• Serum cortisol levels were significantly increased following administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, to patients with affective disorders. A three-to five-week period of treatment with lithium carbonate or monoamine oxidase (MAO) inhibitor augmented the mean 5-HTP-induced increase in serum cortisol concentration in manic or depressed patients, respectively: tricyclic antidepressant (TCA) and second-generation antidepressant treatment diminished the mean serum cortisol response in patients with major depression. These results are consistent with the hypothesis that lithium carbonate may enhance serotonin (5-HT) receptor sensitivity, whereas TCA and second-generation antidepressants diminish 5-HT receptor sensitivity. The enhancement of the cortisol response to 5-HTP by MAO inhibitors may be due to decreased metabolism of 5-HT. It is important to assess the effect of thymoleptic drug treatment on various responses to biogenic amine precursors or agonists in patients rather than laboratory animals.
Meltzer HY, Lowy M, Robertson A, Goodnick P, Perline R. Effect of 5-Hydroxytryptophan on Serum Cortisol Levels in Major Affective DisordersIII. Effect of Antidepressants and Lithium Carbonate. Arch Gen Psychiatry. 1984;41(4):391-397. doi:10.1001/archpsyc.1984.01790150081011