TY - JOUR
T1 - Ammonia increases paracellular permeability of rat brain endothelial cells by a mechanism encompassing oxidative/nitrosative stress and activation of matrix metalloproteinases
AU - Skowrońska, Marta
AU - Zielińska, Magdalena
AU - Wójcik-Stanaszek, Luiza
AU - Ruszkiewicz, Joanna
AU - Milatovic, Dejan
AU - Aschner, Michael
AU - Albrecht, Jan
PY - 2012/4
Y1 - 2012/4
N2 - 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.
AB - 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.
KW - ammonia
KW - blood-brain barrier
KW - cerebral capillary endothelial cell line
KW - matrix metalloproteinases
KW - oxidative/nitrosative stress
UR - http://www.scopus.com/inward/record.url?scp=84858699672&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84858699672&partnerID=8YFLogxK
U2 - 10.1111/j.1471-4159.2012.07669.x
DO - 10.1111/j.1471-4159.2012.07669.x
M3 - Article
C2 - 22260250
AN - SCOPUS:84858699672
SN - 0022-3042
VL - 121
SP - 125
EP - 134
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
IS - 1
ER -