Stokkan K A, Nonaka K O, Lerchl A, Vaughan M K, Reiter R J
Department of Arctic Biology, University of Tromsøo, Norway.
J Pineal Res. 1991 Jan;10(1):43-8. doi: 10.1111/j.1600-079x.1991.tb00008.x.
The effect of 24-hr exposure to cold (5 degrees C) was studied in male Syrian hamsters adapted to short days (LD 8:16). Both pineal N-acetyltransferase (NAT) activity and pineal and serum concentrations of melatonin showed a clear, diel rhythm with a moderate but significant increase late in the dark period. The nighttime peak levels of NAT activity and pineal and serum melatonin were significantly higher in the animals that had been exposed to cold than in those remaining in warm (22 degrees C) conditions. The activity of type-II 5'-deiodinase (5'D) in the brown adipose tissue (BAT) was not different after 24 hr of cold exposure between cold- and warm-exposed hamsters, and the enzyme did not show any diel rhythmicity. It has been speculated that some effects of cold exposure may be simulated by melatonin treatment; the present data further support this notion. The apparent lack of response in BAT 5'D activity remains enigmatic and needs further investigation.
研究了适应短日照（光照周期为8小时光照：16小时黑暗，LD 8:16）的雄性叙利亚仓鼠暴露于寒冷环境（5摄氏度）24小时的影响。松果体N-乙酰基转移酶（NAT）活性以及松果体和血清中褪黑素的浓度均呈现明显的昼夜节律，在黑暗期后期有适度但显著的升高。与处于温暖环境（22摄氏度）的仓鼠相比，暴露于寒冷环境的仓鼠夜间NAT活性峰值以及松果体和血清褪黑素水平显著更高。暴露于寒冷环境24小时后，棕色脂肪组织（BAT）中II型5'-脱碘酶（5'D）的活性在冷暴露和暖暴露的仓鼠之间没有差异，并且该酶未表现出任何昼夜节律性。据推测，褪黑素处理可能模拟寒冷暴露的某些效应；目前的数据进一步支持了这一观点。BAT中5'D活性明显缺乏反应仍然是个谜，需要进一步研究。
