Sexual behavior in male rats after nitric oxide synthesis inhibition

Abstract

The influence of the nitric oxide synthase inhibitor N-nitro- l.-arginine methyl ester ( l-NAME) on the copulatory behavior of sexually experienced male Wistar rats was investigated. l-NAME was injected IP 10 min before the onset of a session using a dose of 30 mg/kg ( l-NAME 30 group), or 60 mg/kg ( l-NAME 60 group). The copulatory sessions were terminated after the third ejaculation in the control group or after 1500 s in the l-NAME 30 and l-NAME 60 groups. l-NAME administration reduced the number of rats that achieved ejaculation by 43% and 86% in the l-NAME 30 and 60 groups, respectively. In both experimental groups only a few intromissions and an increased number of mountings were observed. An increase in the number of ultrasonic vocalizations in the 50 kHz band, a dose-dependent effect, was observed. The level of sexual motivation evaluated by mount latency was not influenced by inhibition of NO synthesis.