Objective:To explore the effects of ascorbic acid on the expressions of tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA and protein in renal cortex in rats with streptozotocin-induced diabetes. Methods: 30 male Wistar rats(195±20g)were randomly divided into following groups:group C(control rats);group D(diabetic rats);and group DT(diabetic rats treated with ascorbic acid 90mg/kg·d).The concentrations of ascorbic acid and activity of aldose reductase (AR) in plasma and renal cortex were assayed at 9 weeks.In addition

the protein expression of TIMP-1 in renal cortex was determined by Western-blot and the mRNA expression of TIMP-1 was measured by hybridization in situ. Results: Compared with group C

the levels of ascorbic acid in plasma and kidney decreased significantly in group D( P <0.01)?The activity of aldose reductase

and the expressions of TIMP-1 mRNA and protein increased markedly ( P<0.01

respectively).The concentrations of ascorbic acid in plasma and kidney increased to normal level

and the others were markedly ameliorated after 8 weeks treatment with ascorbic acid in group DT. Conclusion:The findings suggest that administration of ascorbic acid can increase the levels of ascorbic acid and lower the expressions of TIMP-1 mRNA and protein in renal cortex in rats with streptozotocin-induced diabetes

and diabetes-induced expressions of TIMP-1 mRNA and protein may be mediated in part by polyol pathway.