| Hyperammonemia increases the expression and activity of the glutamine/arginine transporter y+ LAT2 in rat cerebral cortex: implications for the nitric oxide/cGMP pathway. | |
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MedLine Citation:
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PMID: 21115085 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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The pathogenesis of hepatic encephalopathy (HE) is associated with hyperammonemia (HA) and subsequent exposure of the brain to excess of ammonia. Alterations of the NO/cGMP pathway and increased glutamine (Gln) content are collectively responsible for many HE symptoms, but how the two events influence each other is not clear. Previously we had shown that Gln administered intracerebrally inhibited the NO/cGMP pathway in control rats and even more so in rats with HA, and we speculated that this effect is due to inhibition by Gln of arginine (Arg) transport (Hilgier et al., 2009). In this study we demonstrate that a 3-day HA in the ammonium acetate model increases the expression in the brain of y(+)LAT2, the heteromeric transporter which preferentially stimulates Arg efflux from the cells in exchange for Gln. The expression of the basic amino acid transporter CAT1, transporting Arg but not Gln remained unaffected by HA. Multiple parameters of Arg or Gln uptake and/or efflux and their mutual dependence were altered in the cerebral cortical slices obtained from HA rats, in a manner indicating enhanced y(+)LAT2-mediated transport. HA elevated Gln content and decreased cGMP content as measured both in the cerebral cortical tissue and microdialysates. Intracortical administration of 6-diazo-5-oxo-L-norleucine (DON), which inhibits Gln fluxes between different cells of the CNS, attenuated the HA-induced decrease of cGMP in the microdialysates of HA rats, but not of control rats. The results suggest that, reduced delivery of Arg due to enhanced y(+)LAT2-mediated exchange of extracellular Gln for intracellular Arg may contribute to the decrease of NO/cGMP pathway activity evoked in the brain by HA. |
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Authors:
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Magdalena Zielińska; Joanna Ruszkiewicz; Wojciech Hilgier; Inez Fręśko; Jan Albrecht |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-11-27 |
Journal Detail:
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Title: Neurochemistry international Volume: 58 ISSN: 1872-9754 ISO Abbreviation: Neurochem. Int. Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2011-01-10 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8006959 Medline TA: Neurochem Int Country: England |
Other Details:
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Languages: eng Pagination: 190-5 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 Elsevier Ltd. All rights reserved. |
Affiliation:
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Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5 Str, 02-106 Warsaw, Poland. madziul@cmdik.pan.pl |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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