Effects of Antidepressants on the Exploration, Spontaneous Motor Activity and Isolation-induced Aggressiveness in Mice

Objective: To study the role of different antidepressants on exploration, spontaneous motor activity and isolation-induced aggressiveness in mice, further to discuss different mechanisms of their anti-aggression.

Methods: With an aggressive model induced by isolation housing in mice, antagonism of different antidepressants against isolation-induced aggression was evaluated. In the group-housed mice given the same treatment as aggressive test, exploration and spontaneous motor activity were measured.

Results: (1) Mianserin (0.5-5 mg/kg-1), buspirone (2.5-10 mg.kg-1) and meclobemide (2.5-10 mg.kg-1) significantly inhibited the exploration in the group-housed mice, but not fluoxetine (2.5-10 mg.kg-1), imipramine (2.5-10 mg.kg-1) and DOI (0.5-2 mg.kg-1); (2) Both mianserin and buspirone, but not fluoxetine, imipramine, meclobemide and DOI, obviously reduced spontaneous motor activity; (3) Fluoxetine, miaserin, imipramine and buspirone significantly and dose-dependently antagonized isolation-induced aggressive behavior, whereas meclobemide failed to attenuate aggression. DOI dual-regulated aggressiveness in isolation mice.

Conclusion: Our findings suggest that the effects of fluoxetine, mianserin, buspirone, imipramine, meclobemide and DOI on exploration, spontaneous motor activity and isolation-induced aggression in mice are different, which may involve different pharmacological mechanisms underlying their anti-aggression in isolation mice. 5-HT1A and 5-HT2A/2C receptors may mediate isolation-induced aggressive behavior in mice. The involvement of 5-HT receptor subtypes needs further clarification.