The analgesic effect of tricyclic antidepressants.

The analgesia produced by tricyclic antidepressants (TCAs) in rats and the role of serotonin in this analgesia have been investigated in this study. Rats received intraperitoneal injections of imipramine and amitriptyline, which are TCAs, and the serotonin synthesis inhibitor, pCPA. An acute analgesic effect was measured 90 min after the first injections; a chronic effect was measured 24 h after the last injections, on the 7th and 15th days using the hot-plate method.