The mechanisms by which administration of interferon-alpha induces neuropsychiatric side effects, such as depressive symptoms and changes in cognitive function, are not clear as yet. Direct influence on serotonergic neurotransmission may contribute to these side effects. In addition, the enzyme indoleamine 2,3-dioxygenase (IDO), which converts tryptophan into kynurenine, may play an important r...

The definition of dual tryptophan pathways has increased the understanding of the mind-body, body-mind dichotomy. The serotonergic pathway highlights the primary (endogenous) psychiatric disorders. The up-regulation of the kynurenine pathway by physical illnesses can cause neuropathic and immunological disorders1 associated with secondary neuropsychiatric symptoms. Tryptophan and nicotinamide d...

Kotake and Nakayama (1) observed the conversion of kynurenine to anthranilic acid and alanine by a mammalian liver extract. Subsequently the enzyme responsible for this reaction in the mammal was partly purified (2,3) and the enzyme, prepared from vitamin Be-deficient animals, was shown to require pyridoxal phosphate for its maximal activity (2). During an investigation of tryptophan metabolism...

The kynureninase-type enzymes of three fungi and one bacterium were isolated and examined kinetically for their ability to catalyze the hydrolysis of L-kynurenine and L-3-hydroxykynurenine. The phycomycete Rhizopus stolonifer was found to contain a single, constitutive enzyme with Km for L-3-hydroxykynurenine and L-kynurenine of 6.67 times 10-minus 6 and 2.5 times 10-minus 4 M, respectively. Th...

The kynurenine pathway of tryptophan metabolism has an important role in mediating the behavioral effects of inflammation, which has implications in understanding neuropsychiatric comorbidity and for the development of novel therapies. Inhibition of the rate-limiting enzyme, indoleamine 2,3-dioxygenase (IDO), prevents the development of many of these inflammation-induced preclinical behaviors. ...

BACKGROUND Circulating neopterin and the ratio of kynurenine to tryptophan (KYN/TRP) concentrations are biomarkers of immune activation that have been linked to cardiovascular and total mortality. Several in vitro studies indicated that tea flavonoids and other antioxidants can modulate tryptophan breakdown rates and neopterin production in immune cells. We aimed to assess the effects of regula...

Neurologic symptoms and neurodegeneration are important causes of morbidity and mortality in man. Although many pathogenic mechanisms could account for neurologic dysfunction, considerable interest has focused on a group of neurotoxins known as the ‘excitotoxins’. Quinolinic acid (QUIN) is an excitotoxic L-tryptophan and kynurenine pathway metabolite that is an agonist of N-methyl-uaspartate (N...

Pattern recognition receptors and receptors for pro-inflammatory cytokines provide critical signals to drive the development of protective immunity to infection. Therefore, counter-regulatory pathways are required to ensure that overwhelming inflammation harm host tissues. Previously, we showed that lipoxins modulate immune response during infection, restraining inflammation during infectious d...

HE classic pathway for brown pigment synthesis in Drosophila melanogaster, as determined by the accumulation of intermediates, involves the sequence, tryptophan -+ formyl kynurenine + kynurenine -+ 3-hydroxykynurenine -+ brown pigments (for review see ZIEGLER 1961). Two of the enzymes in this pathway. tryptophan pyrrolase (BAGLIONI 1959, 1960; KAUFMAN 1962; MARZLUF 1965a, b) and kynurenine form...

Several studies suggest a role for kynurenic acid (KYNA) in the pathophysiology of schizophrenia. It has been proposed that increased brain KYNA levels in schizophrenia result from a pathological shift in the kynurenine pathway toward enhanced KYNA formation, away from the other branch of the pathway leading to quinolinic acid (QUIN). Here we investigate the levels of QUIN in cerebrospinal flui...