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Showing posts sorted by relevance for query vagus nerve. Sort by date Show all posts
Showing posts sorted by relevance for query vagus nerve. Sort by date Show all posts

Wednesday 30 October 2013

The Vagus Nerve and Autism

It is good to know that there are some brilliant minds out there, willing to cross disciplines.  A case in point is Professor Stephen Porges, a neuroscientist with particular interests in understanding the neurobiology of social behavior.  He is a Professor in the Department of Psychiatry and the Director of the Brain-Body Center in the College of Medicine at the University of Illinois at Chicago.  He has an equally clever wife who is a world leader in the role of neuropeptides oxytocin and vasopressin in social cognition.
You would want to think twice before inviting this couple round for dinner, unless you had spent the day before boning up on your science. 

Porges is best known for his Polyvagal Theory.  The Wikipedia article does not really do justice to the theory.  Here are two highly cited papers:-

He has only written one paper on autism, it is certainly not a light read but it shows a brilliant mind.

This paper is actually a chapter in a book and can be accessed via Google Books.

His paper explains odd autistic behaviours in terms of the functioning of the vagus nerve.  For example, the neural mechanism for making eye contact is shared with those needed to listen to the human voice.  So if you struggle to make eye contact, you will struggle to listen to what somebody is saying to you.  We can infer that if your ABA program trains you to make eye contact, you will likely become a better listener in the process.  Also, don’t talk to somebody unless you are facing them.
He comments on the regulation of the gut, the vagus and the immune system, vagal regulation of the HPA axis, all with reference to ASD.

Having read his paper you really will need no more convincing to go tune up your child’s vagus nerve. 

Tuning up the Vagus Nerve
Unlike Professor Porges, I like to simplify things so you do not read them more than once.  Clearly Kevin Tracey and Porges are the experts on the vagus nerve, but they do not go as far as telling you what you really want to know – how to improve its function using today's technology.  Fortunately, there is plenty of research on the Cholinergic System, of which the vagus nerve is part.  The following paper is a good example:-


You may recall from my earlier post Biomarkers in Autism: The Cholinergic system, that there are two types of cholinergeric receptors, nicotinic and muscarinic.  This paper is telling us how in autism these receptors are fewer in number than normal and the ones that are there, are not working (binding) as they should.
So this goes some way to perhaps explain why so many odd behaviours can be tracked back to the autistic vagus nerve; it is damaged.



In his paper, Porges is basically telling you to go try a vagus nerve stimulator, of the kind that already exists for epilepsy (see photo above) and Kevin Tracey is developing for arthritis (another inflammatory condition).  Right now this is not very feasible, but chemical stimulation of the vagus nerve does not look beyond the wit of man, using currently available technology.


 

Monday 14 October 2013

IBS, IBD and Autism, leading to Cholinergic Signaling and the Vagus Nerve


This post is all about those stomach problems typical of many kids with ASD and some of their neuro-typical close relatives. Since Monty, aged 10 with ASD, does not have any of these problems, it is not something I have looked into earlier.  As you will see later in this post, by understanding the underlying science, we can move another step towards inhibiting systemic inflammation, which affects all people with ASD.
 
Irritable bowel syndrome (IBS) and Inflammatory Bowel Disease (IBD),
First of all we need to differentiate two common conditions with very similar symptoms.  IBS is the less serious condition, though it causes lots of discomfort.
 
Irritable Bowel syndrome - IBS
Irritable bowel syndrome (IBS) sufferers show no sign of disease or abnormalities when the colon is examined.

IBS does not produce the destructive inflammation found in IBD. It does not result in permanent harm to the intestines, intestinal bleeding, or the harmful complications often occurring with IBD. People with IBS are not at higher risk for colon cancer, nor are they more likely to develop IBD or other gastrointestinal diseases
The exact cause of IBS is unknown.   The most common theory is that IBS is a disorder of the interaction between the brain and the gastrointestinal tract, although there may also be abnormalities in the gut flora and immune system.

