Evidence for the existence of alpha- and beta-adrenoceptors on neurones and glial cells of cultured rat central nervous system--an autoradiographic study

Autoradiographic localization of binding sites for the delta sleep-inducing peptide ( [3H]DSIP) on neurons of cultured rat brainstem

Binding of the delta sleep-inducing peptide (DSIP) was studied in cultures of rat brainstem by means of autoradiography. Binding sites for [3H]DSIP were observed on small, medium-sized and large brainstem neurons but not on glial cells. Addition of unlabeled DSIP inhibited or markedly reduced binding of [3H]DSIP. It is suggested that brainstem neurons might possess receptors for this sleep-inducing peptide.

Evidence for the existence of alpha- and beta-adrenoceptors on cultured glial cells--an electrophysiological study

The action of adrenergic alpha- and beta-agonists and antagonists has been studied on the membrane potential and resistance of glial cells of cultured rat central nervous system. Noradrenaline and the alpha-adrenoceptor stimulating agents phenylephrine and clonidine (10(-7) to 10(-4)M) depolarized the glial membrane, whereas the beta-agonist isoprenaline caused a hyperpolarization at low concentrations (10(-7) and 10(-6)M). The effects of noradrenaline and phenylephrine were reversibly blocked by the alpha-antagonist phentolamine, whereas those of isoprenaline were antagonized by the beta-blocker atenolol. Atenolol did not affect the depolarization by noradrenaline. The glial depolarization induced by the alpha-agonists was not the consequence of a change in the extracellular K+-concentration unlike that produced by amino acid transmitters. The present results, together with those of biochemical and autoradiographic binding studies, suggest that alpha- and beta-adrenoceptors occur on glial cells and that the glial depolarization is mediated by alpha-receptors, whereas the hyperpolarization is due to activation of beta-receptors.