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Elevated prolactin responses to L-tryptophan infusion in medication-free depressed patients

Lookup NU author(s): Dr Richard Porter, Dr Peter GallagherORCiD, Dr Stuart Watson, Margaret Smith, Professor Allan Young


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Rationale: Several previous neuroendocrine studies have demonstrated reduced 5-HT1A receptor function in major depressive disorder (MDD). However, hypercortisolaemia or previous drug treatment may have been significant confounds. Objectives: To replicate previous studies in subjects with MDD who had been drug free for at least 8 weeks and to relate the findings to measures of HPA axis function. Methods: Hormonal responses to L-tryptophan infusion were measured in patients with MDD (n=20) and healthy controls (n=20). Basal salivary cortisol and DHEA were also profiled. Results: No attenuation of 5-HT1A receptor-dependent neuroendocrine responses (growth hormone, prolactin) was observed in patients with MDD. The prolactin response to L-tryptophan was significantly greater in MDD patients than in healthy controls (P=0.008). There was a significant negative correlation between prolactin response and basal salivary cortisol secretion over the 3 days prior to the test. Conclusions: These data do not support previous findings of reduced 5-HT1A function in MDD and suggest that hypercortisolaemia or psychotropic medication may have accounted for the attenuation. Basal cortisol, DHEA and the cortisoL-DHEA ratio did not differ between patients and controls, and all patients were psychotropic medication-free. The greater prolactin response to L-tryptophan infusion in depressed subjects may be the result of an increase in dopamine receptor sensitivity, secondary to reduced dopamine levels.

Publication metadata

Author(s): Porter RJ, Gallagher P, Watson S, Smith MS, Young AH

Publication type: Article

Publication status: Published

Journal: Psychopharmacology

Year: 2003

Volume: 169

Issue: 1

Pages: 77-83

Print publication date: 01/08/2003

ISSN (print): 0033-3158

ISSN (electronic): 1432-2072

Publisher: Springer


DOI: 10.1007/s00213-003-1475-1

PubMed id: 12728300


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