Expression of neurotrophins in the adult spinal cord in vivo

Potential roles of trophins in the normal and injured spinal cord are large ly undefined, However, a number of recent studies suggest that adult spinal cord expresses neurotrophin receptors and responds to the neurotrophins, b rain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3), particula rly after injury. The data indicate that trophins may enhance regrowth afte r damage and may represent a new therapeutic approach to injury. Neurotroph ins are reportedly present in the spinal cord, but the cellular localizatio n is unknown. This information is critical to begin delineating mechanisms of actions. To approach this problem, we examined whether spinal cord glia express BDNF and NT3 in vivo and have begun to define cellular distribution . Specific antibodies directed against the neurotrophins were utilized to v isualize neurotrophin protein. Initial studies indicated that small cells i n the white matter of adult rat spinal cord express BDNF and NT3, Large neu rotrophin-positive neurons were also identified in the ventral cord, To ide ntify the neurotrophin-positive cells, co-localization studies were perform ed utilizing neurotrophin polyclonal antisera together with monoclonal anti bodies directed against the astrocyte marker, glial fibrillary acidic prote in (GFAP), In the white matter of adult spinal cord, GFAP-positive and GFAP -negative cells expressed BDNF and NT3, Our study suggests that astrocyte a nd non-astrocyte cells provide trophic support to the adult spinal cord. J. Neurosci. Res, 56:1-7, 1999. (C)1999 Wiley-Liss, Inc.