Dose-dependent effects of acute kainic acid treatment on sexual behavior of male rats

Abstract

Male rats of the Wistar strain were selected as good copulators (displaying at least 1 ejaculation in each of three consecutive tests for male sexual behavior) and sexually sluggish animals (displaying no ejaculations in each of three consecutive tests). The administration of low doses (1 and 2.5 mg/kg, i.p.) of kainic acid in sexually sluggish rats induced an enhancement of some parameters of copulatory behavior. In particular, significant reductions in latency to the first mount and intromission and increases in frequency of mounts and intromissions were observed. In contrast, the drug failed to exert any effect in good copulators. At the dose of 5 mg/kg (i.p.) kainic acid exerted an inhibitory effect on sexual behavior parameters both in good copulators and in sluggish rats. A persistent increase in latency to the first mount, intromission and ejaculation, and reduction in frequency of mounts, intromissions and ejaculation both in good copulators and in sluggish rats were observed 20 days after kainic acid treatment at the higher dose. No persistent effect of kainic acid 1 and 2.5 mg/kg was observed 20 days after treatment. These results suggest that kainic acid may affect in a dose-dependent manner several copulatory parameters of male sexual behavior repertoire. The bimodal effects could be explained considering a possible interaction of kainic acid with different neurotransmissions or receptor subtypes.