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Ammonia increases paracellular permeability of rat brain endothelial cells by a mechanism encompassing oxidative/nitrosative stress and activation of matrix metalloproteinases
Author(s) -
Skowrońska Marta,
Zielińska Magdalena,
WójcikStanaszek Luiza,
Ruszkiewicz Joanna,
Milatovic Dejan,
Aschner Michael,
Albrecht Jan
Publication year - 2012
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2012.07669.x
Subject(s) - chemistry , nitric oxide , oxidative stress , biochemistry , pharmacology , biology , organic chemistry
J. Neurochem. (2012) 121 , 125–134. Abstract Ammonia is responsible for cerebral edema associated with acute liver failure, but the role of the vasogenic mechanism has been a matter of dispute. Here, we tested the hypothesis that ammonia induces changes in blood–brain barrier (BBB) permeability by a mechanism coupled to oxidative/nitrosative stress (ONS) evoked in the BBB‐forming cerebral capillary endothelial cells. Treatment of a rat brain endothelial cell line with ammonia (5 mmol/L, 24 h) caused accumulation of ONS markers: reactive oxygen species, nitric oxide and peroxidation products of phospholipid‐bound arachidonic acid, F2‐isoprostanes. Concurrently, ammonia increased the activity of extracellular matrix metalloproteinases (MMP‐2/MMP‐9), increased cell permeability to fluorescein isothiocyanate‐dextran (40 kDa), and increased the expression of y+LAT2, a transporter that mediates the uptake to the cells of the nitric oxide precursor, arginine. The increase of cell permeability was ameliorated upon co‐treatment with a MMP inhibitor, SB‐3CT and with an antioxidant, glutathione diethyl ester, which also reduced F2‐isoprostanes. Ammonia‐induced ONS was attenuated by cytoprotective agents l‐ ornithine, phenylbutyrate, and their conjugate l‐ ornithine phenylbutyrate, an ammonia‐trapping drug used to treat hyperammonemia. The results support the concept that ONS and ONS‐related activation of MMPs in cerebral capillary endothelial cells contribute to the alterations in BBB permeability and to the vasogenic component of cerebral edema associated with acute liver failure.