A role for protein kinase C in astrocyte glycogen metabolism

Astrocytes accumulated 2-[3H]deoxyglucose (2-DG) from the incubation medium and incorporated a proportion of it into glycogen. When cells were exposed to the phorbol ester, phorbol 12-myristate 13-acetate (PMA), or the diacylglycerol analogue, dioctanoylglycerol, there was a 30% reduction in the amount of 3H recovered in the glycogen pool. This effect was abolished in cells which had been depleted of protein kinase C (PKC) by prior exposure to PMA. Activation of adenylate cyclase with forskolin caused an increase (40%) in glycogen labelling indicating enhanced glycogen turnover. However, this effect was potentiated when astrocytes were incubated with forskolin and PMA in combination. We suggest that there is an interaction between PKC and adenylate cyclase in the regulation of astrocyte glycogen metabolism.