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J Psychosom Res. 1992 Feb;36(2):191-7.

Disturbances in dexamethasone suppression test and lower availability of L-tryptophan and tyrosine in early puerperium and in women under contraceptive therapy.

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1
Department of Psychiatry, University of Antwerp, Belgium.

Abstract

This study investigates the function of the hypothalamic-pituitary-adrenal (HPA)-axis and the availability of L-tryptophan and tyrosine to the brain in postpartum women and in women taking long-term oral contraceptives. To this end, we have measured the following parameters in 50 women (i.e. 9 normal controls, 10 women taking oral contraceptives, and 31 postpartum females): plasma cortisol, L-tryptophan, tyrosine and the amino acids (CAA) known to compete with them for transport through the blood-brain barrier. We have determined the effects of 1 mg of dexamethasone on the above-mentioned biological markers in postpartum females. Plasma cortisol and tyrosine were significantly higher and lower, respectively, in puerperium and in women under contraceptive therapy as opposed to normal controls. L-Tryptophan was significantly lower in postpartum females, whilst the L-tryptophan/CAA ratio did not differ across the three study groups. Postpartum females revealed a significant negative relationship between the availability of L-tryptophan to the brain and postpartum mood, as measured by Zung's Depression and Anxiety Scales and State Anxiety Inventory. Dexamethasone had a significant suppressive effect on L-tryptophan/CAA and tyrosine/CAA ratios, with cortisol nonsuppression appearing in 82% of the postpartum females.

PIP:

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.

PMID:
1560430
[Indexed for MEDLINE]
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