Further evidence that noradrenaline is not involved in the anti-immobility activity of chronic desipramine in the rat.

The effect of 10 mg/kg per day desipramine for 7 days on performance in the forced swimming test was studied in rats given various treatments aimed at reducing central noradrenergic transmission. 6-Hydroxydopamine-induced destruction of noradrenaline-containing neurons originating in the locus coeruleus or ascending in the ventral bundle had no effect on the anti-immobility activity of desipramine. Likewise, no changes in the effect of desipramine were seen with an intraperitoneal injection of DSP-4 (50 mg/kg) which destroyed brain noradrenergic neurons, particularly those of the dorsal bundle ascending to the forebrain. The results argue against a role of noradrenaline in the mechanism by which repeated treatment with desipramine reduces the immobility of rats in the forced swimming test.