Same-sex cohabitation under the effects of quinpirole induces a conditioned socio-sexual partner preference in males, but not in female rats

Conditioned same-sex partner preference in male rats is facilitated by oxytocin and dopamine: Effect on sexually dimorphic brain nuclei

“…Sexual training and surgery. As in our previous studies [17,18] males that functioned as stimulus received at least 10 trials of multi-ejaculatory sexual experience with receptive females prior to the start of the experiment, whereas experimental males were sexually naïve. In those previous studies we observed that cohabitation between two sexually naive males results in a strong same-sex socia preference, but less robust sexual preference.…”

“…For example, stimuli associated with nurture and juvenile play are rewarding only during periods of early development and can facilitate the crystalization of partner preferences that will be displayed after puberty [6][7][8][9][10]. In adulthood, other stimuli such as sexual reward [2,[11][12][13][14], cohabitation [15], mild stress [16] or even pharmacological manipulations [16][17][18][19] may function as reinforcers.…”

“…If repeated cohabitation occurs between two male rats and one of them is treated with QNP, a strong conditioned same-sex socio/sexual preference develops towards the cagemate in a subsequent drug-free preference test [17,18]. In our studies, same-sex partner preference occurs many days after the last pharmacological manipulation, and it is inferred when a male displays more social and sexual behaviors towards the male he previously cohabited with even if a sexually receptive female rat is concurrently available as a partner choice [17,18]. For example, conditioned males from previous studies preferred a male over a female as he spent more time together (70% of the time), displayed more visits, body contacts, and genital investigations.…”

Sex differences in partner preferences in humans and animals

“…For example, young female rats allowed to express juvenile play with artificially scented males will in adulthood show a sexual preference for males bearing the same odour over other males [95]. More directly related to the present topic, male rats that were allowed to cohabit three times during 24 h with another almond-scented male immediately after being treated with quinpirole, a D2 dopaminergic agonist, developed a social and sexual preference during later drug-free tests for this scented male over a novel unscented male partner [96] and over a sexually receptive female, but such a preference did not develop if males were injected with saline before the cohabitation periods [97]. Also such preferences do not develop in females even if they are exposed to quinpirole before the cohabitation periods [96].…”

“…More directly related to the present topic, male rats that were allowed to cohabit three times during 24 h with another almond-scented male immediately after being treated with quinpirole, a D2 dopaminergic agonist, developed a social and sexual preference during later drug-free tests for this scented male over a novel unscented male partner [96] and over a sexually receptive female, but such a preference did not develop if males were injected with saline before the cohabitation periods [97]. Also such preferences do not develop in females even if they are exposed to quinpirole before the cohabitation periods [96]. A similar same-sex socio-sexual preference developed in male rats who cohabitated with an almond-scented male under the influence of oxytocin alone or combined with quinpirole [98].…”