Pentoxifylline and cGP (an IGF-1 normalizer) from Blackcurrants, for Autism?

 

 

Readers may be wondering at what point Peter will run out of things to write about.  I do sometimes wonder the same thing. I was going to also write about Loperamide (Imodium), but the post would have been too long. Next time!

Pentoxifylline

Pentoxifylline has been in use to treat autism for 50 years. The original studies did suggest its effect was greatest among small children.  I have been in some discussions with a US psychiatrist, Dr Powell, who is a big fan of the off-label use of this drug to affect the brain in adults.  He has even written a book on the subject.

My previous posts on Pentoxifylline can be found here: 

https://www.epiphanyasd.com/search/label/Pentoxifylline

Dr Powell’s patients with autism tend to be older children, not the toddlers who did well in clinical trials in Japan in the 1970s.  He sees significant improvement in many, but not all, of his patients with autism.  The parents report improved social interactions and having higher-level discussions with their child.

What is notable is that he uses frequent dosing, 4 times a day, always after food to avoid the GI side effects.

Pentoxifylline is inexpensive, but its effect does not last long, hence the frequent dosing.  Some people take taking this drug 5-6 times a day.

Pentoxifylline has multiple modes of action, it should increase blood flow to the brain and it is broadly anti-inflammatory.  It is a non-selective PDE inhibitor, normally used treat muscle pain in people with peripheral artery disease. It increases red blood cell flexibility and it reduces the viscosity of blood.

There are PDEs 1 to 11. It all gets quite complicated, for example PDE1 subtype A2 has a potential role in neurodegenerative diseases, including:

·        Parkinson's disease

·        Axonal neurofilament degradation

·        Motorneuronal degradation

·        Neuronal ischemia

·        Alzheimer's disease

·        Epilepsy

Recall that PDE4 inhibitors are used to treat asthma and COPD. We can potentially repurpose those to improve myelination in MS, or autism, and at specific low doses they can improve cognition.

 

cGP (from Black Currants)

I did write quite a lot in this blog about growth factors and autism.  The familiar ones are BDNF, NGF and IGF-1, but there are many more. 

My previous posts on IGF-1 can be found here: 

https://www.epiphanyasd.com/search/label/IGF-1

We know that growth signaling in autism is disturbed, but it is not simple.  As the disease progresses (the fetus develops, the baby is born and grows into a toddler) the imbalance in growth signaling changes.  This means that what would be helpful in a 6 month old baby might well be inappropriate in a 6 year old.  This is a good example of what I call the what, when and where of treating autism. Here it is the “when” that matters.

Some people lack BDNF while others have too much. Very possibly, this changes over time in the same child.

One possible therapy for autism is injections of IGF-1 (Insulin-like Growth Factor 1).  IGF-1 plays an important role in childhood growth.

A synthetic analog of IGF-1 is used in children for the treatment of growth failure.  This drug called Mecasermin was used in autism trials and in Rett syndrome trials.

In Rett syndrome the search has been on for an oral therapy.

Trofinetide (NNZ-2566) is a potential therapy for Rett syndrome being developed by Neuren Pharmaceuticals in Australia.

Trofinetide is derived from IGF-1.

Trofinetide got to phase 2 trials as a therapy for Fragile-X in 2015.

The second product in development at Neuren is NNZ-2591.  It is aimed at normalizing the level of IGF-1.

This is in the pipeline to treat:

• Phelan-McDermid syndrome (Shank3 gene and others not working)
• Angelman syndrome (UBE3A gene not working)
• Pitt Hopkins syndrome (TCF4 gene not working)
• Prader-Willi syndrome (MAGEL2 gene and others not working)

https://www.neurenpharma.com/irm/content/product-development-pipeline.aspx?RID=483&RedirectCount=1

 

What is NNZ-2591?

It is an analogue (modified version) of cyclic glycine proline (cGP)

Cyclic glycine-proline (cGP), a metabolite of IGF-1, is neuroprotective through improving IGF-1 function.

There is also research focused on Parkinson’s and Alzheimer’s where it seems that cGP is reduced.

In New Zealand they found that supplementation of Blackcurrant anthocyanins (pigments) increased cGP in the spinal fluid of patients with Parkinson’s.

This also led the way to the idea of increasing cGP as means of protecting the brain during aging. There is now a commercial OTC product in New Zealand to do just this.

Our reader Daniel, who has a daughter with Rett syndrome, is assessing the benefit of cGP, using the OTC product cGPMAX. The results so far are promising.

Rett is very specific because we know for sure that IGF-1 and NGF are disturbed.

Is cGP going to be beneficial in broader autism?  May be yes, but we come back to the what, when and where.  It may well depend on when a specific person takes it.  We have both hypoactive pro-growth signalling autism and hyperactive pro-growth signalling autism.

 

 

Unfortunately, what the clever researchers who came up with the above concept did not consider is that you may start out hyper in the womb and switch to hypo a few short years later.

  

Conclusion

Frequently dosed Pentoxifylline looks like a potentially interesting therapy for many with autism, including some with high IQ.  Take note our Aspie readers.

Daniel’s idea to look at the Neuren’s non-Rett therapy as a Rett therapy is interesting.  In effect you do not need to wait for the Australian drug, you can hop across the Tasman Sea to New Zealand and use their cGP supplement, developed for protection against dementia.

You would also think that parents of children with:

• Phelan-McDermid syndrome (Shank3 gene and others not working)
• Angelman syndrome (UBE3A) gene not working)
• Pitt Hopkins syndrome (TCF4 gene not working)
• Prader-Willi syndrome (MAGEL2 gene and others not working)

might want to follow Daniel’s lead.

