Possible involvement of nitric oxide in pilocarpine induced seminal emission in rats

Intraperitoneal injection of pilocarpine (0.75-3.0 mg/kg) caused a dose-rel ated seminal emission in adult male rats. The seminal emission response to 3 mg/kg of pilocarpine was greatly reduced in atropinized (5 and 10 mg/kg, SC) animals, suggesting a cholinomimetic effect. N-w-nitro-L-arginine methy l ester (5, 10, and 20 mg/kg, SC), a nitric oxide synthesis inhibitor, also inhibited the pilocarpine-induced seminal emission, which was reversed by L-arginine (600 mg/kg, SC) or by coinjection of sodium nitroprusside (0.5 m g/kg, SC). Urine analysis for levels of nitric oxide metabolites, nitrate/n itrite (NO3-/NO2-), showed marked alterations in accordance with the drug t reatments. The results suggest that nitric oxide mediates the inhibitory ne urotransmission responsible for seminal emission in pilocarpine stimulated rats. (C) 2000 Elsevier Science Inc. All rights reserved.