Effects of nucleus accumbens lesion on female rat sexual receptivity and proceptivity in a partner preference paradigm

Abstract

A partner preference paradigm, stud male vs estrous female, was used to study sexual behavior. Ovariectomized Wistar rats received bilateral electrolytic ( n = 33) or sham ( n = 16) lesion of the nucleus accumbens. Animals were tested in two different experimental situations, either with stimulus animals tethered (test with possibility of mating) or with stimulus animals behind a wire mesh (test without possibility of mating). Each test was carried out once prior to surgery and twice postoperatively following priming with estradiol benzoate and progesterone. Lordosis, rejection behaviors and soliciting patterns were scored in tests with tethered stimulus animals. The tendency of the experimental female to approach and remain in the vicinity of each stimulus animal was quantified to study the partner preference. Nucleus accumbens lesion increased the number of rejection responses to male mount attempts without modifying either receptivity estimated by lordosis reflex or soliciting behaviors. Control females showed a statistically significant preference for the male throughout the experiments. Lesioned females exhibit a preference for the male only in the test without sexual interaction possibility. This preference disappeared in the test with possibility of mating and it was even reversed when the male showed copulatory activity. These results, together with the absence of changes in lordosis behavior and soliciting activity, suggest that both the inversion in preference and the higher levels of mount rejections found in the lesioned animals are more likely attributable to hyperreactivity to the copulatory stimulus rather than an alteration in the female's rat sexual motivation.