As you can see, there is a lot of trial and error in science.  Back in 2009 NNZ-2566 was in clinical trials for the treatment of cognitive deficits following traumatic brain injury.  That must not have worked out.  Fragile-X did not work out and now it is phase 3 for Rett girls, which seems to be going well.

 

IGF-1 for old people

The same growth factor IGF-1 that is key during development also plays a key role in aging. Dr Jian Guan made a world first discovery. She discovered that cGP (cyclic Glycine-Proline) was responsible for controlling the IGF-1 hormone in our body. Thus by increasing the level of cGP in our body, the cGP will essentially command the IGF-1 to build more blood vessels.

Dr Jian Guan, was then recognised as the world-wide authority on cGP. In 2017 she discovered that New Zealand blackcurrants contained high volumes of natural cGP which could regulate optimum levels of IGF-1 in the body.

So now we have Antipodeans/Kiwis fending off dementia, and potentially metabolic syndrome, by taking their locally made cGPMax.

Will it help you case of autism? Who knows, but if it does not, just give the leftover pills to Grandma, Granddad or take them yourself!

 

All the supporting papers from New Zealand.

https://cgpmax.com/pages/our-science

 

Genetic Mutations vs Differentially Expressed Genes (DEGs) in Autism

 

Genes make proteins and you need the right amount in the right place

at the right time.

I should start this post by confessing to not having carried out genetic testing on Monty, now aged 18 with autism.  When I did mention this to one autism doctor at a conference, I was surprised by her reply:- “ You did not need to.  Now there’s no point doing it”.

I got lucky and treated at least some of Monty’s Differentially Expressed Genes (DEGs) by approaching the problem from a different direction.

People do often ask me about what diagnostic tests to run and in particular about genetic testing.  In general, people have far too high expectations regarding such tests and assume that there will be definitive answers, leading to effective therapeutic interventions.

I do include an interesting example today where parent power is leading a drive towards an effective therapeutic intervention in one single gene type of autism.  The approach has been to start with the single gene that has the mutation and look downstream at the resulting Differentially Expressed Genes (DEGs). The intervention targets one of the DEGs and not the mutated gene itself.

This is a really important lesson.

It can be possible to repurpose existing drugs to treat DEGs quite cheaply.  Many DEGs encode ion channels and there are very many existing drugs that affect ion channels.

Entirely different types of autism may share some of the same DEGs and so benefit from the same interventions.

 

Genetic Testing 

Genetic testing has not proved to be the holy grail in diagnosing and treating autism, but it remains a worthwhile tool at a population level (i.e. maybe not in your specific case).  What matters most of all are Differentially Expressed Genes (DEGs), which is something different.

A paper was recently published that looked into commercially available genetic testing.  Its conclusion was similar to my belief that you risk getting a “false negative” from these tests, in other words they falsely conclude that there is no genetic basis for the person’s symptoms of autism. 

 

Brief Report: Evaluating the Diagnostic Yield of Commercial Gene Panels in Autism

Autism is a prevalent neurodevelopmental condition, highly heterogenous in both genotype and phenotype. This communication adds to existing discussion of the heterogeneity of clinical sequencing tests, “gene panels”, marketed for application in autism. We evaluate the clinical utility of available gene panels based on existing genetic evidence. We determine that diagnostic yields of these gene panels range from 0.22% to 10.02% and gene selection for the panels is variable in relevance, here measured as percentage overlap with SFARI Gene and ranging from 15.15% to 100%. We conclude that gene panels marketed for use in autism are currently of limited clinical utility, and that sequencing with greater coverage may be more appropriate.

 

To save time and money, the commercial gene panels only test genes that the company defines as autism genes.  There is no approved list of autism genes. 

You have more than 20,000 genes and very many are implicated directly, or indirectly, in autism and its comorbities. To be thorough you need Whole Exome Sequencing (WES), where you check them all.  

There are tiny mutations called SNPs ("snips") which you inherit from your parents; there are more than 300 million known SNPs and most people will carry 4-5 million.  Some SNPs are important but clearly most are not.  Some SNPs are very common and some are very rare. 

Even WES only analyses 2% of your DNA, it does not consider the other 98% which is beyond the exome.  Whole Genome Sequencing (WGS) which looks at 100% of your DNA will be the ideal solution, but at some time in the future.  The interpretation of WES data is often very poor and adding all the extra data from WGS is going to overwhelm most people involved. 

Today we return to the previous theme of treating autism by treating the downstream effects caused by Differentially Expressed Genes (DEGS).

Genetics is very complicated and so people assume that is must be able to provide answers. For a minority of autism current genetics does indeed provide an answer, but for most people it does not.

Early on in this blog I noted so many overlaps between the genes and signaling pathways that drive cancer and autism, that is was clear that to understand autism you probably first have to understand cancer; and who has time to do that!

Some people’s cancer is predictable. Chris Evert, the American former world No. 1 tennis player, announced that she has ovarian cancer.  Her sister had exactly the same cancer.  Examining family history can often yield useful information and it is a lot less expensive that genetic testing.  Most people’s cancer is not so predictable; sure if you expose yourself to known environmental triggers you raise its chances, but much appears to be random.  Cancer, like much autism, is usually a multiple hit process. Multiple events need to occur and you may only need to block one of them to avoid cancer. We saw this with a genetic childhood leukemia that you can prevent with a gut bacteria. 

Learning about Autism from the 3 Steps to Childhood Leukaemia

What is not random in cancer are the Differentially Expressed Genes (DEGs).

We all carry highly beneficial tumor suppressing genes, like the autism/cancer gene PTEN.  You would not want to have a mutation in one of these genes.

