Chronic treatment with clomipramine and mianserin increases the hierarchical position of subdominant rats housed in triads.

Male Wistar rats housed in triads under a 12h: 12h light-dark schedule exhibit intense levels of social behaviour, involving all group members equally, at the onset of every dark phase. Analysis of this social behaviour yields the group's hierarchical structure (based on the proportion of wins attained during social interaction) consisting of a dominant, subdominant and subordinate rat. Chronic treatment of the subdominant rats with the antidepressant drugs clomipramine, 10µmol/kg day, and mianserin, 0.33µmol/kg/day, via subcutaneously-implanted osmotic mini-pumps, increased the proportion of wins attained during encounters with their sham-operated cage partners by day 6 of treatment. This increase was maintained throughout the remaining period of treatment and was generally at the expense of the level of dominance of the dominant rat. It is argued that the ability of clomipramine and mianserin to increase the proportion of wins attained by subdominant rats parallels the previously-reported drug-induced release of social and agonistic behaviour which is thought to be indicative of antidepressant activity.