Influence of the D-2 dopamine receptor agonist quinpirole on the odor detection performance of rats before and after spiperone administration.

The influence of five doses of the D-2 receptor agonist quinpirole (0.025, 0.05, 0.075, 0.10, and 0.20 mg/kg IP) on the odor detection performance of 21 adult male Long Evans rats was assessed using high precision olfactometry and a go/no-go operant task. Additionally, ten rats were pre-treated with the D-2 receptor antagonist spiperone (0.62 mg/kg IP) and their performance monitored following quinpirole administration. Treatments were administered every third day in a counterbalanced order, with the quinpirole injections occurring 15 min before, and the spiperone injections 35 min before, the 260-trial test sessions. Quinpirole injection resulted in a dose-dependent decrease in odor detection performance, as measured by the percentage of correct trials and by the non-parametric signal detection sensitivity index SI. Prior treatment with spiperone eliminated these effects. Dose-related influences of quinpirole on (a) the average latency to initiate a detection response (i.e., the S + response latency), (b) the total session duration, and (c) the number of aborted trials were also eliminated or greatly attenuated by prior spiperone injection. These results suggest that D-2 receptors may be involved in the modulation of odor detection performance and related behaviors.