Benzodiazepines and behavioral effects of reward (water) omission in the rat

Two behaviors related to nonreward (omission of water in an enclosure where the rats were habituated to drink) were studied. The time spent licking the bottles during water omission and the time spent drinking during a subsequent 5-min drinking session (water available) were recorded. The drinking session was performed 30 min after the water-omission session. Rats subjected to water omission showed an enhanced drinking time that varied with the length of the water omission session, with the motivational state of the animals, and with the previous number of water-omission sessions. Diazepam, chlordiazepoxide, lorazepam, and meprobamate (i.p., 30 min before water omission), increased the time spent licking the empty bottles, but failed to abolish subsequently enhanced drinking. However, some of our data suggested that minor tranquilizers weakly reduced the increased drinking induced by nonreward, despite their direct stimulation on water drinking. It is proposed that either minor tranquilizers are devoid of general antifrustration activity or nonreward-induced frustration and nonreward-induced drive enhancement may not be correlated.