2016 To-do List

I expect many readers of this blog have a list of things to trial in 2016; I certainly do.

Monty’s older brother, codenamed Ted, did say to me recently, “I thought you said you’d be all finished with this, in a couple of years”; that was indeed the intention.  

A medicine cabinet to be proud of, but not mine

It has now been three years.  I never really intended to go so deeply into the science, and I never expected there to be so many “obvious” things un/under-investigated by researchers.

Most people diagnosed these days with “autism” are fortunate to be relatively mildly affected.  Parents of those kids likely find this blog rather shocking; how can so many pills be needed and still you want more?

Some other people also diagnosed with autism, face really big challenges, not limited to:-

  

     ·        Unable to talk
·        Unable to walk
·        Unable to eat (must use G tube)
·        Unable to be toilet trained
·        Unable to read
·        Unable to write
·        Have seizures 

So when asked by a teacher at school, if Monty, now aged 12, has severe autism I responded in the negative.  He does not tick any of the above boxes.

If you have more than “mild autism” it seems that there are likely many dysfunctions and the more you treat, the better the result.  A quest without an end.

School

Ted hates his relatives discussing his school grades and I agree with him that they are entirely his business.  We all know that typical kids vary in how smart they are and how motivated they are.  NT kids tend to get the grades they deserve.

I do break these rules with Monty, but that is because I really want to show that when a person has numerous neurological dysfunctions, as those found in classic autism, if you treat them with science (not with bleach and other nonsense), you can end up in a different, better place. 99.99999% of the world do not know this; perhaps 500 people do know.

Improving IQ will improve the person’s ability to understand and compensate for the dysfunctions that have not been treated.  

Grading academic performance at school is something we all understand and along with its limitations.  We have all been there, so let's use it.

Kids with classic autism do not get the grades they potentially deserve.  Most can be made smarter and it is easy to measure.

Before coming to my to-do list, I did receive another question about what exactly is the effect of bumetanide. 

When I collected Monty from school the other day, his assistant was proudly holding up the latest “quick fire” math test, where speed is seemingly even more important than the right answer.

So Monty, the only one with autism, came first and by a long way. 3 minutes and 35 seconds, with the runner up taking 3:56.  He got 90% correct, but that is enough to keep first place.   The previous test before Christmas he got 100%, but finished 7^th out of 16 on speed.  It must be the turkey.

The questions are very simple, since you have to be very fast; but until the age of 9, and the introduction of Bumetanide, the class teacher would never have dreamt of having Monty compete at all.  Coming a distant last in everything would be disheartening, for the teacher. Monty would not have even noticed, let alone cared.

People with Classic Autism, or what Knut termed SDA (strict definition autism), are usually hopeless academically; but with Bumetanide, it does not have to be that way. 

Many people with classic autism leave school 18 years old, still at the level of single digit addition and subtraction, or perhaps up to 20.

If you reach the academic level of Grade 2 (Year 3 in the UK system), that of a typical 7 or 8 year old, by the time you “graduate” high school, you are doing above average.

So Ted is not alone in being able to get good grades.  The PolyPill is indeed worth all the bother.

To-do list

I did have to go through by supply cupboard to see what I had not got round to testing and that I still think has some potential merit.  Some things did get thrown out.

Some old ideas are worth revisiting.

·        Biotin (high dose)

This did seem to have a marginal positive effect and is both cheap and harmless. 

·        Pregnenolone (very low dose)

This also appeared to have some positive effect and should affect GABA subunit expression. High doses have been used in a Stanford clinical trial. We saw in earlier posts that allopregnanolone possesses biphasic, U-shaped actions at the GABA_A receptor, meaning that a tiny dose can have the same effect as a large dose.

 I like low doses.  

Old ideas worth developing:-

·        Miyairi 588 bacteria, but at higher doses

This is the bacteria used as a probiotic in Japan for humans, since the 1940s.  It is also added to animal feed to avoid inflammatory disease and so produce healthier animals.

The science showed that it should be helpful to raise Butyrate levels.  It can be achieved directly via supplementation, with sodium butyrate, and indirectly by adding a butyrate-producing bacteria, such as Clostridium Butyricum or Miyari 588.

I have been using a tiny dose of Miyari 588 for months.  It achieves what it is sold for in Japan, in that it reduces gas, which is the only obvious negative side effect of Monty’s Polypill, other than diuresis.

