5-HT2A receptor and Asperger.
TheMachine1
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Cortical serotonin 5-HT2A receptor binding and social communication in adults with Asperger's syndrome: an in vivo SPECT study.
Murphy DG, Daly E, Schmitz N, Toal F, Murphy K, Curran S, Erlandsson K, Eersels J, Kerwin R, Ell P, Travis M.
Institute of Psychiatry, Department of Psychological Medicine, London, UK. [email protected]
OBJECTIVE: The cause of autistic spectrum disorder (i.e., autism and Asperger's syndrome) is unknown. The serotonergic (5-HT) system may be especially implicated. However, cortical 5-HT2A receptor density in adults with the disorder has not been examined, to the authors' knowledge. METHOD: The authors investigated cortical 5-HT2A receptor binding in eight adults with Asperger's syndrome and in 10 healthy comparison subjects with single photon emission computed tomography and the selective 5-HT2A receptor ligand 123I iodinated 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150). RESULTS: People with Asperger's syndrome had a significant reduction in cortical 5-HT2A receptor binding in the total, anterior, and posterior cingulate; bilaterally in the frontal and superior temporal lobes; and in the left parietal lobe. Also, reduced receptor binding was significantly related to abnormal social communication. CONCLUSIONS: The authors' findings suggest that adults with Asperger's syndrome have abnormalities in cortical 5-HT2A receptor density and that this deficit may underlie some clinical symptoms.
PMID: 16648340 [PubMed - indexed for MEDLINE]
This got me thinking how alot of aspie have tried http://en.wikipedia.org/wiki/Risperidone to treat some problems with
aspergers. Risperidone amoung other things is a 5-HT2A antagonist
. Which seems counter intuitive to take a drug that will reduce
serotonin binding in person who may have reduce serotonin binding.
5-HT2A receptor http://en.wikipedia.org/wiki/5-HT2A_receptor agonists include the psychedelic drugs LSD, Mescaline, psilocin, etc.
A list of current med in reseach do not reveal any drugs (that I see)
that boost 5-HT2A binding. http://www.neurotransmitter.net/newdrugs.html Most drugs being developed are 5-HT2A antagonist
for sleep aids ,etc. Since agonists tend to be psychedelic drugs an
SSRI that was selective for 5-HT2A maybe be interesting to test
for persons with Aspergers.
http://ajp.psychiatryonline.org/cgi/con ... l/158/1/78 in this study paroxetine (Paxil) was shown to effect 5-HT2A in a different
way in the young (20-30) and the older (30-40). Little effect in the older and 10% decrease in 5-HT2A binding potential in the young
(indicating increased agonism). That has me a little confused. The
different effect in age and the words decrease binding I hope I'm
not missunderstanding the first study. In which I assume aspergers
is associated with reduce binding means thats 5-HT2A antagonist
should be avoided. If I am confused thats good because a number of selective 5-HT2A antagonist are under development as sleep aids
and in low doses might aid aspergers in a simular way as Risperidone with lowwer side effects. The exsist a SSRI that has
strong 5-HT2A antagonism to YM992 http://jpet.aspetjournals.org/cgi/conte ... /302/3/983
This study showed a 5-HT2A antagonist in combo with an SSRI drug
like fluoxetine http://cat.inist.fr/?aModele=afficheN&cpsidt=17283954 improved the
antidepressant effects.
TheMachine1
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http://www.futurepundit.com/archives/002127.html
http://news-info.wustl.edu/tips/page/normal/864.html
This links talkes about "depressed people have fewer 5-HT2A serotonin receptors"
Yes but they is different types of depression, traumatic / emotional / chemical , trying to attack the 2 first ones with a drug would be just a mood lifter, my doctor has dropped bothering with drugs as I have refused to go on multi ones....
The thought pattern would be more likely the source of the start of depression as you need something to trigger depression, chemical will work on people that has gone out of whack but not with people who are depressed from outside sources, plus drugs don't work on they own, as its just a mood-stabilizer, if you don't take away what is coursing it to trigger it won't help...
I think they need to put more research into this as I find it stupid just to stick drugs at someone, and not try other methods if they don't work after a month or so, along side it...
Really this way of looking at things really needs to change, as everything left right and centre will be thrown out but the truth… Always someone who reopens it and puts more effort into it who figures it out… Would it not be cheaper to put 100% into it than focus on 1 thing...
I must be in the 30%...
TheMachine1
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http://www.erowid.org/chemicals/ssris/ssris_info1.shtml
The chart want format right so you will have to use the above link if you the one guy out there interested in my posts
IC50 for 5-HT reuptake for 5HT2A
Clomiprimine 36
Fluoxetine 100
Sertraline 45000
Paroxetine 62,000
Fluvoxamine 3,200
Citalopram 3,100
I've used fluoxetine, sertraline, paroxetine. The 5HT2A reuptake is
related to the sexual side effects (delayed oragsm usually). The above numbers confirm my own testing. Fluoxetine has low sexual side effects in men comapred to the other ssri's. Interesting I did feel more social on sertaline and paxil which got ,me thinking there maybe something to the 5HT2A receptors and social anxiety.
http://psy.psychiatryonline.org/cgi/con ... 5/3/217/T1
Don't know what venlafaxine xl, is called in america, hate that every country has a different name... nearly..
