Scott Christopher J, Mariani Michael, Clarke Iain J, Tilbrook Alan J
Department of Physiology, Monash University, Victoria, Australia.
Biol Reprod. 2003 Dec;69(6):2015-21. doi: 10.1095/biolreprod.103.016956. Epub 2003 Aug 20.
Enkephalin appears to exert an inhibitory action on LH secretion, but whether testosterone regulates enkephalin gene expression is unknown. This study tested the hypothesis that testosterone and/or season modulate preproenkephalin mRNA expression in specific areas of the hypothalamus. Romney Marsh rams were castrated (wethers) either during the breeding season or nonbreeding season and received intramuscular injections of either oil or testosterone propionate (five/group). Blood samples were taken for the assay of plasma LH and testosterone. Preproenkephalin mRNA expression was quantified in hypothalamic sections by in situ hybridization. Mean plasma LH concentrations were reduced and the interpulse interval for LH pulses was greater in testosterone propionate-treated wethers compared with oil-treated wethers, with no change in LH pulse amplitude. Testosterone propionate treatment reduced proenkephalin expression in the diagonal band of Broca, the caudal preoptic area, and the bed nucleus of the stria terminalis. Seasonal differences in proenkephalin expression were observed in the bed nucleus of the stria terminalis, lateral septum, periventricular nucleus, and paraventricular nucleus. No differences were observed between treatments in seven other regions examined. We conclude that testosterone and season regulate proenkephalin mRNA levels in the preoptic area/hypothalamus in the ram in a region-specific manner.
脑啡肽似乎对促黄体生成素（LH）的分泌发挥抑制作用，但睾酮是否调节脑啡肽基因表达尚不清楚。本研究检验了以下假设：睾酮和/或季节调节下丘脑特定区域中前脑啡肽原mRNA的表达。在繁殖季节或非繁殖季节对罗姆尼沼泽公羊（阉羊）进行去势，并对其进行肌肉注射，注射物为油或丙酸睾酮（每组五只）。采集血样用于检测血浆LH和睾酮。通过原位杂交对下丘脑切片中的前脑啡肽原mRNA表达进行定量。与接受油注射的阉羊相比，接受丙酸睾酮治疗的阉羊的平均血浆LH浓度降低，LH脉冲的脉冲间期更长，而LH脉冲幅度没有变化。丙酸睾酮治疗降低了布罗卡斜带、视前尾侧区和终纹床核中的脑啡肽原表达。在终纹床核、外侧隔、室周核和室旁核中观察到脑啡肽原表达的季节性差异。在其他七个检查区域中，各治疗组之间未观察到差异。我们得出结论，睾酮和季节以区域特异性方式调节公羊视前区/下丘脑中前脑啡肽原mRNA水平。
