Effects of diazepam and ripazepam on two measures of adjunctive drinking in rats.

Four rats were maintained at 85% of their pre-experimental body weights and were given daily 1 hr sessions during which they were each placed in a test chamber in which a 45 mg food pellet was delivered regularly every min independently of behavior. During these sessions water spouts were available to the rats and all 4 animals developed high levels of adjunctive drinking, a burst of licking typically following the consumption of each food pellet. This behavior was found to be sensitive to the effects of diazepam and ripazepam. Small doses of both drugs increased the volume of water consumed during a session. The number of licks was not increased to the same extent, however. Larger doses of both drugs resulted in decreased numbers of licks and decreased water intake although licking appeared on several occasions to be more sensitive than water intake to this action of the drugs. A possible explanation of these effects is that the drugs affected the topography of the rats' licking at the water spouts. Whatever the mechanism involved, however, these results suggest that in such experiments measures of both water intake and number of licks should be obtained.