Occurrence of depressive behavior at mature age was studied in rats exposed neonatally to antidepressant drugs. Early antidepressant treatments have been shown to increase voluntary alcohol consumption and the percentage of rapid-eye-movement (REM) sleep relative to total sleep time in adult rats as well as to cause long-lasting reduction in the concentrations of monoamines in the forebrain. In the present study rats were daily given either 5 mg/kg desipramine or 25 mg/kg zimeldine from the 7th to the 18th postnatal days. When they were 2 months and 5 months of age behavioral 'despair' was studied by using a modified version of Porsolt's swim-test. At both ages the desipramine-treated and zimeldine-treated rats expressed lengthened immobility times in the water pail. The findings indicate that neonatal exposure of rats to desipramine or zimeldine induces behavioral 'despair' at mature age. Thus, early exposure of rats to antidepressants causes long-lasting behavioral disorders, and, moreover, may be used to devise an animal model of subsequent depression.
- Behavioral 'despair'
- Newborn rats