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The role of melatonin in hypothalamic regulation of pituitary hormone secretion in cattle.

褪黑激素在牛下丘脑调节垂体激素分泌中的作用。

基本信息

批准号：
17580251
负责人：
KASUYA Etsuko
金额：
$ 2.18万
依托单位：
National Institute of Agrobiological Sciences
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17580251/
关键词：
melatonin cattle growth hormone hypothalamus pituitary third ventricle neuroendocrinology stereotaxic surgery 第3脳室明暗脳

项目摘要

The present project was conducted to clarify the role of melatonin in hypothalamic regulation of growth hormone (GH) secretion from the anterior pituitary in cattle.In the first year of the project (2005), a chronic cannula was implanted in the third ventricle using a stereotaxic apparatus designed for cattle, and the effect of intracerebroventricular injection (icv) of melatonin through the cannula was evaluated in prepubertal Holstein steers. The icv injection of melatonin significantly stimulated GH release.In 2006, a series of experiments was performed in order to investigate the relationship between endogenous melatonin and GH secretions in steers. Animals were kept in the light controlled room (LIGHT 6:00-18:00, DARK 18:00-6:00 ; 12L:12D). Blood samples were collected during daytime (LIGHT, 11:00-15:00) and nighttime (DARK, 23:00-3:00), and the concentrations of melatonin, GH and prolactin (PRL) were determined. In addition, the response of GH secretion to GH-releasing hormone (GHRH) injection was investigated in each period. The secretion of melatonin showed a typical circadian rhythm (low during daytime and high during nighttime). A nocturnal GH increase was observed in the present study and this pattern of GH secretion has never been reported in this species before. Furthermore, the increase in GH after GHRH injection tended to be higher during nighttime than that during daytime.In summary, the present results suggest that melatonin is involved in the regulatory mechanism of GH secretion from the anterior pituitary via the hypothalamus in cattle.

本研究旨在阐明褪黑激素在下丘脑调节牛垂体前叶生长激素分泌中的作用。在研究的第一年（2005年），使用为牛设计的立体定位装置在第三脑室植入慢性插管，并对青春期前荷斯坦肉牛进行了侧脑室注射褪黑素的效果评价。icv注射褪黑素能显著促进生长激素的分泌。2006年，本研究进行了一系列试验，以研究内源性褪黑素与生长激素分泌的关系。将动物饲养在光照控制室（光照6：00-18：00，黑暗18：00-6：00 ; 12 L：12 D）。分别于白天（LIGHT，11：00-15：00）和夜间（DARK，23：00-3：00）采集血样，测定血清褪黑素、生长激素（GH）和催乳素（PRL）浓度。此外，在每个时期，生长激素释放激素（GHRH）注射GH分泌的反应进行了研究。褪黑激素的分泌呈典型的昼夜节律（白天低，夜间高）。在本研究中观察到夜间GH增加，这种GH分泌模式以前从未在该种属中报告过。此外，生长激素的增加后，GHRH注射后，往往是在夜间高于白天。综上所述，目前的研究结果表明，褪黑激素参与的调节机制，生长激素分泌的垂体前叶通过下丘脑在牛。