Cyourui saakadian rizumu no shinnke naibunnpitsu kikou

鸟类的昼夜节律是由包括松果体、眼睛和下丘脑振荡器在内的多个振荡系统调节的。这个项目的目的是了解这些昼夜节律组成部分之间的相互作用，这对维持明显的昼夜节律至关重要。为此，我们建立了测定鸽子松果体褪黑激素昼夜节律的微透析技术。使用这种技术，局部光照对眼睛的影响松果体褪黑激素释放进行了研究。这是阐明眼睛和松果体器官之间功能联系的方法之一。这项研究的结果表明，光接收视网膜几乎没有贡献的松果体褪黑激素释放的抑制。由于松果体褪黑激素完全被其他大脑区域而不是眼睛的光暴露所抑制，因此已经表明光诱导的褪黑激素抑制是由鸽子的视网膜外光感受器引起的。微透析也可用于研究光诱导的松果体褪黑激素节律的相移。当鸽子在黑暗中暴露于光时（CT 18; CT 0是活动的开始），松果体褪黑激素节律发生相移。此外，在CT 12和CT 18处施用的单个光脉冲分别在仅具有视网膜照明和具有视网膜和视网膜外照明的鸽子中诱导相位提前和相位延迟。这些结果提出了光诱导的松果体褪黑激素抑制和光诱导的松果体褪黑激素节律的相移是由不同的神经连接控制的可能性。

Avian circadian rhythms are regulated by a multiple oscillating system including the pineal, the eye and the hypothalamic oscillator(s). The object of this project is to understand the interactions between these circadian components which are essential for maintaining overt circadian rhythms. For this purpose, we have established the microdialysis technique for measuring circadian rhythms of pineal melatonin in pigeons. Using this technique, effects of local light exposure to the eye on pineal melatonin release were studied. This is one of the ways to elucidate the functional connection between the eye and the pineal organ. The results of this study have indicated that light received by the retina hardly contribute to suppression of pineal melatonin release. Because pineal melatonin was completely suppressed by light exposure of other brain areas than the eye, it has been indicated that light induced suppression of melatonin is caused by extraretinal photoreceptors in pigeons. Microdialysis is also available for studying light induced phase shift of pineal melatonin rhythms. when pigeons were exposed to light during the dark (CT 18; CT 0is the onsets of activity), phase shifts of pineal melatonin rhythms occurred. Moreover a single light pulse administered at CT 12 and CT 18 induced phase advances and phase delays, respectively in both pigeons with only retinal illumination and with retinal and extraretinal illumination. These results have raised the possibility that light induced suppression of pineal melatonin and light induced phase-shifts of pineal melatonin rhythms are controlled by different neural connection in pigeons.