Aversive and appetitive properties of anxiogenic and anxiolytic agents.

The place-conditioning paradigm was used to assess the appetitive or aversive nature of anxiolytic and anxiogenic drugs. Rats were given a pre-conditioning preference test in which the time that they spent on each side of a two-compartment chamber was measured; each side was visually distinct. On two days they were confined to one side immediately after drug injection, and on alternate days they were confined to the other side after vehicle injection. The rats were then given a postconditioning preference test. The change in preference was used as the measure of the reinforcing properties of the drugs. The anxiolytic drugs diazepam, lorazepam, alprazolam, adinazolam, U-43, 465 and tracazolate produced a clear preference for the drug-associated side, indicating the appetitive qualities of these drugs. Preference was less clear for the anxiolytics chlordiazepoxide and buspirone. This suggests that it is possible to dissociate the rewarding and anxiolytic properties of drugs. All the anxiogenic drugs tested (CGS 8216, picrotoxin and yohimbine) produced conditioned aversion.