What happens in many cancers is that the individual carries two good copies of the gene like PTEN, but the gene is turned off. For example, in many people with prostate cancer, the tumor suppressor gene PTEN is turned off in that specific part of the body.  There is no genetic mutation, but there is a harmful Differentially Expressed Gene (DEG). If you could promptly turn PTEN expression back on, you would suppress the cancer.

Not surprisingly, daily use of drugs that increase PTEN expression is associated with reduced incidence of PTEN associated cancer.  Atorvastatin is one such drug.

 

DEGs are what matter, not simply mutations

 

In many cases genetic mutations are of no clinical relevance, we all carry several on average.  In some cases they are of immediate critical relevance.  In most cases mutations are associated with a chance of something happening, there is no certainty and quite often further hits/events/triggers are required.

A good example is epilepsy. Epilepsy is usually caused by an ion channel dysfunction (sodium, potassium or calcium) that is caused by a defect in the associated gene. Most people are not born with epilepsy, the onset can be many years later.  Some parents of a child with autism/epilepsy carry the same ion channel mutation but remain unaffected. 

 

Follow the DEGs from a known mutation 

There is a vanishingly small amount of intelligent translation of autism science to therapy, or even attempts to do so.  I set out below an example of what can be done.

 

Pitt Hopkins (Haploinsufficiency of TCF4) 

The syndrome is caused by a reduction in Transcription factor 4, due to mutation in the TCF4 gene.  One recently proposed therapy is to repurpose the cheap calcium channel blocker Nicardipine. Follow the rationale below.

 

↓  means down regulated

↑ means up regulated

1.     Gene/Protein TCF4 (Transcription Factor 4) ↓↓↓↓

2.     Genes SCN10a  ↑↑    KCNQ1 ↑↑

3.     Encoding ion channels  Na_v1.8   ↑↑     K_v7.1   ↑↑

4.     Repurpose approved drugs as inhibitors of K_v7.1 and Na_v1.8 

5.     High throughput screen (HTS) of 1280 approved drugs.

6.     The HTS delivered 55 inhibitors of K_v7.1 and 93 inhibitors of Na_v1.8

7.     Repurposing the Calcium Channel Inhibitor Nicardipine as a Na_v1.8 inhibitor 

           

The supporting science: 

Psychiatric Risk Gene Transcription Factor 4 Regulates Intrinsic Excitability of Prefrontal Neurons via Repression of SCN10a and KCNQ1

  

Highlights

•TCF4 loss of function alters the intrinsic excitability of prefrontal neurons 

•TCF4-dependent excitability deficits are rescued by SCN10a and KCNQ1 antagonists 

•TCF4 represses the expression of SCN10a and KCNQ1 ion channels in central neurons 

•SCN10a is a potential therapeutic target for Pitt-Hopkins syndrome

  

Na_v1.8 is a sodium ion channel subtype that in humans is encoded by the SCN10A gene

K_v7.1 (KvLQT1) is a potassium channel protein whose primary subunit in humans is encoded by the KCNQ1 gene.

  

Transcription Factor 4 (TCF4) is a clinically pleiotropic gene associated with schizophrenia and Pitt-Hopkins syndrome (PTHS).  

SNPs in a genomic locus containing TCF4 were among the first to reach genome-wide significance in clinical genome-wide association studies (GWAS) for schizophrenia  These neuropsychiatric disorders are each characterized by prominent cognitive deficits, which suggest not only genetic overlap between these disorders but a potentially overlapping pathophysiology.

We propose that these intrinsic excitability phenotypes may underlie some aspects of pathophysiology observed in PTHS and schizophrenia and identify potential ion channel therapeutic targets.

Given that TCF4 dominant-negative or haploinsufficiency results in PTHS, a syndrome with much more profound neurodevelopmental deficits than those observed in schizophrenia, the mechanism of schizophrenia risk associated with TCF4 is presumably due to less extreme alterations in TCF4 expression at some unknown time point in development

The pathological expression of these peripheral ion channels in the CNS may create a unique opportunity to target these channels with therapeutic agents without producing unwanted off-target effects on normal neuronal physiology, and we speculate that targeting these ion channels may ameliorate cognitive deficits observed in PTHS and potentially schizophrenia.

 

 

Disordered breathing in a Pitt-Hopkins syndrome model involves Phox2b-expressing parafacial neurons and aberrant Nav1.8 expression

Pitt-Hopkins syndrome (PTHS) is a rare autism spectrum-like disorder characterized by intellectual disability, developmental delays, and breathing problems involving episodes of hyperventilation followed by apnea. PTHS is caused by functional haploinsufficiency of the gene encoding transcription factor 4 (Tcf4). Despite the severity of this disease, mechanisms contributing to PTHS behavioral abnormalities are not well understood. Here, we show that a Tcf4 truncation (Tcf4^tr/+) mouse model of PTHS exhibits breathing problems similar to PTHS patients. This behavioral deficit is associated with selective loss of putative expiratory parafacial neurons and compromised function of neurons in the retrotrapezoid nucleus that regulate breathing in response to tissue CO₂/H⁺. We also show that central Nav1.8 channels can be targeted pharmacologically to improve respiratory function at the cellular and behavioral levels in Tcf4^tr/+ mice, thus establishing Nav1.8 as a high priority target with therapeutic potential in PTHS. 

