones and autism, I think we have established beyond any doubt that ketones can do some amazing things for numerous dysfunctions and diseases.
The question remains how much you need to achieve the various possible benefits. 
The next question, already put to me by one parent, is how do you measure such a benefit.  Some people’s idea of treating autism is just to eradicate disturbing behaviours like SIB and ensure a placid, cooperative child when out in public.  Other people notice small cognitive and speech changes, because they spend hours a day teaching their child. Small but significant cognitive improvement may not show up on autism rating scales.
You would expect a dose dependent response, so the more ketones the bigger the response, which suggests that the full Ketogenic Diet (KD) is the ultimate option.
A lot does seem to be possible just with BHB and C8 (caprylic acid) as supplements to a regular diet.
Adults with Alzheimer’s, or Huntington’s, or Multiple Sclerosis (MS) all stand to potentially benefit from ketone supplements.
Children/adults with certain single-gene autisms, not limited to Kabuki and Pitt Hopkins potentially should benefit from ketone supplements.
Interestingly, another benefit of BHB is on mood; it seems to make some people just feel much better, apparently all due to the effect on microglia. So perhaps autism parents who take antidepressants should try BHB instead.







Thursday 19 July 2018

Ketones and Autism Part 2 - Ketones as a Brain Fuel to treat Alzheimer’s, GLUT1 Deficiency and perhaps more



Today’s post looks at the role ketones can play as a fuel for the brain.

The research has already shown that in young babies there is insufficient glucose to fuel their power-hungry growing brains and so ketones provide up to 40% of the fuel to their brains.
Glucose or Ketones at the pump?

This does show any sceptics that you can indeed safely combine two sources of fuel at the same time in humans; we have all done it.
This process works in tiny babies because their diet is rich in medium chain fatty acids, which become the ketones.
Only mitochondria in your brain and your muscles can be fuelled by ketones; some elite athletes take advantage of this.
People who are overweight have excess adipose tissue (fat) and when in ketosis, fatty acids from this tissue are released into your blood and travel to the liver where they produce ketones. Mitochondria can also burn fatty acids directly. People losing weight on the ketogenic diet are burning fat and ketones as their main fuel source. To lose weight you do have to be in calorie deficit, you cannot just eat unlimited fat.
Athletes want to improve their performance and some use ketones to achieve this. The fat they are burning is from diet, not from accumulated over-eating.
Ketones as a brain fuel is a niche subject, but a growing one.

Low brain glucose uptake
Low brain glucose uptake is a feature or Alzheimer’s disease and also of a rare inborn condition called GLUT1 deficiency, which appears as epilepsy, MR/ID and with features of autism. Infants with GLUT1 deficiency syndrome have a normal head size at birth, but growth of the brain and skull is slow, in severe cases resulting in an abnormally small head size (microcephaly).

GLUT1, GLUT3 and GLUT4
GLUT1 (glucose transporter 1) occurs in almost all tissues, with the degree of expression typically correlating with the rate of cellular glucose metabolism. It is expressed in the endothelial cells of barrier tissues such as the blood brain barrier.
Glucose delivery and utilization in the human brain is mediated primarily by GLUT1 in the blood–brain barrier and GLUT3 in neurons.
GLUT3 is most known for its specific expression in neurons and was originally designated as the neuronal glucose transporter.
GLUT4 is the insulin-regulated glucose transporter found primarily in adipose tissues (fat) and striated muscle (skeletal and cardiac), but also in the brain.
So, in neurological disorders it is important to optimize GLUT1, GLUT3, GLUT4 and insulin.  In GLUT1 deficiency, as the name suggests, there is an inadequate supply of glucose crossing the blood brain barrier. In people with insulin resistance (T2 diabetes, Alzheimer’s etc) GLUT4 may be impaired.

