Neurotrophin‐4/5 (NT‐4/5) increases adult rat retinal ganglion cell survival and neurite outgrowth in vitro

Abstract

Retinal ganglion cell (RGC) survival and neurite outgrowth were investigated in retinal explants from adult rats. Neutrotrophin‐4/5 (NT‐4/5) caused dose‐dependent increases in neurite outgrowth with one‐half maximal effects at approximately 0.5 ng/ml and maximal effects at 5 ng/ml. In explants treated for 7 days, the actions of NT‐4/5 were similar to those of brain‐derived neurotrophic factor (BDNF); with either neurotrophin, nearly twice as many RGCs survived and there was a two‐ to threefold increase in the number of neurites formed by RGCs. Combinations of saturating concentrations of NT‐4/5 and BDNF did not enhance these in vitro effects, implying that both neurotrophins share a common signaling pathway. In contrast, nerve growth factor (NGF), neurotrophin‐3 (NT‐3), or ciliary nuerotrophic factor (CNTF) appeared to exert minimal influences on RGC survival or neurite outgrowth. 1994 John Wiley & Sons, Inc.