 

Repurposing Approved Drugs as Inhibitors of K_v7.1 and Na_v1.8 To Treat Pitt Hopkins Syndrome

Purpose:

Pitt Hopkins Syndrome (PTHS) is a rare genetic disorder caused by mutations of a specific gene, transcription factor 4 (TCF4), located on chromosome 18. PTHS results in individuals that have moderate to severe intellectual disability, with most exhibiting psychomotor delay. PTHS also exhibits features of autistic spectrum disorders, which are characterized by the impaired ability to communicate and socialize. PTHS is comorbid with a higher prevalence of epileptic seizures which can be present from birth or which commonly develop in childhood. Attenuated or absent TCF4 expression results in increased translation of peripheral ion channels K_v7.1 and Na_v1.8 which triggers an increase in after-hyperpolarization and altered firing properties.

Methods:

We now describe a high throughput screen (HTS) of 1280 approved drugs and machine learning models developed from this data. The ion channels were expressed in either CHO (K_V7.1) or HEK293 (Na_v1.8) cells and the HTS used either ⁸⁶Rb⁺ efflux (K_V7.1) or a FLIPR assay (Na_v1.8).

Results:

The HTS delivered 55 inhibitors of K_v7.1 (4.2% hit rate) and 93 inhibitors of Na_v1.8 (7.2% hit rate) at a screening concentration of 10 μM. These datasets also enabled us to generate and validate Bayesian machine learning models for these ion channels. We also describe a structure activity relationship for several dihydropyridine compounds as inhibitors of Na_v1.8.

Conclusions:

This work could lead to the potential repurposing of nicardipine or other dihydropyridine calcium channel antagonists as potential treatments for PTHS acting via Na_v1.8, as there are currently no approved treatments for this rare disorder.

  

Repurposing the Dihydropyridine Calcium Channel Inhibitor Nicardipine as a Na_v1.8 inhibitor in vivo for Pitt Hopkins Syndrome

Individuals with the rare genetic disorder Pitt Hopkins Syndrome (PTHS) do not have sufficient expression of the transcription factor 4 (TCF4) which is located on chromosome 18. TCF4 is a basic helix-loop-helix E protein that is critical for the normal development of the nervous system and the brain in humans. PTHS patients lacking sufficient TCF4 frequently display gastrointestinal issues, intellectual disability and breathing problems. PTHS patients also commonly do not speak and display distinctive facial features and seizures. Recent research has proposed that decreased TCF4 expression can lead to the increased translation of the sodium channel Na_v1.8. This in turn results in increased after-hyperpolarization as well as altered firing properties. We have recently identified an FDA approved dihydropyridine calcium antagonist nicardipine used to treat angina, which inhibited Na_v1.8 through a drug repurposing screen.

 

All of the above was a parent driven process.  Well done, Audrey!

Questions remain.

Is Nicardipine actually beneficial to people with Pitt Hopkins Syndrome? Does it matter at what age therapy is started? What about the K_v7.1 inhibitor?

 

Conclusion 

Genetics is complicated, ion channel dysfunctions are complicated; but just a superficial understanding can take you a long way to understand autism, epilepsy and many other health issues.

There is a great deal in this blog about channelopathies/ion channel dysfunctions.

https://epiphanyasd.blogspot.com/search/label/Channelopathy

Almost everyone with autism has one or more channelopathies. Most channelopathies are potentially treatable.

Parents of children with rare single gene autisms should get organized and make sure there is basic research into their specific biological condition.  They need to ensure that there is an animal model created and it is then used to screen for existing drugs that may be therapeutic.  I think they also need to advocate for gene therapy to be developed.  This all takes years, but the sooner you start, the sooner you will make an impact.

Very likely, therapies developed for some single gene autisms will be applicable more broadly.  A good example may be the IGF-1 derivative Trofinetide, for girls with Rett Syndrome. IGF-1 (Insulin-like growth factor 1) is an important growth factor that is required for proper brain development. In the brain, IGF-1 is broken down into a protein fragment called glypromate (GPE). Trofinetide is an orally available version of GPE.

The MeCP2 protein controls the expression of several genes, such as Insulin-like Growth Factor 1 (IGF1), brain-derived neurotrophic factor (BDNF) and N-methyl-D-aspartate (NMDA).  All three are implicated in broader autism. 

https://rettsyndromenews.com/trofinetide-nnz-2566/

In girls with Rett Syndrome the genetic mutation is in the gene MeCP2, but one of the key DEGs (differentially expressed genes) is the FXYD1; it is over-expressed. IGF-1 supresses the activity of FXYD1 and hopefully so does Trofinetide.  Not so complicated, after all!

Medicine is often driven by the imperative to do no harm.

In otherwise severely impaired people, perhaps the imperative should be to try and do some good.

In medicine, time is of the essence; doctors in the ER can be heard to say "Stat!", from the Latin word for immediately, statim.  

How about some urgency in translating autism science into therapy? But then, what's the hurry? Why rock the boat?

On an individual basis, much is already possible, but you will have to do most of the work yourself - clearly a step too far for most people.

   

 

Neuroligins, Estradiol and Male Autism

Today’s post looks deeper into the biology of those people who respond to the drug bumetanide, which means a large sub-group of those with autism, likely those with Down Syndrome and likely some with schizophrenia.

It is a rather narrow area of science, but other than bumetanide treatment, there appears to be no research interest in further translating science into therapy.    So it looks like this blog is the only place to develop such ideas.

I did not expect this post would lead to a practical intervention, but perhaps it does. As you will discover, the goal would be to restore a hormone called estradiol to its natural higher level, perhaps by increasing an enzyme called aromatase, which appears to be commonly downregulated in autism.  This should increase expression of neuroligin 2, which should increase expression of the ion transporter KCC2; this will lower intracellular chloride and boost cognition.

