Insulin-like growth factor I reverses experimental diabetic autonomic neuropathy

Recent studies have suggested a role for neurotrophic substances in the pat hogenesis and treatment of diabetic neuropathy. In this study, the effect o f insulinlike growth factor I (IGF-I) on diabetic sympathetic autonomic neu ropathy was examined in an experimental streptozotocin-induced diabetic rat model. Two months of IGF-I treatment of chronically diabetic rats with est ablished neuroaxonal dystrophy (the neuropathological hallmark of the disea se) involving the superior mesenteric ganglion and heal mesenteric nerves r esulted in nearly complete normalization of the frequency of neuroaxonal dy strophy in both sites without altering the severity of diabetes. Treatment with low-dose insulin (to control for the transient glucose-lowering effect s of IGF-I) failed to affect the frequency of ganglionic or mesenteric nerv e neuroaxonal dystrophy or the severity of diabetes. The striking improveme nt in the severity of diabetic autonomic neuropathy shown with IGF-I treatm ent in these studies and the fidelity of the rat model to findings in diabe tic human sympathetic ganglia provide promise for the development of new cl inical therapeutic strategies.