Antagonism of behavioural depression produced by clonidine in the Mongolian gerbil: a potential screening test for antidepressant drugs.

The effects of various antidepressant drugs and some other therapeutic agents on the depression of locomotion and exploratory activity induced by clonidine (0.1 mg/kg IP) were investigated in the Mongolian gerbil (Meriones unquiculatus). In parallel experiments, the effect of yohimbine on clonidine-induced sedation was observed. The following behavioral components were analysed: ambulation, rearing and novel object investigation. Yohimbine antagonized the effects of clonidine in a dose-dependent manner. All antidepressants similarly antagonized the effect of clonidine on ambulation but they differed to a greater extent in their potency in counteracting the clonidine action on exploration, particularly the novel object investigation. On the other hand diazepam and neuroleptic agents such as pimozide and flupentixol failed to antagonize the clonidine effects. The antagonism of clonidine-induced behavioral depression might be used in the selection of antidepressants.