Inflammatory Bowel Disease -  IBD
Inflammatory bowel disease is a group of inflammatory conditions of the colon and small intestine. The major types of IBD are Crohn's disease and ulcerative colitis

Crohn’s disease has a strong genetic component and is far more prevalent among smokers.  The usual onset is between 15 and 30 years old.
Ulcerative colitis is an auto-immune disease with no known cause.  The symptoms are very similar to Crohn’s disease, but there are some stark differences.  Ulcerative colitis is far less prevalent among smokers

Autistic Colitis / Ulcerative Colitis
The Inflammatory Bowel Disease (IBD) that seems to be relevant in Autism is ulcerative colitis, so much so that Wakefield and Krigsman sought to name a sub-type Autistic Enterocolitis.  Due to all the furore about vaccinations and autism, the research of these two gastroenterologists has been blacklisted.

Dr Krigsman has an informative website and has published some interesting research.
If you spend all day looking via the endoscope  at children with ASD, you are bound to notice a thing or two.  Ignoring what Krigsman observes is bizarre.

In case you are wondering what he does, he is going through the mouth to do an Upper Endoscopy; for the Colonoscopy he goes in from below.  He does both procedures under general anaesthetic.  That will be painless; I once had an endoscopy under general anaesthetic and you have no bad effects.  I had the misfortune to have another one without any anaesthetic, which was one of the most unpleasant experiences of my life.
Ulcerative colitis looks like a nasty condition but Krigsman finds it is generally treatable with some combination of anti-inflammatory medication, antimicrobials, probiotics, digestive enzymes and dietary restriction.

One thing he does not mention is nicotine, more of that later.

GERD
Gastroesophageal reflux disease (GERD) is a very common disease.  The acid within the stomach rises up into the esophagus and in doing so, damages its lining.

Most children will outgrow their reflux by their first birthday. However, a small but significant number of them will not outgrow the condition. This is particularly true when a family history of GERD is present.   It is estimated that 15% of adults of adults are affected by GERD.
Krigsman find that in kids with ASD and their siblings, GERD is relatively common.

 
Mechanisms linking IBS and IBD to Autism
I have already written about the link between food allergies, autism and behaviour.  In those posts it was histamine released from mast cells (along with cytokines and other nasties) that was the culprit.  The treatments included antihistamines and mast cell stabilizers (Ketotifen, Intal etc).  I would presume this would fall into the IBS category.

When it comes to IBD, things get interesting.
In 1936 the Nobel Prize for Physiology was awarded to Sir Henry Dale and Otto Loewi.  One had identified the neurotransmitter acetylcholine and the other had shown how the vagus nerve releases acetylcholine to control heartbeat.

It later became apparent how important the vagus nerve is.  The vagus nerve is a modulator of inflammation throughout the body.  Acetylcholine, the principle neurotransmitter released by the vagus nerve, can exert its anti-inflammatory effect via binding to nicotinic acetylcholine receptors (nAChRs), which are expressed on macrophages and other immune cells.
 
In a recent post I showed that autistic brain samples have diminished acetylcholine and nicotinic receptor activity.  I showed how this could be corrected either by drugs that mimic acetylcholine (eg nicotine or acetylcholine) or with an acetylcholinesterase inhibitor (Galantamine or Donepezil).

I found it very interesting that IBD can be successfully treated by mild smoking (3 cigarettes a day) or with nicotine patches. 
This then connects various comorbidities in a very useful way and opens up therapeutic directions.  The vagus nerve is also key to epilepsy.  Vagus nerve stimulation is currently used to treat epilepsy and depression.

Experimentally, vagus nerve stimulation is already used in autism.  

CONCLUSIONS:


Patients with ASD and intractable epilepsy respond as favorably as all other patients receiving VNS therapy. In addition, they may experience a number of QOL improvements, some of which exceed those classically observed following placement of a VNS device.

