Amacrine-Signaled Loss of Intrinsic Axon Growth Ability by Retinal Ganglion Cells

TLDR

The CNS loses regenerative capacity early in development, a phenomenon whose cause remains unclear, and the retina has long served as a tractable model for studying CNS regeneration. Amacrine cells trigger neonatal rat retinal ganglion cells to irreversibly lose intrinsic axon growth ability, while retinal maturation enhances dendritic growth, suggesting that adult CNS neurons fail to regenerate because of both glial inhibition and loss of intrinsic axon growth capacity.

Abstract

The central nervous system (CNS) loses the ability to regenerate early during development, but it is not known why. The retina has long served as a simple model system for study of CNS regeneration. Here we show that amacrine cells signal neonatal rat retinal ganglion cells (RGCs) to undergo a profound and apparently irreversible loss of intrinsic axon growth ability. Concurrently, retinal maturation triggers RGCs to greatly increase their dendritic growth ability. These results suggest that adult CNS neurons fail to regenerate not only because of CNS glial inhibition but also because of a loss of intrinsic axon growth ability.