Olfactory conditioned same-sex partner preference in female rats: Role of ovarian hormones.

The dopamine D2-type receptor agonist quinpirole (QNP) facilitates the development of conditioned same-sex partner preference in males during cohabitation, but not in ovariectomized (OVX) females, primed with estradiol benzoate (EB) and progesterone (P). Herein we tested the effects of QNP on OVX, EB-only primed females. Females received a systemic injection (every four days) of either saline (Saline-conditioned) or QNP (QNP-conditioned) and then cohabited for 24h with lemon-scented stimulus females (CS+), during three trials. In test 1 (female-female) preference was QNP-free, and females chose between the CS+ female and a novel female. In test 2 (male-female) they chose between the CS+ female and a sexually experienced male. In test 1 Saline-conditioned females displayed more hops & darts towards the novel female, but QNP-conditioned females displayed more sexual solicitations towards the CS+ female. In test 2 Saline-conditioned females displayed a clear preference for the male, whereas QNP-conditioned females displayed what we considered a bisexual preference. We discuss the effect of dopamine and ovarian hormones on the development of olfactory conditioned same-sex preference in females.

Effect of copulation on potentially precancerous prostate lesions, serum testosterone and prolactin levels in rats.

UNLABELLED: The prostate is an exocrine reproductive gland that participates in ejaculation and it is prone to diseases, including cancer. AIM: In the pre-sent study, we assessed the long-term effects of copulation on the development of precancerous lesions in rats, and compared them with testosterone-induced prostatic lesions. MATERIALS AND METHODS: One group of Wistar males was given 10 copulatory sessions to one ejaculation with ovariectomized, hormone-primed females. Sessions occurred twice per week for a total of ten trials. A second group was exposed to females during the same trials, but physical contact was prevented. In addition, each group received a subcutaneous implant in the back either filled with testosterone propionate (T, 100 mg/kg) or empty. This resulted in four subgroups: 1) Control + No sex, 2) Control + Sex, 3) T + No sex and 4) T + Sex. Two days after the 10(th) trial all the males were sacrificed for prostate histo-logy (H&E) and hormone analysis (testosterone and prolactin). RESULTS: Males from the group Control + No sex expressed normal histo-logy. However, those in the groups Control + Sex and T + No sex expressed metaplasia and dysplasia in both the dorsolateral and ventral portions of the prostate, respectively. Interestingly, males from the group T + Sex expressed dysplasia in the dorsolateral prostate only, but not in the ventral prostate. CONCLUSIONS: These results indicate that constant copulation may facilitate the development of prostatic lesions in males with normal levels of testosterone. However, copulation induces less lesions in the ventral prostate of males treated with testosterone.