Heme oxygenase 1 improves glucoses metabolism and kidney histological alterations in diabetic rats

Abstract

One important concern in the treatment of diabetes is the maintenance of glycemic levels and the prevention of diabetic nephropathy. Inducible heme oxygenase 1 (HO-1) is a rate-limiting enzyme thought to have antioxidant and cytoprotective roles. The goal of the present study was to analyze the effect of HO-1 induction in chronically hyperglycemic rats. The hyperglycemic rats were divided into two groups: one group, called STZ, was given a single injection of streptozotocin; and the other group was given a single streptozotocin injection as well as daily injections of hemin, an HO-1 inducer, over 60 days (STZ + HEME). A group of normoglycemic, untreated rats was used as the control (CTL).Body weight, diuresis, serum glucose levels, microalbuminuria, creatinine clearance rate, urea levels, sodium excretion, and lipid peroxidation were analyzed. Histological alterations and immunohistochemistry for HO-1 and inducible nitric oxide synthase (iNOS) were assessed. After 60 days, the STZ group exhibited an increase in blood glucose, diuresis, urea, microalbuminuria, and sodium excretion. There was no weight gain, and there was a decrease in creatinine clearance in comparison to the CTL group. In the STZ + HEME group there was an improvement in the metabolic parameters and kidney function, a decrease in blood glucose, serum urea, and microalbuminuria, and an increase of creatinine clearance, in comparison to the STZ group.There was glomerulosclerosis, collagen deposition in the STZ rats and increase in iNOS and HO-1 expression. In the STZ + HEME group, the glomerulosclerosis and fibrosis was prevented and there was an increase in the expression of HO-1, but decrease in iNOS expression and lipid peroxidation. In conclusion, our data suggest that chronic induction of HO-1 reduces hyperglycemia, improves glucose metabolism and, at least in part, protects the renal tissue from hyperglycemic injury, possibly through the antioxidant activity of HO-1.

Figure 1

(A) Light microscopy of kidney sections stained with hematoxylin-eosin at 10x (HE 100), Picro-sirius red 20x (PC 200), 10x (polarized light, PC 100) and immunohistochemistry for HO-1 (200), iNOS (200) in control rats (CTL), rats treated with streptozotocin (STZ), and rats treated with STZ and daily injection of hemin (STZ+HEME). (B) Quantitative analyses of kidney sections stained for heme-oxygenase-1 (HO-1), induced nitric oxide synthase (iNOS) expressed as pixels/field, stained with HE (glomerulosclerosis) expressed as arbitrary units (AU). Data were expressed as the mean ± SEM. The significance level for a null hypothesis was set at 5% (p < 0.05) (*) significantly different in comparison to CTL group and (#) significantly different in comparison to STZ group.

Figure 2

(A) TBARS levels (nM/mg of creatinine) and (B) Hydroperoxides (μM/mg of creatinine) in the control group (CTL), rats treated with streptozotocin (STZ) and rats treated with streptozotocin + hemin (STZ+HEME) at 0, 30 and 60 days. Data were expressed as the mean ± SEM. The significance level for a null hypothesis was set at 5% (p < 0.05) (*) significantly different in comparison to CTL group and (#) significantly different in comparison to STZ group.