Gasser P J, Gern W A
Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, 82070, USA.
Gen Comp Endocrinol. 1997 Feb;105(2):210-7. doi: 10.1006/gcen.1996.6822.
The effects of calcium depletion and of three calcium channel drugs on melatonin synthesis in pineal organs of rainbow trout (Oncorhyncus mykiss) were examined. Dark-induced melatonin synthesis was inhibited by calcium depletion, by treatment with nitrendipine (NTR), an antagonist of the L-type voltage-sensitive calcium channel, and by treatment with omega-Conotoxin GVIA, an antagonist of the N-type voltage-sensitive calcium channel. Bay K 8644, an agonist of the L-type channel, had no significant effect on pineal melatonin synthesis. These data represent evidence that calcium entry into trout pineal photoreceptor cells through voltage-sensitive calcium channels is important in the maintenance of dark-induced melatonin synthesis and that light's inhibitory effect on melatonin synthesis may be mediated by closure of these channels. NTR-induced inhibition of dark-induced melatonin synthesis was abolished when dibutyryl cyclic AMP (db-cAMP) was administered to NTR-treated pineal organs, suggesting that calcium acts upstream of cAMP in regulating melatonin synthesis.
研究了钙耗竭及三种钙通道药物对虹鳟（Oncorhyncus mykiss）松果体褪黑素合成的影响。钙耗竭、用L型电压敏感性钙通道拮抗剂尼群地平（NTR）处理以及用N型电压敏感性钙通道拮抗剂ω-芋螺毒素GVIA处理均抑制了黑暗诱导的褪黑素合成。L型通道激动剂Bay K 8644对松果体褪黑素合成无显著影响。这些数据表明，通过电压敏感性钙通道进入鳟鱼松果体光感受器细胞的钙对于维持黑暗诱导的褪黑素合成很重要，并且光对褪黑素合成的抑制作用可能是由这些通道的关闭介导的。当向经NTR处理的松果体器官施用二丁酰环磷腺苷（db-cAMP）时，NTR诱导的黑暗诱导的褪黑素合成抑制被消除，这表明钙在调节褪黑素合成中作用于cAMP的上游。
