- Growth hormone (GH) has been implicated in the pathogenesis of renal sclerosis. To determine the effects of long term diabetes on renal GH-R expression, we examined GH-R and GH-BP mRNA levels by solution hybridization-RNase protection assay in kidney of STZ-diabetic rats. Adult female Wistar rats received either i.v. STZ (55 mg/kg) or saline. Rats were sacrificed at 7, 30, 90, and 180 days following STZ treatment. Right kidney cortex was separated from medulla. Total RNA was extracted from both areas and analyzed for GH-R/GH-BP mRNA content. Blood glucose levels were 5-fold higher in diabetic animals (>25 nmol/L) and remained elevated throughout the study. Urinary albumin concentration were markedly elevated from days 30 to 180 in the diabetic animals. We observed no changes in either GH-R or GH-BP mRNA levels in the medulla of diabetic rats. A significant increase in GH-BP(p<0.05) but not in GH-R mRNA levels was observed in the cortex of diabetic rats at 30 (140.8±15.9%; mean±sem); 90 (147.0±14.9%); and 180 days (165.6±16.3%).