The positive side effect of the Polypill is near perfect asthma control.  Asthma is an auto-immune/inflammatory disease, highly comorbid with autism. 

The effect of Miyari 588 is reversible because this bacteria cannot survive long in the intestines, which is why you have to take it every day.  It crowds out some of the other bacteria in the intestines, but they will soon grow back.

New ideas already in this blog:-

·        Diamox

I did suggest on several occasions that it might be possible to get a “Bumetanide plus” effect by adding Diamox.

Diamox (Acetazolamide) is another diuretic and it is a carbonic anhydrase inhibitor

Acetazolamide is a carbonic anhydrase inhibitor, hence causing the accumulation of carbonic acid Carbonic anhydrase is an enzyme found in red blood cells that catalyses the following reaction:

hence lowering blood pH, by means of the following reaction that carbonic acid undergoes:

The mechanism of diuresis involves the proximal tubule of the kidney. The enzyme carbonic anhydrase is found here, allowing the reabsorption of bicarbonate, sodium, and chloride. By inhibiting this enzyme, these ions are excreted, along with excess water, lowering blood pressure, intracranial pressure, and intraocular pressure. By excreting bicarbonate, the blood becomes acidic, causing compensatory hyperventilation, increasing levels of oxygen and decreasing levels of carbon dioxide in the blood

This change in bicarbonate will also affect the AE3 and NDAE exchangers.

As you will see in the figure below the regulation of bicarbonate HCO3- and pH is directly connected to chloride Cl- homeostasis.  This means that via AE3 and NDAE you can affect intracellular chloride levels by change the level of HCO3-

In turns this means that Diamox (Acetazolamide) really should have an effect on the level of intracellular chloride.

This in turn suggested to me that Diamox could augment the effect that bumetanide has on NKCC1.

 In the case that Bumetanide can lower intracellular chloride, but not to the optimal level to correct the GABA dysfunction, Diamox might be able to lower chloride levels a little further so further shifting GABA to inhibitory.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1317631/

Neuronal activity results in significant pH shifts in neurons, glia, and interstitial space. Several transport mechanisms are involved in the fine-tuning and regulation of extra- and intracellular pH. The sodium-independent electroneutral anion exchangers (AEs) exchange intracellular bicarbonate for extracellular chloride and thereby lower the intracellular pH. Recently, a significant association was found with the variant Ala867Asp of the anion exchanger AE3, which is predominantly expressed in brain and heart, in a large cohort of patients with idiopathic generalized epilepsy. To analyze a possible involvement of AE3 dysfunction in the pathogenesis of seizures, we generated an AE3-knockout mouse model by targeted disruption of Slc4a3. AE3-knockout mice were apparently healthy, and neither displayed gross histological and behavioral abnormalities nor spontaneous seizures or spike wave complexes in electrocorticograms. 

After only a couple of days of Diamox, it is pretty clear that there is indeed a “bumetanide plus” effect.  So the same changes that were noted when starting bumetanide appear again.

A promising start to 2016.

·        Ponstan

This is the NSAID that is also suggested to be useful to affect the ion channels expressed by the genes ANO 2/4/7 & KCNMA1.  We saw in this post

http://epiphanyasd.blogspot.com/2015/12/autism-treatments-proposed-by-clinical.html

where Knut highlighted that Fenamates act as CaCC inhibitors and also stimulate BKCa channel activity.  Ponstan is a Fenamate.

·        Vitamin A

This was Maja’s discovery, that in some people vitamin A will stimulate oxytocin, via upregulation of CD38.

·        Zinc

Zinc should affect GABA, particularly in immature neurons.  Zinc homeostasis is disturbed in some autism and perhaps, in some people, a small dose of zinc may actually have a positive effect.  Simple to check.

Clioquinol, the drug that shifts zinc to the “right” place, is not without risks.

·        Picamilon

Once the GABA switch has been repaired, it may be time for a little extra GABA.  GABA should not be able to cross the blood brain barrier (BBB), but in the form of Picamilion, it does cross the BBB.

·        Inositol

This it naturally produced in the body from glucose and used to be known as vitamin B8.  In some people Inositol reduces OCD and stereotypy.  Simple to check.

·        Montelukast

This is an asthma drug, considered very safe in children, that Dr Kelley (formerly of Johns Hopkins and likely the cleverest autism clinician)  uses in children with AMD, as a short term therapy, when they are sick and, very interestingly, before immunizations.  This is to avoid further mitochondrial damage.  Montelukast is a leukotriene receptor antagonist (LTRA) used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergies.

