Bosc M J
Station de Physiologie de la Reproduction, Institut National de la Recherche Agronomique, Monnaie, France.
J Reprod Fertil. 1987 Jul;80(2):563-8. doi: 10.1530/jrf.0.0800563.
Two experiments were carried out with rats isolated at mating (Day 1 of gestation) and kept in a standard light regimen of 14 h light (14L:10D). All treatments started on Day 8 of gestation; periodicities of 23:45 h, 24:00 h and 24:15 h were applied to the light phase (14L) in Exp. I and to daily treatment with melatonin (0.3 mg/rat) or its vehicle in Exp. II. In Exp. II, the animals were placed in a continuous dim light regimen and injections were given at a time corresponding to lights off. In all groups, rats delivered on the afternoon of Day 22 and on the morning of Day 23 after a cessation of parturitions. The rates of births during these two times depended on the periodicities of the light phase or those of melatonin administration. With a periodicity of 24:15 h, 85.7% of rats in Exp. I and 85.7% of rats in Exp. II delivered on Day 22. With a periodicity of 23:45 h, 83.0% of births occurred on Day 23 in Exp. I and 57.7% in Exp. II with melatonin instead of 25.9% in the corresponding vehicle controls. These results suggest that melatonin secretion may be a mechanism whereby photoperiod regulates the time of parturition in the rat.
进行了两项实验，实验对象为在交配时（妊娠第1天）隔离并饲养在14小时光照（14L:10D）标准光照方案下的大鼠。所有处理均在妊娠第8天开始；实验I中，将23:45小时、24:00小时和24:15小时的周期应用于光照阶段（14L），实验II中则应用于褪黑素（0.3毫克/只大鼠）或其赋形剂的每日处理。在实验II中，动物被置于持续昏暗光照方案下，并在对应熄灯的时间进行注射。在所有组中，大鼠在分娩停止后的第22天下午和第23天上午分娩。这两个时间段的出生率取决于光照阶段或褪黑素给药的周期。周期为24:15小时时，实验I中85.7%的大鼠和实验II中85.7%的大鼠在第22天分娩。周期为23:45小时时，实验I中83.0%的分娩发生在第23天，实验II中使用褪黑素的大鼠为57.7%，而相应赋形剂对照组为25.9%。这些结果表明，褪黑素分泌可能是光周期调节大鼠分娩时间的一种机制。
