The outgrowth response of the axons of developing and regenerating rat retinal ganglion cells in vitro to neurotrophin treatment
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- Avwenagha, O., Campbell, G. & Bird, M.M. J Neurocytol (2003) 32: 1055. doi:10.1023/B:NEUR.0000021902.65233.8d
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BDNF and NT-4 (but not NT-3 or CNTF) significantly enhanced the outgrowth of early embryonic and adult regenerating RGC axons when provided with a supportive substrate in vitro. BDNF and NT-4 treatment transiently increased RGC axon outgrowth from E15 rat retinas but not from retinas at older embryonic ages. The transient effect of BDNF and NT-4 and the inability of the neurotrophins to promote outgrowth from older embryonic retinal explants suggests a time frame of neurotrophin action and that other chemical factors (target-derived or otherwise) may be necessary for the continued maintenance of developing RGC axons. BDNF and NT-4 also enhanced the outgrowth of regenerating axons from adult retinal explants, but appeared to have a more subtle effect on axon outgrowth, in that the growth-promoting effects of BDNF and NT-4 appeared continuous throughout the incubation period. The suppression of RGC axon outgrowth from embryonic and adult retinae cultured in trkB-IgG-containing medium suggests that the response of developing and regenerating axons, to BDNF and NT-4 are likely to occur through trkB signalling.