Tryptophan and its metabolite, kynurenine, stimulate expression of nerve growth factor in cultured mouse astroglial cells

Abstract

Effects of l-tryptophan and its metabolites were evaluated on expression of nerve growth factor (NGF) in primary culture of mouse astroglial cells. l-Tryptophan produced concentration-dependent increases in accumulation of NGF transcripts in the cells. l-Kynurenine, a metabolite of the kynurenine pathway, markedly increased the levels of mRNAs for NGF, the maximal increases (4–5 fold) occurred at its dose of 1 μM. Kynurenine-induced increase in mRNA levels for NGF occurred as early as 1 h after the addition of the compound, peaked at 4 h and declined thereafter. In contrast to kynurenine, other tryptophan metabolites such as quinolinic acid, kynurenic acid and serotonin had little effect on the levels of NGF mRNA.