[Study of pharmacological activation of the male sexual behavior]

The model of sexual exhaustion of male rats was used in the study. The specific aim was to compare the effects of cocaine on the mount latency, number of mounts, intromissions and ejaculations during the entire copulatory cycle with the same indices during the first 30 min of observation (the latter is most frequently used in laboratory settings). Experiments consisted of four 3-day test periods. On days 1 and 2, male rats were allowed to interact with receptive females until the satiation criterion was reached (30 min without mounts). On day 3, male rats were injected with cocaine (5, 10, or 30 mg/kg, i.p.) or its vehicle 15 min prior to testing. Cocaine administration in a dose-dependent way increased the total number of mounts and ejaculations during the entire observation session but not during the initial 30-min period. The mount latency was unaffected by cocaine treatment. The results suggest that the expression of the stimulating effects of cocaine on sexual behavior depends on the duration of the observation period.