Characteristics of physiological and biochemical properties and metabolic rhythms in hereditary microphthalmic rat.

点击翻译按钮获取中文摘要

The characteristics in the physiological, biochemical and hormonal properties, and the rhythms of spontaneous locomotor activity and some metabolic enzyme activities were examined in the microphthalmic rat of the Donryu strain. The hereditary microphthalmic rats were produced through brother-sister mating in our laboratory. The growth of the mutant was retarded as compared to that of normal rat from the same strain. The mutant exhibited almost normal properties of biochemical and physiological functions except for glucose metabolism. Responses of the biochemical parameters of protein, lipid and mineral metabolism to restricted food access in the mutant did not differ from those in normal rats. Normal rats showed basically nocturnal pattern of the locomotor activity rhythm, but most of microphthalmic rats manifested free-running rhythms and a few of them showed arrhythmic. When food access was restricted only for 6 h in the light period of the LD cycle, the normal and hereditary blind r … More ats generated gradually new patterns of the locomotor rhythm in which the animals showed to be more active in the light phase. The activities of ornithine decarboxylase in the mutant were found not to undergo a remarkable circadian fluctuation. The pineal enzyme activities and the mRNA levels of serotonin N-acetyltransferase in normal rats increased more than 50-fold at night than the day value, but some of the mutant showed highly abundant the mRNA but the others exhibited no detectable amount of the mRNA both in the light and in the dark period, and similar circadian patterns were found in enzyme activity, suggesting that the rhythms in the mutant became free-running, asynchronous. While, the pineal enzyme activity increased at the subjective night but depressed at the subjective day. As for the infradian rhythms, the mutant rat manifested irregular sexual cycle estimated by lutenizing hormone (LH) surge. By immunohistochemical detection of tyrosine hydroxylase and the concentrations of monoamines, the metabolic aspects of catecholamine in the substantia nigra and hypothalamus in the mutant were approximately the same as those of normal rats. Thesr results suggest that microphthalmic mutant rats maintain the ability to shift and to synchronize their circadian phases induced by restricted access to food, even if they completely lack their optic nerve and visual input to the circadian clock. This hereditary microphthalmic rat will be useful as the model experimental animals for The studies of chronobiology. Less