Dr Kelley also uses Ibuprofen as a short term therapy to counter the effects of increased cytokine production.  Montelukast is more potent and has different side effects, meaning it might be a better choice than ibuprofen for some people.

Ibuprofen may be OTC, but, more than very occasional use, can cause side effects in many people.  These side effects are caused by NSAIDs also being COX-2 inhibitors, which leads to stomach and intestinal adverse reactions.

Since I have determined that in the case of autism I deal with, the surge in cytokines like IL6 causes behavioral regression, Montelukast might be a good alternative to Ibuprofen to treat some types of autism flare.  

So a new addition to the autism flare-up toolkit, I hope.

  

Ideas not yet in this blog:-

·        Curcumin

Curcumin, and particularly some of the substances within it, have been shown to have very interesting autism-relevant effects, particularly in vitro (in test tubes).  Whether taking curcumin orally, in reasonable doses, produces any of these effects in humans is a big question.  Many such substances like luteolin and resveratrol fail to meet expectations in humans, due to poor bioavailability.

There are various ways to improve the bioavailability of curcumin, so it seems worth investigating.

·        5-loxin

Frankincense has been used for 5,000 years.  More recently, two thousand years ago, three wise men did bring gifts of gold, frankincense, and myrrh.

Frankincense is an aromatic resin obtained from trees of the genus Boswellia.  Boswellia is used for inflammatory conditions like arthritis in a similar way to curcumin.

There are six boswellic acids, one is most active. This fraction is called AKBA. 5-Loxin is a boswellia supplement claiming to deliver a high standardized level of AKBA.

5-Loxin does seem to help some people with arthritis, but does it have any benefit for the pro-inflammatory aspects found in some autism?  I am not expecting much, but you never know.

  

Ideas suggested to me by others, that look interesting:-

·        Mint/Menthol

This is Natasa’s discovery and there is evidence to show that Menthol does indeed affect GABA_A receptors.

Menthol enhances phasic and tonic GABAA receptor-mediated currents in midbrain periaqueductal grey neurons

These results suggest that menthol positively modulates both synaptic and extrasynaptic populations of GABA_A receptors in native PAG neurons. The development of agents that potentiate GABA_A-mediated tonic currents and phasic IPSCs in a manner similar to menthol could provide a basis for novel GABA_A-related pharmacotherapies.

  

·        NIAGEN / Nicotinamide Riboside

This was highlighted by Tyler and is another potential therapy for oxidative stress.  Not as cheap as peppermint, but definitely interesting, perhaps particularly for those with autism and mitochondrial dysfunction.

Also note that there are odd recurring links between some autism and obesity. This is not the first anti-obesity therapy that potentially has some benefit for autism.

The NAD+ Precursor Nicotinamide Riboside Enhances Oxidative Metabolism and Protects against High-Fat Diet-Induced Obesity

Summary

As NAD⁺ is a rate-limiting cosubstrate for the sirtuin enzymes, its modulation is emerging as a valuable tool to regulate sirtuin function and, consequently, oxidative metabolism. In line with this premise, decreased activity of PARP-1 or CD38—both NAD⁺ consumers—increases NAD⁺ bioavailability, resulting in SIRT1 activation and protection against metabolic disease. Here we evaluated whether similar effects could be achieved by increasing the supply of nicotinamide riboside (NR), a recently described natural NAD⁺ precursor with the ability to increase NAD⁺ levels, Sir2-dependent gene silencing, and replicative life span in yeast. We show that NR supplementation in mammalian cells and mouse tissues increases NAD⁺ levels and activates SIRT1 and SIRT3, culminating in enhanced oxidative metabolism and protection against high-fat diet-induced metabolic abnormalities. Consequently, our results indicate that the natural vitamin NR could be used as a nutritional supplement to ameliorate metabolic and age-related disorders characterized by defective mitochondrial function.

