Alpha- and beta-adrenoceptors on cultured glial cells

The action of alpha- and beta-adrenoceptor agonists and antagonists has been studied on the membrane potential of glial cells in cultured rat central nervous system. Noradrenaline and the alpha-agonist phenylephrine caused a depolarization which was reversibly blocked by the alpha-antagonist phentolamine. In contrast, the beta-agonist isoprenaline hyperpolarized the glial membrane. This hyperpolarization was not associated with measurable changes in membrane resistance and was antagonized by the beta-blocker atenolol. These results suggest that the glial depolarization is mediated by activation of alpha-receptors, whereas the hyperpolarization is due to stimulation of beta-receptors. The existence of alpha- and beta-adrenoceptors on glial cells is further supported by autoradiographic studies showing binding of noradrenaline and alpha- and beta-antagonists to astrocytes.