Glomerular metalloprotease activity in streptozotocin- treated rats and in spontaneously diabetic rats (BB/DP)

Differences in the type and extent of diabetic glomerular injury occur in rats made diabetic with streptozotocin (STZ) and in a spontaneously diabetic rat model of the BB/Wor strain. The diabetes prone (BB/DP) rat develops no mesangial matrix expansion with diabetes, whereas the STZ-treated Sprague Dawley rat does. The present study was performed to determine if glomerular metalloprotease activities were decreased in these two rat models of diabetes. Rats were studied at 8 weeks following the onset of hyperglycemia. All diabetic rats were maintained moderately hyperglycemic (plasma glucose = 350 mg/dL) with daily injection of insulin. Glomerular preparations were made and metalloprotease activities were assayed by hydrolysis of gelatin. Metalloprotease activities were decreased by 40-50% in STZ-treated Sprague Dawley rats, but not in BB/DP rats or diabetes resistant rats (BD/DR--the control for the BB/DP) made diabetic by STZ-injection. These data suggest that the decrease in glomerular metalloprotease activity may contribute to mesangial matrix expansion in the diabetic Sprague Dawley rats.