| Research Abstract |
The all living organisms in the earth are exposed to cyclic environmental factors which are produced by earth's rotation and revolution. They had a biological clock to adapt to these cyclic environments. This biological clock regulate the circadian or circanual rhythms of various physiological functions. The purpose of this study is to examine how circadian clock regulate the physiological rhythm, and to examine the relationship between the circadian oscillator and regulator of food intake.
The avian pineal gland posses the circadian clock, photoreceptor and melatonin synthetic capacity, and these three components are rinks all together. Therefore it has been assumed that melatonin regulate the biological rhythm. The administration of melatonin caused decrease of body temperature and inhibition of locomotor activity in house sparrow and Japanese quail. These results suggest that melatonin secretion from pineal gland during night time inhibits the locomotor activity and decrease body temperature, results in resting time.
We discovered that ghrelin, a GH stimulating hormone, is a potent stimulator of food intake, and that neuromedin U is a inhibitor of food intake. Therefore, we examined the effect of them on the biological clock. The neuromedin U caused phase-shift of circadian rhythm in the time-dependent manner. Further, Immunohystochemistly revealed that immunostained cells for neuromedin U locate in suprachiasmatic nucleus which is circadian oscillator. Theses results indicate that neuromedin U may be involved in both regulation of food-intake and circadian oscillation system.
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