Posted by Scott L. Schofield on April 17, 2000, at 8:35:14
In reply to Re: SSRI's may not be so benign? - To Sean, posted by Cam W. on April 16, 2000, at 21:35:14
>
> > well, I did some homework on this and TCA's and
> > SRI's bind different locations of the serotonin
> > neurons. both increase net serotonin transmission
> > but by different means.
> >
> > sean
>
> Sean - I find the above to be a very interesting statement.
>
> *Could you please supply the references to back up your claims of TCAs bind to different serotonin receptors than the SSRIs?*
>
> I was under the impression that the TCAs bound to (and affected) mainly five different receptors (serotonin reuptake, norepinephrine reuptake, muscarinic/cholinergic, alpha-adrenergic and the histamine-H1 receptors). The SSRIs, to varying degrees also bind to some of these receptors, but not usually to an appreciable extent. I thought that the TCAs and SSRIs affected the same serotonin receptors. There are at least 15 different serotonin receptor subtypes, but I have not heard of any currently marketed antidepressant to adversely affect any of these.
>
> If you have found some new information about TCAs bind to different serotonergic receptors, I am very much interested. This may change our thinking on the long term effects of other serotonergic drugs (eg buspirone, LSD, Imitrex, etc.).
>
> This would be ground-breaking information that I think the whole scientific community will need to embrace. Hoping to hear from you soon.
>
> Sincerely - Cam W.
The receptor site for reuptake blockade is the membrane reuptake transporter protein of the presynaptic neuron. This site serves an entirely different function than those receptors usually referred to on this board. The transporter acts as a shuttle to bring the released neurotransmitter back into the interior of the presynaptic neuron so that it can be used again. If a very "sticky" molecule (drug) "sits" on the "seat" of the "shuttle" and refuses to give it up, it prevents the neurotransmitter from getting its "ride" back into the cell.I know that there are subtle differences between some of the dopamine transporters. Perhaps the same is true of serotonin reuptake transporters. My guess is that any such differences in serotonin transporter, should they exist, are not significant with respect to the actions of these drugs to inhibit reuptake. Not sure.
Although the sites on the transporter where both the neurotransmitter and drug bind are technically receptors, it may be clearer to state that they "bind to the reuptake transporter", so as not to confuse this action with those that effect neuron stimulation and regulation.
- Scott
poster:Scott L. Schofield
thread:29745
URL: http://www.dr-bob.org/babble/20000411/msgs/30315.html