Anticholinergic drugs and the central control of thirst.

Atropine and scopolamine were compared with their centrally inactive quaternary analogs, atropine methyl nitrate and scopolamine methyl nitrate, for effects on water and food intake in rats. All drugs inhibited eating, but only the centrally active compounds inhibited drinking. Anticholinergic drugs evidently block drinking by a central effect and eating by a peripheral effect.