title: Mercaptoethylguanidine attenuates caustic esophageal injury in rats: a role for scavenging of peroxynitrite.
abstract: BACKGROUND
  After ingestion of caustic material, tissue damage is caused by reactive oxygen species and reactive nitrogen species such as peroxynitrite. Mercaptoethylguanidine (MEG) is a well-known scavenger of peroxynitrite. This study was designed to determine whether MEG has a beneficial effect on caustic esophageal injury.
  
  
  METHODS
  Forty-five rats were allocated into 3 groups: sham-operated, untreated, and treated groups. Caustic esophageal burn was created by instilling 15% NaOH in the distal esophagus. The rats were left untreated or treated with 10 mg/kg per day MEG intraperitoneally for 5 days. All rats were killed at 28 days. Efficacy of the treatment was assessed both histopathologically and biochemically.
  
  
  RESULTS
  Of 15 rats, 6 (40%) died in the untreated group, and only 1 (7%) rat died in the treated group. The stenosis index (SI) and the histopathologic damage score were significantly lower in the MEG treatment group than the untreated group, which showed a correlation with tissue hydroxyproline level. In the untreated group, tissue oxidative stress parameters (malondialdehyde and protein carbonyl content) were significantly higher; and antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase) were significantly lower. Administration of MEG ameliorated oxidative stress parameters and antioxidant enzyme activities. Urinary nitrate and nitrite levels increased in the treated and untreated groups in the first 3 days, suggesting increased nitrosative stress; but at the fourth day, nitrate and nitrite level reached control values in the treated group.
  
  
  CONCLUSIONS
  Peroxynitrites play an important role in the healing process of caustic esophagitis. As a peroxynitrites scavenger, MEG potentially might be a useful adjuvant agent in the treatment of esophageal caustic burn by modulating the antioxidant defense mechanism.
authors.affiliation: Department of Pediatric Surgery, Gulhane Military Medical Academy, 06170 Etlik, Ankara, Turkey. drahmetguven@yahoo.com
authors.forename: Ahmet
authors.initials: A
authors.lastname: Guven
authors.forename: Bulent
authors.initials: B
authors.lastname: Uysal
authors.forename: Bahadir
authors.initials: B
authors.lastname: Caliskan
authors.forename: Emin
authors.initials: E
authors.lastname: Oztas
authors.forename: Haluk
authors.initials: H
authors.lastname: Ozturk
authors.forename: Ahmet
authors.initials: A
authors.lastname: Korkmaz
mesh_terms: D000818:Animals; D002057:Burns, Chemical / Q000188:drug therapy* / Q000209:etiology*; D002424:Caustics / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D004940:Esophageal Stenosis / Q000139:chemically induced* / Q000188:drug therapy*; D006146:Guanidines / Q000627:therapeutic use*; D030421:Peroxynitrous Acid / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002424:Caustics; D004791:Enzyme Inhibitors; D006146:Guanidines; D030421:Peroxynitrous Acid; C100078:2-mercaptoethylguanidine