Acquisition process and effects of psychoactive drugs on discrete shuttle avoidance response in Mongolian gerbils (Meriones unguiculatus).

The acquisition process of the discrete shuttle avoidance response and effects of psychoactive drugs on the established avoidance response were examined in Mongolian gerbils. The gerbils acquired the avoidance response very fast and attained an avoidance rate of higher than 90% until the 2nd training session. The established response rate (frequency of shuttles) was about 2.2/min. Methamphetamine, cocaine, scopolamine, atropine and morphine facilitated the avoidance response, eliciting an increase in the response rate. In particular, the effect of morphine was very marked. In contrast, chlorpromazine, haloperidol, pilocarpine, physostigmine, pentobarbital and diazepam suppressed the avoidance response, eliciting a dose-dependent decrease in both the response and avoidance rates. Methamphetamine, cocaine, scopolamine, atropine and morphine increased spontaneous motor activity in the experimental chamber in which neither electric shock nor conditioned stimulus was delivered during the observation period. However, the drug effects were not quantitatively identical with those in the avoidance response. These results suggest that the behavioral characteristics of gerbils are similar to those of mice in the discrete shuttle avoidance situation.