Effects of chronic oral administration of imipramine in the rat forced swimming test.

Male Wistar rats were treated with imipramine hydrochloride (IMI) in a dose of 2 or 10 mg/kg/24 h in drinking water for 2 weeks, 1, 3 or 6 months. Two or 72 h after the final treatment forced swimming test was performed. It was shown that 2 h after the final dose of 10 mg/kg of IMI the immobility time was reduced following a period of 1-6 month treatment but not after 2 weeks of IMI administration. The dose of 2 mg/kg of IMI has not changed this type of behavior at any time after IMI treatment. After 24 h IMI (2 or 10 mg/kg) decreased the immobility of rats. This paper presents for the first time that also after long-term treatment with IMI the evident effect on the time of immobility in the rat forced swimming test occurs.