Animal depression model by neonatal clomipramine: reduction of shock induced aggression

Clomipramine, administered to neonatal rats, has been reported to produce adult behavioral and REM sleep abnormalities. They include decreased sexual behavior, increased ambulation in the outer part of an open-field arena, increased REM sleep % of total sleep time, and in descriptive data, short REM latency, and increased REM phasic events. Since these abnormalities resemble some found in human endogenous depression, we have hypothesized that the adult rats represent an animal model of depression. Diminished aggressive behavior is a common characteristic of endogenous depression. This study tested the validity of the animal depression model by determining in rats the effect of neonatal clomipramine on adult shock-induced fighting. Experimental rats were treated neonatally with clomipramine and control rats were treated neonatally with saline. When they matured, compared with control rats, experimental rats had significantly fewer offensive fighting responses, and significantly more defensive fighting responses. The findings add some support to the validity of the animal depression model produced by neonatal clomipramine.