1992 Fiscal Year Final Research Report Summary
Cyourui saakadian rizumu no shinnke naibunnpitsu kikou
| Project/Area Number |
03660279
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
畜産学(含草地学)
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| Research Institution | Nagoya University |
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Principal Investigator |
EBIHARA Shizufumi Nagoya University School of Agriculture Associate Professor, 農学部, 助教授 (50135331)
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| Project Period (FY) |
1991 – 1992
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| Keywords | サーカディアンリズム / 松果体 / メラトニン / ダイアリシス / ハト |
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| Research Abstract |
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.
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