Imipramine and REM sleep: cholinergic mediation in animals

To date it has not been established whether the anticholinergic properties of imipramine are responsible for the drug's suppresion of REM and prolongation of REM induction. A cholinesterase inhibitor, physostigmine, was administered in conjunction with imipramine to determine if these effects of imipramine were cholinergically medicated. Sleep EEG recordings were observed in rats administered either physostigmine (1.0 mg/kg), or imipramine (1.25, 2.5 or 5.0 mg/kg), alone or in combination. The results indicate that physostigmine blocks the effects of imipramine on REM latency.