It seems that those people using Atorvastatin may have already started this process, since this statin increases IGF-1 and insulin is one of the few things that increases the aromatise enzyme. 

This process is known as the testosterone-estradiol shunt.  In effect, by becoming slightly less male, you may be able to correct one of the key dysfunctions underlying autism. Options would include insulin, IGF-1, estradiol and a promoter of aromatase.




The testosterone – estradiol shunt

It would seem that this sub-group of autism is currently a little bit too male, which might be seen as early puberty and in other features. In this group the balance between testosterone and estradiol is affected not just in the brain, which is actually a good thing.  This should be measurable, if it is not visible.

  

NKCC1, KCC2 and AE3

As we have seen in earlier posts, some people with autism have too little of a transporter called KCC2 that takes chloride out of neurons and too much of NKCC1 that lets chloride in.  The result is an abnormally high level of chloride, which changes the way the GABA neurotransmitter functions.  This reduces cognitive function and increases the chance of seizures.

It is likely that a group may exist that has mis-expression of an ion exchanger called AE3. Potentially some have just an AE3 dysfunction and some may have AE3, KCC2 and NKCC1 mis-expression.  I will come back to this in a later post, but in case I forget, here is the link:

NKCC1 and AE3 Appear to Accumulate Chloride in Embryonic Motoneurons

“NKCC1 seems to be responsible for approximately two thirds of the steady-state chloride accumulation, whereas AE3 is responsible for the remaining third”

Genetic dysfunction of AE3 is not surprisingly associated with seizures and should respond to treatment with Diamox/Acetazolamide.

Block NKCC1 with Bumetanide and/or increase KCC2 expression

I was recently updating the Bumetanide researchers about my son’s near four years of therapy with their drug and my ideas to take things further.

My plan is to apply other methods to reduce intracellular chloride levels.  I think that over time, blocking NKCC1 with bumetanide may trigger a feedback loop that leads to a further increase in NKCC1 expression.  So bumetanide continues to work, but the effect is reduced. One way to further reduce intracellular chloride levels is to increase expression of KCC2, the transport that takes chloride out of neurons.

The best way to do this would be to understand why KCC2 is down regulated in the first place. I have touched on this in earlier posts, where I introduced neuroligin 2.

Today’s post will look at neuroligins in autism and how they are connected to the female hormone Estradiol.  We will also look at how estrogen receptor expression may help explain why more males have autism. Taken together this suggests that an  estrogen receptor agonist might be an effective autism therapy in this sub-group.

The difficulty with hormones is that, due to evolution, each one performs numerous different functions in different parts of the body and they react with each other.  So a little extra estradiol/estrogen might indeed increase neuroligin 2 expression and hence increase KCC2 expression in the brain, but it would have other effects elsewhere.  In female hormone replacement therapy care is usually taken to direct estradiol/estrogen to where it is needed, rather than sending it everywhere.

I suspect that in this subgroup of autism the lack of estradiol is body-wide, not just in the brain.  If not you would either need an estrogen receptor agonist that is cleverly developed to be brain specific, or take the much easier route of delivering an existing agonist direct to the brain, which may also be possible.

In the paper below NL2 and neuroligin-2 mean the same thing. 

An unexpected role of neuroligin-2 in regulating KCC2 and GABA functional switch

Background

GABA_A receptors are ligand-gated Cl^- channels, and the intracellular Cl^- concentration governs whether GABA function is excitatory or inhibitory. During early brain development, GABA undergoes functional switch from excitation to inhibition: GABA depolarizes immature neurons but hyperpolarizes mature neurons due to a developmental decrease of intracellular Cl^- concentration. This GABA functional switch is mainly mediated by the up-regulation of KCC2, a potassium-chloride cotransporter that pumps Cl^- outside neurons. However, the upstream factor that regulates KCC2 expression is unclear.

Results

We report here that KCC2 is unexpectedly regulated by neuroligin-2 (NL2), a cell adhesion molecule specifically localized at GABAergic synapses. The expression of NL2 precedes that of KCC2 in early postnatal development. Upon knockdown of NL2, the expression level of KCC2 is significantly decreased, and GABA functional switch is significantly delayed during early development. Overexpression of shRNA-proof NL2 rescues both KCC2 reduction and delayed GABA functional switch induced by NL2 shRNAs. Moreover, NL2 appears to be required to maintain GABA inhibitory function even in mature neurons, because knockdown NL2 reverses GABA action to excitatory. Gramicidin-perforated patch clamp recordings confirm that NL2 directly regulates the GABA equilibrium potential. We further demonstrate that knockdown of NL2 decreases dendritic spines through down-regulating KCC2.

Conclusions

Our data suggest that in addition to its conventional role as a cell adhesion molecule to regulate GABAergic synaptogenesis, NL2 also regulates KCC2 to modulate GABA functional switch and even glutamatergic synapses. Therefore, NL2 may serve as a master regulator in balancing excitation and inhibition in the brain.

  

Neuroligins and Neurexins

The following paper has an excellent explanation of neuroligins, neurexins and their role in autism.  It does get complicated.

Neuroligins and Neurexins Link Synaptic Function to Cognitive Disease

Neurexins (Nrxns) and neuroligins (Nlgns) are arguably the best characterized synaptic cell-adhesion molecules, and the only ones for which a specifically synaptic function was established^8,9. In the present review, we will describe the role of Nrxns and Nlgns as synaptic cell-adhesion molecules that act in an heretofore unanticipated fashion. We will show that they are required for synapse function, not synapse formation; that they affect trans-synaptic activation of synaptic transmission, but are not essential for synaptic cohesion of the pre- and postsynaptic specializations; and that their dysfunction impairs the properties of synapses and disrupts neural networks without completely abolishing synaptic transmission as^10–12. As cell-adhesion molecules, Nrxns and Nlgns probably function by binding to each other and by interacting with intracellular proteins, most prominently PDZ-domain proteins, but the precise mechanisms involved and their relation to synaptic transmission remain unclear. The importance of Nrxns and Nlgns for synaptic function is evident from the dramatic deficits in synaptic transmission in mice lacking Nrxns or Nlgns.

