Pelletier J, Brieu V, Ravault J P
C R Acad Sci III. 1985;301(6):323-8.
Light entrainment and stimulation of PRL release were studied in rams submitted to artificial light regimes: In a first experiment four groups of animals were submitted to light regimes with a period of 6, 4, 3 or 2 months respectively (T6 to T2 groups) and amplitude of 8-16 h of daylength. In all four groups PRL level was significantly correlated with daylength (r greater than 0.51; P less than 0.01). However in July, when temperatures were indeed high, an additional PRL increase was observed in the T6, T4 and T3 groups, although the role of temperature appears debatable. In a second experiment, animals were exposed daily to 8 hrs. of light given in two photofractions. The first fraction of 7 hrs. began at the same time as "dawn", and the second of 1 hr ended at the same time as "dusk" of the T6 group in the first experiment which served as control group. Correlation of plasma prolactin in rams receiving 8 h light in one or two photofractions was highly significant (r = 0.66; P less than 0.001). This suggests that rams measured daylength between two limits considered as "dawn" and "dusk" even if lights were turned off during part of this interval.
在处于人工光照条件下的公羊中研究了光对催乳素（PRL）释放的诱导和刺激作用：在第一个实验中，将四组动物分别置于光照周期为6、4、3或2个月（T6至T2组）且日长幅度为8 - 16小时的光照条件下。在所有四组中，PRL水平与日长显著相关（r大于0.51；P小于0.01）。然而在7月，当气温确实很高时，在T6、T4和T3组中观察到PRL额外升高，尽管温度的作用似乎存在争议。在第二个实验中，动物每天暴露于8小时的光照，分为两个光照时间段。第一个7小时的时间段与“黎明”同时开始，第二个1小时的时间段与第一个实验中作为对照组的T6组的“黄昏”同时结束。接受一个或两个光照时间段共8小时光照的公羊血浆催乳素的相关性非常显著（r = 0.66；P小于0.001）。这表明公羊即使在该时间段的部分时间关灯，也能测量两个被视为“黎明”和“黄昏”的界限之间的日长。
