beta-carotene 15,15 '-dioxygenase activity in streptozotocin-induced diabetic rats

We measured retinol levels and beta -carotene 15,15'-dioxygenase activity i n rats with streptozotocin-induced diabetes mellitus to assess the relation ship between the disease and the conversion of beta -carotene to retinol. T he plasma retinol level was significantly lower in diabetic rats than in co ntrol rats, but the hepatic retinol level was significantly higher than the control. The hepatic dioxygenase activity but not that of the intestinal m ucosa, was significantly lower in diabetic rats than in control rats. The h epatic dioxygenase activity showed a significant negative correlation with the hepatic retinol levels, The results suggest the disturbed secretion of retinol from the liver and suppression of hepatic dioxygenase activity by t he retinol increased in the liver in diabetic rats.