Insulin resistance in the brain
Insulin resistance in the brain is highly complex and only partially understood; but it does lead to numerous problems. Glucose in the blood does not get taken up adequately into neurons which then become starved of fuel. We will see how this can be overcome by reverting to ketones as an alternative fuel.
At this point I digress a little into the detail of insulin resistance and glucose transport.                                                                             

Insulin resistance is a condition in which cells fail to respond normally to the hormone insulin. The body produces insulin when glucose starts to be released into the bloodstream from the digestion of carbohydrates  in diet. Under normal conditions of insulin reactivity, this insulin response triggers glucose being taken into body cells, to be used for energy, and inhibits the body from using fat for energy, thereby causing the concentration of glucose in the blood to decrease as a result, staying within the normal range even when a large amount of carbohydrates is consumed. During insulin resistance, excess glucose is not sufficiently absorbed by cells, even in the presence of insulin, causing an increase in the level of blood sugar.

The following paper is very interesting, if you can access the full text version


Considerable overlap has been identified in the risk factors, comorbidities and putative pathophysiological mechanisms of Alzheimer disease and related dementias (ADRDs) and type 2 diabetes mellitus (T2DM), two of the most pressing epidemics of our time. Much is known about the biology of each condition, but whether T2DM and ADRDs are parallel phenomena arising from coincidental roots in ageing or synergistic diseases linked by vicious pathophysiological cycles remains unclear. Insulin resistance is a core feature of T2DM and is emerging as a potentially important feature of ADRDs. Here, we review key observations and experimental data on insulin signalling in the brain, highlighting its actions in neurons and glia. In addition, we define the concept of 'brain insulin resistance' and review the growing, although still inconsistent, literature concerning cognitive impairment and neuropathological abnormalities in T2DM, obesity and insulin resistance. Lastly, we review evidence of intrinsic brain insulin resistance in ADRDs. By expanding our understanding of the overlapping mechanisms of these conditions, we hope to accelerate the rational development of preventive, disease-modifying and symptomatic treatments for cognitive dysfunction in T2DM and ADRDs alike. 

Sources of insulin in the brain. Insulin levels in cerebrospinal fluid (CSF) are much lower than in plasma but these levels are correlated, indicating that most insulin in the brain derives from circulating pancreatic insulin. Insulin enters the brain primarily via selective, saturable transport across the capillary endothelial cells of the blood–brain barrier (BBB).
Despite glucose being the major energy source for the brain, the uptake, transport and utilization of glucose in neurons is only influenced by insulin and is not dependent on it
The insulinindependent glucose transporter GLUT3 is the major glucose transporter in neurons and is present in very few other cell types in the body. The density and distribution of GLUT3 in axons, dendrites and neuronal soma correlates with local cerebral energy demands. Insulin is not required for GLUT3mediated glucose transport; instead, NMDA receptormediated depolarization stimulates consumption of glucose, which prompts glucose uptake and utilization via GLUT3. 
Although most glucose uptake in neurons occurs via GLUT3, insulinregulated GLUT4 is also coexpressed with GLUT3 in brain regions related to cognitive behaviours — at least in rodents. These regions include the basal forebrain, hippocampus, amygdala and, to lesser degrees, the cerebral cortex and cerebellum. 
Activation by insulin induces GLUT4 translocation to the neuron cell membrane via an AKTdependent mechanism and is thought to improve glucose flux into neurons during periods of high metabolic demand, such as during learning. Interestingly, GLUT4 is also expressed in the hypothalamus, a key area for metabolic control. Deletion of GLUT4 from the CNS in mice results in impaired glucose sensing and tolerance, which might be due in part to an absence of GLUT4 in the hypothalamus.

