Pharmacological characterization of the excitatory cholinergic receptors of rat central neurones

The actions of acetylcholine and of various cholinomimetics on neurones of the rat central nervous system have been determined. Excitations of cortical and ventrobasal thalamic neurones and of Renshaw cells of the spinal cord in response to acetylcholine were mimicked both by muscarinic and nicotinic agonists. The excitations elicited by acetylcholine and acetyl-β-methylcholine were antagonized by atropine, and those produced by acetylcholine and nicotinic agonists were blocked by dihydro-β-erythroidine, curare and mecamylamine.Comparison of these results with those obtained by others suggests that there exists a difference between excitatory receptors for acetylcholine in the rat and in the cat. The nature of the receptors in the rat is not easily described as being either nicotinic, muscarinic or mixed; they rather appear to lack selectivity toward the pharmacological agents with which they interact.