title: Kynurenine Pathway Metabolism is Involved in the Maintenance of the Intracellular NAD Concentration in Human Primary Astrocytes.
abstract: Efficient synthesis of NAD(+) is critical to maintaining cell viability in all organs of the body. However, little is known of the pathway(s) by which cells of the central nervous system produce NAD(+). The aim of this study was to investigate the relationship, between tryptophan degradation via the kynurenine pathway (KP) and de novo NAD(+) synthesis in human astrocytes, a major cell type within the brain. In this study we observed that inhibition of single enzymes of the KP resulted in significant decreases in NAD(+) levels in astroglial cells after a 24 hr period. We also observed that astrocytes cultured in media deficient in tryptophan, nicotinic acid and nicotinamide resulted in a 50% decrease in NAD(+) levels after 24 hrs. This decrease in NAD(+) was partially restored by supplementation of the culture media with either tryptophan or kynurenine, or nicotinic acid or with supply of the salvage pathway precursor nicotinamide.
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney NSW Australia.
authors.forename: Ross
authors.initials: R
authors.lastname: Grant
authors.forename: Susan
authors.initials: S
authors.lastname: Nguyen
authors.forename: Gilles
authors.initials: G
authors.lastname: Guillemin
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