Brain insulin resistance definition. Insulin resistance in T2DM has been defined as “reduced sensitivity in body tissues to the action of insulin”. Similarly, brain insulin resistance can be defined as the failure of brain cells to respond to insulin. Mechanistically, this lack of response could be due to downregulation of insulin receptors, an inability of insulin receptors to bind insulin or faulty activation of the insulin signalling cascade. At the cellular level, this dysfunction might manifest as the impairment of neuroplasticity, receptor regulation or neurotransmitter release in neurons, or the impairment of processes more directly implicated in insulin metabolism, such as neuronal glucose uptake in neurons expressing GLUT4, or homeostatic or inflammatory responses to insulin. Functionally, brain insulin resistance can manifest as an impaired ability to regulate metabolism — in either the brain or periphery — or impaired cognition and mood 

Studies have yet to show whether T2DMassociated cognitive impairment and brain neuroimaging findings are a consequence of brain insulin resistance or are due to other factors that cooccur with systemic insulin resistance. Common comorbidities of systemic insulin resistance in T2DM — such as hyperglycaemia, advanced glycation end products, oxidatively dam aged proteins and lipids, inflammation, dyslipidaemia, athero sclerosis and microvascular disease, renal failure and hypertension — all have their own complex effects on brain function through a variety of mechanisms independent of insulin signalling. Furthermore, evidence suggests that systemic insulin resistance or high circulating levels of insulin affects the function of the BBB by downregulating endothelial insulin receptors and thus decreasing permeability of the BBB to insulin. This change in permeability is potentially of great importance as it could lead to decreased brain insulin levels and decreased insulinfacilitated neural and glial activity40. On the other hand, T2DM can lead to damage of the BBB, which results in increased permeability to a variety of substances

Brain insulin resistance in ADRDs
• Increasing age is associated with decreasing cortical insulin concentration and receptor binding in older adults without dementia 
•Brain tissue from those with Alzheimer disease (AD) shows major abnormalities in insulin signalling, including - Decreased insulin, insulin receptor and insulin receptor substrate 1 (IRS1) mRNA and/or protein expression levels
Decreased activation of insulin pathway molecules (for example, IRS1 and AKT) with ex vivo stimulation
Increased basal phosphorylation levels of multiple insulin–IRS1–AKT pathway molecules
 Positive correlation between phosphorylated IRS1 and other pathway molecules and AD pathology 
• Intranasal insulin administration improves cognitive functioning in humans with AD or mild cognitive impairment and improves measures of insulin signalling, amyloid-β and cognitive behaviours in AD model mice 
Brain insulin resistance might be a feature of other neurodegenerative diseases

Insulin receptor expression is decreased and AKT signalling is abnormal in the substantia nigra in Parkinson disease
Abnormal phosphorylated IRS1 expression is observed in tauopathies but is not seen in synucleinopathies or TDP-43 proteinopathies
Aside from treatment with insulin itself, insulinsensitizing medicines commonly used in T2DM have attracted growing interest as potential therapies for brain insulin resistance in ADRD. For instance, investigators have begun testing of metformin, the most commonly prescribed drug for T2DM, in nondiabetic individuals with MCI or early dementia due to AD, with some signs of benefit. In addition, thiazolidinedionebased nuclear peroxisome proliferatoractivated receptorγ (PPARγ) agonists, which were originally developed as insulin sensitizers for T2DM, have shown numerous beneficial neural effects in animal models of neuro degenerative diseases

Autism and GLUT1 deficiency:


Another excellent paper:-  


Brain energy metabolism in Alzheimer’s disease (AD) is characterized mainly by temporo-parietal glucose hypometabolism. This pattern has been widely viewed as a consequence of the disease, i.e. deteriorating neuronal function leading to lower demand for glucose. This review will address deteriorating glucose metabolism as a problem specific to glucose and one that precedes AD. Hence, ketones and medium chain fatty acids (MCFA) could be an alternative source of energy for the aging brain that could compensate for low brain glucose uptake. MCFA in the form of dietary medium chain triglycerides (MCT) have a long history in clinical nutrition and are widely regarded as safe by government regulatory agencies. The importance of ketones in meeting the high energy and anabolic requirements of the infant brain suggest they may be able to contribute in the same way in the aging brain. Clinical studies suggest that ketogenesis from MCT may be able to bypass the increasing risk of insufficient glucose uptake or metabolism in the aging brain sufficiently to have positive effects on cognition.

