Astrocytes as gate-keepers in optic nerve regeneration — A mini-review

摘要: Animals that develop without extra-embryonic membranes (anamniotes--fish, amphibians) have impressive regenerative capacity, even to the extent of replacing entire limbs. In contrast, animals within (amniotes--reptiles, birds, mammals) limited capacity for regeneration as adults, particularly in central nervous system (CNS). Much is known about process nerve development fish and mammals after lesions CNS mammals. Because retina eye optic are functionally part brain accessible fish, frogs, mice, lesion (ONR) has been extensively used a model study regeneration. When mouse severed, axons leading into degenerate. Initially, cut end on proximal, eye-side injury sprout neurites which begin grow lesion. Simultaneously, astrocytes become activated initiate wound repair first step reestablishing structural integrity nerve. This activation appears cascade molecular signals resulting apoptotic cell death retinal ganglion cells make up neural component nerve; fails permanent. Evidence specifically implicating comes from studies showing selective poisoning at lesion, along with gene whose product blocks apoptosis cells, creates conditions favorable sprouting proximal stump, growing through distal portion injured nerve, eventually reaching appropriate targets brain. anamniotes, ostensibly present no such obstacle since occurs intervention; however, systematic glial involvement done. vigorously few days re-enervate review offers new perspective role glia, astrocytes, "gate-keepers;" i.e., being permissive or inhibitory, by comparison between function during ONR.