The tryptophan utilization concept in pregnancy

The decrease in maternal plasma total (free + albumin-bound) tryptophan (Trp) during the third pregnancy trimester is attributed to induction of indoleamine 2,3-dioxygenase (IDO). When measured, free [Trp] is increased because of albumin depletion and non-esterified fatty acid elevation. The Trp depletion concept in pregnancy is therefore not supported because of incorrect interpretation of changes in Trp disposition and also for not addressing mouse strain differences in Trp-related responses and potential inhibition of Trp transport by the IDO inhibitor 1-methyl tryptophan. Application of the Trp utilization concept in pregnancy offers several physiological advantages favoring fetal development and successful outcome, namely provision of Trp for fetal protein synthesis and growth, serotonin for signaling pathways, kynurenic acid for neuroprotection, quinolinic acid for NAD+ synthesis, and other kynurenines for suppression of T cell responses. An excessive increase in Trp availability could compromise pregnancy by undermining T cell suppression, e.g., in pre-eclampsia.

Effects of Glutamine Supplement on the Concentration of Free Tryptophan in Serum and Brain, and 5-hydroxytryptamine in Brain after Exhaustion Treadmill Running in Rat / 中国运动医学杂志

Objective To examine the changes of brain inhibitory neurotransmitters and their precursors with glutamine supplement. The hypothesis is that the supplement of glutamine may delay the fatigue of central nervous system involved in exercise. Methods Rats were suffered with exhaustion treadmill running after different dosages of glutamine supplement of twenty days duration and sacrificed right after the running. Rat free tryptophan (F-Trp), branched chain amino acids (BCAA) in serum and brain, glucose in serum, and 5-hydroxytryptamine (5-HT) in the brain had been quantified with the double blind procedure. Results The results showed that the serum glutamine had no statistical significance among each group. The ratios of F-Trp/BCAA in the serum and brain were lower significantly in large dosage group than the placebo group. The 5-HT level of large dosage group was lower significantly than the other groups, while serum glucose was significantly higher than all the other groups. The ratios of F-Trp/BCAA in the brain were lower significantly in small dosage glutamine supplement rats than the other groups. Conclusion The results suggest that glutamine supplement take advantage of the balance of serum glutamine level. Glutamine supplement improves rat central nerves performance in long time treadmill running, that may due to the decrease of precursor of inhibitory neurotransmitter and itself, and large dosage supplement is more effective than small one.