Barenton B, Pelletier J, Ortavant R
C R Seances Acad Sci III. 1983;297(6):327-30.
The influence of photoperiod on GH release has been studied in Rams subjected to two different light regimes. The first group was submitted to natural daylight variations. The second group received daily the following split photoperiod: 7 L, 9 D, 1 L, 7 D, known to stimulate the release of prolactin. The experiment lasted 5 months, from January to June. In the first group, plasma GH concentrations decreased significantly from January to February (10.1 +/- 0.4 vs 8.7 +/- 0.3 ng X hr./ml; P less than 0.02), then increased from April to June (9.3 +/- 0.4 vs 10.5 +/- 0.7 ng X hr./ml; P less than 0.02). In the second group, GH concentrations were higher than in the first group in April (11.9 +/- 0.9 vs 9.3 +/- 0.4 ng X h/ml; P less than 0.05). However, it decreased between April and June (11.9 +/- 0.9 vs 9.7 +/- 0.4 ng X hr./ml; P less than 0.02) and then did not differ from that of the first group. These results show that plasma GH concentrations are affected by photoperiodic changes and suggest the existence of seasonal variations in GH plasma levels in the Ram.
在处于两种不同光照条件下的公羊中，研究了光周期对生长激素（GH）释放的影响。第一组接受自然日光变化。第二组每天接受以下分段光周期：7小时光照、9小时黑暗、1小时光照、7小时黑暗，已知这种光周期会刺激催乳素的释放。实验从1月持续到6月，为期5个月。在第一组中，血浆GH浓度从1月到2月显著下降（10.1±0.4对8.7±0.3纳克·小时/毫升；P<0.02），然后从4月到6月升高（9.3±0.4对10.5±0.7纳克·小时/毫升；P<0.02）。在第二组中，4月份的GH浓度高于第一组（11.9±0.9对9.3±0.4纳克·小时/毫升；P<0.05）。然而，它在4月至6月间下降（11.9±0.9对9.7±0.4纳克·小时/毫升；P<0.02），然后与第一组没有差异。这些结果表明，血浆GH浓度受光周期变化影响，并提示公羊血浆中GH水平存在季节性变化。