  

Nicotinamide Riboside Ameliorates Hepatic Metaflammation by Modulating NLRP3 Inflammasome in a RodentModel of Type 2 Diabetes

Low-grade chronic inflammation (metaflammation) is a major contributing factor for the onset and development of metabolic diseases, such as type 2 diabetes, obesity, and cardiovascular disease. Nicotinamide riboside (NR), which is present in milk and beer, is a functional vitamin B₃ having advantageous effects on metabolic regulation. However, the anti-inflammatory capacity of NR is unknown. This study evaluated whether NR modulates hepatic nucleotide binding and oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome. Male, 8-week-old KK/HlJ mice were allocated to the control or NR group. NR (100 mg/kg/day) or vehicle (phosphate-buffered saline) was administrated by an osmotic pump for 7 days. Glucose control, lipid profiles, NLRP3 inflammasome, and inflammation markers were analyzed, and structural and histological analyses were conducted. NR treatment did not affect body weight gain, food intake, and liver function. Glucose control based on the oral glucose tolerance test and levels of serum insulin and adiponectin was improved by NR treatment. Among tested lipid profiles, NR lowered the total cholesterol concentration in the liver. Histological and structural analysis by hematoxylin and eosin staining and transmission electron microscopy, respectively, showed that NR rescued the disrupted cellular integrity of the mitochondria and nucleus in the livers of obese and diabetic KK mice. In addition, NR treatment significantly improved hepatic proinflammatory markers, including tumor necrosis factor-alpha, interleukin (IL)-6, and IL-1. These ameliorations were accompanied by significant shifts of NLRP3 inflammasome components (NLRP3, ASC, and caspase1). These results demonstrate that NR attenuates hepatic metaflammation by modulating the NLRP3 inflammasome

  

NLRP3 inflammasome and itsinhibitors: a review

  

Activation and regulation of the inflammasomes

  

An apparently crazy idea of my own, but actually serious:-

·        Propolis tincture, without the propolis

The BIO 30 Propolis from New Zealand is a (mild) PAK1 inhibitor.  One reader is convinced of its cognitive enhancing effects in autism .  I also think it had an effect, but in our case not as potent as that reader.  Now I am wondering what was it that produced this effect. 

Most propolis is made as a tincture with ethanol.  Propolis is not soluble in water.  They typically use 70% ethanol to make propolis tincture.  “Non-alcoholic” tinctures use glycol.

In the last post we saw ethanol has pronounced effects on several GABA_A receptor subunits, mainly delta but also alpha, including possibly down regulating alpha 5.

So was it the propolis, or the ethanol that has the effect?

Propolis tincture is either made with ethanol (grain alcohol) or if it is “alcohol free” they use propylene glycol.  Propylene glycol actually is a food ingredient but it is also used to de-ice aircraft in winter.  Ethylene glycol is the antifreeze in your car and you would not want to drink that.

Compared to ethanol, glycol can dissolve less propolis, 

A quick check of school chemistry reminds us that if it is an –ol , it’s an alcohol.

·        Alcohols have at least one hydroxyl group

·        Diols have two hydroxyl groups

Propylene glycol is  C₃H₈O₂  and as you can see below it has two hydroxyl groups (the – OH), so it is both a diol and an alcohol. 

So your Propolis tincture can be ethanol-free, but it cannot be alcohol-free.  Someone might point that out to the supplement makers.

It also should be noted that propylene glycol has known effects on GABA very similar to ethanol.

Propylene glycol elicits anxiolytic responses to the elevated plus-maze in male mice

  

This suggests that the users of ethanol-free BIO30 may also be seeing responses unrelated to propolis.

Propylene glycol even has an E-number, it is E1520.  It is cheap and they even sell it on Amazon.

Food grade ethanol is normally not sold to the public.

In lay terms, ethanol and alcohol are interchangeable, so one corner of the supermarket contains food grade ethanol, with some impurities.

Japanese research suggests that these impurities are much more potent than ethanol in modulating GABA receptors.  It is the fragrant compounds that accumulate over the years on wooden barrels that cause this effect.

The twenty drops of propolis suggested to me by the Japanese PAK1 researcher/doctor contained about 1ml of ethanol.  It seems that to get an effect on GABA similar to this amount of ethanol would require a much smaller amount to well-aged Japanese whiskey.

So if someone over 18 responds well to twenty drops of BIO 30 propolis, it would helpful if they could compare the effect with 1ml of Propylene glycol (E1520), 1ml of ethanol, if they find it, and with a few drops of well-aged whiskey.

Altered Homeostasis in Autism: Cl-, K+, Ca2+, and quite possibly Zn2+

Today’s post will highlight how, perhaps, in 50 years’ time, autism might be understood by the non-scientist.  Sometimes it helps to oversimplify a complex problem in order not to get lost in all the complexities and see what underlying mechanisms may exist.

Homeostasis

Homeostasis is a fancy word for balance or equilibrium.  It is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.

