title: Experimental carcinogenesis on the oropharyngeal mucosa of rats with hydrochloric acid, sodium nitrate and pepsin.
abstract: OBJECTIVE
  To investigate the carcinogenic action of hydrochloric acid, pepsin and sodium nitrate on the oropharyngeal mucosa of rats, simulating the reflux of gastric contents.
  
  
  METHODS
  Eighty-two Wistar rats were divided in seven groups and submitted to 2 or 3 weekly applications of hydrochloric acid, pepsin and sodium nitrate on the pharyngeal mucosa during six months. Study groups comprised 12 animals each. Rats in groups I and II were submitted to 2 (GI) or 3 (GII) weekly applications of 0.1N hydrochloric acid. Groups III and IV were submitted to 2 (GIII) or 3 (GIV) weekly applications of 0.1N hydrochloric acid solution with pepsin. Groups V and VI were submitted to 2 (GV) or 3 (GVI) weekly applications of 0.1N hydrochloric acid and treated with daily nitrate diluted in water. Group VII consisted of 10 animals submitted to 2 weekly applications of filtered water.
  
  
  RESULTS
  No dysplasia, intra-epithelial neoplasia or invasive carcinomas were detected. Inflammatory changes were observed in varying degrees and mast cells were more common in Groups V and VI (p=0.006).
  
  
  CONCLUSIONS
  The data of the current study could not corroborate the hypothesis that gastroesophageal and pharyngolaryngeal refluxes are carcinogenic factors to the laryngopharyngeal mucosa, and more studies are necessary in the future.
authors.affiliation: Division of Head and Neck, Department of Surgery, UNICAMP, Brazil. docdnegro@yahoo.com.br
authors.forename: André
authors.initials: A
authors.lastname: Del Negro
authors.forename: Marina Raquel
authors.initials: MR
authors.lastname: Araújo
authors.forename: Alfio José
authors.initials: AJ
authors.lastname: Tincani
authors.forename: Luciana
authors.initials: L
authors.lastname: Meirelles
authors.forename: Antônio Santos
authors.initials: AS
authors.lastname: Martins
authors.forename: Nelson Adami
authors.initials: NA
authors.lastname: Andreollo
mesh_terms: D000818:Animals; D015197:Carcinogenicity Tests; D002273:Carcinogens / Q000633:toxicity*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced* / Q000473:pathology; D004353:Drug Evaluation, Preclinical; D005765:Gastrointestinal Agents / Q000633:toxicity*; D006851:Hydrochloric Acid / Q000633:toxicity*; D008297:Male; D009061:Mouth Mucosa / Q000473:pathology; D009566:Nitrates / Q000633:toxicity*; D009959:Oropharyngeal Neoplasms / Q000139:chemically induced* / Q000473:pathology; D010434:Pepsin A / Q000633:toxicity; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002273:Carcinogens; D005765:Gastrointestinal Agents; D009566:Nitrates; C031618:sodium nitrate; D010434:Pepsin A; D006851:Hydrochloric Acid