Microinjection of neostigmine into the pontine reticular formation of cats enhances desynchronized sleep signs.

Microinjection of the acetylcholinesterase inhibitor neostigmine into the dorsal pontine tegmentum of intact, freely moving cats produced significant changes in electrographic desynchronized (D) sleep signs and D sleep-like behavior. The percentage, frequency and duration of D sleep signs were increased and the latency to onset of D sleep signs was significantly reduced after neostigmine administration. The effects of neostigmine were dose-dependent and could be blocked by centrally administered atropine. This is the first demonstration that microinjection of an acetylcholinesterase inhibitor into the pons enhances D sleep signs. These data suggest that endogenously released acetylcholine can initiate and maintain the state of D sleep and strongly support the cholinergic hypothesis of D sleep generation.