Yáñez J, Meissl H
Max-Planck-Institut für Physiologische und Klinische Forschung, W. G. Kerckhoff-Institut, Bad Nauheim, Germany.
Neurochem Int. 1995 Aug;27(2):195-200. doi: 10.1016/0197-0186(95)00028-7.
Synthesis and release of the pineal hormone melatonin is in all vertebrates primarily regulated by the light/dark cycle. In pineal organs of teleost fish, like in other non-mammalian vertebrates, melatonin formation is regulated by a direct photoreception of the pineal organ. We performed measurements in explanted, perifused pineal organs of the rainbow trout, Oncorhynchus mykiss, to examine whether melatonin can influence its own production. For this purpose we have continuously perifused isolated pineal organs under light- and dark-adapted conditions and measured the release of melatonin and other methoxy-indoles by HPLC with electrochemical detection. Addition of 2-iodomelatonin to the perifusate in a concentration of 2 ng/ml significantly inhibited melatonin release in light-, as well as in dark-adapted organs. The release of 5-methoxytryptamine and 5-methoxytryptophol was also significantly reduced in light-adapted organs. These results indicate that extracellular melatonin may act as a paracrine or autocrine feedback signal and may be important for the illumination-dependent melatonin production.
松果体激素褪黑素的合成与释放，在所有脊椎动物中主要受光/暗周期调节。在硬骨鱼的松果体器官中，与其他非哺乳动物脊椎动物一样，褪黑素的形成受松果体器官的直接光感受调节。我们对虹鳟（Oncorhynchus mykiss）离体灌流的松果体器官进行了测量，以研究褪黑素是否会影响其自身的产生。为此，我们在光适应和暗适应条件下对分离的松果体器官进行连续灌流，并通过高效液相色谱-电化学检测法测量褪黑素和其他甲氧基吲哚的释放。向灌流液中添加浓度为2 ng/ml的2-碘褪黑素，可显著抑制光适应和暗适应器官中褪黑素的释放。在光适应器官中，5-甲氧基色胺和5-甲氧基色醇的释放也显著减少。这些结果表明，细胞外褪黑素可能作为旁分泌或自分泌反馈信号，并且可能对光照依赖性褪黑素的产生很重要。
