Promoting effect of phenobarbital on N-bis (2-hydroxypropyl)nitrosamine thyroid tumorigenesis in rats. Effect of varying duration of exposure to phenobarbital.
Male Wistar rats were injected subcutaneously with a single dose of 280 mg N-bis(2-hydroxypropyl)nitrosamine (DHPN) per 100 g body weight and then given a diet containing 500 mg/kg phenobarbital (PB) for 6, 12 and 19 weeks. Exposure to PB for 12 or 19 weeks enhanced the development of thyroid tumours in rats treated with DHPN. The incidences of thyroid tumours at the end of the experiment were 87% in rats given DHPN and then PB for 19 weeks, 83% in rats given DHPN and then PB for 12 weeks, 42% in rats given DHPN and then PB for 6 weeks, and 37% in rats given DHPN. The incidence of thyroid cancer was 12% in rats given DHPN and then PB for 19 weeks. The total numbers of thyroid tumours were: 241 in rats given DHPN and then PB for 19 weeks, 125 in rats given DHPN and then PB for 12 weeks, 65 in rats given DHPN and then PB for 6 weeks, and 23 in rats given DHPN alone. The total numbers of thyroid tumours were proportional to the period of exposure to PB.
D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D007668:Kidney / Q000473:pathology; D007700:Kinetics; D008099:Liver / Q000473:pathology; D008297:Male; D009602:Nitrosamines / Q000633:toxicity*; D009929:Organ Size / Q000187:drug effects; D009928:Organ Specificity; D010634:Phenobarbital / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000187:drug effects / Q000473:pathology; D013964:Thyroid Neoplasms / Q000139:chemically induced*; D013997:Time Factors
D002273:Carcinogens; D009602:Nitrosamines; C012457:diisopropanolnitrosamine; D010634:Phenobarbital