title: Morphine does no promote esophageal carcinogenesis in rats exposed to diethylnitrosamine.
abstract: BACKGROUND
  The high incidence of esophageal cancer in the north of Iran has been associated to the consumption of opium and exposure to nitrosamines. Diethylnitrosamine has an established potential of producing experimental cancer in the esophagus and liver.
  
  
  OBJECTIVE
  To evaluate by histopathology the effect of oral administration of morphine and diethylnitrosamine during 23 weeks on the hepatic and esophageal carcinogenesis on 176 rats.
  
  
  METHODS
  We divided the rats into the following groups: Morph: morphine; Den: diethylnitrosamine; Den+morph: Den and morphine in the same solution; Den/morph: Den and morphine in different solutions and days.
  
  
  RESULTS
  Morphine did not promote neoplasias. The highest neoplastic incidents were found: a) in the esophagus, Den in relation to Den/morph and Den+morph (71.1%, 55.8%, and 50.0%); b) in the liver, Den and Den/morph in relation to Den+morph (73.8%, 81.4%, and 40.9%); c) higher incident of hepatic neoplasia than esophageal in Den/morph (81.4% and 55.8%). Different doses of diethylnitrosamine were ingested among the groups Den, Den/morph, and Den+morph, respectively 2.9, 2.8, and 2.3 mg/kg/day.
  
  
  CONCLUSIONS
  These results show that the morphine did not promote esophageal carcinogenesis and may have stimulated the hepatic metabolism of the first pass of the carcinogen.
authors.affiliation: Department of Surgery, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. carlos.dillenburg@terra.com.br
authors.forename: Carlos Frota
authors.initials: CF
authors.lastname: Dillenburg
authors.forename: Cleber Dario Pinto
authors.initials: CD
authors.lastname: Kruel
authors.forename: Carlos Thadeu
authors.initials: CT
authors.lastname: Cerski
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Edelweiss
authors.forename: Tiago Luís Dedavid E
authors.initials: TL
authors.lastname: Silva
authors.forename: André Silvio
authors.initials: AS
authors.lastname: Schier
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D000701:Analgesics, Opioid / Q000633:toxicity*; D000818:Animals; D015197:Carcinogenicity Tests; D004052:Diethylnitrosamine / Q000633:toxicity*; D004938:Esophageal Neoplasms / Q000139:chemically induced* / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000473:pathology; D009020:Morphine / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000477:Alkylating Agents; D000701:Analgesics, Opioid; D004052:Diethylnitrosamine; D009020:Morphine