All living organisms depend on maintaining a complex set of interacting metabolic chemical reactions. From the simplest unicellular organisms to the most complex plants and animals, internal processes operate to keep the conditions within tight limits to allow these reactions to proceed. Homeostatic processes act at the level of the cell, the tissue, and the organ, as well as for the organism as a whole.

Many diseases involve a disturbance of homeostasis.

Autism is clearly a condition of altered homeostasis, but not severe enough as to become degenerative.

First Chloride Cl^-, Calcium Ca²⁺ , then Potassium K⁺ and now perhaps Zinc Zn²⁺

We have already seen that three very simple ions, chloride Cl^- , calcium Ca²⁺, potassium K⁺ are in the “wrong place” or in the “wrong concentration” in autism.  This in effect tells us that there is altered homeostasis.

Would it then come as a surprise that a fourth ion, zinc Zn²⁺ also appears to be in the “wrong place”, in at least some autism?

Perhaps there is a common mechanism behind this dysfunctional homeostasis? It might be related to cell adhesion molecules like neuroligins (see below), which will be looked at in another post.

Source: By Sarahlobescheese (Created on Paintbrush and Microsoft Word) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Supplementation and Homeostasis

When the lay person hears that something simple is involved in the pathology of autism, the immediate reaction seems to be that you either need more, or less, of it.  So more calcium, more zinc, more magnesium etc.

The problem is more complex; there is enough calcium (and your bones are full of it) but it is not all quite in the right place, so it needs moving around a bit.

When I came across the recent research from Taiwan about the effect of zinc on the NMDA receptors in the brain, I did a quick check and found lots of people supplementing zinc. Some people because the level in their child’s hair was high and some because it was low; the therapy remained the same, more zinc.

Just as Ben-Ari really has figured out many aspects of the excitatory/inhibitory imbalance in GABA in autism and chosen a therapy that indirectly corrects it, the Taiwanese have also gone into their receptor, the NMDA, in detail.  They put forward a well thought out case for modulating it.

Just as Ben Ari choose to move chloride to outside the cells with his drug (Bumetanide), Yi-Ping Hsueh, the Taiwanese researcher, uses an existing  drug called Clioquinol to move zinc from a presynaptic terminal to postsynaptic sites in the brain.  Again, like Ben Ari, she also showed it to be effective in two different mouse models of autism.

Trans-synaptic zinc mobilization improves social interaction in two mouse models of autism through NMDAR activation

“Here we report that trans-synaptic Zn mobilization rapidly rescues social interaction in two independent mouse models of ASD. In mice lacking Shank2, an excitatory postsynaptic scaffolding protein, postsynaptic Zn elevation induced by clioquinol (a Zn chelator and ionophore) improves social interaction. Postsynaptic Zn is mainly derived from presynaptic pools and activates NMDA receptors (NMDARs) through postsynaptic activation of the tyrosine kinase Src. Clioquinol also improves social interaction in mice haploinsufficient for the transcription factor Tbr1, which accompanies NMDAR activation in the amygdala. These results suggest that trans-synaptic Zn mobilization induced by clioquinol rescues social deficits in mouse models of ASD through postsynaptic Src and NMDAR activation”

Clioquinolmay help people with autism: study

Scientists compared the interactions of test mice by placing the subjects in a box, mice that had been unchanged, mice with their Tbr1 and Shank2 proteins “knocked off” and another “stranger” mouse.

They found that unchanged mice engaged in high-level interaction with the “stranger” mouse, while mice with Tbr1 and Shank2 deficiencies interacted very little.

Hsueh’s team had previously determined that Tbr1 is a contributing factor of autism, while a team led by South Korean scientist and project coleader Eunjoon Kim discovered that Shank2 is also implicated in the condition.

Both deficiencies hamper the transmission of zinc ions to the NMDAR (N-methyl-D-aspartate) receptor, impairing function.

About 30 percent of children with autism suffer from zinc deficiency.

Hsueh said that previous projects had determined that autism is linked to zinc deficiency, but the research undertaken by Academia Sinica and the South Korean researchers is the first to provide a scientific explanation for the phenomenon by establishing that the social inhibitions caused by autism can be changed by revitalizing the NMDAR receptor.

Hsueh said the results from the experiment conducted on mice can be extrapolated to humans, with a higher than 90 percent relevance between the two species.

She said that as clioquinol is a prescription drug permitted in Taiwan, her team hopes psychiatrists will prescribe the drug to suitable patients.

