Perinatal testosterone, or its metabolite estradiol, organize the brain toward a male phenotype. Male rodents with insufficient testosterone during this period fail to display sexual behavior and partner preference for receptive females in adulthood. However, cohabitation with non-reproductive conspecifics under the influence of a D2 agonist facilitates the expression of conditioned partner preference via Pavlovian learning in gonadally intact male rats. In the present experiment, three groups of neonatal PD1 males (N = 12/group) were either gonadectomized (GDX), sham-GDX, or left intact and evaluated for social preferences and sexual behaviors as adults. We then examined whether the effects of GDX could be reversed by conditioning the males via cohabitation with receptive females under the effects of the D2 agonist quinpirole (QNP) or saline, along with the size of some brain regions, such as the sexually dimorphic nucleus of the preoptic area (SDN-POA), suprachiasmatic nucleus (SCN), posterior dorsal medial amygdala (MeApd) and ventromedial hypothalamus (VMH). Results indicated that neonatal GDX resulted in the elimination of male-typical sexual behavior, an increase in same-sex social preference, and a reduction of the area of the SDN-POA. However, GDX-QNP males that underwent exposure to receptive females in adulthood increased their social preference for females and recovered the size in the SDN-POA. Although neonatal GDX impairs sexual behavior and disrupts partner preference and brain dimorphism in adult male rats, Pavlovian conditioning under enhanced D2 agonism ameliorates the effects on social preference and restores brain dimorphism in the SDN-POA without testosterone.

中文翻译：

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成年后与接受 D2 型激动的雌性同居可恢复雄性大鼠新生儿性腺切除后的伴侣偏好和 SDN-POA 中的大脑二态性

围产期睾酮或其代谢物雌二醇将大脑组织成男性表型。在此期间，睾丸激素不足的雄性啮齿动物在成年后无法表现出性行为和对接受性雌性的伴侣偏好。然而，在 D2 激动剂的影响下与非生殖同种动物共居，会促进性腺完整的雄性大鼠通过巴甫洛夫学习表达条件性伴侣偏好。在本实验中，三组新生 PD1 雄性（N = 12/组）要么被切除性腺（GDX）、假 GDX，要么保持完整，并评估成年后的社会偏好和性行为。然后，我们检查了 GDX 的影响是否可以通过在 D2 激动剂喹吡罗 (QNP) 或盐水的作用下与接受性雌性同居来调节雄性，以及某些大脑区域的大小（例如性二态性核）来逆转。视前区（SDN-POA）、视交叉上核（SCN）、后背内侧杏仁核（MeApd）和下丘脑腹内侧（VMH）。结果表明，新生儿 GDX 导致男性典型性行为的消除、同性社会偏好的增加以及 SDN-POA 面积的减少。然而，在成年期接触过接受性雌性的 GDX-QNP 雄性增加了对雌性的社会偏好，并恢复了 SDN-POA 中的体型。尽管新生 GDX 会损害成年雄性大鼠的性行为并扰乱伴侣偏好和大脑二态性，但在增强 D2 激动作用下的巴甫洛夫条件反射改善了对社会偏好的影响，并在没有睾酮的情况下恢复了 SDN-POA 中的大脑二态性。