The effect of antidepressants on L-5HTP-induced changes in rat plasma corticosteroids.

The finding that L-5HTP will cause an elevation in rat plasma corticosteroids, presumably through generation of serotonin, has been utilized to evaluate the serotonin potentiating and antagonizing properties of a series of antidepressants. Fluoxetine and zimelidine were most effective in enhancing the effect of low dose (12. 5 mg/kg) L-5HTP. Agents such as chlorimipramine, viloxazine and opipramol were weakly active at potentiating L-5HTP and mianserin and dibenzepine were strong antagonists of the L-5HTP effect. Since antidepressants have been found to either potentiate or antagonize serotonin, it is difficult to envision that the antidepressants exert their therapeutic effect through serotongeric mechanisms.