And I was on 300mgs with nothing but my mouth getting dryer... Click on the doc to make it bigger then expand if you don't have auto large on...
Only pattern I see is the person been under the dilution of this pill will help them, does weight, height, come into it on why the numbers are so different, why some do and some don't... Some get worse... going the wrong way? did they try reversing it on the ones who got worse...
look at number 8, 15 person
Last edited by logitechdog on 18 Jan 2007, 1:28 am, edited 4 times in total.
related to the sexual side effects (delayed oragsm usually). The above numbers confirm my own testing. Fluoxetine has low sexual side effects in men comapred to the other ssri's. Interesting I did feel more social on sertaline and paxil which got ,me thinking there maybe something to the 5HT2A receptors and social anxiety.
Very interesting article. I used one of the 5HT2A agonists on one occation and experienced an increased sense of wellbeing for approx. 3 months.
For me, I didn't experience any decrease in social anxiety from antidepressants due to side effects such as weight gain and sexual side effects, which caused me to become more unhappy with myself and avoidant and thus less social. I believe any increased function from SSRI meds was from the flattening of my moods.
What I am interested in finding out is if I could have an overactive Amygdala and how that relates to my social anxiety/AvPD and possibly the Asperger's.
Last edited by goomba on 18 Jan 2007, 1:05 am, edited 1 time in total.
TheMachine1
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Don't know what venlafaxine xl, is called in america, hate that every country has a different name... nearly..
And I was on 300mgs with nothing but my mouth getting dryer...
Yeah drugs have alot of side effects in some and little benfits for some.
TheMachine1
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Yeah there is a study in which a single dose of psilocin had lasting postive effects in some people. http://en.wikipedia.org/wiki/Psilocybin
This study mentions anxiety and 5-HT2A
Links
Cortical 5-HT2A receptor signaling modulates anxiety-like behaviors in mice.
Weisstaub NV, Zhou M, Lira A, Lambe E, Gonzalez-Maeso J, Hornung JP, Sibille E, Underwood M, Itohara S, Dauer WT, Ansorge MS, Morelli E, Mann JJ, Toth M, Aghajanian G, Sealfon SC, Hen R, Gingrich JA.
Department of Biology, Columbia University and the New York State Psychiatric Institute, New York, NY 10032, USA.
Serotonin [5-hydroxytryptamine (5-HT)] neurotransmission in the central nervous system modulates depression and anxiety-related behaviors in humans and rodents, but the responsible downstream receptors remain poorly understood. We demonstrate that global disruption of 5-HT2A receptor (5HT2AR) signaling in mice reduces inhibition in conflict anxiety paradigms without affecting fear-conditioned and depression-related behaviors. Selective restoration of 5HT2AR signaling to the cortex normalized conflict anxiety behaviors. These findings indicate a specific role for cortical 5HT2AR function in the modulation of conflict anxiety, consistent with models of cortical, "top-down" influences on risk assessment.
PMID: 16873667 [PubMed - indexed for MEDLINE]
This study show how the tolerence one gets from repeated use
of a serotonin agonist maybe related to changes in the 5-HT2A receptors.
Links
Mechanism of tolerance development to 2,5-dimethoxy-4-iodoamphetamine in rats: down-regulation of the 5-HT2A, but not 5-HT2C, receptor.
Smith RL, Barrett RJ, Sanders-Bush E.
John F. Kennedy Center, Nashville, TN 37203, USA.
RATIONALE: Defining the mechanism of tolerance development to hallucinogenic drugs will help to explain their mechanism of action. OBJECTIVES: The present study was conducted to determine first, if tolerance develops to the discriminative stimulus (DS) properties of the hallucinogen, 2,5 dimethoxy-4-iodo-amphetamine (DOI) and second, the mechanism mediating tolerance. METHODS: Rats were trained to discriminate 0.75 mg/kg DOI from saline on a concurrent VI-30-min schedule of reinforcement with a 15-min time-out for incorrect responses. To evaluate tolerance development, rats were assigned to one of four groups and treated with either chronic saline or chronic DOI. Prior to chronic treatment, two groups were tested for choice behavior following vehicle administration while the remaining two groups were tested following the administration of 0.375 mg/kg DOI. One group from each pre-test condition was injected with either saline or DOI (1 mg/kg) for 8 days. Twenty-four hours after the last chronic injection the pre-test treatments were replicated. Using receptor autoradiography, the density of 5-HT2A and 5-HT2C receptors was measured in independent groups of rats that had received identical treatment conditions. RESULTS: Animals receiving chronic DOI showed a 60% decrease in DOI lever responding (from 100% to 40%) when tested on 0.375 mg/kg DOI, while animals receiving chronic saline showed no change in percent choice (100%) on the DOI lever. Significant changes in binding were observed in 5-HT2A receptors but not 5-HT2C receptors. The results of tests with antagonists were consistent with the changes in binding. CONCLUSIONS: These results suggest that behavioral tolerance to DOI reflects neuroadaptive changes in 5-HT2A receptors.
