DEPRESSION OF DRINKING BY TERTIARY AND QUATERNARY CHOLINOLYTIC DRUGS

Cholinolytic drugs in both their tertiary (atropine, scopolamine) and quaternary (atropine methyl bromide, scopolamine methyl bromide) forms, when administered intraperitoneally, were found to depress drinking behavior. Dose-response curves show that total intake during a standard test period is reduced at a decreasing rate as dose increases, eventually approaching an asymptotic level. Significant decrements in drinking occurred at dose levels which have been shown not to produce significant changes in brain acetylcholine levels. Behavioral effects were similar despite the differences between the tertiary and quaternary forms in their capabilities to penetrate the blood-brain barrier and despite the fact that atropine and scopolamine are reported by some workers to be antagonistic in their central actions. The results are interpreted as indicating that some peripheral mechanism is involved in the depressive action of cholinolytic drugs on drinking behavior. © 1969.