Methodological shortcomings present in elicitation of penile erection and ejaculation in anesthetized rats. The present study has demonstrated that intraperitoneal (i.p.) injection of p-chloromethamphetamine (PCMA ; 1-10 mg/kg) and fenfluramine (FEN ; 1-10 mg/kg), the serotonin (5-HT) releasing drugs, elicited dose-dependently both penile erection and ejaculation in anesthetized rats. PCMA (10 mg/kg) and FEN (10 mg/kg) caused an intermittent cluster of genital responses consisting of glans erections and penile cups, which closely resembles the response observed during the ex copula tests in unanesthetized rats. PCMA and FEN also caused frequent ejaculations and the weighing of ejaculates accumulated over 60 min were almost equivalent between both drugs. Pretreatment with a 5-HT synthesis inhibitor p-chlorophenylalanine (150 mg/kg × 3, i.p.) and a selective 5-HT reuptake inhibitor citalopram (1 and 3 mg/kg, i.p.) significantly inhibited the expression of both PCMA- and FEN-induced penile erection and ejaculation, while acute spinal transection (T_) did not affect the responses. These results indicate that PCMA- and FEN-induced penile erection and ejaculation in anesthetized rats are mainly elicited by the release of 5-HT which may be limited to the peripheral sites. Furthermore, the sexual responses of male rats can be easily and reliably elicited by the administration of PCMA and FEN, which may be useful for the study of the mechanisms underlying sexual functions
