FEEDING RHYTHM AND ORNITHINE DECARBOXYLASE ACTIVITY IN HEREDITARY MICROPHTHALMIC RATS

The effects of congenital absence of visual input on daily rhythms of feeding behavior and tissue omithine decarboxylase activity were exami ned in hereditary blind rats. Food intake of normal and hereditary mic rophthalmic rats was determined every 3 h over 48 h under a 12 h-12 h light-dark cycle. Normal rats took their daily food mainly during the dark period, with two clear peaks in the evening and morning, but here ditary microphthalmic rats ate continuously, suggesting that the feedi ng rhythm of the hereditary microphthalmic rats is not entrained by th e light-dark cycle due to a lack of their optic nerve. The hepatic and renal ornithine decarboxylase activities in normal rats showed a circ adian rhythm with a peak at 2000 hours in the dark period as reported previously. In hereditary blind rats, however, the hepatic and renal e nzyme activities were found not to undergo any remarkable diurnal chan ge through the light-dark period. These results mean that the feeding rhythm and hepatic and renal omithine decarboxylase activity rhythm in hereditary blind rats disappeared. (C) 1997 Elsevier Science Inc.