 

Kevin J. Tracey
A neurosurgeon and inventor, Kevin Tracey, is the man behind the inflammatory reflex.  The inflammatory reflex is a neural circuit that regulates the immune response to injury and invasion. All reflexes have an afferent and efferent arc. The Inflammatory reflex has a sensory, afferent arc, which is activated by cytokines, and a motor, or efferent arc, which transmits action potentials in the vagus nerve to suppress cytokine production. Increased signaling in the efferent arc inhibits inflammation and prevents organ damage.
We will be looking at his research and the Cholinergic anti-inflammatory pathway, in later posts


 

Tuesday 13 May 2014

“Spray Fire in my Head” and how putting it out with Verapamil links Histamine, IL6, Mast cells, Calcium Channel Cav1.2, and even the Vagus Nerve


After 18 months of researching autism, things are falling nicely into place.  For regular readers of this blog, it may seem that we have uncovered a bewildering number of issues/dysfunctions that need to be addressed by the science.  In fact, when you look closer still, you will see that many of these issues are interrelated and you do not need to treat each one.  Also, it is clear that many different methods can be used to treat the same dysfunction.  The best methods though would be the simplest, safest, cheapest and the ones that address multiple issues at once.

One such little gem is Verapamil, an extremely cheap calcium channel blocker that has been widely used for 30 years for other conditions. 


Spray Fire in my Head

Monty, aged 10 with ASD, suffers from allergies like many children.  I noticed that his pollen allergy provoked a dramatic increase in his autistic behaviors.  Last year I spent time developing a treatment for these summertime autism flare-ups, to avoid summertime misery for all of us.

My final secret weapon was not a commonly known allergy drug; in fact almost nobody would even consider it for this purpose, except those who read the old research.

Where we live, last the weekend the air was full of tree pollen and it was 280 C/ 820 F; so I was expecting a response from Monty.

He soon had red eyes, briefly rolled about on the floor and declared “spray fire in my head”.

In anticipation of the pollen season, for the last few weeks I have been giving him some mast cell stabilizing treatments, but clearly they were not sufficient; so I mixed up some extra verapamil, and as expected, a few minutes later peace was fully restored.

I have told you about channelopathies in previous posts.  Verapamil blocks the calcium channel called Cav1.2, but I did not tell you that in addition to this Cav1.2 channel affecting behavior and heart disease, it also appears to directly affect allergies and even the vagus nerve.

It would seem that one cheap little pill can address all of these issues.


The take-home points from the literature are these:-

Verapamil is very widely prescribed calcium channel blocker, used to lower blood pressure; but in the literature it is shown that:-
  • Verapamil inhibits mast cells and is shown to successfully treat asthma
  • Verapamil is more potent than the allergy drug Azelastine (the best mast cell stabilizing anti-histamine drug available)
  • Verapamil will reduce histamine release and therefore inflammatory cytokine Interleukin-6 (IL6), already elevated in autism
  • Verapamil activates the Gene for IL6
  • Verapamil alters the balance between parts of the autonomic nervous system's function, with a shift toward decreased sympathetic tone and increased parasympathetic (vagus nerve) tone
  • Autism is associated with an atypical autonomic response to anxiety that is most consistent with sympathetic over-arousal and parasympathetic under-arousal.  So increasing the parasympathetic (vagus nerve) tone is desirable.
  
Verapamil, Allergies and Asthma

Pollen allergies are a common trigger for asthma, and since every year many people die from asthma, the underlying science is well researched/understood.

  
Discussion
This study has demonstrated, for the first time, that mast cell tryptase potentiates the contractile response to histamine in human isolated airways. Moreover, this potentiation occurs only in tissues derived from patients whose bronchi exhibit a contractile response to antigen, i.e. which are sensitized. The potentiation was not observed in nonsensitized tissue. The mechanism underlying the tryptase-induced potentiation is related to Ca2+ flux through voltage-dependent channels, since it was inhibited by verapamil.

Inhibition of rat mast cell degranulation by verapamil.

