Retinoic acid increases BDNF-dependent regeneration of chick retinal ganglion cells in vitro

BRAIN-DERIVED neurotrophic factor (BDNF) supports survival and regeneration of retinal ganglion cells (RGC). Since the expression of its receptor TrkB can be induced by the transcriptional activator retinoic acid (RA), we have investigated the possibility that RA promotes axonal regeneration of differentiated chick RGC synergistically with BDNF. After injection of all-trans RA onto the chorio-allantoic membrane of stage E16 chick embryos, axonal regeneration was monitored in organ cultures supplemented with BDNF. RA enhanced neurite outgrowth of retinal ganglion cells 2- to 3-fold. The dose-dependent effect was observed only after application of RA in ovo and subsequent use of the neurotrophin, not with RA alone. (C) 1999 Lippincott Williams & Wilkins.