Posted by SLS on June 18, 2015, at 10:27:28
In reply to Indivduals w social phobia have too much serotonin, posted by PeterMartin on June 18, 2015, at 1:20:21
It's good to see this in print. To go one step further: excessive serotonin 5-HT2c receptor stimulation (in the amygdala) leads to anxiety. This is probably why some SSRIs produce anxiety as a startup side effect that soon disappears. Things are not so simple when it comes to serotonergic neurotransmission, though. For example, fluoxetine (Prozac) is one of the worst offenders when it comes to startup anxiety, yet acts as a competitive 5-HT2c receptor antagonist. Perhaps the increase in serotonin acts to displace fluoxetine within the first few days, allowing the anxiety to appear. Whatever the reasons, it is not incomprehensible that both too little and too much serotonin in illness can be reregulated by SSRIs and SNRIs. My guess is that, upon chronic exposure to serotonin reuptake inhibitors, the presynaptic negative feedback loops that act as thermostats are recalibrated by the neuron in an effort to accommodate to the new conditions. Of course, postsynaptic receptor downregulation also occurs, which reduces membrane sensitivity. It is as if pushing the system hard enough acts as a reset to a default dynamic, regardless of what the baseline amount of serotonin is. In fact, it may not even matter in which direction the system is pushed. Tianeptine (Stablon) is a drug that acts as the reverse of SSRIs. It causes the presynaptic neuron to increase its rate of reuptake (reuptake enhancer), yet acts as an antidepressant. Again, the system must reregulate itself to accommodate the new conditions. The key is to trigger the system to assume a default dynamic which is probably coded for genetically. It might be epigenetics that screw everything up in the first place.
Who knows? I try to keep an open mind and revise my thinking as new facts and opinions emerge.
- Scott
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> http://medicalxpress.com/news/2015-06-individuals-social-phobia-serotoninnot.html
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> 6/17/15 article:
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> Previous studies have led researchers to believe that individuals with social anxiety disorder/ social phobia have too low levels of the neurotransmitter serotonin. A new study carried out at Uppsala University, however, shows that the situation is exactly the opposite. Individuals with social phobia make too much serotonin. The more serotonin they produce, the more anxious they are in social situations.
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> Many people feel anxious if they have to speak in front of an audience or socialise with others. If the anxiety becomes a disability, it may mean that the person suffers from social phobia which is a psychiatric disorder.
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> Social phobia is commonly medicated using SSRI compounds. These change the amount of the neurotransmitter serotonin in the brain. Based on previous studies, it was believed that individuals with social phobia had too little serotonin and that SSRIs increased the amount of available serotonin. In a new study published in the scientific journal JAMA Psychiatry, researchers from the Department of Psychology at Uppsala University show that individuals with social phobia make too much serotonin.
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> The research team, led by professors Mats Fredrikson and Tomas Furmark, used a so-called PET camera and a special tracer to measure chemical signal transmission by serotonin in the brain. They found that patients with social phobia produced too much serotonin in a part of the brain's fear centre, the amygdala. The more serotonin produced, the more anxious the patients were in social situations.
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> A nerve cell, which sends signals using serotonin, first releases serotonin into the space between the nerve cells. The nerve signal arises when serotonin attaches itself to the receptor cell. The serotonin is then released from the receptor and pumped back to the original cell.
> "Not only did individuals with social phobia make more serotonin than people without such a disorder, they also pump back more serotonin. We were able to show this in another group of patients using a different tracer which itself measures the pump mechanism. We believe that this is an attempt to compensate for the excess serotonin active in transmitting signals", says Andreas Frick, a doctoral student at Uppsala University Department of Psychology.
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> This discovery is a major leap forward when it comes to identifying changes in the brain's chemical messengers in people who suffer from anxiety. Earlier research has shown that nerve activity in the amygdala is higher in people with social phobia and thus that the brain's fear centre is over-sensitive. The new findings indicate that a surplus of serotonin is part of the underlying reason.
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> "Serotonin can increase anxiety and not decrease it as was previously often assumed", says Andreas Fric
Some see things as they are and ask why.
I dream of things that never were and ask why not.- George Bernard Shaw
poster:SLS
thread:1079832
URL: http://www.dr-bob.org/babble/20150520/msgs/1079835.html