EGF ENHANCES THE SURVIVAL OF DOPAMINE NEURONS IN RAT EMBRYONIC MESENCEPHALON PRIMARY-CELL CULTURE

Epidermal growth factor (EGF) immunoreactive material has been demonstrated to be present in the basal ganglia. In this study, we investigated the effect of EGF on cells cultured from 16-day embryonic rat mesencephalon, which included dopamine neurons that project to the striatum in vivo. EGF receptors were detected in untreated cultures by [I-125]-EGF binding. Treatment of the cultures with EGF resulted in up to 50-fold increases in neuronal high-affinity dopamine uptake. Scatchard analysis of uptake kinetics and counting of tyrosine hydroxylase-immunoreactive cells suggest that the effect of EGF on uptake is due to increased survival and maturation of dopaminergic neurons. By contrast, the high-affinity uptake for serotonin was increased only threefold over its controls. There was no significant effect on high-affinity gamma-aminobutyric acid (GABA) uptake. These results suggest that EGF is acting as a neurotrophic agent preferential for dopaminergic neurons in E16 mesencephalic cultures. Immunocytochemistry for glial fibrillary acidic protein demonstrated an increase in astroglia with EGF treatment. Fluorodeoxyuridine, an agent that is toxic to proliferating cells was able to eliminate the effect of EGF on dopamine uptake, suggesting that EGF may be increasing dopaminergic cell survival largely through a population of dividing cells.