Aim: To explore the feasibility of human growth hormone (hGH) receptor antagonist in the treatment of end-stage diabetic renal complications.
Methods: Two hGH mutants, hGHA1 (Cys-hGH-del1-4, G120R, K168A, E174A, C182S, del186-191) and hGHA2 (hGH-H21A, G120R, E174A) were expressed in E coli. The IC50 (Mean+/-SD) values for the mutants for inhibiting 125I-hGH binding to rabbit growth hormone receptor were (65+/-10) ng for hGHA1, (27+/-5.6) ng for hGHA2, and (10+/-0.6) ng for wild type hGH, respectively.
Results: After treatment for 12 weeks, the renal histology analysis showed that treatment with hGHA2 at 4 mg/kg body weight daily markedly suppressed glomerulosclerosis in streptozotocin-induced diabetic Sprague-Dawley (SD) rats; hGHA1 at the same dosage slightly increased the renal damage compared with saline; while wild type hGH at 1 U/kg body weight daily severely worsened the glomerulo-sclerosis in diabetic SD rats.
Conclusion: The data indicated that hGHA2 inhibited the end-stage glomerulosclerosis in diabetic rats, but hGHA1 mildly increased the glomerulosclerosis.