Kynurenic acid ELISA test in serum (KYNA)

TDO is primarily expressed within the liver and 10
IDO is an extrahepatic cytokine inducible enzyme. The next step in the synthesis of kynurenine is catalyzed by formylkynurenine formamidase. The main end product of kynurenine catabolism is nicotinamide adenosine dinucleotide (NAD+). Another biologically active product, KYNA, is generated from kynurenine by kynurenine aminotransferase.

Numerous studies were conducted to investigate the role of KYNA in the physiology and pathology of the central nervous system (CNS). Since both the concentration of KYNA in the human brain and penetration of KYNA through a blood-brain barrier are low, studies of peripheral KYNA gained popularity. Research has pointed to the reality that kynurenic acid is the key component of dopamine neuron firing, and when its levels are too high among the central nervous system, neuropathic and even disorienting conditions can prevail.

Kynurenic acid contributes to the pathogenesis of schizophrenia and link the dopamine hypothesis of schizophrenia together with the idea of a deficiency in glutamatergic function in this disease. Kynurenic acid acts in the brain as a glycine-site NMDAr antagonist, key in glutamatergic neurotransmission system, which is thought to be involved in the pathophysiology and pathogenesis of schizophrenia. High levels of kynurenic acid have been identified in patients suffering from tick-borne encephalitis, schizophrenia and HIV-related illnesses. In all these situations increased levels were associated with confusion and psychotic symptoms.