Abstract
Calcium antagonists, e.g. verapamil, prevent exercise-induced asthma. This protective effect may proceed from inhibition of contraction of bronchial smooth muscle, release of mediators by primary effector cells, e.g. mast cells, or both. Therefore, we studied the inhibitory effect of increasing concentrations of verapamil on both in vitro antigen-induced degranulation and ionophore A23187-induced release of labelled serotonin by rat peritoneal mast cells. There was a dose-dependent inhibition by verapamil of both ovalbumin-induced degranulation of mast cells passively sensitized by incubation with mice IgE-rich serum and ionophore-induced release of tritiated serotonin by mast cells previously incubated with (3H)-5HT; the 50% inhibiting concentration was 1.4 X 10(-4) mol I-1 and 5.2 X 10(-5) mol I-1, respectively. An attractive explanation of our results is that verapamil inhibits the antigen-induced release of mediators by mast cells through its calcium antagonist effect. Our results also suggest that the preventing effect of calcium antagonists on asthma may be multi-factorial since other authors have clearly shown that these drugs inhibit contraction of guinea-pig tracheal smooth muscle in vitro.

COMPARATIVE STUDY OF AZELASTINE AND VERAPAMIL IN THE MODIFICATION OF OVALBUMIN SENSITIZED LUNGPARENCHYMAL TISSUES OF GUINEA PIGS IN VITRO

The inhibition of mediator released by Azelastine may help to explain their protective action in anaphylaxis. Our observations are in agreement that Azelastine exerts inhibitory effect on synthesis and release of chemical mediators from mast cell (Chand et al., 1983), including the leukotrienes (Hamasaki et al., 1996).

 Azelastine is a second-generation antihistamine approved for treatment ofallergic conditions. This randomized, double-blind, placebo- and active-controlled, parallel group clinical trial evaluated the efficacy and safety of Azelastine in patients with moderate to-severe seasonal allergic conditions (Shah et al., 2009).  Reussi et al. (1980) have demonstrated the inhibition of release of chemical mediators from mast cells by Ca++ channel blocker in animals in vivo and demonstrate the inhibition of antigen-induced brocho-constriction by Verapamil in sheep, allergic to ascaris sum antigen but Verapamil failed to block in the same non-sensitized animal. It is speculated that calcium channel blocker protect against the allergic broncho-constriction predominantly by preventing the release of chemical mediators from the mast cells.

Fig. 2. Graph shows dose dependent inhibitory effect of Azelastine and Verapamil with the treatment of EC50 ovalbumin. Line in the box indicates the ovalbumin EC50 induced contraction (Control). Each point represent mean of six observationsSyed Saud Hasan et al. 49  On the other hand Henderson et al. (1983) found significant inhibition of allergic response with Nifedipine and Lee at al. (1983) also supported the finding, which observed inhibition of mediator release from human lung in vitro by Verapamil.

   Verapamil in concentration 10-10 g/ml did not exhibit any inhibition but as the concentration increases to 10-9 g/ml showed marked inhibition in contractile effect of ovalbumin EC50 (0.3x10-6). Further increases in concentration of Verapamil i.e. 10-8 g/ml completely antagonized the ovalbumin induced contraction. Azelastine in concentration of 10-9 g/ml (1ng/ml) did not exhibit any inhibition as the concentration increase to 10-8 g/ml showed mark inhibition i.e. 20% contraction to EC50 (0.3x10-6) ovalbumin, when compared before treatment with Azelastine and the concentration 10-7 g/ml antagonized the effect of EC50 (Table and Figure 2).







CONCLUSION It can be inferred from the observations that response produced by antigen can be controlled better with Verapamil than Azelastine and emerging with similar activity regardless of exact mechanism involved.




Verapamil and the IL-6 Gene


Conclusions—The results demonstrate that CCB of all 3 subclasses are capable of activating NF-IL6 and NF-kB. CCB may thus directly regulate cellular functions by affecting the activity of transcription factors independent of changes of intracellular calcium concentrations, an observation that is of interest considering the biological effects induced by CCB.