Push-pull: two distinct strategies to supply the brain with energy substrates. Glucose is the brain’s main fuel and is taken up by the brain in relation to demand. Hence, this is a “pull” strategy because glucose is pulled into the cell following neuronal activation and the subsequent decrease in neuronal glucose concentrations. Ketones are the brain’s main alternate fuel to glucose and are taken up by the brain in relation to their presence in blood. Hence, this is a “push” strategy because ketones are pushed into the brain in direct proportion to their concentrations in the blood.

5 Cognitive benefits of increasing brain ketone supply


Since brain ketone uptake is still normal in mild to moderate AD and the problem of low brain glucose uptake appears to be contributing to declining cognition in AD, it is reasonable to hypothesize that providing the brain with more ketones may delay any further cognitive decline. This hypothesis has been supported by results from acute and chronic studies in AD patients and in the prodromal condition to AD – mild cognitive impairment. Other trials with ketogenic supplements in AD are ongoing. Conditions involving acute or long-term cognitive problems including post-insulin hypoglycemia and epilepsy also respond to a ketogenic diet or supplement.

One of the reasons that type 2 diabetes is such an important risk factor for AD may be due to insulin resistance. The brain has long been thought to function independently of insulin, but this is now being challenged. Insulin resistance not only affects glucose uptake by peripheral tissues but it also blocks ketogenesis, thereby limiting production of ketones to be taken up by the brain. Indeed, if the insulin resistance of type 2 diabetes in some way impairs brain glucose metabolism, brain energy supply is in fact in double jeopardy because insulin excess also blocks ketogenesis from long chain fatty acids stored in adipose tissue thereby restricted access not just of the brain’s primary fuel (glucose) but its main back-up fuel (ketones) as well. One potential solution is that ketogenesis from MCFA appears to be independent of insulin, in which case a ketogenic MCFA supplement should still be able to supply the brain with ketones despite the presence of insulin resistance or type 2 diabetes. This is an active area of research.  

6 Ketones and infant brain development


Raising plasma ketones is commonly viewed as risky, primarily because ketosis is associated with uncontrolled type 1 diabetes, i.e. an acute and severe absence of insulin. However, pathological ketosis needs to be distinguished from nutritional ketosis: the former is associated with metabolic ketoacidosis, i.e. plasma ketones exceeding 15 mM, which is medically serious condition requiring rapid treatment. In contrast, the latter is associated with plasma ketones below 5 mM and can be safely induced by short- or long-term dietary modification. The very high fat ketogenic diet induces nutritional, not pathological ketosis. It has been used for nearly 100 years as a standard-of-care for intractable childhood epilepsy and is rarely associated with serious side-effects despite producing plasma ketones averaging 2–5 mM for periods commonly exceeding 2 years. Its mechanism of action is still poorly understood but the efficacy of this dietary ketogenic treatment for intractable epilepsy is greater in younger infants suggesting a possible link the well-established but often overlooked importance of ketones in infant brain development.

During lactation, the human infant brain metabolises >50% of the fuel provided, despite the brain representing only 12–13% of body’s weight. Glucose supplies about 30% of the late term fetus’s brain energy requirements and about 50% of the neonate’s brain energy requirements; the difference is provided by ketones. Therefore, ketones are an obligate brain fuel during an infant’s development, as opposed to being an alternative brain fuel in the adult human, i.e. only needed when glucose is limiting. Ketones are more than just catabolic substrates (fuel) for the developing brain – they are also important anabolic substrates because they supply the majority of carbon used to synthesize brain lipids such as cholesterol and long chain saturated and monounsaturated fatty acids. 


                                        

Unique route of medium chain fatty acid (MCFA) absorption compared to other common long chain dietary fatty acids. The lymphatic and peripheral circulation1 distribute most common long chain fatty acids as chylomicrons throughout the body, whereas MCFA are mostly absorbed directly via the portal vein to the liver2  

MCFA are more rapidly absorbed from the gut directly to the liver via the portal vein compared to long chain fatty acids which are absorbed primarily via the lymphatic duct and into the peripheral circulation. MCFA are also more easily β-oxidized in mitochondria because they do not require activation to CoA esters by carnitine. Both the rapid absorption and β-oxidation of MCFA suggest these fatty acids have a physiologically important function. Theoretically, this function could include elongation to long-chain fatty acids but, in practice, is probably limited to ketogenesis, especially in infancy which is the only period when it is normal to be regularly consuming MCFA.

