ADRENOCEPTORS ON CENTRAL NEURONS - MICROELECTROPHORETIC STUDIES

A survey of the literature shows that noradrenaline applied by microelectrophoresis has a dual effect on single neurones in many parts of the brain : both excitatory and depressant responses have been described. Experiments involving the use of specific adrenoceptor agonists and antagonists suggest that the neuronal responses to noradrenaline are mediated by pharmacologically distinct receptors: the excitatory responses, in many cases, by α-adrenoceptors, and the depressant responses by β-adrenoceptors. Furthermore, there is evidence indicating that the functionally antagonistic α- and β-receptors may occur on the same neurone. In some structures the proportions of cells excited or depressed by noradrenaline seem to be influenced by such factors as the spontaneous firing rate and the general anaesthetic used; it is suggested that these factors may act by altering the relationship between the functionally antagonistic excitatory and inhibitory receptors. © 1979.