Region selective alterations of soluble guanylate cyclase content and modulation in brain of cirrhotic patients

Authors

  • Regina Corbalán,

    1. Laboratory of Neurobiology, Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomédicas, Valencia, Spain
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    • R. Corbalan is a fellow of Generalitat Valenciana.

  • Nicolas Chatauret,

    1. Neuroscience Research Unit, Saint-Luc Hospital (CHUM), University of Montreal, Montreal, Quebec, Canada
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  • Sönke Behrends,

    1. Institute of Pharmacology, University of Hamburg, Hamburg, Germany
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  • Roger F. Butterworth,

    1. Neuroscience Research Unit, Saint-Luc Hospital (CHUM), University of Montreal, Montreal, Quebec, Canada
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  • Vicente Felipo

    Corresponding author
    1. Laboratory of Neurobiology, Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomédicas, Valencia, Spain
    • Laboratory of Neurobiology, Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomédicas, Amadeo de Saboya 4, 46010 Valencia, Spain. fax: (34) 96 3601453.
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Abstract

Modulation of soluble guanylate cyclase (sGC) by nitric oxide (NO) is altered in brain from experimental animals with hyperammonemia with or without liver failure. The aim of this work was to assess the content and modulation of sGC in brain in chronic liver failure in humans. Expression of the α-1, α-2, and β-1 subunits of sGC was measured by immunoblotting in autopsied frontal cortex and cerebellum from cirrhotic patients and controls. The contents of α-1 and α-2 subunits of guanylate cyclase was increased both in cortex and cerebellum, whereas the β-1 subunit was not affected. Addition of the NO-generating agent S-nitroso-N-acetyl-penicillamine (SNAP) to homogenates of frontal cortex from controls increased the activity of sGC 87-fold, whereas, in homogenates from cirrhotic patients, the increase was significantly higher (183-fold). In contrast, in cerebellum, activation of guanylate cyclase by NO was significantly lower in patients (156-fold) than in controls (248-fold). A similar regional difference was found in rats with portacaval anastomosis. In conclusion, these findings show that the NO-guanylate cyclase signal transduction pathway is strongly altered in brain in patients with chronic liver failure and that the effects are different in different brain areas. Given that activation of sGC by NO in brain is involved in the modulation of important cerebral processes such as intercellular communication, learning and memory, and the sleep-wake cycle, these changes could be implicated in the pathogenesis of hepatic encephalopathy in these patients.

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