Zinc Deficiency or Zinc Transmission Deficiency?

A quick review of the research does show very odd levels of zinc in people with autism.  It also transpires that different ways of measuring zinc levels (hair, blood etc) can produce the opposite result.  So it is hard to ascertain that somebody really does have a zinc deficiency.

The key point is the transmission of that Zinc to the NMDA receptors in the brain.  Note the Zn²⁺ modulatory site in the diagram below.

Clioquinol

Clioquinol, has a very tainted past in Japan. The drug was widely used for various conditions in the 1960s, at doses higher than in other countries.  Its use was tied to the emergence of a new condition called Subacute myelo-optico-neuropathy (SMON) , which only seems to have occurred in Japan.

Clioquinol is banned in some countries, but widely available in other countries, like Taiwan,

Clioquinol is showing promise in research into Alzheimer’s.

Some argue that Clioquinol is totally safe and argue for a combined therapy of Clioquinol and zinc.

Treatment with a Copper-Zinc Chelator Markedly and Rapidly Inhibits β-Amyloid Accumulation in Alzheimer's Disease Transgenic Mice

Clioquinol Synergistically Augments Rescue by Zinc Supplementation in a Mouse Model of Acrodermatitis Enteropathica

Conclusions

These studies suggest that oral CQ (or other 8-hydroxyquinolines) coupled with zinc supplementation could provide a facile approach toward treating zinc deficiency in humans by stimulating stem cell proliferation and differentiation of intestinal epithelial cells.

  

SMON: toxicity of clioquinol and the status quo

Subacute myelo-optico-neuropathy (SMON) is a disease characterized by subacute onset of sensory and motor disorders in the lower half of the body and visual impairment preceded by abdominal symptoms. A large number of SMON were observed throughout Japan, and the total number of cases reached nearly 10,000 by 1970. Despite clinical features mimicking infection or multiple sclerosis, SMON was confirmed as being caused by ingestion of clioquinol, an intestinal antibacterial drug, based on extensive epidemiological studies. After the governmental ban on the use of clioquinol in September 1970, there was a dramatic disappearance of new case of SMON. In the 1970s, patients with SMON initiated legal actions against the Government and pharmaceutical companies, and the court ruled that the settlements would be made as health management allowances and lasting medical check-ups. The physical condition of patients with SMON remains severe owing to SMON as well as gerontological complications. The pathological findings in patients with SMON included symmetrical demyelination in the lateral and posterior funiculi of the spinal cord and severe demyelination of the optic nerve in patients with blindness. Although clioquinol may show activity against Alzheimer's disease or malignancy, its toxic effects cause severe irreversible neurological sequelae. Thus, caution must be exercised in the clinical use of clioquinol

Zinc Effects on NMDA Receptor Gating Kinetics

Zinc is an essential micronutrient that accumulates in brain and is required for normal development and function. Both deficiency and excess of zinc alter behavior and can cause brain abnormalities and neuropathies, of which epilepsy, ischemia, and Alzheimer’s degeneration have been the most studied. Aside from catalytic and structural functions in many proteins, ionic zinc (Zn2+) may play important roles in neurotransmission. Free Zn2+ accumulates in the synaptic vesicles of a specific subset of glutamatergic neurons and is coreleased with glutamate in an activity-dependent manner. Upon release, free Zn2+ may modulate neurotransmitter receptors and transporters, activate zinc-sensing metabotropic receptors, and/or gain cellular access through Ca2+-permeable channels. At certain glutamatergic synapses, a primary role for vesicular zinc is to reduce N-methyl-D-aspartate (NMDA) receptor currents . A wide range of extracellular Zn2+ concentrations directly and specifically inhibit NMDA receptor responses, and in the hippocampus, a region highly enriched in vesicular zinc, zinc-positive glutamatergic synapses are also enriched in NMDA receptors. The inhibitory effects of Zn2+ on NMDA receptors have received considerable attention due in part to the pivotal role played by these receptors in synaptic transmission and plasticity. Still, the mechanism by which the inhibition occurs is incompletely understood.

Other ways of modifying NDMA receptors

As the excellent recent paper below from Korea points out, “correcting NMDAR dysfunction has therapeutic potential for ASDs”.  The problem is that in some autism there is too much NMDAR function, and in others there is too little.

So we should not expect much success from any “one size fits all” therapy.

NMDA receptor dysfunction in autism spectrum disorders.

