SLEEP PATTERNS AFTER CARBACHOL DELIVERY IN THE VENTRAL ORAL PONTINE TEGMENTUM OF THE CAT

This study examines dose-related effects on sleep produced by low-volu me and low-dose carbachol microinjections in the ventral part of the c at nucleus reticularis pontis oralis. Carbachol microinjections (0.04, 0.08, 0.8 or 4 mu g; volume 20 nl) in this location triggered paradox ical sleep with a very short dose-unrelated latency. The four carbacho l doses effectively generated all the polygraphic and behavioral signs of paradoxical sleep when microinjected at any level within the ventr al part of the nucleus reticularis pontis oralis (AP 0.5 to -3.5, L 0. 5-3.5, V 3.5-5.0, on the Reinoso-Suarez atlas [Topographischer Hirnatl as der Katze (1961); Merck, Darmstadt]). The dose-related increase of total paradoxical sleep time was due to the increase In both the durat ion and number of paradoxical sleep episodes. This paradoxical sleep i ncrease was associated with a dose-related decrease in the amount of t ime spent in both slow wave sleep and drowsiness, but not with any dec rease in total wakefulness. The lengthening of the latency to slow wav e sleep onset was dose related. These results show that the ventral or al pontine tegmentum is a very sensitive site for the induction and ma intenance of paradoxical sleep. (C) 1998 IBRO. Published by Elsevier S cience Ltd.