Changes in adrenocortical monooxygenase activities in alloxan-diabetic rabbits

Studies were carried out to determine if diabetes mellitus influenced the activities of adrenal steroidogenic enzymes. Adult male rabbits were made diabetic by an i.v. infusion of alloxan (100 mg/kg) and were killed 1 or 2 months later. Mitochondrial cytochrome P-450 concentrations were not affected by diabetes but steroid 11 beta-hydroxylase activity was greater in the diabetics than in controls after both 1 and 2 months. The type I spectral change produced by 11-deoxycorticosterone, the substrate for 11 beta-hydroxylation, was also greater in mitochondria from diabetics. By contrast, mitochondrial cholesterol side-chain cleavage activity was similar in controls and diabetics. Microsomal cytochrome P-450 concentrations were unaffected by diabetes but 21-hydroxylase activity was significantly lower in adrenal microsomes from diabetics than from controls. The results indicate that alloxan-induced diabetes alters adrenocortical steroid metabolism which may contribute to changes in the pattern of steroid secretion noted by other investigators.