Johnson A E, Coirini H, McEwen B S, Insel T R
Laboratory of Clinical Sciences, National Institute of Mental Health, Poolesville, Md.
Neuroendocrinology. 1989 Aug;50(2):199-203. doi: 10.1159/000125222.
Oxytocin (OT) binding sites are modulated by estrogens in several brain regions including the ventromedial hypothalamic nucleus (VMN) in both male and female rats. To further study steroid regulation of OT receptor binding, we examined the effect of androgen replacement in castrated male rats on OT binding with quantitative autoradiographic methods. Castrated adult male rats were treated with either 250 micrograms testosterone propionate (TP) or oil for 2 days and killed 48 h after the last injection. Brain sections through the preoptic area and VMN were labeled with 5.0 nM[3H]-OT +/- 5.0 microM unlabeled OT or 1.0 microM[Thr4,Gly7]OT and apposed to tritium-sensitive film for 7 weeks. Results of this study show that TP increased [3H]-OT binding up to 5-fold in the ventrolateral VMN and 4-fold in the bed nucleus of the stria terminalis. In addition [Thr4,Gly7]OT completely displaced [3H]-OT binding in the VMN indicating that binding in this brain region was specific to OT receptors. Because estrogens also increase OT receptor binding in male rats, it is possible that TP affects OT binding after being converted by aromatase to estradiol.
在包括雄性和雌性大鼠的腹内侧下丘脑核（VMN）在内的几个脑区中，雌激素可调节催产素（OT）结合位点。为了进一步研究类固醇对OT受体结合的调节作用，我们采用定量放射自显影方法，检测了去势雄性大鼠中雄激素替代对OT结合的影响。将成年去势雄性大鼠用250微克丙酸睾酮（TP）或油处理2天，并在最后一次注射后48小时处死。通过视前区和VMN的脑切片用5.0 nM [3H]-OT ± 5.0 μM未标记的OT或1.0 μM [Thr4,Gly7]OT进行标记，并与对氚敏感的胶片贴合7周。本研究结果表明，TP使腹外侧VMN中的[3H]-OT结合增加了5倍，使终纹床核中的结合增加了4倍。此外，[Thr4,Gly7]OT完全取代了VMN中的[3H]-OT结合，表明该脑区中的结合对OT受体具有特异性。由于雌激素也会增加雄性大鼠中的OT受体结合，因此TP有可能在被芳香化酶转化为雌二醇后影响OT结合。
