- Summary Growth hormone (GH) may have a role in the development of diabetic nephropathy. The effect ofexperimental diabetes on renal expression of the growth hormone receptor gene products, including the receptor itself (GHR) and its binding protein (GHBP) was examined. Adult female rats received i.v. streptozotocin and were killed at 7, 30, 90 and 180 days after the induction of diabetes. Diabetic animals had a pronounced increase in kidney weight and progressive albuminuria. In renal cortex, no change was seen in GHR mRNA levels throughout the observation period of 6 months, while a significant increase in cortical GHBP mRNA levels was observed after 1 month of diabetes and sustained for the rest of the study period. Immunohistochemical analysis of kidney sections revealed a stronger staining for GHBP at the cortical and inner medullary areas in the diabetic animals. These data indicate that although the GHR and GHBP mRNAs originate from the same gene, their renal levels are differentially regulated during the development of experimental diabetic kidney disease, suggesting a functional role for GHBP.