ROLE OF KYNURENINE PATHWAY METABOLITES IN DEPRESSION-A REVIEW

Abstract

Today most common psychiatric problem across the world is depression and stress is main source of ailment. According to World health organization, it will be the main cause of morbidity by 2020 in the world. Depression can critically affects the quality of life  as it is characterized by many symptoms like unhappy feeling, lack of interest and pleasure, down energy, inadequacy, regret feeling, slow-down of thoughts or reduction in physical movement, speech can affects, altered appetite or sleep, sad,  and increase the risk of suicide. Human body is inadequate to produce tryptophan which is a crucial amino acid; therefore it must be required from diet. After absorption, L-tryptophan crosses the BBB (Blood brain barrier) by non-specific L-type amino acid transporter and act as precursor to various metabolic pathways in central nervous system (CNS). Kynurenine is an important pathway that is associated with tryptophan (TRP) metabolism, where it develops a lot of metabolites such as 3-hydroxykynurenine (3HK), anthranilic acid (AA), kynurenic acid (KYNA), 3-hydroxyanthranilic acid (3HAA) and quinolinic acid (QUIN) known as kynurenines. It is already reported previously that disturbance in neuroprotective and neurotoxic metabolites leads to many psychiatric disorders. This review summarizes the role of kynurenine pathway metabolites in depression.