Effect of forskolin on primary cultures of astrocytes and oligodendrocytes.

Forskolin, a unique diterpene which activates adenylate cyclase, stimulated production of cyclic AMP in primary cultures of astrocytes and oligodendrocytes prepared from the cerebral cortex of neonatal rats. At low concentration, forskolin in also potentiated the action of agents (e.g. isoproterenol, prostaglandin E1) which are known to elicit accumulations of cyclic AMP in these cultures. Agents that can stimulate the adenylate cyclase system in astrocyte cultures are inhibited by an alpha-adrenergic agonist, and this alpha-adrenergic mediated inhibition was not observed in oligodendrocyte cultures. Results from this study indicate that forskolin in activation of adenylate cyclase is susceptible to inhibition by an alpha-adrenergic agonist in astrocyte cultures but not in oligodendrocyte cultures. Phenylephrine, which was thought to be acting as a pure alpha-agonist on glial cells, was shown to have both alpha- and beta-adrenergic activities in the same system.