Triiodothyronine potentiation of antidepressant-induced reversal of learned helplessness in rats.

Several clinical investigations have suggested that a special relationship exists between thyroid function and affective disorders and/or therapeutic response to antidepressants. The present report describes that the reversal by antidepressants (imipramine, desipramine, and nomifensine) of depressive-like behavior in rats (escape deficits produced by previous exposure to uncontrollable stress) was significantly hastened in animals given daily triiodothyronine (T3). The learned helplessness paradigm might be a useful model for approaching in animals the neurohormonal correlates of affective disorders and the neurobiochemical bases of the reported T3 enhancement of antidepressants.