Effect of repeated administration of antidepressant drugs on the isoprenaline-induced drinking in rats.

The effect of acute (single dose) and repeated (twice daily, for 21 days) administration of imipramine, amitriptyline, citalopram, mianserin and rolipram (the latter drug in a dose of 5 mg/kg po, all the other drugs in a dose of 10 mg/kg po) on drinking induced by isoprenaline (50 micrograms intracerebroventricularly (icv), 2 h after the single dose, 2 and 72 h after the last does of the antidepressants) was studied in rats. It was found that repeated, but not acute, treatment with imipramine, amitriptyline and rolipram significantly reduced the response to isoprenaline. The effect of amitriptyline and rolipram was observed 2 and 72 h after their last administration, while that of imipramine only 72 h after its last dose. Citalopram and mianserin were ineffective after both acute and repeated administration.