6-Hydroxydopamine Lesions in Female Hamsters (Mesocricetus auratus) Abolish the Sensitized Effects of Sexual Experience on Copulatory Interactions With Males.

Abstract

This study examined the effects of sexual experience in female hamsters (Mesocricetus auratus) on copulatory interactions with male hamsters. Female sexual experience improved the copulatory efficiency of sexually naive males, an effect that persisted for at least 6 weeks without further sexual behavior testing. In a 2nd study, dopamine lesions made in the region of the nucleus accumbens prior to sexual experience specifically blocked the effects of the female's sexual experience on the hit rate of naive males. These results suggest that sexual experience in female hamsters increases the efficiency of copulatory interactions with males, that these effects persist in the absence of further sexual experience, and that dopamine neurotransmission in the basal forebrain underlies this effect of sexual experience.

Sexual experience in female rodents: Cellular mechanisms and functional consequences

“…From this framework we can conceive of a pattern of behavior in which vaginal stimulation received by females during copulation stimulates dopamine neurotransmission. Though initially this response is unconditioned [55], with experience females learn to produce subtle perineal movements that increase the likelihood of receiving vaginal stimulation from the mounting male [8]. In turn, there is greater dopamine activation, which feeds forward to maintain the behavioral responding.…”

“…Infusions of the dopamine neurotoxin, 6-hydroxydopamine (6-OHDA), into the region of the nucleus accumbens prior to sexual experience eliminated the effect of the female hamster's sexual experience on the copulatory efficiency (hit rate) of naïve males (*p<0.05 relative to lesioned females). Data from [8]. Repeated pairings of copulation with the gray compartment in a conditioned place preference (CPP) apparatus resulted in the female hamsters spending more time in that compartment in the absence of copulation (*p<0.05).…”

“…The hit rate (proportion of mounts culminating in intromission) of the males was higher when mated with sexually-experienced (Exp Females) compared to naïve females (*p<0.05) and this effect of experience persisted even with a 6 week hiatus in behavioral testing. Data from [8]. Infusions of the dopamine neurotoxin, 6-hydroxydopamine (6-OHDA), into the region of the nucleus accumbens prior to sexual experience eliminated the effect of the female hamster's sexual experience on the copulatory efficiency (hit rate) of naïve males (*p<0.05 relative to lesioned females).…”

“…To test this proposition, we examined female hamsters that were sexually naive or females that had previously received 6 weekly, 10 minute sexual interactions with males [8]. We then let each female mate with a sexually naive male hamster and recorded the copulatory behavior.…”

“…An additional experiment implicated dopamine in the effects of the female's sexual experience on the male's copulatory performance [8]. The dopamine neurotoxin, 6-hydroxydopamine, was injected into the basal forebrain, including the nucleus accumbens, of female hamsters prior to receipt of sexual experience.…”