CENTRAL AND PERIPHERAL COMPONENTS OF THE INHIBITORY ACTIONS OF 5-HTP ON ETHANOL-CONSUMPTION IN THE RAT

When administered under a backward conditioning paradigm, 5-HTP admini stration resulted in a decrease in ethanol intake followed by a persis tently decreased ethanol consumption. A central component to this inhi bitory effect was suggested by the inability of xylamidine to signific antly reduce the initial inhibitory effect of 5-HTP. The persistent re jection was prevented by xylamidine. Methysergide reduced the initial as well as the persistent effects of 5-HTP. In studies utilizing a for ward conditioning paradigm, 5-HTP and lithium were each effective in d eveloping CTAs to ethanol and saccharin. Only the ethanol-5-HTP pairin g showed a persistent aversion. A peripheral component to the actions of 5-HTP was suggested by xylamidine blocking the CTAs induced by 5-HT P. Xylamidine also prevented the persistent ethanol avoidance induced by 5-HTP, but was ineffective in antagonizing lithium-induced CTAs. Th ese results suggest central as well as peripheral components associate d with the inhibitory effects of 5-HTP on ethanol consumption. Central actions appear to mediate the initial inhibitory effects while periph eral actions appear to be associated with persistent avoidance of etha nol following 5-HTP treatment.