Johnson A L
Proc Soc Exp Biol Med. 1987 Jan;184(1):118-22. doi: 10.3181/00379727-184-42455.
Experiments were conducted in the horse mare to study the effects of photoperiod and season on serum prolactin and pituitary responsiveness to thyrotropin-releasing hormone (TRH). Increasing the photoperiod to 16 hr light:8 hr dark beginning in December (Experiment 1) and September (Experiment 2) increased serum prolactin, but the rate of increase was greater when the photoperiod treatment was initiated in September. In addition, TRH-induced prolactin secretion was found to be affected by season, in that pituitary secretion (net increase in prolactin and total prolactin secreted) was significantly greater in June compared with that of January (Experiment 3). These data suggest that in the mare, photoperiod plays an important role in controlling circulating levels of prolactin, but that in addition to photoperiod, other seasonally related factors, such as temperature, are involved in modulating the seasonal rhythm of serum prolactin.
在母马身上进行了实验，以研究光周期和季节对血清催乳素以及垂体对促甲状腺激素释放激素（TRH）反应性的影响。从12月（实验1）和9月（实验2）开始，将光周期增加到16小时光照：8小时黑暗，血清催乳素增加，但9月开始进行光周期处理时，催乳素增加的速率更大。此外，发现TRH诱导的催乳素分泌受季节影响，6月垂体分泌（催乳素净增加量和分泌的总催乳素）相比1月显著更高（实验3）。这些数据表明，在母马中，光周期在控制催乳素循环水平方面发挥重要作用，但除光周期外，其他与季节相关的因素，如温度，也参与调节血清催乳素的季节性节律。
