Opioids and XXXX in the male @entity35 .

@entity251 @entity146 @entity1510 @entity1286 @entity5171 @entity35
@entity1510 in the doses of 4 or 16 mg/kg failed to affect copulatory behavior of @entity251 -treated castrated male @entity35 . @entity1286 10 mg/kg, administered 60 min before behavioral observation, reduced the proportion of animals displaying @entity146 . Doses of 2.5 or 5 mg/kg reduced the latency to the second ejaculation, whereas the few animals still copulating after @entity1286 10 mg/kg showed a reduced latency to the first ejaculation. The same doses of @entity1286 administered 5 min before behavioral observation produced a dose-dependent reduction of mount, intromission and ejaculation percentages. However, those animals that did copulate showed a normal copulatory behavior. @entity5171 ( @entity5171 ) infused into the left cerebral ventricle in a dose of 5 micrograms 5 or 60 min before tests had no effect. When the peptide was infused 30 sec after the first intromission, the number of intromissions as well as the latency to ejaculation were reduced. Opioids may facilitate ejaculatory mechanisms, perhaps as a consequence of their rewarding properties. Moreover, in animals treated with @entity5171 after the first intromission, the number of intromissions and the latency to ejaculation were similar for the first and second copulatory series, while these parameters were much reduced upon the second ejaculation for control animals. It is possible that liberation of endogenous opioids is the cause of ejaculation-induced facilitation of subsequent @entity146 .
