title: Inhibition of neutral sphingomyelinase decreases elevated levels of nitrative and oxidative stress markers in liver ischemia-reperfusion injury.
abstract: Oxidative stress and excessive nitric oxide production via induction of inducible nitric oxide synthase (NOS)-2 have been shown in the pathogenesis of liver ischemia-reperfusion (IR) injury. Neutral sphingomyelinase (N-SMase)/ceramide pathway can regulate NOS2 expression therefore this study determined the role of selective N-SMase inhibition on nitrative and oxidative stress markers following liver IR injury. Selective N-SMase inhibitor was administered via intraperitoneal injections. Liver IR injury was created by clamping blood vessels supplying the median and left lateral hepatic lobes for 60 min, followed by 60 min reperfusion. Nitrative and oxidative stress markers were determined by evaluating NOS2 expression, protein nitration, nitrite/nitrate levels, 4-hydroxynonenal (HNE) formation, protein carbonyl levels and xanthine oxidase/xanthine dehydrogenase (XO/XDH) activity. Levels of sphingmyelin and ceramide in liver tissue were determined by an optimized multiple reaction monitoring method using ultra-fast liquid chromatography coupled with tandem mass spectrometry (MS/MS). Spingomyelin levels were significantly increased in all IR groups compared to controls. Treatment with a specific N-SMase inhibitor significantly decreased all measured ceramides in IR injury. NOS2 expression, nitrite/nitrate levels and protein nitration were significantly greater in IR injury and decreased with N-SMase inhibition. Treatment with a selective N-SMase inhibitor significantly decreased HNE formation, protein carbonyl levels and the hepatic conversion of XO. Data confirm the role of nitrative and oxidative injury in IR and highlight the protective effect of selective N-SMase inhibition. Future studies evaluating agents blocking N-SMase activity can facilitate the development of treatment strategies to alleviate oxidative injury in liver I/R injury.
authors.affiliation: a Department of Pathology, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Betul
authors.initials: B
authors.lastname: Unal
authors.affiliation: b Department of Medical Biochemistry, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Filiz
authors.initials: F
authors.lastname: Ozcan
authors.affiliation: b Department of Medical Biochemistry, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Hazal
authors.initials: H
authors.lastname: Tuzcu
authors.affiliation: b Department of Medical Biochemistry, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Kırac
authors.affiliation: a Department of Pathology, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Gulsum O
authors.initials: GO
authors.lastname: Elpek
authors.affiliation: b Department of Medical Biochemistry, Faculty of Medicine , Akdeniz University , Antalya 07070 , Turkey.
authors.forename: Mutay
authors.initials: M
authors.lastname: Aslan
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000814:Aniline Compounds / Q000627:therapeutic use; D000818:Animals; D001597:Benzylidene Compounds / Q000627:therapeutic use; D002518:Ceramides / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000627:therapeutic use; D007150:Immunohistochemistry; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D013108:Sphingomyelin Phosphodiesterase / Q000235:genetics / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D000814:Aniline Compounds; D001597:Benzylidene Compounds; D002518:Ceramides; C468773:GW 4869; D013109:Sphingomyelins; D009569:Nitric Oxide; D000410:Alanine Transaminase; D013108:Sphingomyelin Phosphodiesterase; D004121:Dimethyl Sulfoxide
keywords: Ischemia–reperfusion injury; Liver; Neutral sphingomyelinase; Nitrative stress