Autophagy Inhibition in Endogenous and Nutrient-Deprived Conditions Reduces Dorsal Root Ganglia Neuron Survival and Neurite Growth In Vitro

Peripheral neuropathies can result in cytoskeletal changes in axons, ultimately leading to Wallerian degeneration and cell death. Recently, autophagy has been studied as a potential target for improving axonal survival and growth during peripheral nerve damage. This study investigates the influence of autophagy on adult dorsal root ganglia (DRG) neuron survival and axonal growth under control and nutrient deprivation conditions. Constitutive autophagy was modulated with pharmacological activators (rapamycin; Rapa) and inhibitors (3-methyladenine, bafilomycin A1) in conjunction with either a nutrient-stable environment (standard culture medium) or a nutrient-deprived environment (Hank's balanced salt solution + Ca2+/Mg2+). The results demonstrated that autophagy inhibition decreased cell viability and reduced neurite growth and branching complexity. Although autophagy was upregulated with nutrient deprivation compared with the control, it was not further activated by rapamycin, suggesting a threshold level of autophagy. Overall, both cellular and biochemical approaches combined to show the influence of autophagy on adult DRG neuron survival and growth. (C) 2016 Wiley Periodicals, Inc.