Effects of triazolam on drinking in baboons with and without an oral self-administration history: a reinstatement phenomenon.

In a test of the reinforcing efficacy of triazolam under an oral drug self-administration procedure, three baboons consumed higher volumes of triazolam than of vehicle. Although these results suggested that triazolam was serving as a reinforcer, the unconditioned effect of triazolam itself on drinking remained unclear. Therefore, the effect of pretreatment with triazolam on consumption of a nondrug fluid was assessed in sessions that were otherwise identical to oral drug self-administration sessions. Following oral pretreatment with triazolam (0.6-19.2 mg total dose), there was a dose-dependent increase in drinking, suggesting that triazolam increased fluid consumption per se. However, subsequent manipulations showed that following pretreatment with triazolam, there was no systematic change in tap water consumption from the regular drinking spout and that the dipsogenic effect of pretreatment with triazolam was not specific to a particular fluid; however, the effect was specific to prior experience with the oral self-administration procedure. Thus, the dose-related increase in consumption from the drinkometer spout following triazolam pretreatment most likely is explained as the "priming" or "reinstatement" of an operant that previously had produced drug reinforcement, even though extinction (i.e., substitution of the drug vehicle) was in effect.