Darrow J M, Tamarkin L, Duncan M J, Goldman B D
Biol Reprod. 1986 Aug;35(1):74-83. doi: 10.1095/biolreprod35.1.74.
Daily rhythms of pineal and serum melatonin content were characterized for adult female Turkish hamsters (Mesocricetus brandti) exposed to long days (16L:8D, 22 degrees C) or after transfer to short days (10L:14D, 22 degrees C). The nocturnal peak of pineal melatonin content was found to be approximately 3 b greater in duration on short than on long days. Changes in levels of serum melatonin closely paralleled those of pineal melatonin. Thus, an effect of photoperiod on synthesis and secretion of pineal melatonin was demonstrated. In a separate experiment, female hamsters were induced to hibernate by exposure to a short-day, cold environment (10L:14D, 6 degrees C). During the 4 to 5-mo hibernation season, Turkish hamsters are known to display 4 to 8-day hours of torpor (body temperature = 7-9 degrees C) alternating with 1 to 3-day intervals of euthermia (body temperature = 35-37 degrees C). Little evidence of nocturnal synthesis or secretion of pineal melatonin was detected in females sampled during torpor. However, animals sampled during the first day after arousal from a torpor bout displayed melatonin rhythms no different in phase or amplitude from those seen in females held at 22 degrees C. Thus, despite the absence of pineal melatonin output during torpor, the pineal gland of hibernating Turkish hamsters produces an appropriately phased, rhythmic melatonin signal during intervals of euthermia.
对暴露于长日照（16小时光照：8小时黑暗，22摄氏度）或转至短日照（10小时光照：14小时黑暗，22摄氏度）环境下的成年雌性土耳其仓鼠（布氏中仓鼠）的松果体和血清褪黑素含量的每日节律进行了表征。发现短日照条件下松果体褪黑素含量的夜间峰值持续时间比长日照条件下大约长3倍。血清褪黑素水平的变化与松果体褪黑素的变化密切平行。因此，证明了光周期对松果体褪黑素合成和分泌的影响。在另一个实验中，通过暴露于短日照、寒冷环境（10小时光照：14小时黑暗，6摄氏度）诱导雌性仓鼠冬眠。在4至5个月的冬眠季节中，已知土耳其仓鼠会表现出4至8天的蛰伏期（体温 = 7 - 9摄氏度），与1至3天的正常体温期（体温 = 35 - 37摄氏度）交替出现。在蛰伏期采样的雌性仓鼠中几乎未检测到松果体褪黑素的夜间合成或分泌迹象。然而，在从一次蛰伏发作苏醒后的第一天采样的动物，其褪黑素节律在相位或幅度上与在22摄氏度饲养的雌性仓鼠中观察到的节律没有差异。因此，尽管在蛰伏期松果体没有褪黑素输出，但冬眠的土耳其仓鼠的松果体在正常体温期会产生相位适当、有节律的褪黑素信号。
