Increased L-Tryptophan, 5-Hydroxyindoleacetic Acid, 3-Hydroxykynurenine and Quinolinic Acid Concentrations in Cerebral Cortex Following Systemic Endotoxin Administration

Abstract

Systemic infections and administration of lipopolysaccharide (LPS) are known to increase L-tryptophan (L-TRP) release from skeletal muscle, accelerate systemic L-TRP catabolism through the kynurenine pathway (Rapoport et al., 1970; Takikawa et al., 1986), and increase the excretion of L-kynurenine and xanthurenic acid (Rapoport et al., 1970; Takikawa et al., 1986). This increase in kynurenine pathway metabolites may, in part, be secondary to the induction of indoleamine-2, 3-dioxygenase (IDO), the first enzyme in the kynurenine pathway in extrahepatic tissues (Takikawa et al., 1986; Yoshida et al., 1986). Although there are numerous reports on the effects of infection and LPS on systemic L-TRP metabolism, the effects of immunologie stimulation on brain L-TRP metabolism have received little attention.