Effects of photoperiod on salmon GnRH mRNA levels in brain of castrated underyearling precocious male masu salmon
Effects of photoperiod on salmon GnRH mRNA levels in brain of castrated underyearling precocious male masu salmon
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DOI：
10.1006/gcen.1999.7286
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发表时间：
1999-07-01
影响因子：
2.7
通讯作者：
Aida, K
中科院分区：
文献类型：
--
作者：
Amano, M;Ikuta, K;Aida, K
以前的研究表明，激活鲑鱼促性腺激素释放激素（sGnRH）产生的神经元诱导的光周期和类固醇激素的联合作用在未成年男性的masu鲑鱼，Oncorhynchus masou。本研究进一步评估了光周期和类固醇激素对sGnRH合成活性的影响，并通过操纵光周期从8月到10月持续60天，检查了阉割的未成年早熟雄性马苏鲑鱼大脑中sGnRH mRNA水平的变化。在血浆睾酮水平降低至低水平的去势雄性中，视前区（POA）的sGnRH mRNA水平在短光周期（8L-16 D）下增加，而在长光周期（16 L-8 D）下持续2个月保持在低水平。在假手术的男性，sGnRHmRNA水平腹侧端脑和POA的增加，在10月与睾丸成熟，即使在长光周期与短光周期组相比，延迟1个月。这些结果表明，视前sGnRH产生神经元接收短的光周期信号和短的光周期或类固醇激素分泌所需的未成年早熟男性马苏鲑鱼sGnRH合成的激活。(C)北京：科学出版社.
Previous studies have suggested that activation of salmon gonadotropin-releasing hormone (sGnRH)-producing neurons is induced by the combined effects of photoperiod and steroid hormones in underyearling males of the masu salmon, Oncorhynchus masou. The present study further assesses the effects of photoperiod and steroid hormones on sGnRH synthetic activity and examines the changes in sGnRH mRNA levels in the brains of castrated underyearling precocious male masu salmon by manipulating the photoperiod for 60 days from August through October. In castrated males in which plasma testosterone levels decreased to low levels, sGnRH mRNA levels in the preoptic area (POA) increased under a short photoperiod (8L-16D), whereas they remained at low levels under a long photoperiod (16L-8D) for a 2-month duration. In sham-operated males, sGnRH mRNA levels in the ventral telencephalon and those in the POA increased in October with testicular maturation even under a long photoperiod with a delay of 1 month compared with the short photoperiod group. These results suggest that preoptic sGnRH-producing neurons receive short photoperiodic signals and that either short photoperiod or steroid hormone secretion is required for the activation of sGnRH synthesis in underyearling precocious male masu salmon. (C) 1999 Academic Press.