PMID: 10435391 [PubMed - indexed for MEDLINE]
Which suggest the physical reason why one dose of a drug like
Psilocybin might have effects for weeks after its uses.
I had very positive effects from occasional(4X a year)use of LSD.Very spiritual and at peace with myself and the world....very NOT like my normal state of thinking/feeling.Cant say how long it lasted but at least a few weeks.I also really liked Robotussien....Only took 4ozs to make me feel at peace.Had to give up both out of fear of long term effects.
I recently tried Wellbutrin to help quit smoking and it seemed to be very helpful until I broke out in a rash and had to stop taking it....my hands itched so badly I had to take time off from work....it was horrid.
I still think there is a link between my depression and my IBS.....if 85% of serotonin is created in the "gut" it has to have some effect that my gut is "hyper-active" or "stalled".
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This is very interesting information. I like studying the chemistry of the brain and all the receptors that mediate the effects of all these chemicals. It would be interesting to understand the implications of the reduced binding in social communication-impaired autistics, but it seems we don't understand nearly enough about the precise functions of the individual receptors.
That chart of drug potencies at the various brain targets is interesting. I had seen some of that information before (such as the relative 5HTRI vs. NARI vs. DARI potencies of the various drugs), since I recently wrote a paper where I modeled the three-dimensional structures of the proteins involved in reuptake and tried to rationalize the activities based on chemical structures.
Unfortunately, the data you presented came from binding (as opposed to functional) experiments, so the effect of the drugs (agonist or antagonist) at the 5-HT2A receptor cannot be inferred from it. I would assume that clomipramine is an antagonist, by considering its chemical structure and the fact that I know it is an antagonist at most of the other receptors listed.
Overall, for clomipramine it's really difficult saying what of its effect is due to 5-HT2A binding, considering the similar potencies at many targets. In addition to serotonin and norepinephrine uptake inhibition, there's a H1 blocking effect that causes drowsiness, an alpha blocking effect that causes blood pressure changes, and particularly importantly an antimuscarinic (ACh) effect that causes dry mouth and constipation.
Back in elementary school, there was a period in which psychiatrists put me on lots of antidepressants because they had no idea what was wrong, and the tricyclics (which include clomipramine) were still the first thing people tried at that time. I was on one of those drugs for all of about a month, over which I lost a lot of weight, before the constipation got so bad that there was no option other than to discontinue it. Among psychoactive drugs, my negative impression of the tricyclic antidepressants is matched only by that for the phenothiazine antipsychotics, which I luckily have never had to take and hopefully never will. Both classes tend to block neurotransmitter receptors very non-selectively, almost guaranteeing that they will cause more problems through their unwanted effects than their intended effects solve.
Later I was put on SSRIs, and fluoxetine made me giggly all the time (in fact my mom credits it with having started my ongoing bipolar-ness due to this hypomanic effect, even though I discontinued it long ago). The others just seemed to make me not sleep well. I haven't been on any antidepressants for years.
TheMachine1
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Yeah your right. I think you need to do a second experiment in
which you use a labeled agonist or labeled antagonist to confirm
how the SSRI is functionally effecting the receptor.
That reminds me Trazodone has a major metabolite of m-chlorophenylpiperazine (mCPP) and has 5-HT2A antagonistic
effects (amoung others). And I can confirm Trazodone will put you
to sleep. So 5-HT2A antagonist will be effective sleeping pills.
Not sure if thats the effect I think i want from a medication.
Yeah your right. I think you need to do a second experiment in
which you use a labeled agonist or labeled antagonist to confirm
how the SSRI is functionally effecting the receptor.
Actually, you need to measure the intracellular signal from the activated receptor, since both labeled agonist and (competitive) antagonist will be displaced by either type of compound. This signal appears to be mainly the so-called phosphoinositide pathway for 5-HT2A, though it seems there are multiple signals that can be sent by different agonists, according to a really interesting guy I know about who has done lots of research on the mechanism of hallucinogens.
effects (amoung others). And I can confirm Trazodone will put you
to sleep. So 5-HT2A antagonist will be effective sleeping pills.
Not sure if thats the effect I think i want from a medication.
Yes, I was on trazodone for a while, along with buspirone I believe, in order to counteract the sleep-inhibiting effects of one of the SSRIs (I don't remember which one).
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