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Adult retinal ganglion cells retain the ability to regenerate their axons up to several weeks after axotomy
Author(s) -
Thanos S.,
Vanselow J.
Publication year - 1989
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490220206
Subject(s) - axotomy , retina , axon , optic nerve , anatomy , transplantation , lesion , ganglion , crush injury , biology , retinal ganglion cell , retinal , central nervous system , neuroscience , medicine , pathology , surgery , biochemistry
Abstract The present work was to elucidate whether the ability of adult central neurons to regrow their lesioned axons is retained for long periods of time. Using the rat retina as an experimental paradigm, the optic nerve was lesioned by crush in situ. Up to 6 weeks after the trauma, the optic nerve (ON) was again exposed and transected close to the first lesion and autologous sciatic nerve segments were anastomosed at the ocular ON stump. Alternatively, the retina corresponding to the lesioned ON was dissected for in vitro cultivation 1–6 weeks after the crush‐axatomy was applied. Both experimental strategies revealed a regrowth of the lesioned retinal ganglion cell (RGC) axons. When peripheral nerve (PN) segments were grafted without previous ON crush, axon stumps started to reelongate and to penetrate the grafted piece of nerve 6 days later. In contrast, when the PN graft was apposed to the ON stump 1–6 weeks after crush, it was penetrated by regrowing axons within 24 hr. Maximal numbers of regenerating axons were observed if transplantation occurred within the first week after the crush. The numbers of axons decreased progressively if transplantation was performed later than 1 week postcrush and approximated zero values at the 6th week. When the noncrushed retina was explanted and cultured in vitro in a chemically defined, serumfree medium, there was almost no extending fiber. In contrast, explantation of the retina for which the ON had been precrushed in situ resulted in massive regrowth of RGC axons. The numbers of regenerating axons and their temporal changes paralleled those described for the transplantation experiments. The data indicate that axomotized central neurons sustain their ability for axon regrowth over considerable periods of time and can make use of this elongation capability if regeneration‐permissive environmental conditions are provided.