Scopolamine and adjunctive drinking in rats.

Nine, food-deprived rats were each given daily sessions during which 60 45-mg food pellets were delivered individually at 60-sec intervals, independently of behaviour. Water spouts were available to the animals and the intermittent delivery of food induced high levels of adjunctive drinking. The administration of scopolamine (0.125, 0.25, 0.5, 1.0 mg/kg) produced a dose-related attenuation of this drinking. A dose of physostigmine (0.2 mg/kg) was found to slightly reduce levels of drinking but this dose did not consistently modify the action of scopolamine on this behaviour. Tolerance was found to occur to the action of the highest dose of scopolamine (1.0 mg/kg).