4-hydroxy-2-nonenal and Hepatic-Encephalopathy

The major difficulty in establishing a clinical effective bioartificial liver assist device for treatment of fulminate hepatic failure is limitation of our knowledge and technologies about fresh cell behaviors in culture and a lack of knowledge about the etiology and pathogenesis of hepatic coma. Increasing data from clinical and laboratory investigation have accrued indicating that toxins from necrotic liver tissue, mainly as oxygen reactive substances, have a role in the pathogenesis of hepatic encephalopathy and even multiple system organs failure. This paper presents the data available and suggests a new pathway for artificial and bioartificial liver assist system.

Topics: Aldehydes; Animals; Bioreactors; Brain; Cells, Cultured; Equipment Design; Free Radicals; Glutathione; Hepatic Encephalopathy; Humans; Inactivation, Metabolic; Lipid Peroxidation; Liver; Liver Failure; Liver Transplantation; Liver, Artificial; Multiple Organ Failure; Necrosis; Oxidative Stress; Rabbits; Toxins, Biological

Oxidative stress induced by a high ammonia concentration has been suggested to be implicated in the pathophysiology of hepatic encephalopathy (HE). Therefore, oxidative damage of brain biomolecules could contribute towards explaining the neurological and motor alterations observed in HE.. Portacaval-shunted (PCS) rats (n = 5) were used as an animal model of chronic HE. Plasma and brain ammonia were measured by the l-glutamate dehydrogenase method. Reactive oxygen species was measured by the dichlorodihydrofluorescein diacetate method. Lipid peroxidation was measured as thiobarbituric acid-reactive substances (TBARS) by a colorimetric method; malondialdehyde (MDA) and 4-hydroxy-2-noneal (HNE) were measured by HPLC and an immunological method respectively. Protein oxidation (carbonylation) was measured as total carbonyl after labelling with 2,4-dinitrophenyl hydrazine (DNPH) using a spectrophotometric method. Individual protein oxidation was studied, after labelling with DNPH and its separation by one-dimensional (1D) electrophoresis, by an immunological method.. Ammonia-induced oxidative stress in PCS rats was associated with increased MDA and HNE, together with increased protein oxidation, evidenced by total carbonyl quantification and by the analysis of individual protein bands separated by 1D electrophoresis. However, lipid peroxidation measured as TBARS did not show differences.. Our data show an increased evidence of oxidative stress in PCS rat brain; moreover, PCS rat brain proteins are oxidized (carbonylated), some proteins being more sensitive to oxidation than others. These data also show that at least six specific brain proteins in PCS rats are highly sensitive to carbonylation. Identification of these proteins may be crucial for a better understanding of HE pathophysiology.

Topics: Aldehydes; Ammonia; Animals; Brain; Chromatography, High Pressure Liquid; Electrophoresis; Glutamate Dehydrogenase; Hepatic Encephalopathy; Lipid Peroxidation; Male; Malondialdehyde; Oxidation-Reduction; Oxidative Stress; Portacaval Shunt, Surgical; Rats; Rats, Wistar; Reactive Oxygen Species; Thiobarbituric Acid Reactive Substances

Ammonia is neurotoxic and believed to play a major role in the pathogenesis of hepatic encephalopathy (HE). It has been demonstrated, in vitro and in vivo, that acute and high ammonia treatment induces oxidative stress. Reactive oxygen species (ROS) are highly reactive and can lead to oxidization of proteins resulting in protein damage. The present study was aimed to assess oxidative status of proteins in plasma and brain (frontal cortex) of rats with 4-week portacaval anastomosis (PCA). Markers of oxidative stress, 4-hydroxy-2-nonenal (HNE) and carbonylation were evaluated by immunoblotting in plasma and frontal cortex. Western blot analysis did not demonstrate a significant difference in either HNE-linked or carbonyl derivatives on proteins between PCA and sham-operated control rats in both plasma and frontal cortex. The present study suggests PCA-induced hyperammonemia does not lead to systemic or central oxidative stress.

Topics: Aldehydes; Ammonia; Animals; Biomarkers; Blotting, Western; Brain; Disease Models, Animal; Frontal Lobe; Hepatic Encephalopathy; Hyperammonemia; Liver Failure, Acute; Male; Oxidative Stress; Portacaval Shunt, Surgical; Protein Carbonylation; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species