Effects of restricted food access on diurnal fluctuation of behaviors and biochemical functions in hereditary microphthalmic rats

Author(s): Shim, S., Hitomi, Y., Sugita, S., Sugahara, K.

Journal/Book: Physiol Behav. 1999; 67: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 167-172.

Abstract: The characteristics in circadian rhythms of spontaneous locomotor activity, and some metabolic properties were examined in microphthalmic mutant rats of the Donryu strain under ad lib or restricted food access conditions. The growth of microphthalmic rats was retarded compared to that of normal-sighted rats from the same strain. Under a 12:12-h light:dark (LD) cycle with free access to food, normal-sighted rats showed basically nocturnal patterns of the locomotor activity rhythms, 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 rats generated gradually new patterns of the locomotor activities in which the animals showed to be more active in the light period. Plasma glucose concentration in normal rats showed a peak after food consumption, but microphthalmic mutants exhibited no periodic changes of the glucose levels. Responses of the biochemical parameters of protein and mineral metabolism to restricted food access in the mutants did not differ from those in normal rats. These results suggest that microphthalmic mutant rats show the free-running circadian rhythm of locomotor activity due to a complete lack of their optic nerve and visual input to the circadian clock, but the mutants maintained the ability to shift their circadian phase induced by restricted food access similar to that in control rats, and also that the mutants have almost normal properties of biochemical and physiological functions except for glucose metabolism.

Note: Article Tanaka H, Utsunomiya Univ, Fac Agr, Dept Appl Biol Chem, Mine 350, Utsunomiya, Tochigi 3218505, JAPAN

Keyword(s): circadian rhythm; locomotor activity; blood glucose; food restriction; hereditary microphthalmic rat; SEROTONIN N-ACETYLTRANSFERASE; CIRCADIAN-RHYTHMS; LOCOMOTOR-ACTIVITY; SUPRACHIASMATIC NUCLEUS; RUNNING ACTIVITY; LIGHT; SYNCHRONIZATION; LESIONS; SLEEP

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