N-acetylcysteine protects against renal injury following bilateral ureteral obstruction.
BACKGROUND
Obstructive nephropathy decreases renal blood flow (RBF) and glomerular filtration rate (GFR), causing tubular abnormalities, such as urinary concentrating defect, as well as increasing oxidative stress. This study aimed to evaluate the effects of N-acetylcysteine (NAC) on renal function, as well as on the protein expression of aquaporin 2 (AQP2) and endothelial nitric oxide synthase (eNOS), after the relief of bilateral ureteral obstruction (BUO).


METHODS
Adult male Wistar rats were divided into four groups: sham (sham operated); sham operated + 440 mg/kg body weight (BW) of NAC daily in drinking water, started 2 days before and maintained until 48 h after the surgery; BUO (24-h BUO only); BUO + NAC-pre (24-h BUO plus 440 mg/kg BW of NAC daily in drinking water started 2 days before BUO); and BUO + NAC-post (24-h BUO plus 440 mg/kg BW of NAC daily in drinking water started on the day of BUO relief). Experiments were conducted 48 h after BUO relief.


RESULTS
Serum levels of thiobarbituric reactive substances, which are markers of lipid peroxidation, were significantly lower in NAC-treated rats than in the BUO group rats. The administration of NAC provided significant protection against post-BUO GFR drops and reductions in RBF. Renal cortices and BUO rats presented decreased eNOS protein expression of eNOS in the renal cortex of BUO group rats, whereas it was partially recovered in BUO + NAC-pre group rats. Urine osmolality was significantly lower in BUO rats than in sham group rats or NAC-treated rats, the last also presenting less interstitial fibrosis. Post-BUO downregulation of AQP2 protein expression was averted in the BUO + NAC-pre group rats.


CONCLUSIONS
This study demonstrates that NAC administration ameliorates the renal function impairment observed 48 h after the relief of 24-h BUO. Oxidative stress is important for the suppression of GFR, RBF, tissue AQP2 and eNOS in the polyuric phase after the release of BUO.
Shimizu
Maria Heloisa Massola
MH
1Department of Nephrology, University of São Paulo School of Medicine, CEP 01246-000 São Paulo, Brazil.
Danilovic
Alexandre
A
Andrade
Lucia
L
Volpini
Rildo A
RA
Libório
Alexandre B
AB
Sanches
Talita R C
TR
Seguro
Antonio Carlos
AC
D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D007674:Kidney Diseases / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000187:drug effects; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014517:Ureteral Obstruction / Q000150:complications* / Q000188:drug therapy* / Q000503:physiopathology; D014556:Urine / Q000737:chemistry
C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D017392:Thiobarbituric Acid Reactive Substances; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D000111:Acetylcysteine