Piva F, Limonta P, Dondi D, Pimpinelli F, Martini L, Maggi R
Department of Endocrinology, University of Milano, Italy.
J Steroid Biochem Mol Biol. 1995 Jun;53(1-6):343-8. doi: 10.1016/0960-0760(95)00072-8.
The experiments reported here add further evidence in support of the view that sex steroids may influence the binding characteristics of brain opioid receptors. In particular, it has been shown that: (a) the number of mu-opioid receptors varies in the hypothalamus of regularly cycling female rats according to the different phases of the estrous cycle, which are characterized by fluctuations of circulating levels of sex steroids; (b) the number of mu-opioid receptors decreases in the hypothalamus and in the corpus striatum when ovariectomized rats are submitted to treatments with estradiol and progesterone able to induce a "positive" feedback effect on LH release. A treatment with estrogen alone able to induce a "negative" feedback effect on LH release brings about an increase of the number of mu-opioid receptors in the thalamus and in the hippocampus; (c) in addition to the mu-receptors, receptors of the delta type may also be involved in the control of gonadotropin secretion; recent results here presented indicate that a line of immortalized hypothalamic cells (GT1 cells), which synthesize and secrete LHRH, present delta opioid receptors on their membranes; these are apparently involved in the control of LHRH release from these cells.
此处报道的实验进一步证明了性类固醇可能影响脑阿片受体结合特性这一观点。具体而言，研究表明：(a) 在正常发情周期的雌性大鼠下丘脑，μ-阿片受体数量会根据发情周期的不同阶段而变化，这些阶段的特征是性类固醇循环水平的波动；(b) 当切除卵巢的大鼠接受能对促黄体生成素（LH）释放产生“正”反馈作用的雌二醇和孕酮治疗时，下丘脑和纹状体中的μ-阿片受体数量会减少。单独使用能对LH释放产生“负”反馈作用的雌激素治疗会导致丘脑和海马体中μ-阿片受体数量增加；(c) 除了μ-受体外，δ型受体也可能参与促性腺激素分泌的控制；此处展示的最新结果表明，永生化下丘脑细胞系（GT1细胞）能合成并分泌促性腺激素释放激素（LHRH），其细胞膜上存在δ阿片受体；这些受体显然参与了这些细胞释放LHRH的控制。
