REM sleep deprivation treatment enhances the effect of clozapine in the forced swimming test.

1. Effect of REM sleep (REMs) deprivation treatment on clozapine response in the forced swimming test was investigated. 2. Clozapine significantly increased the swimming activity in REMs-deprived mice at a dose of 5 mg/kg (i.p.) which did not affect the activities in the control groups. 3. Physostigmine (0.3 mg/kg, i.p.), an acetylcholinesterase inhibitor, blocked the increasing effect of 5 mg/kg clozapine on swimming activity in REMs-deprived animals. 4. These results suggest that the REMs deprivation treatment-induced enhancement of effect of clozapine on swimming activity is mediated by the functional change of central cholinergic system following the treatment.