can receptor desentization be seen in brain scan

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redditorx4
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can receptor desentization be seen in brain scan

Unread post by redditorx4 »

like pet scans if not why dont we rule this theory out? :?:
sylv
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Re: can receptor desentization be seen in brain scan

Unread post by sylv »

It can be, but that would need a selective radioligands and recorded baseline scan ( before PSSD ) or control group for comparison. Only available in the research or If you have your own equipment ( PET scanner )
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guacamo
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Re: can receptor desentization be seen in brain scan

Unread post by guacamo »

It is possible but less selective than when taking sample, anyway if you mean checking out 5-ht1a receptor desensitization then there is much more things that influence certain receptor function than it's expression in the brain.

There are studies that show reduction of 5-HT1A expression in midbrain after SSRI intake.There are 5-ht1a receptors in other brain areas but those are not downregulated, probably because they are coupled to the different g protein. Proteins are basically amino acids coupled together by peptide bonds, in layman terms they then create chain of amino acids and such chain is called protein. 5-HT1A is such chain of amino acids and thus 5-HT1A is a protein.

Receptor is a specific type of protein that is able to elicit chemical reactions by binding specific chemical called ligand, in case of 5-HT1A receptor the ligand is serotonin. Every serotonin receptor apart of 5-HT3 receptor is called "G protein coupled receptor", because every serotonin receptor protein has G protein nearby, thus is "g protein coupled". G proteins are essential to the function of serotonin receptors, because after serotonin receptor meets serotonin, part of it's signaling is due to G protein.

Just as there are different serotonin receptors, there are different g proteins and these different g proteins elicit different chemical reactions, even for the same receptor they may be coupled to different g protein variant. Actually what studies show and should be alarming is not the fact that 5-ht1a expression is lowered after SSRI intake, because expression of receptor fluctuates due to many factors, and it is unlikely that study on PSSD person would show abnormality in that regard years after someone quit SSRI, but the fact that 5-ht1a reaction with g protein is different after SSRI intake.

G proteins coupled to 5-HT1A reacts with another protein called "G protein-coupled inwardly-rectifying potassium channel", shortly called "GIRK". In case of 5-HT1A in midbrain its either GIRK2 or GIRK3 isoform, such GIRK2/GIRK3 channel is responsible for control of serotonin output. If you inhibit GIRK, you then disinhibit serotonin outflow. That is the mechanism behind SSRI 5-HT1A receptor mediated serotonin level regulation. After taking SSRIs, GIRK serotonin level modulation is changed. So if there would be study on 5-ht1a it should not focus on receptor expression but 5-HT1A G protein-GIRK2/GIRK3 interaction.
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