Kynurenic Acid x Quinolinic Acid

Kynurenic Acid

The pathway of tryptophan metabolism may produce neurotoxic compounds or activate to production of Serotonin. This pathway serves the following functions:

A. Clearance of excess L-tryptophan

B. Maintenance of nicotinic acid levels

C. Regulation of glutamatergic neuronal activity

D. Enhancement of macrophage defense functions

- Kynurenic acid elevated: Kynurenic acid antagonizes glutamate receptors and has a preferential affinity for NMDA receptors that governs synaptic plasticity, learning and memory. Studies suggest that elevated kynurenic acid represent conditions that are seen in schizophrenia, mediated by vitamin B6.

- Kynurenic acid is a biochemical precursor to quinolinic acid and found to be simultaneously elevated in inflammatory responses. Because quinolinic acid is a powerful agonist of NMDA receptor and kynurenate antagonizes this effect, the relative amount of the two metabolites should relate to neuronal degradation.

- Consider: Vitamin B6 and magnesium.

 

Quinolinic Acid

Quinolinic acid provides a critical link between the immune system and the brain. Quinolinic acid is produced from tryptophan via interferon-gamma (IFN-y), stimulated astroglial cells and macrophages, a Th1-driven response. It is associated with increased oxidative stress, virus, fungal bacterial and parasitic infection gastrointestinal overgrowth, autoimmune disorder or irritable bowel disease (IBD).

Quinolinic acid interacts with NMDA receptors of the glutaminergic neurons that respond to pain and peripheral signals. If this is overstimulated, glutamate excitotoxicity occurs. Quinolinic acid toxicity is suspected as an etiologic factor in Alzheimer’s disease. A useful outcome of the conversion of Tryptophan to quinolinic acid is the ultimate production of nicotinic acid support to supply its cofactor form, NAD.

- Quinolinic acid elevated: Avoid tryptophan and consider magnesium supplementation.

-5-hydroxyindoleacetate (5-HIAA) low: Low values of 5-hydroxyindoleacetate (5-HIAA) may indicate inadequate production of serotonin.

-Consider: Tryptophan, 5-HTP, vitamin B6, iron, BH4.