Effects of psychoactive drugs on conditioned avoidance response in Mongolian gerbils (Meriones unguiculatus): comparison with Wistar rats and dd mice.

In order to examine applicability of Mongolian gerbils as experimental animals in the field of behavioral pharmacology, the acquisition process of a discrete lever-press avoidance response and effects of psychoactive drugs thereon were studied. The results were compared with those in Wistar rats and dd mice. The gerbils learned the avoidance response much better than the rats and mice. The response rates established were higher in an order of the mice, the gerbils and the rats. Methamphetamine (0.13-1 mg/kg SC), cocaine (2.5-20 mg/kg SC) and morphine (1.3-10 mg/kg SC) facilitated the gerbils' avoidance response, i.e., eliciting a dose-dependent increase in the response rate and a slight increase in the avoidance rate. In contrast, chlorpromazine (0.5-4 mg/kg SC), haloperidol (0.025-0.2 mg/kg SC), pilocarpine (1-8 mg/kg SC), physostigmine (0.05-0.4 mg/kg SC), pentobarbital (5-20 mg/kg SC) and diazepam (0.5-2 mg/kg SC) suppressed the gerbils' avoidance response, i.e., eliciting a dose-dependent decrease in both the response and avoidance rates. Atropine (1.3-10 mg/kg SC) decreased only the response rate without a marked change in the avoidance rate. Scopolamine (0.031-0.5 mg/kg SC) did not produce a marked change in the avoidance response. The qualitative changes in the avoidance response in the gerbils were similar with those in the rats and mice after administration of central stimulants, antipsychotics, cholinergic agonists, central depressant and antianxiety drug, though the sensitivities were different. In particular, the gerbils showed a high sensitivity to the avoidance-suppressing effect of diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)