Brann D W, Zamorano P L, Chorich L P, Mahesh V B
Department of Physiology and Endocrinology, Medical College of Georgia, Augusta 30912-3000.
Neuroendocrinology. 1993 Dec;58(6):666-72. doi: 10.1159/000126607.
Previous work has demonstrated that N-methyl-D-aspartate (NMDA) is capable of stimulating luteinizing hormone release in a variety of species. Interestingly, the ability of NMDA to stimulate luteinizing hormone release is significantly compromised in castrated male and female rats as compared to intact animals. The purpose of the present study was to determine if a difference exists in the number or affinity of NMDA receptors in the hypothalamus of intact or castrated adult male and female rats and whether steroid replacement has any effect on NMDA receptor binding. NMDA receptor mRNA levels were also determined in the respective models. The cerebral cortex was used as a control to check for specificity of any observed differences. The number of NMDA binding sites in the hypothalamus was found to be approximately 25% of that found in the cerebral cortex and the equilibrium association constant was similar in both tissues. In the female rat, neither ovariectomy nor ovariectomy with estrogen pellet replacement or estrogen and progesterone injections altered NMDA receptor binding or the equilibrium association constant in the hypothalamus or cerebral cortex as compared to intact controls. Similar to the case in the female, NMDA receptor binding in the hypothalamus and cerebral cortex of male rats did not change after castration or after treatment with testosterone propionate. Neither ovariectomy nor ovariectomy with estradiol replacement brought about any change in the NMDA receptor mRNA levels in the hypothalamus. However, in the cerebral cortex ovariectomy with estrogen replacement brought about a small but significant increase in NMDA receptor mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)
先前的研究表明，N-甲基-D-天冬氨酸（NMDA）能够刺激多种物种的促黄体生成素释放。有趣的是，与未阉割的动物相比，NMDA刺激促黄体生成素释放的能力在阉割的雄性和雌性大鼠中显著受损。本研究的目的是确定完整或阉割的成年雄性和雌性大鼠下丘脑NMDA受体的数量或亲和力是否存在差异，以及类固醇替代对NMDA受体结合是否有任何影响。还在各自的模型中测定了NMDA受体mRNA水平。使用大脑皮层作为对照，以检查任何观察到的差异的特异性。发现下丘脑NMDA结合位点的数量约为大脑皮层中发现数量的25%，并且两种组织中的平衡缔合常数相似。在雌性大鼠中，与完整对照相比，卵巢切除术、卵巢切除术加雌激素颗粒替代或雌激素和孕酮注射均未改变下丘脑或大脑皮层中的NMDA受体结合或平衡缔合常数。与雌性情况类似，雄性大鼠下丘脑和大脑皮层中的NMDA受体结合在阉割后或用丙酸睾酮治疗后没有变化。卵巢切除术或卵巢切除术加雌二醇替代均未引起下丘脑NMDA受体mRNA水平的任何变化。然而，在大脑皮层中，卵巢切除术加雌激素替代使NMDA受体mRNA水平有小幅但显著的增加。（摘要截断于250字）
