Steger R W, Gay-Primel E
Department of Physiology, Southern Illinois University School of Medicine, Carbondale 62901-6512.
Biol Reprod. 1990 Feb;42(2):217-21. doi: 10.1095/biolreprod42.2.217.
Chronic afternoon (PM) but not morning injections of melatonin (MEL) induced significant reductions in testicular and seminal vesicle weights as well as attenuating serum prolactin (PRL) and luteinizing hormone (LH) levels. Although there were no treatment-induced effects on hemipituitary weights, PM-Mel injections led to significant reductions in in vitro PRL secretion and tended to increase the ability of dopamine to inhibit PRL release. It was also shown that LH-releasing hormone (LHRH) could inhibit in vitro PRL release from hamster pituitaries. Basal or LHRH-stimulated LH secretion from incubated pituitaries was not affected by Mel in vivo. From these results we conclude that properly timed Mel injections do not reduce pituitary's ability to secrete LH but severely attenuate PRL secretion. These findings are similar to those observed in pituitaries from hamsters housed in short-photoperiod conditions.
慢性午后（下午）而非早晨注射褪黑素（MEL）可显著降低睾丸和精囊重量，并减弱血清催乳素（PRL）和促黄体生成素（LH）水平。尽管治疗对垂体半侧重量没有影响，但下午注射褪黑素导致体外PRL分泌显著减少，并倾向于增强多巴胺抑制PRL释放的能力。研究还表明，促性腺激素释放激素（LHRH）可抑制仓鼠垂体的体外PRL释放。体内褪黑素对孵育垂体的基础或LHRH刺激的LH分泌没有影响。从这些结果我们得出结论，适时注射褪黑素不会降低垂体分泌LH的能力，但会严重减弱PRL分泌。这些发现与在短光照条件下饲养的仓鼠垂体中观察到的结果相似。
