FIBROBLAST GROWTH FACTOR-2 STIMULATES CELL-PROLIFERATION AND DECREASES SEXUALLY DIMORPHIC CELL-DEATH IN AN AVIAN SONG CONTROL NUCLEUS

The neural system controlling song in birds has proven a useful model for investigating how neuronal growth and survival are regulated by se xual differentiation. The present study focused on one song control ar ea, the robust nucleus of the archistriatum (RA), and explored how sex differences in the proliferation of putative glia cells in this regio n influence sexually dimorphic cell survival. In zebra finches (Poephi la guttata), RA neuron death is much greater in young females than in males, resulting in marked sex differences in RA neuron number. An ear lier study indicated that just prior to this sexually dimorphic neuron death the proliferation of putative glia cells within the RA is signi ficantly lower in females than in males and remains so throughout the peak of neuron death. This suggests that sex differences in glia (or g lia-derived molecules) might regulate neuron survival during sexual di fferentiation of the RA. To determine whether increased cell prolifera tion within the RA favors increased cell survival, we infused the pote nt glia mitogen fibroblast growth factor-2 (FGF-2) into the RA unilate rally in young females. We find that FGF-2 infusions increase RA cell proliferation and concurrently decrease the incidence of degenerating RA cells, results consistent with the hypothesis that glia exert neuro trophic effects on RA neurons during sexual differentiation. (C) 1998 John Wiley & Sons, Inc.