1993 Volume 24 Issue 2 Pages 233-246
It has been known that on sexual behavior in male rats LH-RH as a stimulating factor and opioid peptide as an inhibitory factor are involved. However, the details of their interrelations are not fully understood. In the present study, effects of LH-RH antagonist on increased sexual behavior in intact and castrated male rats induced by the opioid peptide antagonist naloxone was examined. Adult male rats (Wister-Imamichi strain) weighing 300-350g, were administrated naloxone hydrochloride intracerebroventricularly (i. c. v. 5μg/rat) and subcutaneously (s. c. 1 mg/kg). In all of the group receiving i. c. v. and s. c. administration of naloxone, sexual behavior increased. Pretreatment with LH-RH antagonist (s. c. 500ng/rat) inhibited significantly the naloxone-induced increase in sexual behavior in rats. The results of this study suggest that the central opioid peptidergic system is very closely related to the central LH-RH system in sexual behavior of male rats.
