Peripheral neuropathies and neurotrophic factors: animal models and clinical perspectives

A large body of data exists showing that a wide variety of neurotrophic factors can promote the survival or growth of different neuronal populations in vitro. More recently, several studies have been published on the survival-promoting effects of particular factors in animal models of peripheral neuropathies. Thus, the effect of axotomy on neuropeptide expression in dorsal root ganglion cells is partially reversed by nerve growth factor treatment, and the effect on choline acetyltransferase expression in motoneurones is partially reversed by glial-derived neurotrophic factor, neurotrophin-4/5 and brain-derived neurotrophic factor. Nerve growth factor also ameliorates some of the changes seen in sensory neurones in animal models of diabetic neuropathy and small fibre cytostatic drug neuropathy, whereas neurotrophin-3 has been found to reverse some changes in large sensory neurones associated with cisplatin neurotoxicity. The results of these studies provide grounds for optimism in the clinical uses of such factors, and, indeed, several clinical studies are now under way.