Posted by Racer on May 8, 2005, at 14:33:42
In reply to AD'S and weight gain, posted by bart on May 3, 2005, at 10:46:01
Well, since nothing came from this, I'll add in the tiny bit of information I've come across:
SSRIs indirectly activate the 5HT2c receptors, and some of them are direct agonists for these same receptors. That explains the initial weight *loss* on these meds. It doesn't explain the long term weight gain, though. Other receptors involved in the weight gain from psychotropic medications are the H1 and D2 receptors. All APs act on the D2 receptors, and some ADs act on the H1 receptors. All of these are involved in appetite, although I'm a bit unclear about just how.
If I had to guess -- and thus expose my ignorance -- I'd speculate that the reason for long term weight *gain* on those SSRI type meds is that your body gets the idea that the 5HT2c receptors are going to be overstimulated, and then either decreases the number or ramps down their sensitivity. That's just a guess, though.
I do know that about 95% of the 5HT in your body is expressed in your gastrointestinal tract, rather than your central nervous system or brain. That leads me to believe that there must be some connection between that and the weight changes associated with pretty much *all* the medications that target the Big Three monoamines.
I hope that someone will come along and say, "Yeah -- I just saw a great journal article on PubMed about exactly this! Here's a link!" Since that hasn't happened -- yet -- here's a link to a site that has some abstracts about various topics relating to psychotropics: http://www.biopsychiatry.com/antideps/
Hope that helps. If it doesn't help, at least I hope someone else will jump in and correct what I've written! {hint?}
poster:Racer
thread:493098
URL: http://www.dr-bob.org/babble/20050504/msgs/495226.html