Antagonism by lisuride and 8-OH-DPAT of 5-HTP-induced prolongation of the performance of male rat sexual behavior.

Both lisuride and 8-OH-DPAT dose dependently antagonized the 5-HTP-induced inhibition of male rat sexual behavior. The increase in the number of intromissions and/or the ejaculation latency produced by 5-HTP, 25 mg/kg i.p. (-60 min) in combination with the peripheral 5-HTP decarboxylase inhibitor benserazide, 25 mg/kg i.p. (-90 min), were antagonized by lisuride, 0.05-0.1 mg/kg i.p. (-15 min) and by 8-OH-DPAT, 0.025-0.05 mg/kg i.p. (-15 min). Thus, in this model lisuride and 8-OH-DPAT behave as 5-HT antagonists.