Effects of phorbol ester on immunoreactive protein kinase C, insulin binding, and glucose uptake in astrocytic glial and neuronal cells from the brain.

Phorbol esters, potent stimulators of protein kinase C (PKC), stimulate [3H]2-deoxy-D-glucose (dGlc) uptake and [125I] insulin binding in cultured glial cells but not neuronal cells from neonatal rat brains. Using an antibody to the alpha and beta forms of PKC we have demonstrated that both neuronal and glial cells contain an immunoactive PKC of Mr approximately 80 kD, although the PKC level in neurons is greater than 4-fold that in glia. The majority of immunoactive PKC (63%) is cytosolic in glial cells although the reverse is true in neuronal cells, in which 88% of the PKC is membrane-bound in the basal state. The most potent phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), stimulates a redistribution of this enzyme in neuronal and glial cells. The TPA-stimulated translocation of PKC from cytosol to membrane precedes TPA's effects on [3H]dGlc uptake and insulin binding in glial cells.