Nitrous oxide-induced conditioned taste aversions in rats: the role of duration of drug exposure and its relation to the taste aversion-self-administration "paradox".

Inhalation by rats of nitrous oxide immediately after ingestion of a solution of 0.1% saccharin resulted in a conditioned avoidance of the solution following recovery from the drug (Conditioned Taste Aversion). With a constant duration of inhalation (30 min), aversive properties of nitrous oxide in this behavioural paradigm were related to concentration over the range 0-80%. At constant concentrations (70% and 80%), the aversive potency of nitrous oxide was directly related to duration of inhalation of the gas over the range 0-4 hr. These data provide the first direct support for the hypothesis [5,6] that a major determinant of aversive potency of a drug in the taste aversion paradigm is its duration of action. Different temporal components of drug action may mediate self-administration and conditioned aversion.