Long chain fatty acids are the main alternate fuel to glucose for most tissues. They can also be taken up by the brain but the reason they are not a useful fuel for the brain is because their rate of uptake is insufficient to meet the demand for energy once glucose becomes limiting. However, MCFA such as octanoate (caprylic acid) can be taken up rapidly and be metabolized by the brain. Whether MCFA have direct effects on the brain or are principally metabolized to ketones before exerting any effect as fuels, lipid substrates or lipid signalling molecules remains to be seen. 



Ketones for Alzheimer’s? AC1202/4 
A lot of money is being spent on developing variants of caprylic acid (C8) as a medical food to treat one feature of Alzheimer’s. This medical food market has even attracted Nestle, the Swiss chocolate to baby food giant, to invest in ketones.
Even though clinical trials have not yet been successfully completed, American doctors are already prescribing a product called Axona to people with Alzheimer’s.
It looks like there are plenty of sceptics, but it looks like plenty of people are paying $80 a month for their Axona (>95% C8 oil). One packet of Axona powder, contains 20 grams MCTs almost exclusively C8.
You can see from the clinicals trials that Accera have been comparing the effectiveness of generic (unpatentable) C8 vs their two proprietary powders called AC-1202 and AC-1204. Clearly Accerra want to maximize plasma BHB, but in a way that has patent protection.
Since C8 is not so expensive when bought in bulk, the obvious alternative is just to drink C8 and in the way that best promotes its absorption and the production of ketones, which would seem to be when you wake up and before you have eaten anything.


http://www.about-axona.com/us/en/cgp/how-axona-could-help/how-axona-works.html



CNS therapeutics company Accera's AC-1204 has failed to demonstrate a positive outcome in the Phase III trial for the treatment of patients with mild-to-moderate Alzheimer's disease. 
AC-1204 is a small-molecule drug compound designed to leverage the physiological ketone system in order to address the deficient glucose metabolism in Alzheimer's. 
The ketones are thought to have a potential to restore and improve neuronal metabolism, resulting in better cognition and function.
The trial results indicated that the drug did not show a statistically significant difference at week 26 when compared with placebo, as measured by the Alzheimer's disease assessment scale-cognitive subscale test (ADAS-Cog). 
"The formulation of the drug was changed between the Phase II and Phase III studies."
The double-blind, randomised, placebo-controlled, parallel-group Phase III (NOURISH AD) trial evaluated the effects of daily administration of AC-1204 in the subjects for 26 weeks.
Accera research and development vice-president Samuel Henderson said: "The formulation of the drug was changed between the Phase II and Phase III studies. 
"Unfortunately, this change in formulation had the unintended consequence of lowering drug levels in patients. We are confident that our newly developed formulation will provide increased exposure and allow a more conclusive test of drug efficacy." 
The primary and key secondary endpoints of the trial are the measure of AC-1204 effects on memory, cognition and global function. 
While the drug was found to be safe with high levels of tolerability, a detailed pharmacokinetic analysis showed that the modified formulation used in the study led to a decrease in drug plasma levels when compared to prior formulations. 


FDA hit Accera with a warning letter in 2013 on the grounds its marketing materials caused Axona to be classed as a drug. Accera continues to market Axona as a medical food for Alzheimer’s but has tweaked its website since the warning letter.
Axona and AC-1204 both provide patients with a source of caprylic triglyceride—also known as fractionated coconut oil—that is intended to increase the availability of ketones to the brain. The potential of the therapeutic approach has enabled Accera to pull in more than $150 million from backers including Nestlé, according to SEC filings.