As we will describe, the role of Nrxns and Nlgns in synaptic function almost predestines them for a role in cognitive diseases, such as schizophrenia and autism spectrum disorders (ASDs), that have been resistant to our understanding. One reason for the difficulties in understanding cognitive diseaseas is that they may arise from subtle changes in a subset of synapses in a neural circuit, as opposed to a general impairment of all synapses in all circuits. As a result, the same molecular alteration may produce different circuit changes and neurological symptoms that are then classified as distinct cognitive diseases. Indeed, recent studies have identified mutations in the genes encoding Nrxns and Nlgns as a cause for ASDs, Tourette syndrome, mental retardation, and schizophrenia, sometimes in patients with the same mutation in the same family^13–27. Viewed as a whole, current results thus identify Nrxns and Nlgns as trans-synaptic cell-adhesion molecules that mediate essential signaling between pre- and postsynaptic specializations, signaling that performs a central role in the brain’s ability to process information and that is a key target in the pathogenesis of cognitive diseases.

Neuroligins and neurexins in autism

ASDs are common and enigmatic diseases. ASDs comprise classical idiopathic autism, Asperger’s syndrome, Rett syndrome, and pervasive developmental disorder not otherwise specified^73,74. Moreover, several other genetic disorders, such as Down syndrome, Fragile-X Mental Retardation, and tuberous sclerosis, are frequently associated with autism. Such syndromic forms of autism and Rett syndrome are usually more severe due to the nature of the underlying diseases. The key features of ASDs are difficulties in social interactions and communication, language impairments, a restricted pattern of interests, and/or stereotypic and repetitive behaviors. Mental retardation (~70% of cases) and epilepsy (~30% of cases) are frequently observed; in fact, the observation of epilepsy in patients with ASDs has fueled speculation that autism may be caused by an imbalance of excitatory vs. inhibitory synaptic transmission. In rare instances, idiopathic autism is associated with specialized abilities, for example in music, mathematics, or memory. The relation of ASDs to other cognitive diseases such as schizophrenia and Tourette’s syndrome is unclear. As we will see below with the phenotypes caused by mutations in Nlgns and Nrxns, the boundaries between the various disorders may not be as real as the clinical manifestations suggest.

A key feature of ASDs is that they typically develop before 2–3 years of age^73,74. ASDs thus affect brain development relatively late, during the time of human synapse formation and maturation. Consistent with this time course, few anatomical changes are associated with ASDs⁷⁵. An increase in brain size was repeatedly reported⁷⁶, but is not generally agreed upon⁷⁵. Thus, similar to other cognitive diseases, ASDs are not a disorder of brain structure but of brain function. Among cognitive diseases, ASDs are the most heritable (~ 80%), suggesting that they are largely determined by genes and not the environment. ASDs exhibit a male:female ratio of approximately 4:1, indicating that ASDs involve the X-chromosome directly, or that the penetrance of pathogenic genes is facilitated in males^73,74.

Mutations in many genes have been associated with familial ASDs. A consistent observation emerging from recent studies is the discovery of mutations in the genes encoding Nrxn1, Nlgn3, and Nlgn4. Specifically, seven point mutations, two distinct translocation events, and four different large-scale deletions in the Nrxn1 gene were detected in autistic patients^13–18. Ten different mutations in the Nlgn4 gene were observed (2 frameshifts, 5 missense mutations, and 3 internal deletions), and a single mutation in the Nlgn3 gene (the R451C substitution)^21–24. Besides these mutations, five different larger deletions of X-chromosomal DNA that includes the Nlgn4 locus (referred to as copy-number variations) were detected in autism patients^18,25–27.

In addition to the Nrxn/Nlgn complex, mutations in the gene encoding Shank3 – an intracellular scaffolding protein that binds indirectly to Nlgns via PSD-95 and GKAP (Fig. 1)⁶⁶ – may also be a relatively frequent occurrence in ASDs. An astounding 18 point mutations were detected in the Shank3 gene in autistic patients, in addition to several cases containing CNVs that cover the gene^18,77–82. Indeed, the so-called terminal 22q deletion syndrome is a relatively frequent occurrence that exhibits autistic features, which have been correlated with the absence of the Shank3 gene normally localized to this chromosome section. Shank3 is particularly interesting because it not only indirectly interacts with Nlgns, but also directly binds to CIRL/Latrophilins which in turn constitute α-latrotoxin receptors similar to Nrxns, suggesting a potential functional connection between Shank3 and Nrxns⁸³.

Overall, the description of the various mutations in the Nrxn/Nlgn/Shank3 complex appears to provide overwhelming evidence for a role of this complex in ASDs, given the fact that in total, these mutations account for a significant proportion of autism patients. It should be noted, however, that two issues give rise to skepticism to the role of this complex in ASDs.

First, at least for some of the mutations in this complex, non-symptomatic carriers were detected in the same families in which the patients with the mutations were found. Whereas the Nlgn3 and Nlgn4 mutations appear to be almost always penetrant in males, and even female carriers with these mutations often have a phenotype, the Shank3 point mutations in particular were often observed in non-symptomatic siblings^77,78. Thus, these mutations may only increase the chance of autism, but not actually cause autism.

