title: Alterations in urethan-induced adenoma formation in mice exposed to selenium and arsenic.
abstract: Female Swiss were exposed to sodium selenite (3 micrograms/ml selenium content) and sodium arsenate (80 micrograms/ml arsenic content) in the drinking water individually or in combination on alternate days for 15 weeks. Comparable water consumption was observed in all individual or combined metal-exposure groups. After 3 weeks of metal exposure, the mice were administered urethan (1.5 mg/g) intraperitoneally. Pulmonary adenoma formation was evaluated 12 weeks later. Arsenic exposure reduced the tumor incidence (P = 0.0046) and tumor size (P less than 0.0001). Selenium exposure did not alter the tumor incidence but caused a reduction in tumor size (P = 0.022). No selenium-arsenic interactions associated with tumor size or number were observed. Urethan-induced sleeping times were unaffected by exposure to selenium (P = 0.832) or arsenic (P = 0.42), although combined metal exposure reduced the duration of urethan-induced sleep (P = 0.029) as compared to the individual metal exposures. This metal-metal interaction, which appeared to enhance the rate of urethan elimination as indicated by the reduced sleeping time, did not influence adenoma formation significantly.
mesh_terms: D000236:Adenoma / Q000139:chemically induced*; D000818:Animals; D001151:Arsenic / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D004326:Drinking / Q000187:drug effects; D004347:Drug Interactions; D005260:Female; D008175:Lung Neoplasms / Q000139:chemically induced*; D051379:Mice; D012643:Selenium / Q000494:pharmacology*; D012890:Sleep / Q000187:drug effects; D014520:Urethane
chemical_list: D014520:Urethane; D012643:Selenium; D001151:Arsenic