Ketones for GLUT1 deficiency?  C7 Triheptanoin
It looks like the star clinician/researcher for people with GLUT1 deficiency is Dr. Juan Pascual, Associate Professor of Neurology and Neurotherapeutics, Pediatrics, and Physiology at UT Southwestern Medical Center.
As we saw earlier you need the transporter GLUT1 for glucose to cross the blood brain barrier and then provide fuel for the mitochondria in the brain. 
It has been known for some time that people with GLUT1 deficiency make improvements on the ketogenic diet.  Now in the previous post we saw how the effect on epilepsy of the KD comes via a change in the mix of bacteria in the gut; this eventually leads to a sharp increase in the ratio of GABA/Glutamate in the brain. This reduces seizures, which are a feature of GLUT1 deficiency.
Dr Pascual wants a second benefit from the ketogenic diet, having got the benefit from the gut bacteria he wants to benefit from the ketones as a fuel, just like some Alzheimer’s researchers.
This time though he has picked another MCT (medium chained triglyceride) he picked C7.
C7 is not something you can pick up from your specialist ketone supplier. It is still very much a research chemical.
Dr Pascual did not start with C8 because he has done his homework.  He actually wants some help for his GLUT1 deficient patients from some C5 ketones and a good way to produce them is from C7.
Using C7 oil Dr Pascual is also going to produce BHB (beta-hydroxybutyrate) and acetoacetate, just like all those athletes, body builders, slimmers and older people with Alzheimer’s are doing with the KD, C8 and BHB.




           Metabolism of glucose, C7-derived heptanoate and 5-carbon (C5) ketones in the brain

Glial metabolism is distinct from neuronal metabolism. Glucose can access both glia (via GLUT1) and neurons (via GLUT3), fueling the TCA cycle (CAC). In glia, pyruvate is converted into oxaloacetate (OAA) via carboxylation, donating net carbon to the TCA cycle (anaplerosis). This reaction can be impaired in G1D. Like glucose, the C7 derivative heptanoate and related metabolites (i.e., the 5-carbon ketones beta-ketopentanoate and beta-hydroxypentanoate) also generate acetyl-coenzyme A (Ac-CoA) but, unlike the 4-carbon ketone bodies beta-hydroxybutyrate and acetoacetate, they can also be incorporated into succinyl-coenzyme A (Suc-CoA) via propionyl-CoA (Prop-CoA) formation, supplying net, anaplerotic carbon to the cycle. In addition to 5-carbon (C5) ketones, the 4-carbon ketone bodies beta-hydroxybutyrate and acetoacetate are also metabolites of C7.




Dr. Pascual led the JAMA study that relied on data from a worldwide registry he created in 2013 for Glut1 deficiency patients. The research tracked 181 patients for three years, finding that a modified Atkins diet that includes less fat and slightly more carbohydrates than the standard ketogenic diet helped reduce seizures and improved the patients' long-term health. The study also found earlier diagnosis and treatment of the disease improved their prognosis.
In addition, Dr. Pascual is overseeing national clinical trials that are testing whether triheptanoin (C7) oil improves the intellect of patients by providing their brains an alternative fuel to glucose. The trials will last five years and are funded with more than $3 million from the National Institutes of Health.

So far, the nearly 40,000 Americans potentially living with the disease have had only one primary option for treating symptoms: a high-fat, low-carbohydrate ketogenic diet that can limit seizures. The diet works in about two-thirds of patients but does not improve their intellect and carries long-term risks such as kidney stones and metabolic abnormalities.

Dr. Pascual expects the modified diet from the JAMA study and the C7 oil will prove at least as effective as the ketogenic diet in preventing seizures - without the health risks - while feeding the brain vital fuel to improve learning.


Background: Ketones are the brain's main alternative fuel to glucose. Dietary medium-chain triglyceride (MCT) supplements increase plasma ketones, but their ketogenic efficacy relative to coconut oil (CO) is not clear.

Objective: The aim was to compare the acute ketogenic effects of the following test oils in healthy adults: coconut oil [CO; 3% tricaprylin (C8), 5% tricaprin (C10)], classical MCT oil (C8-C10; 55% C8, 35% C10), C8 (>95% C8), C10 (>95% C10), or CO mixed 50:50 with C8-C10 or C8.

