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Calpain Inhibition Attenuates iNOS Production and Midzonal Hepatic Necrosis in a Repeat Dose Model of Endotoxemia in RatsDepartment of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4467, USA Correspondence: Address correspondence to: Shashi K. Ramaiah, Department of Pathobi-ology, College of Veterinary Medicine, Texas A&M University, MS-4467, College Station, TX 77843-4467, USA; e-mail:sramaiah{at}cvm.tamu.edu Systemic exposure to bacterial lipopolysaccharide (LPS, endotoxin) induces hypotension, disseminated intravascular coagulation and neutrophil infiltration in various organs including the lung, kidney and liver. A rat endotoxemic neutrophilic hepatitis model (repeat dose LPS, 10 mg/kg, i.v. 24 hours apart) was developed exhibiting hepatic neutrophil infiltration and mid-zonal hepatic necrosis. The goal of the study was to investigate the role of the intracellular enzyme calpain in the development of neutrophilic hepatitis with midzonal necrosis in this model. A second goal was to compare the observed protective effects of calpain inhibition with a relatively selective inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) and an inhibitor of coagulation, heparin. When compared to rats administered LPS alone, administration of calpain 1 inhibitor prior to LPS significantly reduced hepatic iNOS expression, hepatic neutrophil infiltration and attenuated midzonal hepatic necrosis. Administration of AG or heparin prior to LPS also decreased liver iNOS expression, hepatic neutrophil infiltration and liver pathology comparable to calpain inhibition. Blood neutrophil activation, as measured by the neutrophil adhesion molecule CD11b integrin, was upregulated in all the LPS treated groups regardless of inhibitor administration. We conclude that amelioration of liver pathology via calpain inhibition is likely dependent on the down-regulation of iNOS expression in the rat model of LPS-mediated hepatitis.
Key Words: Calpain • endotoxin • hepatitis • INOS • liver • neutrophils • midzonal necrosis • toxicity Abbreviations: AG, aminoguanidine • APTT, Activated partial thromboplastin time • CYP450, Cytochrome P450 • iNOS, inducible nitric oxide synthase • LPS, Lipopolysaccharide • NO, nitric oxide • NFkB, Nuclear factor kappa • PT, Prothrombin time • ROS, Reactive oxygen species
Toxicologic Pathology, Vol. 34, No. 6,
785-794 (2006) This article has been cited by other articles:
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