The effect of lighting conditions on the rhythmicity of growth hormone secretion in Holstein steers
The effect of lighting conditions on the rhythmicity of growth hormone secretion in Holstein steers
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DOI：
10.1111/j.1740-0929.2011.00949.x
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发表时间：
2012-01-01
影响因子：
2
通讯作者：
Sutoh, Madoka
中科院分区：
文献类型：
--
作者：
Kasuya, Etsuko;Kushibiki, Shiro;Sutoh, Madoka
测定了阉牛生长激素（GH）的分泌规律以及光照条件和生长激素释放激素（GHRH）对生长激素分泌的影响。首先，将阉牛保持在12：12 L：D条件下（光照：06.0018.00小时）。然后，动物在光照开/关条件下提前1小时（分别为05.00和17.00小时）。在每种条件的第七天，以1小时的间隔采集血液24小时。第二，GHRH在12：12 L：D下于12.00和00.00小时静脉内（IV）注射，并以15 min间隔采集血液，持续4 h（注射前1 h和注射后3 h）。用放射免疫法测定血浆GH浓度。用最大熵功率谱分析法计算GH分泌曲线的周期性。血浆GH浓度显示由四个不同峰组成的特征性模式。生长激素分泌曲线的平均周期为5.7小时，它没有改变任何光照条件的变化。静脉注射GHRH可增加GH的昼夜分泌。夜间注射GHRH后GH分泌量的增加与白天相当。本研究结果表明，阉牛垂体前叶分泌的GH具有一定的规律性。
Growth hormone (GH) secretion regularity and the effects of lighting condition and GH-releasing hormone (GHRH) on GH release were determined in steers. First, steers were kept under 12:12 L : D conditions (light: 06.0018.00 hours). The animals were then subjected to a 1-h advancement in lighting on/off conditions (05.00 and 17.00 hours, respectively). Blood was sampled for 24 h at 1-h interval on the seventh day of each condition. Second, GHRH was injected intravenously (IV) at 12.00 and 00.00 hours under 12:12 L : D and blood was sampled at 15-min interval for 4-h (1 h before and 3 h after the injection). Plasma GH concentrations were measured by a radioimmunoassay. Periodicity of GH secretory profile was calculated by power spectrum analysis using the maximum entropy method. Plasma GH concentrations showed a characteristic pattern consisting of four distinct peaks. Mean periodicity of GH secretory profile was 5.7 h, and it was not altered by any change in lighting conditions. IV injection of GHRH increased GH secretion during the day and night. The increase in GH secretory volume after GHRH injection during the night was equal to that during the day. The present results suggest that GH secreted from the anterior pituitary have regularity in steers.