A major result of our investigations is the discovery of the activation of  transcription factors resulting from CCB treatment. In general, CCB are postulated to exert their biological effects by decreasing the intracellular concentration of calcium ions.1–4 Experimentally, this effect is usually achieved at micromolar concentrations of the drugs. However, accumulating evidence suggests that CCB, used at therapeutically effective doses (ie, at the nanomolar range), activate calcium in dependent signal transduction pathway(s) altering gene expression.14–17 Here, we show that CCB directly activate the transcription factors NF-IL6 and NF-kB in human VSMC, independent of intracellular calcium levels. This is supported by the existence of multiple regulatory regions within the intracellular part of the L-type calcium channel. It remains to be investigated, however, along which signal transduction pathway this action of CCB occurs.


Verapamil and the Vagus Nerve

Two of the most popular subjects on this blog are “autism and allergies” and “autism and the vagus nerve”.

The vagus nerve connects many parts of the body and seems to be a conduit for inflammatory signaling within the body.  It is deeply involved the process leading to arthritis and epilepsy; by stimulating this nerve with electrical signals, both epilepsy and arthritis can be reduced markedly in certain people.  It is often suggested that the GI problems in many autistic people and linked to aberrant behaviors via the vagus nerve, what some call the “gut brain connection”.

To understand what is going on and why is does affect autism we need to introduce something new, the autonomic nervous system.  For those who already know about this, the interesting finding is that:-

Verapamil alters the balance between parts of the autonomic nervous system's function  with a shift toward decreased sympathetic tone and increased parasympathetic (vagus nerve) tone.

The source of this statement is:


and their sources were:-




We learned in an earlier post about autism and the Vagus Nerve that it seems to link many strange things in autism.

We learned from Professor Porges that, for example, the neural mechanism for making eye contact is shared with those needed to listen to the human voice; people with autism struggle with both.  Anything that can “wake up” the vagus nerve system could be interesting.
  

In the complicated science we will see that the vagus nerve is also called the parasympathetic nervous system.  The paper below shows how this parasympathetic (Vagus) system is out of balance with the opposing sympathetic nervous system, this then leads to anxiety commonly found in autism.


Assessment of anxiety symptoms in autism spectrum disorders (ASD) is a challenging task due to the symptom overlap between the two conditions as well as the difficulties in communication and awareness of emotions in ASD. This motivates the development of a physiological marker of anxiety in ASD that is independent of language and does not require observation of overt behaviour. In this study, we investigated the feasibility of using indicators of autonomic nervous system (ANS) activity for this purpose. Specially, the objectives of the study were to 1) examine whether or not anxiety causes significant measurable changes in indicators of ANS in an ASD population, and 2) characterize the pattern of these changes in ASD. We measured three physiological indicators of the autonomic nervous system response (heart rate, electrodermal activity, and skin temperature) during a baseline (movie watching) and anxiety condition (Stroop task) in a sample of typically developing children (n = 17) and children with ASD (n = 12). The anxiety condition caused significant changes in heart rate and electrodermal activity in both groups, however, a differential pattern of response was found between the two groups. In particular, the ASD group showed elevated heart rate during both baseline and anxiety conditions. Elevated and blunted phasic electrodermal activity were found in the ASD group during baseline and anxiety conditions, respectively. Finally, the ASD group did not show the typical decrease in skin temperature in response to anxiety. These results suggest that 1) signals of the autonomic nervous system may be used as indicators of anxiety in children with ASD, and 2) ASD may be associated with an atypical autonomic response to anxiety that is most consistent with sympathetic over-arousal and parasympathetic under-arousal.



The following explanation of the Autonomic Nervous System is edited from Wikipedia.


Autonomic Nervous System (ANS)

The autonomic nervous system (ANS) is the part of the peripheral nervous system that acts as a control system that functions largely below the level of consciousness to control functions,] including heart rate, digestion, respiratory rate, salivation, perspiration, pupillary dilation, micturition (urination), sexual arousal, breathing and swallowing. Most autonomous functions are involuntary but they can often work in conjunction with the somatic nervous system which provides voluntary control.

