Parhar I S, Soga T, Sakuma Y
Department of Physiology, Nippon Medical School, Tokyo, 113-8602,
Gen Comp Endocrinol. 1998 Dec;112(3):406-14. doi: 10.1006/gcen.1998.7143.
We investigated the effects of castration and progesterone administration on the three gonadotropin-releasing hormone (GnRH)-encoding mRNAs in sexually mature male tilapia Oreochromis niloticus. In situ hybridization histochemistry was performed using 35S-labeled antisense oligonucleotide probes complementary to salmon-, seabream-, and chicken II-GnRH cDNAs to quantify cellular GnRH mRNA expression in the terminal nerve ganglia (nucleus olfactoretinalis), preoptic area, and midbrain tegmentum of animals castrated for 2 weeks and injected intraperitoneally with sesame oil or progesterone. Castration significantly elevated salmon-GnRH mRNA but not seabream- or chicken II-GnRH mRNA levels. Progesterone treatment had no effect on salmon-, seabream-, or chicken II-GnRH mRNA levels. Comparisons between intact, castrated, and progesterone-treated animals showed no change in the total volume of nucleus olfactoretinalis, cell sizes, and total numbers of cells expressing GnRH mRNA within the midbrain and preoptic area. These results demonstrate that salmon-GnRH but not seabream- or chicken II-GnRH-synthesizing neurons are under a gonadal steroid negative feedback control and that progesterone might not be the main hormone regulating the three GnRH-encoding mRNAs in the male tilapia.
我们研究了去势和注射孕酮对性成熟雄性尼罗罗非鱼三种促性腺激素释放激素（GnRH）编码mRNA的影响。使用与鲑鱼、海鲷和鸡II型GnRH cDNA互补的35S标记反义寡核苷酸探针进行原位杂交组织化学，以量化去势2周并腹腔注射芝麻油或孕酮的动物终末神经节（嗅视网膜核）、视前区和中脑被盖中细胞GnRH mRNA的表达。去势显著提高了鲑鱼GnRH mRNA水平，但未提高海鲷或鸡II型GnRH mRNA水平。孕酮处理对鲑鱼、海鲷或鸡II型GnRH mRNA水平没有影响。完整、去势和孕酮处理动物之间的比较表明，嗅视网膜核的总体积、细胞大小以及中脑和视前区内表达GnRH mRNA的细胞总数没有变化。这些结果表明，合成鲑鱼GnRH的神经元而非合成海鲷或鸡II型GnRH的神经元受到性腺类固醇负反馈控制，并且孕酮可能不是调节雄性罗非鱼三种GnRH编码mRNA的主要激素。
