BACKGROUND: The mechanism by which rapid tryptophan depletion (RTD) paradigm induces depressive relapse in recently remitted patients with depression is unknown. AIMS: To determine the effects of RTD on brain 5-HT(2) receptors using positron emission tomography (PET) and (18)F-labelled setoperone. METHOD: Ten healthy women under went two PET scans. Each scan was done 5 h after the ingestion of either a balanced or a tryptophan-deficient amino acid mixture, and the two test sessions were separated by at least 5 days. RESULTS: The RTD decreased plasma free tryptophan levels significantly but it had no significant effects on mood. Subjects showed a significant decrease in brain 5-HT(2) receptor binding in various cortical regions following the RTD session. CONCLUSIONS: When taken with the evidence that antidepressant treatment is associated with a decrease in brain 5-HT(2) receptors, these findings suggest that a decrease in 5-HT(2) binding following RTD might be an adaptive response that provides protection against depressive symptoms.
BACKGROUND: The mechanism by which rapid tryptophan depletion (RTD) paradigm induces depressive relapse in recently remitted patients with depression is unknown. AIMS: To determine the effects of RTD on brain 5-HT(2) receptors using positron emission tomography (PET) and (18)F-labelled setoperone. METHOD: Ten healthy women under went two PET scans. Each scan was done 5 h after the ingestion of either a balanced or a tryptophan-deficient amino acid mixture, and the two test sessions were separated by at least 5 days. RESULTS: The RTD decreased plasma free tryptophan levels significantly but it had no significant effects on mood. Subjects showed a significant decrease in brain 5-HT(2) receptor binding in various cortical regions following the RTD session. CONCLUSIONS: When taken with the evidence that antidepressant treatment is associated with a decrease in brain 5-HT(2) receptors, these findings suggest that a decrease in 5-HT(2) binding following RTD might be an adaptive response that provides protection against depressive symptoms.
Authors: Christina R Di Iorio; Tristan J Watkins; Mary S Dietrich; Aize Cao; Jennifer U Blackford; Baxter Rogers; Mohammed S Ansari; Ronald M Baldwin; Rui Li; Robert M Kessler; Ronald M Salomon; Margaret Benningfield; Ronald L Cowan Journal: Arch Gen Psychiatry Date: 2011-12-05
Authors: Paul P Allen; Anthony J Cleare; Francis Lee; Paolo Fusar-Poli; Nigel Tunstall; Cynthia H Y Fu; Micheal J Brammer; Philip K McGuire Journal: Psychopharmacology (Berl) Date: 2006-07-06 Impact factor: 4.530