Second, the same mutations can be associated with quite different phenotypes in different people. For example, a microdeletion in Nlgn4 was found to cause severe autism in one brother, but Tourette’s syndrome in the other²⁶. This raises the issue whether the ‘autism’ observed in patients with mutations in these genes is actually autism, an issue that could also be rephrased as the question of whether autism is qualitatively distinct from other cognitive diseases, as opposed to a continuum of cognitive disorders. In support of the latter idea, two different deletions of Nrxn1α have also been observed in families with schizophrenia^19,20, indicating that there is a continuum of disorders that involves dysfunctions in synaptic cell adhesion and manifests in different ways. Conversely, very different molecular changes may produce a similar syndrome, as exemplified by the quite different mutations that are associated with ASDs⁸⁴.

At present, the relation between the Nrxn/Nlgn synaptic cell-adhesion complex and ASDs is tenuous. On one hand, many of the mutations observed in familial ASD are clearly not polymorphisms but deleterious, as evidenced by the effect of these mutations on the structure or expression of the corresponding genes, and by the severe autism-like phenotypes observed in Nlgn3 and Nlgn4 mutant mice^85–87. On the other hand, the nonlinear genotype/phenotype relationship in humans, evident from the only 70–80% heritability and from the occasional presence of mutations in non-symptomatic individuals, requires explanation. Elucidating the underlying mechanisms for this incomplete genotype/phenotype relationship is a promising avenue to insight into the genesis of autism. Furthermore, in addition to the link of Nrxn1α mutations to schizophrenia^19,20, linkage studies have connected Nrxn3 to different types of addiction^88,89. It is possible that because of the nature of their function, mutations in genes encoding Nrxns and Nlgns constitute hotspots for human cognitive diseases.

  

As you will have seen from the above paper, whose author seems to be very well informed of the broader picture (a continuum of disorders that involves dysfunctions in synaptic cell adhesion, and even the link to addiction), neuroligins and neurexins are very relevant to autism and other cognitive disease.

Let’s get back on subject and focus on Neuroligin 2 

The very recent paper below mentions sensory processing defects and NLG2 alongside what we already have figured out so far.

Neuroligin 2 nonsense variant associated with anxiety, autism, intellectual disability, hyperphagia, and obesity

Abstract

Neuroligins are post-synaptic, cellular adhesion molecules implicated in synaptic formation and function. NLGN2 is strongly linked to inhibitory, GABAergic signaling and is crucial for maintaining the excitation-inhibition balance in the brain. Disruption of the excitation-inhibition balance is associated with neuropsychiatric disease. In animal models, altered NLGN2 expression causes anxiety, developmental delay, motor discoordination, social impairment, aggression, and sensory processing defects. In humans, mutations in NLGN3 and NLGN4 are linked to autism and schizophrenia; NLGN2 missense variants are implicated in schizophrenia. Copy number variants encompassing NLGN2 on 17p13.1 are associated with autism, intellectual disability, metabolic syndrome, diabetes, and dysmorphic features, but an isolated NLGN2 nonsense variant has not yet been described in humans. Here, we describe a 15-year-old male with severe anxiety, obsessive-compulsive behaviors, developmental delay, autism, obesity, macrocephaly, and some dysmorphic features. Exome sequencing identified a heterozygous, de novo, c.441C>A p.(Tyr147Ter) variant in NLGN2 that is predicted to cause loss of normal protein function. This is the first report of an NLGN2 nonsense variant in humans, adding to the accumulating evidence that links synaptic proteins with a spectrum of neurodevelopmental phenotypes

After some investigation I learned that both estradiol/estrogen and progesterone increase expression of neuroligin 2, at least in rats.

Increasing neuroligin 2/NLGN2/NL2 looks a promising strategy.

Gene expression analysis of the pro-oestrous-stage rat uterus reveals neuroligin 2 as a novel steroid-regulated gene

In addition, neuroligin 2 mRNA levels were increased by both 17beta-oestradiol (E(2)) and P(4), although P(4) administration upregulated gene expression to a greater extent than injection of E(2). These results indicate that neuroligin 2 gene expression in the rat uterus is under the control of both E(2) and P(4), which are secreted periodically during the oestrous cycle.[1]

So a female steroid-regulated gene is down-regulated in male-dominated autism.  Another example of the protective nature of female hormones?  I think it is.

Estrogens Suppress a Behavioral Phenotype in Zebrafish Mutants of the Autism Risk Gene, CNTNAP2

Highlights

·         Zebrafish mutants of the autism risk gene cntnap2 have GABAergic neuron deficits

·         High-throughput behavioral profiling identifies nighttime hyperactivity in mutants

·         cntnap2 mutants exhibit altered responses to GABAergic and glutamatergic compounds

·         Estrogenic compounds suppress the cntnap2 mutant behavioral phenotype

Summary

Autism spectrum disorders (ASDs) are a group of devastating neurodevelopmental syndromes that affect up to 1 in 68 children. Despite advances in the identification of ASD risk genes, the mechanisms underlying ASDs remain unknown. Homozygous loss-of-function mutations in Contactin Associated Protein-like 2 (CNTNAP2) are strongly linked to ASDs. Here we investigate the function of Cntnap2 and undertake pharmacological screens to identify phenotypic suppressors. We find that zebrafish cntnap2 mutants display GABAergic deficits, particularly in the forebrain, and sensitivity to drug-induced seizures. High-throughput behavioral profiling identifies nighttime hyperactivity in cntnap2 mutants, while pharmacological testing reveals dysregulation of GABAergic and glutamatergic systems. Finally, we find that estrogen receptor agonists elicit a behavioral fingerprint anti-correlative to that of cntnap2 mutants and show that the phytoestrogen biochanin A specifically reverses the mutant behavioral phenotype. These results identify estrogenic compounds as phenotypic suppressors and illuminate novel pharmacological pathways with relevance to autism.

