Disturbances in dexamethasone suppression test and lower availability of L-tryptophan and tyrosine in early puerperium and in women under contraceptive therapy
Maes, M.; Claes, M.; Schotte, C.; Delbeke, L.; Jacquemyn, Y.; Verkerk, R.; De Meester, I.; Scharpé, S.
Journal of Psychosomatic Research 36(2): 191-197
1992
ISSN/ISBN: 0022-3999 PMID: 1560430 DOI: 10.1016/0022-3999(92)90028-zDocument Number: 317353
The possible role of amino acid availability and a functional hypothalamic-pituitary-adrenal axis in the mood disturbances often reported in postpartum women and in users of the oral contraceptive was examined by measuring amino acids and doing a dexamethasone suppression test. Plasma cortisol, tryptophan, tyrosine, their competing amino acids in brain uptake (CAA), and the effect of 1mg dexamethasone were determined in 10 women taking oral contraceptives, 31 women 3 days postpartum, and 9 controls. The pill contained 30 mcg ethinyl estradiol and .075 mg gestodene (2 women), and 30 mg ethinyl estradiol and .15 mg desogestrel (8 women). The subject also took self-rating mood scales: Zung Depression, Zung Anxiety, Beck Depression and State Anxiety Inventory. Cortisol was significantly higher in postpartum women and pill users than in normal controls. Tryptophan, valine, isoleucine and leucine were lower in postpartum women. Tyrosine and tyrosine CAA were lower in postpartum women and pill users. 80% of the postpartum group had negative dexamethasone suppression tests, i.e., cortisol 5 mcg/dl 24 hours after 1 mg dexamethasone. After dexamethasone valine was significantly higher and tryptophan/CAA and tyrosine/CAA ratios were lower, as a result of slightly lower tryptophan and tyrosine and slightly higher CAAs. Furthermore, effects on the amino acid ratios were only evident in women exhibiting dexamethasone suppression. There was a significant negative correlation between depression and anxiety scores and the tryptophan/CAA ratio. The results indicated first that the dexamethasone suppression test is an invalid marker for major depression, and also that availability of the amino acid precursors of brain neurotransmitters may affect mood in the puerperium.