Coirini H, Johnson A E, Schumacher M, McEwen B S
Laboratory of Neuroendocrinology, Rockefeller University, New York, N.Y. 10021.
Neuroendocrinology. 1992 Mar;55(3):269-75. doi: 10.1159/000126125.
The facilitation of sexual receptivity by oxytocin (OT) in female rats is related to the regulation of oxytocin receptors (OTR) by ovarian steroids in the ventromedial nuclei (VMN) of the hypothalamus. In a previous study, we have shown that estradiol benzoate (EB) causes a twofold increase in OTR binding in the VMN. Progesterone (P) then modulates levels of the estrogen-induced OTR and increases the area occupied by the receptors by acting on the neuronal membrane. In the present study, we compared the effects of EB and P on OTR binding between males and females. In both sexes, EB increased the density of OTR and the area covered by the receptors at the level of the medial and caudal VMN. In estrogen-primed females, P further increased OTR levels in the medial VMN and the area covered by OTR at the level of the caudal VMN. By contrast, P did not modulate OTR binding in estrogen-primed males. Thus, the behavioral insensitivity of male rats to ovarian hormones, in particular to P, may be related to sex differences affecting the modulation of OTR binding.
催产素（OT）对雌性大鼠性接受能力的促进作用与下丘脑腹内侧核（VMN）中卵巢类固醇对催产素受体（OTR）的调节有关。在先前的一项研究中，我们已经表明，苯甲酸雌二醇（EB）会使VMN中的OTR结合增加两倍。然后，孕酮（P）调节雌激素诱导的OTR水平，并通过作用于神经元膜增加受体占据的面积。在本研究中，我们比较了EB和P对雄性和雌性之间OTR结合的影响。在两性中，EB都增加了VMN内侧和尾部水平的OTR密度以及受体覆盖的面积。在雌激素预处理的雌性中，P进一步增加了内侧VMN中的OTR水平以及尾部VMN水平上OTR覆盖的面积。相比之下，P并未调节雌激素预处理雄性中的OTR结合。因此，雄性大鼠对卵巢激素，特别是对P的行为不敏感性，可能与影响OTR结合调节的性别差异有关。
