A Novel Type of Nicotinic Receptor in the Rat Central Nervous System Characterized by Patch-clamp Techniques

We present a functional characterization of a neuronal nicotinic receptor in the CNS using patch-clamp techniques and a preparation of acutely isolated neurons from the medial habenular nucleus of 10- to 20-d-old rats. The salient pharmacological and electrophysiological properties of this nicotinic response are (1) its association with a channel that is relatively nonselective for cations and has a unitary conductance of 26.2 (+)+/- 5pS at room temperature; (2) its insensitivity to alpha-bungarotoxin and to neuronal bungarotoxin; (3) its activation by the ganglionic nicotinic agonists nicotine, 1,1-dimethyl-4-phenylpiperazinium and cytisine and its blocking by several nicotinic antagonists, mecamylamine, hexamethonium, d-tubocurarine, and dihydro-beta-erythroidine. The combination of these properties has not been reported for any other known type of nicotinic receptor.