Re: Does St. John's Wort affect the serotoginic system of the brain? How?

Jenny,
	The actual mechanism of action of St 
John's wort is not known, but it has been 
shown to block the reuptake of 5-HT 
(serotonin) (Raffa RB (1998). Life Sci  
(England), 62(16) pPL265-70). Serotonin 
in the brain, as you may well know, is 
involved in sleep/wakefulness cylces and 
mood. Therefore, the more 5HT, the more 
mood altering that can occur. If the active 
ingredient of St John's wort, hypericum 
perforatum, blocks 5-HT reuptake, it keeps 
5-HT in the synapse, resulting in
increased levels of 5-HT--thereby altering 
mood.
	Now, as for MAO, hypericum 
perforatum has also been shown to inhibit 
MAO (Raffa RB (1998). Life Sci (England), 
62(16) pPL265-70). MAO is the lead 
catalyst in the breakdown of 5-HT. 
Therefore, if hypericum perforatum can 
block this action, again, more 5-HT would 
be around to alter moods. It is important to 
point out that these effects of St. John's 
wort are only speculative, since the St 
John's wort extract used clinically consists 
of multiple compounds, not just hypericum 
perforatum.

That's basically how it all works in a 
nutshell. Hope it answers your question!!

-Benjamin