Phorbol ester stimulates proliferation of astrocytes in primary culture

Near-confluent primary cultures of astrocytes from the neonatal rat cerebral cortex were transferred to low serum (0.1%) growth medium for 24 h before a single addition of phorbol-12-myristate-13-acetate (0.01-100 ng X ml-1), a phorbol ester which mimics diacylglycerol activation of protein kinase C. After 48 h the cultures were pulsed with [methyl-3H]thymidine. Cultures exposed to phorbol ester exhibited dose-dependent increases in thymidine incorporation which were reversed by amiloride.