Astroglial and fibroblast growth factors have neurotrophic functions for cultured peripheral and central nervous system neurons

Abstract

Embryonic and neonatal neurons require specific trophic supplements for their survival and the induction of transmitter-synthesizing enzymes in vivo and in vitro. Acidic and basic fibroblast growth factor (aFGF, bFGF) and the closely related astroglial growth factors AGF-1 and AGF-2 were studied for putative neurotrophic functions using dissociated, highly neuron-enriched cultures from chick and rat peripheral ganglia and central nervous system tissues. Embryonic chick ciliary ganglion neurons were the only peripheral neurons that responded to bFGF and AGF-2 by enhanced survival equivalent to that obtained with ciliary neurotrophic factor. Half-maximal effects were achieved with bFGF at 360 pg/ml or AGF-2 at 3 ng/ml. Small effects seen with aFGF could be potentiated by adding heparin at 1 microgram/ml. bFGF, but not ciliary neurotropic factor, also promoted neuron survival after the factor was bound to polyornithine and laminin. Both AGF-2 and ciliary neurotropic factor induced choline acetyltransferase activity during 48 hr. AGFs and FGFs also enhanced the long-term survival of embryonic chick spinal cord neurons, including motoneurons that had been retrogradely labeled with rhodamine isothiocyanate. These results demonstrate the potency of a class of mitogenic growth factors as neurotrophic agents for embryonic ciliary ganglion and spinal cord neurons--adding to the emerging evidence that mitogenic and neuronal growth factors are not strictly separate entities.