Effects of pregnancy and delivery on the availability of plasma tryptophan to the brain: relationships to delivery-induced immune activation and early post-partum anxiety and depression.
BACKGROUND
There is now evidence that the availability of plasma tryptophan is decreased during pregnancy and the puerperium and also in patients with major depression and inflammation. The aims of the present study were to examine: (i) the effects of pregnancy and delivery on plasma tryptophan and the amino acids known to compete for the same cerebral uptake mechanism (CAAs), valine, leucine, tyrosine, phenylalanine and isoleucine; (ii) the relationships between the availability of plasma tryptophan and postpartum depression or anxiety; and (iii) the relationships between the availability of plasma tryptophan to the brain and inflammatory markers, such as serum interleukin-6 (IL-6), interleukin-1 receptor-antagonist (IL-1RA) and the leukaemia inhibitory factor receptor (LIF-R).


METHODS
The above variables were measured in 13 healthy non-pregnant and in 98 pregnant women 3 to 6 days before delivery and 1 and 3 days after delivery. On each occasion the parturient women completed the state version of Spielberger State-Trait Anxiety Inventory (STAI) and the Zung Depression Rating Scale (ZDS).


RESULTS
Plasma tryptophan and the tryptophan/CAA ratio were significantly lower at the end of term and after delivery than in the plasma of non-pregnant, healthy women. The tryptophan/CAA ratio was significantly lower in the early puerperium than at the end of term. There were no significant relationships between the availability of plasma tryptophan and either post-partum depression or changes in the STAI or ZDS scores in the early puerperium. The changes in the tryptophan/CAA ratio from the end of term to the early puerperium were significantly and inversely related to serum IL-6, IL-IRA and LIF-R.


CONCLUSIONS
The results show that the reduction in the availability of plasma tryptophan from the end of term to the early puerperium is related to immune activation; and that the lowered availability of plasma tryptophan is not related either to depressive or anxiety symptoms in the early puerperium or to post-partum depression ensuing some months later.
Maes
M
M
Department of Psychiatry and Neuropsychology, University of Maastricht, The Netherlands.
Ombelet
W
W
Verkerk
R
R
Bosmans
E
E
Scharpé
S
S
D000328:Adult; D000596:Amino Acids / Q000097:blood; D001008:Anxiety Disorders / Q000175:diagnosis / Q000276:immunology* / Q000523:psychology; D001921:Brain / Q000276:immunology; D019052:Depression, Postpartum / Q000175:diagnosis / Q000276:immunology* / Q000523:psychology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D010555:Personality Inventory; D011247:Pregnancy; D018121:Receptors, Cytokine / Q000097:blood*; D053606:Receptors, OSM-LIF; D012307:Risk Factors; D014364:Tryptophan / Q000097:blood*
D000596:Amino Acids; D015850:Interleukin-6; C507840:LIFR protein, human; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D018121:Receptors, Cytokine; D053606:Receptors, OSM-LIF; D014364:Tryptophan