The effect of antidepressant drugs on dominance behavior in rats competing for food

Wistar male rats were maintained on a regimen of restricted access to food. The animals were randomly paired and placed in a special apparatus containing the feeder constructed in such a manner that only one rat at a time could drink sweetened milk. The dominance-subordination (d-s) relationship developed in about 80% of the pairs. This was manifested by the dominant rat eating for a longer period of time than the submissive rat. Clonidine (0.1 mg/kg ip) given to the dominant rats abolished the stable d-s hierarchies. Tricyclic antidepressants and mianserin given for 5 consecutive days prevented the clonidine action. Yohimbine, the antagonist of alpha 2 adrenoceptors produced a similar effect. Drugs belonging to other groups (e.g. neuroleptics and anxiolytics) had no effect on the clonidine-induced suppression of dominance.