Bethea C L, Widmann A A
Division of Reproductive Sciences, Oregon Regional Primate Reseach Center, Beaverton, OR 97006, USA.
Neuroendocrinology. 1996 Feb;63(2):132-41. doi: 10.1159/000126949.
Progesterone (P) acts in the central nervous system to increase prolactin secretion in estrogen (E)-primed female monkeys. beta-Endorphin (BE) and Substance P (SP) are two hypothalamic peptides which increase prolactin secretion when administered to rats and monkeys. Studies were performed to determine if P acts on these two potential prolactin-releasing systems. The presence of a nuclear steroid receptor defines the cell as a target for the cognate hormone. Therefore, the hypothalamic populations of BE and SP neurons were examined for the presence and regulation of nuclear progestin receptors (PR) in spayed, E-treated (28 days) and E + P-treated monkeys (14 days E + 14 days E + P). Hypothalamic blocks were prepared after perfusion fixation with 4% paraformaldehyde. Cryosectioning (10 mu m) was followed by double immunocytochemistry (ICC) for PR (black nuclear stain) and either BE or SP (brown cytoplasmic stain). Sections were processed for ICC at 100- or 200-mu m intervals through the hypothalamic block. Peptidergic neurons with and without PR were counted in each section. The E + P-treated monkeys exhibited a significant increase in serum prolactin. BE neurons were found only in the arcuate nucleus (ARC) and median eminence (ME). The colocalization of BE and PR equaled 2% in spayed controls, 21% in the E-treated group and 25% in the E + P-treated group. SP neurons were located in a dorsomedial hypothalamic (DMH) subpopulation which extended caudally under the mamillary nuclei and in a subpopulation located in the ARC and ME. Neither the DMH or submamillary SP neurons contained PR. The percent colocalization of SP and PR in the ARC/ME equaled 5, 26 and 10% in the spayed, E- and E + P-treated groups, respectively. The decrease in PR + SP colocalization with P treatment is probably due to a decrease in SP and not to a decrease in PR immunoreactivity. In summary, E treatment induced PR in BE and SP neurons. Addition of P to the E treatment did not alter the expression of PR in BE neurons, but PR colocalization decreased in SP neurons. Therefore, it is unlikely that SP neurons could transduce the action of P on prolactin secretion in primates, but BE neurons may play an intermediary role.
孕酮（P）作用于中枢神经系统，可增加经雌激素（E）预处理的雌性猴子的催乳素分泌。β-内啡肽（BE）和P物质（SP）是两种下丘脑肽，给大鼠和猴子注射时会增加催乳素分泌。开展研究以确定P是否作用于这两个潜在的催乳素释放系统。核类固醇受体的存在将细胞定义为同源激素的靶细胞。因此，检测了去势、经E处理（28天）和经E + P处理的猴子（14天E + 14天E + P）下丘脑BE和SP神经元群体中核孕激素受体（PR）的存在及调节情况。用4%多聚甲醛灌注固定后制备下丘脑组织块。冷冻切片（10μm）后进行PR（黑色核染色）与BE或SP（棕色胞质染色）的双重免疫细胞化学（ICC）。每隔100或200μm对下丘脑组织块进行ICC处理。对每片中有无PR的肽能神经元进行计数。经E + P处理的猴子血清催乳素显著增加。BE神经元仅见于弓状核（ARC）和正中隆起（ME）。在去势对照组中，BE与PR的共定位为2%，在经E处理组中为21%，在经E + P处理组中为25%。SP神经元位于下丘脑背内侧（DMH）亚群，该亚群在乳头体核下方向后延伸，以及位于ARC和ME的一个亚群中。DMH或乳头体下SP神经元均不含PR。在ARC/ME中，SP与PR的共定位百分比在去势组、经E处理组和经E + P处理组中分别为5%、26%和10%。P处理后PR + SP共定位的减少可能是由于SP减少而非PR免疫反应性降低。总之，E处理诱导BE和SP神经元中PR的产生。在E处理基础上加用P并未改变BE神经元中PR的表达，但SP神经元中PR的共定位减少。因此，SP神经元不太可能转导P对灵长类动物催乳素分泌的作用，但BE神经元可能起中介作用。
