Antidepressant-like effects of triiodothyroacetic acid in mice

Triiodothyroacetic acid (TA3) is a natural thyroid analogue which possesses some of the properties of triiodothyronine (T3). In particular, it has an inhibitory effect on the thyreotropic axis, but its peripheral effects are reduced. Given the activity of T3 on psychopharmacological models of depression in rodents, we investigated the effects of TA3 on some pharmacological and behavioral tests in mice. TA3 antagonized apomorphine- and oxotremorine-induced hypothermia, potentiated yohimbine-induced toxicity and L-5-hydroxy-tryptophan-induced head twitches, but did not affect forced swimming-induced immobility or reserpine-induced hypothermia. Thus, TA3 was effective on the same psychopharmacological tests which have previously been used to demonstrate the antidepressant-like effects of T3. Moreover, TA3 under the same experimental conditions as T3 has little effect on the metabolic clearance rate parameters, and might, therefore, be preferable to T3 for clinical use in depression.