Petitclerc D, Chapin L T, Harkins P A, Tucker H A
Proc Soc Exp Biol Med. 1983 Apr;172(4):478-81. doi: 10.3181/00379727-172-41590.
Changing daily exposure of prepubertal bulls from 8 hr of light: 16 hr of dark (8L:16D) to 16L:8D or 6L:8D:2L:8D increased basal secretion of prolactin 418% 6 weeks later. When daily exposure was changed from 8L:16D (6 weeks) to 6L:14D:2L:2D (6 weeks), basal secretion of prolactin increased only 173%. Among photoperiod exposures, prolactin released into blood after injection of 33 micrograms/100 kg body weight of thyrotropin-releasing hormone paralleled the changes described for basal conditions. There was no repeatable diurnal secretory pattern for secretion of prolactin. The data support the hypothesis that cattle possess a photosensitive rhythm for secretion of prolactin.
将青春期前公牛的每日光照时长从8小时光照：16小时黑暗（8L:16D）改变为16L:8D或6L:8D:2L:8D，6周后催乳素基础分泌增加了418%。当每日光照时长从8L:16D（6周）改变为6L:14D:2L:2D（6周）时，催乳素基础分泌仅增加了173%。在不同的光照周期中，注射33微克/100千克体重促甲状腺激素释放激素后血液中释放的催乳素与基础状态下描述的变化情况相似。催乳素分泌没有可重复的昼夜分泌模式。这些数据支持了牛具有催乳素分泌的光敏节律这一假说。
