Differential Regulation of Kiss1 Expression by Melatonin and Gonadal Hormones in Male and Female Syrian Hamsters

摘要: In seasonal breeders, reproduction is synchronized to seasons by day length via the pineal hormone melatonin. Recently, we have demonstrated that Kiss1, a key activator of reproductive function, down-regulated in sexually inactive hamsters maintained inhibitory short days (SDs). rodents, Kiss1 expressed anteroventral periventricular nucleus (AVPV) and arcuate (ARC). Because both duration nocturnal peak melatonin circulating sex steroid levels vary with photoperiod, aim this study was determine whether steroids differentially regulate expression ARC AVPV. examined situ hybridization male female kept various experimental conditions, observed 1) SD exposure markedly reduced AVPV as compared LD animals, 2) treatment SD-adapted increased number neurons but decreased it ARC, 3) administration LD-adapted mRNA level intact whereas castrated hamsters, rapidly inhibited not AVPV, 4) pinealectomy or conclusion, our data demonstrate Syrian hamster hypothalamus different mechanisms. inhibits direct effect on hypothalamus, probably dependent, decrease appears be secondary melatonin-driven reduction levels. Taken together, support hypothesis mediate effects gonadotropic axis hamster.