Methods: In a crossover design, 9 participants with mean ± SD ages 34 ± 12 y received two 20-mL doses of the test oils prepared as an emulsion in 250 mL lactose-free skim milk. During the control (CTL) test, participants received only the milk vehicle. The first test dose was taken with breakfast and the second was taken at noon but without lunch. Blood was sampled every 30 min over 8 h for plasma acetoacetate and β-hydroxybutyrate (β-HB) analysis.

Results: C8 was the most ketogenic test oil with a day-long mean ± SEM of +295 ± 155 µmol/L above the CTL. C8 alone induced the highest plasma ketones expressed as the areas under the curve (AUCs) for 0–4 and 4–8 h (780 ± 426 µmol h/L and 1876 ± 772 µmol h/L, respectively); these values were 813% and 870% higher than CTL values (P < 0.01). CO plasma ketones peaked at +200 µmol/L, or 25% of the C8 ketone peak. The acetoacetate-to-β-HB ratio increased 56% more after CO than after C8 after both doses.

Conclusions: In healthy adults, C8 alone had the highest net ketogenic effect over 8 h, but induced only half the increase in the acetoacetate-to-β-HB ratio compared with CO. Optimizing the type of MCT may help in developing ketogenic supplements designed to counteract deteriorating brain glucose uptake associated with aging. This trial was registered at clinicaltrials.gov as NCT 02679222. 

Brain glucose uptake is lower in Alzheimer disease (AD). This problem develops gradually before cognitive symptoms are present, continues as symptoms progress, and becomes lower than the brain glucose hypometabolism occurring in normal aging. In contrast to glucose, brain ketone uptake in AD is similar to that in cognitively healthy, age-matched controls. For ketones to be a useful energy source in glucose-deprived parts of the AD brain, the estimated mean daily plasma ketone concentration needs to be >200 μmol/L (21). With a total 1-d dose of 40 mL C8, plasma ketones peaked at 900 μmol/L and the day-long mean was 363 ± 93 μmol/L, whereas with the same amount of CO, they peaked at 300 and 107 ± 57 μmol/L, respectively. Our 2-dose test protocol (breakfast and midday) generated 2 peaks of plasma total ketones throughout 8 h, with the second dose inducing 3.5 and 2.4 times higher ketones with C8 than with CO, respectively. The first dose taken with a meal would be a more typical pattern but resulted in less ketosis that without a meal. One limitation of this study design is that the metabolic study period was only 8 h. A longer-term study lasting several weeks to months would be useful to assess the impact of regular MCT supplementation on ketone metabolism.




Conclusion
I hope Dr Pascual has read the UCLA study on bacteria mediating the effect of the ketogenic diet on seizures. I think this has big implications for how to best manage people with GLUT1 deficiency.
I can see why Nestlé are investing in C8 products to treat Alzheimer’s. It does makes sense to optimize bioavailability, but in the meantime drinking regular liquid C8 would seem a smart idea.

While C8 is being proposed for Alzheimer's as a means of compensating for reduced glucose uptake in the brain, it has other benefits.  In the next post we will look at the anti-inflammatory benefits of the ketone BHB; these benefits are very relevant to Alzheimer's, where we know that the pro-inflammatory cytokine IL-1B is over-expressed. We will discover how BHB reduces expression of IL-1B. 
The amount of C8 required to start partially fuelling the brain is trivial, just 40ml a day. If combined with BHB itself, you would need even less and if I was Nestlé that is what I would develop.
Unless you have GLUT1 deficiency I do not see why C7 is better than C8 as a brain fuel.
In autism you would only benefit from ketones as a brain fuel if you have reduced glucose uptake, reduced insulin sensitivity or a mitochondrial disorder. Clearly, some people diagnosed with autism should benefit from ketones as a secondary brain fuel to glucose. If intranasal insulin helps, ketones are particularly likely to help.