Delgado M J, Vivien-Roels B
Departamento de Biología Animal II, Facultad de Biología, Universidad Complutense, Madrid, Spain.
Gen Comp Endocrinol. 1989 Jul;75(1):46-53. doi: 10.1016/0016-6480(89)90006-3.
Day-night melatonin concentrations were studied in the pineal body, lateral eye, and plasma of the frog Rana perezi in animals maintained in February and July under long (18L:6D) or short (6L:18D) photoperiod and high (25 +/- 1 degree) or low (6 +/- 1 degree) temperature in order to evaluate the influence of these environmental factors. When frogs were kept under short photoperiod and low temperature in February, no melatonin rhythm was observed in the pineal, ocular tissue, and plasma. High temperature at this period of the year induced a day-night rhythm of melatonin levels in the lateral eye and plasma. In July, under long photoperiod and high temperature, animals showed pronounced rhythms of melatonin in the pineal, eye, and plasma. A decrease of environmental temperature in this season abolished the melatonin rhythm. When animals were maintained in August under high (25 +/- 1 degree) temperature and long (18L:6D) or short (6L:18D) photoperiod, the duration of high night time ocular melatonin levels was correlated to the length of the dark phase. In all experiments the high ocular melatonin concentrations and the close parallelism observed between ocular and circulating melatonin profiles suggest that in this species melatonin could be released from the eyes in the general circulation.
研究了处于二月和七月的泽陆蛙松果体、侧眼及血浆中的昼夜褪黑素浓度，这些动物分别处于长（18小时光照：6小时黑暗）或短（6小时光照：18小时黑暗）光周期以及高（25±1摄氏度）或低（6±1摄氏度）温度条件下，以评估这些环境因素的影响。二月时，当青蛙处于短光周期和低温环境下，松果体、眼组织及血浆中未观察到褪黑素节律。一年中的这个时期高温会诱导侧眼和血浆中褪黑素水平出现昼夜节律。七月时，在长光周期和高温条件下，动物的松果体、眼睛及血浆中显示出明显的褪黑素节律。这个季节环境温度降低会消除褪黑素节律。八月时，当动物处于高（25±1摄氏度）温度及长（18小时光照：6小时黑暗）或短（6小时光照：18小时黑暗）光周期条件下，夜间侧眼褪黑素高水平的持续时间与黑暗期长度相关。在所有实验中，高眼内褪黑素浓度以及眼内和循环褪黑素水平之间观察到的紧密平行关系表明，在该物种中褪黑素可能从眼睛释放进入体循环。
