Glutathione effects on vitamin D metabolism in control and streptozotocin diabetic rat

The circulating concentration of 1,25-dihydroxycholecalciferol 1,25-(OH)₂D₃] is a physiologic index of enzymatic activity of the renal 1-hydroxylase of 25-hydroxychole-calciferol (25-OH-D₃). Hydroxylation of 25-OH-D₃ and circulating 1,25-(OH)₂D₃ are decreased in the streptozotocin diabetic rat. We previously found that activity of another redox enzyme system, cytosolic superoxide dismutase, also decreased in streptozotocin diabetes, can be restored by treatment with glutathione. In the present experiment we tested the effect of glutathione treatment on vitamin D metabolism in control and diabetic rats. Enteral glutathione increased circulating 1,25-(OH)₂D₃ and decreased 25-OH-D₃ in both control and diabetic animals. These results suggest that exogenous glutathione increases 25-OH-D₃ 1-hydroxylation both under basal conditions in the normal animal and in diabetes-induced depression.