Posted by JGalt on November 3, 2001, at 22:33:06
In reply to Inhibition of MAO-B Increases GABA, posted by pat c. on November 3, 2001, at 20:44:47
Interesting article...by the way, thats a fun website to read through from time to time, good to see I'm not the only one reading it...anyway, back to your questions...
"It also says that MAO-B is the primary MAO that is inhibited by Nardil to cause this elevation of GABA."
Right here is the source of your confusion, and I can easily see where you got what you did, I thought the same thing when I glanced it over.
What the article is actually saying is that Nardil, while it inhibits MAO-A and MAO-B is also metabolised by the MAO enzymes...basically its stopping those enzymes, and the enzymes are also responsible for stopping it (sudden thought, maybe this is why if Nardil is dosed beyond 80% MAO inhibition it can cause manic episodes, perhaps because the drug level doesn't go down anywhere near as fast thus causing a cumulative effect...anyway) . But when the MAO metabolizes (that isn't the right word but I'll go w/ it) the Nardil, a new compound is formed (undescribed in this article), which according to the article leads to higher GABA levels (this probably accounts for Nardil's generally greater effect than Parnate on social anxiety). K...now when they used selegiline to block MAO-B enzymes, the GABA levels didn't rise anywhere near as much when the subject was exposed to Nardil, but when they used a different drug to inhibit MAO-A enzymes GABA levels weren't effected as much. The selegiline isn't counteracting the Nardil, it is simply further reducing MAO-B levels, thus causing less of the metabolite of Nardil to be produced, thus leading to less increase of GABA. This leads to their conclusion that MAO-B is responsible for the conversion of Nardil to whatever metabolite it is that increases GABA.
Hope that made some sense without being excessively wordy.
JGalt
poster:JGalt
thread:83124
URL: http://www.dr-bob.org/babble/20011025/msgs/83138.html