MUSCARINIC M-1 AND M-2 RECEPTOR SUBTYPE-SELECTIVE DRUGS MODULATE NEOCORTICAL EEG VIA THALAMUS

THE present study was designed to investigate the effects of infusions into reticular nucleus of thalamus (NRT) or intracerebroventricular ( i.c.v.) infusions of muscarinic M-1 and M-2 receptor subtype selective drugs on thalamocortically generated neocortical high voltage spindle s (HVSs) in awake immobile rats. NRT administration of 2.0 and 20.0 mu g McN-A-343, a muscarinic M-1 agonist, and 20.0 mu g methoctramine, a muscarinic M-2 antagonist, suppressed HVSs. The results suggest that the blockade of presynaptic M-2 receptors and activation of post-synap tic M(1 )receptors in the NRT suppress thalamocortical oscillations an d increase neocortical electrical arousal. (C) 1998 Rapid Science Ltd.