Activation of midbrain presumed dopaminergic neurones by muscarinic cholinergic receptors: an in vivo electrophysiological study in the rat

摘要

extracellular single-unit recording and iontophoresis were used to examine the effects of different cholinoceptor agonists and antagonists on the firing rate and firing pattern of A9 and A10 presumed dopaminergic neurones in the anaesthetized rat. Administration of low currents(1-5nA) of the selective muscarinic agonists oxotremorine M(Oxo M) and muscarine and of the non-selective muscarinicicotinic agonist carbamylcholine(CCh) produced A dose-dependent increase in firing rate in most of the A9 and A10 presumed dopaminergic neurones Tested. Oxo M-induced activation could be completely blocked by iontophoretic application of the Muscarinic antagonist butyl-scopolamine or systemic administration of the muscarinic antagonist Scopolamine (300 μg kg~-1, i.v.).