GLUTAMATE STIMULATES [H-3] PHORBOL 12,13-DIBUTYRATE BINDING IN CULTURED BERGMANN GLIA CELLS

The effect of L-glutamate and its structural analog kainate on the binding of [H-3]phorbol 12,13-dibutyrate was examined in cultured chick cerebellar Bergmann glia cells. Both glutamate and kainate evoke a dose-dependent increase in the maximal number of binding sites for [H-3]phorbol 12,13-dibutyrate in intact cells reflecting an activation and translocation of the Ca2+/diacylglycerol-dependent protein kinase (protein kinase C, PKC) from cytosol to the plasma membrane. Glutamate and kainate responses were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) indicating that the increase in [H-3]phorbol 12,13-dibutyrate binding sites is mediated by an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor. Since Bergmann glia AMPA/kainate receptors are probably mediators of the efficacy of the parallel fiber-Purkinje cell synapse, the present findings suggest that the Ca2+/PKC signalling cascade might play a role in such modulation.