Abnormalities and imbalances in neuronal excitatory and inhibitory synapses have been implicated in diverse neuropsychiatric disorders including autism spectrum disorders (ASDs). Increasing evidence indicates that dysfunction of NMDA receptors (NMDARs) at excitatory synapses is associated with ASDs. In support of this, human ASD-associated genetic variations are found in genes encoding NMDAR subunits. Pharmacological enhancement or suppression of NMDAR function ameliorates ASD symptoms in humans. Animal models of ASD display bidirectional NMDAR dysfunction, and correcting this deficit rescues ASD-like behaviors. These findings suggest that deviation of NMDAR function in either direction contributes to the development of ASDs, and that correcting NMDAR dysfunction has therapeutic potential for ASDs.

Pharmacological modulation of NMDAR function can improve ASD symptoms. D-cycloserine (DCS), an NMDAR agonist, significantly ameliorates social withdrawal  and repetitive behavior  in individuals with ASD.

These results suggest that reduced NMDAR function may contribute to the development of ASDs in humans. Elevated NMDAR function is also implicated in ASDs. Memantine, an NMDAR antagonist, and its analogue amantadine improve ASD-related symptoms including social deficits, inappropriate language, stereotypy, cognitive impairments, lethargy, irritability, inattention, and these results, together with the DCS results, highlight the importance of a normal range of NMDAR function, and suggest that deviation of NMDAR function in either direction leads to ASD.  This concept is in line with the emerging view that synaptic function within a normal range is important and its deviation causes ASDs and intellectual disability

Mice lacking neuroligin-1, an excitatory postsynaptic adhesion molecule, show reduced NMDAR function in the hippocampus and striatum, as evidenced by a decrease in NMDA/AMPA ratio and long-term potentiation (LTP) Neuroligin-1 is thought to enhance synaptic NMDAR function, by

directly interacting with and promoting synaptic localization of NMDARs.

CDPPB, a positive allosteric modulator of mGluR5 that potentiates similarly normalizes NMDAR Dysfunction and behavioral deficits, consistent with the idea that indirectly modulating NMDARs through mGluR5 is a viable approach for treating ASDs.

ASDs involve diverse core and comorbid symptoms. Consistent with this, a single autism-related mutation, neuroligin-3 R451C, causes diverse synaptic phenotypes in different brain regions and circuits. Therefore, synaptic changes should be analyzed in greater detail, ideally using brain region-specific and cell type-specific conditional gene ablation, as recently reported.

Modulators of mGluR5, in addition to NMDARs and AMPARs, have been considered to be a new means of regulating glutamatergic transmission. Therefore, pharmacological rescue of animal models of ASD should ideally involve modulation of both NMDARs and mGluR5, or even other NMDA-modulatory approaches, to better facilitate translation to clinical therapy.

Lastly, because our hypothesis associates bidirectional NMDAR dysfunction with ASDs, there may be clinical cases, such as where individuals with reduced NMDAR function are treated with NMDAR antagonists, which might aggravate the situation and affect the interpretation.

None of the existing autism therapies that modify NDMA receptors have been uniform knockout successes, but are effective in some cases.

These include:-

·        Memantine an NMDAR antagonist

·        D-Cycloserine an NMDAR agonist (the opposite of Memantine)

·        Ketamine, an NMDAR antagonist

Intranasal Ketamine Treatment in an Adult With Autism Spectrum Disorder

So if you respond to Memantine, the chances are you would benefit from intranasal ketamine;  but D-Cycloserine would make you worse.

They recently terminated early the large Memantine autism trial.  In a rational world they would try D-Cycloserine on all those kids who failed to respond to Memantine.  We do not live in a rational world.

Conclusion

I have a feeling that several dysfunctions in autism, including the E/I imbalance of GABA, will ultimately be traced back to neuroligins.

This is an area of science in its infancy and so for today we have to treat the consequences individually. 

Fortunately, the Simons Foundation is funding the right people and so, in the end, we will get to the bottom of it all.

Function and dysfunction of neuroligins

I hope the Taiwanese test Clioquinol on some humans with ASD and let us know the results.  

As the clever Korean researcher above has highlighted, Clioquinol will only benefit those with reduced NMDAR function.  So if I have got things the right way round, Clioquinol will help the same group that respond to D-Cycloserine.  The others would need Memantine/Ketamine, or even better, they have perfect NMDAR function and need nothing at all.