Pitrosky B, Pévet P
URA-CNRS 1332, Neurobiologie des fonctions rythmiques et saisonnières, Université Louis-Pasteur, Strasbourg, France.
Biol Signals. 1997 Jul-Dec;6(4-6):264-71. doi: 10.1159/000109137.
The pineal gland conveys photoperiodic information to the brain through its daily pattern of melatonin (MEL) secretion. The duration of MEL secretion is proportional to the duration of the night. To determine the mechanism by which MEL transduces photoperiod, we used a protocol of daily MEL infusion given to sexually active pinealectomized Syrian hamsters. A long MEL signal (10 h) inhibited sexual activity, whereas a 5-hour infusion had no effect. However, animals given a 2.5-hour infusion twice separated by an interval of 3 h produced complete gonadal atrophy. Changes in the time interval between infusions blocked the potency of the MEL infusion, suggesting a tight temporal relationship between MEL signals. Additionally, the infusions were as effective whether applied during the day or during the night, in both long and short photoperiods. These data suggest that there is a rhythm of sensitivity to MEL involved in the photoperiodic response which is entrained by MEL itself.
松果体通过其每日褪黑素（MEL）分泌模式将光周期信息传递给大脑。MEL分泌的持续时间与夜晚的持续时间成正比。为了确定MEL转导光周期的机制，我们采用了对性活跃的松果体切除的叙利亚仓鼠每日进行MEL输注的方案。长时MEL信号（10小时）抑制性活动，而5小时输注则无影响。然而，间隔3小时给予两次2.5小时输注的动物出现了完全性腺萎缩。输注间隔时间的改变阻碍了MEL输注的效力，表明MEL信号之间存在紧密的时间关系。此外，无论在白天还是夜晚、长光周期还是短光周期进行输注，其效果都是一样的。这些数据表明，在光周期反应中存在对MEL的敏感性节律，该节律由MEL自身所调节。