Estrogen receptor expression may help explain why more males have autism

Estrogen is known to help protect premenopausal women from maladies such as stroke and impaired cognition. Exposure to high levels of the male hormone testosterone during early development has been linked to autism, which is five times more common in males than females.

The new findings of reduced expression of estrogen receptor beta as well as that of an enzyme that converts testosterone to estrogen could help explain the high testosterone levels in autistic individuals and higher autism rates in males, Pillai said.

It was the 5-to-1 male-to-female ratio along with the testosterone hypothesis that led Pillai and his colleagues to pursue whether estrogen might help explain the significant gender disparity and possibly point toward a new treatment.

"The testosterone hypothesis is already there, but nobody had investigated whether it had anything to do with the female hormone in the brain," Pillai said. "Estrogen is known to be neuroprotective, but nobody has looked at whether its function is impaired in the brain of individuals with autism. We found that the children with autism didn't have sufficient estrogen receptor beta expression to mediate the protective benefits of estrogen."

Comparing the brains of 13 children with and 13 children without autism spectrum disorder, the researchers found a 35 percent decrease in estrogen receptor beta expression as well as a 38 percent reduction in the amount of aromatase, the enzyme that converts testosterone to estrogen.

Levels of estrogen receptor beta proteins, the active molecules that result from gene expression and enable functions like brain protection, were similarly low. There was no discernable change in expression levels of estrogen receptor alpha, which mediates sexual behavior.

Estrogen receptor expression may help explain why more males have autism

The new findings of reduced expression of estrogen receptor beta as well as that of an enzyme that converts testosterone to estrogen could help explain the high testosterone levels in autistic individuals and higher autism rates in males

They also plan to give an estrogen receptor beta agonist -- which should increase receptor function -- to a mouse with generalized inflammation and signs of autism to see if it mitigates those signs. Inflammation is a factor in many diseases of the brain and body, and estrogen receptor beta agonists already are in clinical trials for schizophrenia.

The following trial was run by a psychiatrist; when I looked at why he thought estrogen might improve schizophrenia, there was no biological explanation.  He is trying to avoid the possible side effects by using of a selective estrogen receptor agonist.  I hope the trial successful.  The question is whether his subjects are starting out as extreme male or just male.

The Efficacy and Safety of a Selective Estrogen Receptor Beta Agonist (LY500307) for Negative Symptoms and Cognitive Impairment Associated With Schizophrenia (Beta)

http://grantome.com/grant/NIH/UH2-TR000955-01

Several lines of investigation have supported the potential therapeutic effects of estrogen for negative and cognitive symptoms in schizophrenia. However, estrogen has had limited therapeutic application for male and premenopausal patients with schizophrenia because of tolerability concerns including uterine cancer liability, and heart disease and feminization effects in men. Selective Estrogen Receptor Beta (ER beta) agonists are a new class of treatments that are relatively free of estrogen's primary side effects and yet have demonstrated estrogen-like effects in brain including improvement in cognitive performance and an association to extremes in social behavior. Thus, these agents may have a therapeutic role for cognitive and negative symptoms in schizophrenia. The primary objectives of this application are to determine if the selective ER beta agonist LY500307 significantly improves negative and cognitive symptoms in patients with schizophrenia. Secondary aims include assessing LY500307 effects on cerebral blood flow during working and episodic memory tasks with fMRI, and electrophysiological indices of auditory sensory processing and working memory. A single seamless phase 1b/2a adaptive design will be used to evaluate two LY500307 doses (25 mg/day and 75 mg/day) in the first stage of the trial (year 1 of the application) to determine which dose should be advanced to stage 2 (years 2and 3 of the application) or if the trial should be discontinued.

More generally:-

Learning and memory: Steroids and epigenetics

Highlights

Steroid hormones exert a considerable influence on several aspect of cognition.

Estrogens and androgens exert positive effects on cognitive functions.

Progesterone and allopregnanolone have variable effects on cognitive functions.

Glucocorticoids act to encode and store information of the emotional events.

Epigenetic modifications are a powerful mechanism of memory regulation.

Conclusion

More female hormones and less male hormones? Seems a good idea.

More of the aromatase enzyme ?  There are numerous drugs to reduce/inhibit aromatase but not specifically to increase it.

Insulin does increase aromatase, as does alcohol and being overweight.

The clever thing to do would be to just correct the reduced level of aromatase, or wait for a selective estrogen receptor beta agonist like LY500307 to come to the market.

In those who are extreme male, a little estradiol might be the simple solution, but not the amount that is currently taken by those that abuse it.  Yes people abuse estradiol – males who want to be females.

Antonio Hardan at Stanford did trial high dose pregnenolone, another hormone mainly found in females, that should increase progesterone.

Brief report: an open-label study of the neurosteroid pregnenolone in adults with autism spectrum disorder.

Overall, pregnenolone was modestly effective and well-tolerated in individuals with ASD.

This steroid should increase the level of progesterone and so might be expected to cause some side effects in males. You would expect it to have an effect on anxiety, but as we saw in an earlier post it should be quite dose specific.

Why Low Doses can work differently, or “Biphasic, U-shaped actions at the GABAa receptor”

So Hardan may have just picked the "wrong dose".

If he would like to trial 0.3mg of oral estradiol in adults with autism, I think he might find a positive response.