Amico J A, Davis A M, McCarthy M M
Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA. amico+@pitt.edu
Brain Res. 2000 Feb 28;857(1-2):279-82. doi: 10.1016/s0006-8993(99)02373-2.
Administration of sequential estradiol (E(2)) and progesterone (P) for 2 weeks followed by withdrawal of P 48 h prior to sacrifice will increase oxytocin (OT) messenger ribonucleic acid (mRNA) levels in the paraventricular and supraoptic nuclei (PVN and SON) of the ovariectomized rat. Progesterone is known to mediate certain of its effects via binding to the gamma aminobutyric acid A (GABA(A)) receptor. E(2) and P are known to modulate the specific binding of the GABA(A) receptor agonist, muscimol, in certain brain regions. In the present study ovariectomized rats received empty or steroid-filled Silastic capsules for 2 weeks according to one of the following schedules: E(2) only (E(2) group) vs. sequential E(2) and P in which P was either removed 48 h prior to killing (E(2)/P- group) or sustained until sacrifice (E(2)/P+ group). [3H]muscimol binding was measured in several brain regions of the animals. The steroid sequence that is known to increase SON OT mRNA (E(2)/P-) selectively decreased [3H]muscimol binding in the SON of ovariectomized rats. The results suggest that changes in GABA(A) receptor binding may, in part, play a role in the regulation of steroid-induced increases in hypothalamic OT expression.
对去卵巢大鼠连续给予雌二醇（E₂）和孕酮（P）2周，然后在处死前48小时撤掉P，这会增加去卵巢大鼠室旁核和视上核（PVN和SON）中催产素（OT）信使核糖核酸（mRNA）的水平。已知孕酮通过与γ-氨基丁酸A（GABAA）受体结合来介导其某些作用。已知E₂和P可调节某些脑区中GABAA受体激动剂蝇蕈醇的特异性结合。在本研究中，去卵巢大鼠按照以下方案之一接受空的或填充有类固醇的硅橡胶胶囊2周：仅给予E₂（E₂组）与序贯给予E₂和P，其中P在处死前48小时撤掉（E₂/P-组）或持续到处死（E₂/P+组）。在动物的几个脑区测量了[³H]蝇蕈醇结合情况。已知能增加SON中OT mRNA的类固醇序列（E₂/P-）选择性降低了去卵巢大鼠SON中[³H]蝇蕈醇的结合。结果表明，GABAA受体结合的变化可能在一定程度上参与了类固醇诱导的下丘脑OT表达增加的调节。