The ANS is divided into three main sub-systems:

PSNS is often considered the "rest and digest" or "feed and breed" system
SNS is often considered the "fight or flight" system
ENS consists of a mesh-like system of neurons that governs the function of the gastrointestinal system

Depending on the circumstances, these sub-systems may operate independently of each other or interact co-operatively.

In many cases, PSNS and SNS have "opposite" actions where one system activates a physiological response and the other inhibits it. The modern characterization is that the sympathetic nervous system is a quick response mobilizing system and the parasympathetic is a more slowly activated dampening system.

In general, ANS functions can be divided into sensory (afferent) and motor (efferent) subsystems. Within both, there are inhibitory and excitatory synapses between neurons. Relatively recently, a third subsystem of neurons that have been named 'non-adrenergic and non-cholinergic' neurons (because they use nitric oxide as a neurotransmitter) have been described and found to be integral in autonomic function, in particular in the gut and the lungs

Neurotransmitters and pharmacology

At the effector organs, sympathetic ganglionic neurons release noradrenaline (norepinephrine), along with other cotransmitters such as ATP, to act on adrenergic receptors, with the exception of the sweat glands and the adrenal medulla:
  • Acetylcholine is the preganglionic neurotransmitter for both divisions of the ANS, as well as the postganglionic neurotransmitter of parasympathetic neurons.
  • Nerves that release acetylcholine are said to be cholinergic. In the parasympathetic system, ganglionic neurons use acetylcholine as a neurotransmitter to stimulate muscarinic receptors.
  • At the adrenal medulla, there is no postsynaptic neuron. Instead the presynaptic neuron releases acetylcholine to act on nicotinic receptors. Stimulation of the adrenal medulla releases adrenaline (epinephrine) into the bloodstream, which acts on adrenoceptors, producing a widespread increase in sympathetic activity.


 Circulatory system

Heart

Target
β1, (β2): increases
M2: decreases

Other

Target
α2: aggregates
---
β2: inhibits

Endocrine system


Target
α2: decreases insulin secretion from beta cells, increases glucagon secretion from alpha cells
M3:[ increases secretion of both insulin and glucagon.[16][17]
N (nicotinic ACh receptor): secretes epinephrine and norepinephrine


Nerve "Wiring Diagram"

The PSNS (parasympathetic nerve system) is wired together via the Vagus Nerve
The SNS (sympathetic nerve system) is wired together via the splanchnic nerves.





Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera.
The viscera are mainly innervated parasympathetically by the vagus nerve and sympathetically by the splanchnic nerves.



Conclusion

For those of you that made it this far, here are my conclusions.

People who have autism and any kind of allergy, be it pollen, food intolerance, asthma or anything similar, might consider asking their doctor to let them trial a very low dose of Verapamil for a couple of days.  The effect is almost instant and so there is no point trialing it for weeks.  Verapamil will lower your blood pressure, in a dose dependent fashion.  The effective autism dose for a severe allergy case is about 1mg/kg.  The half-life varies person to person, so you might need two doses a day, or you might need three.

If you know an adult with severe asthma, look hard and you may see some very mild signs of autism (need for order, anxiety, lack of flexibility etc).

It appears that in all these cases, the gene CACNA1C is misbehaving to varying degrees in different parts of the body.  This gene produces the calcium channel Cav1.2.

You could check if you have the mutated gene, but I do not see the point.  It would only tell you what might happen.  To know what actually has happened, you would need to use proteomics

This emerging science will ultimately be able to provide biomarkers for neurological conditions like autism, depression, bipolar etc, so that the neurologist will know, with certainly, what specific dysfunctions each individual person has.  At that point, behavioral assessments and psychiatry will finally be consigned to history and people will get “smart drugs”, to treat precisely diagnosed neurological dysfunctions.