Neurochemical Research

, Volume 39, Issue 3, pp 593–598

Glutamine in the Pathogenesis of Hepatic Encephalopathy: The Trojan Horse Hypothesis Revisited

  • Kakulavarapu V. Rama Rao
  • Michael D. Norenberg
Overview

Abstract

Hepatic encephalopathy (HE) is major neuropsychiatric disorder occurring in patients with severe liver disease and ammonia is generally considered to represent the major toxin responsible for this condition. Ammonia in brain is chiefly metabolized (“detoxified”) to glutamine in astrocytes due to predominant localization of glutamine synthetase in these cells. While glutamine has long been considered innocuous, a deleterious role more recently has been attributed to this amino acid. This article reviews the mechanisms by which glutamine contributes to the pathogenesis of HE, how glutamine is transported into mitochondria and subsequently hydrolyzed leading to high levels of ammonia, the latter triggering oxidative and nitrative stress, the mitochondrial permeability transition and mitochondrial injury, a sequence of events we have collectively termed as the Trojan horse hypothesis of hepatic encephalopathy.

Keywords

Ammonia Astrocytes Glutamine Glutaminase Hepatic encephalopathy l-Histidine 6-Diazo-5-oxo-l-norleucine (DON) Mitochondrial permeability transition Oxidative stress 

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Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Kakulavarapu V. Rama Rao
    • 1
  • Michael D. Norenberg
    • 1
    • 2
    • 3
  1. 1.Department of PathologyUniversity of Miami Miller School of MedicineMiamiUSA
  2. 2.Biochemistry and Molecular BiologyUniversity of Miami Miller School of MedicineMiamiUSA
  3. 3.Veterans Affairs Medical CenterMiamiUSA

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