Enhancement by testosterone of dimethylnitrosamine carcinogenesis in lung, liver and kidney of inbred NZR/Gd female rats.

The effect of androgenic treatments on single dose dimethylnitrosamine (DMN) carcinogenesis was studied in 60 female NZR/Gd inbred rats, 25 of which were intact and received DMN 20 mg/kg i.p. in one dose after 48 h starvation, while 35 received DMN combined with testosterone injections every 4 weeks beginning 15 days before or after DMN, and in 29 rats combined also with ovariectomy. Sixteen female rats underwent ovariectomy and received testosterone every 4 weeks with no DMN. There were also 107 untreated intact contemporaneous control female rats. A single dose of DMN induced alveologenic lung (16%), hepatocellular (24%) and kidney epithelial (44%) tumours in intact rats, and the incidences of lethal tumours at these sites were significantly enhanced by androgenic treatments following the carcinogen, most markedly in the kidney. Androgenic treatment given before DMN injection had no significant effect on kidney or liver tumour incidences, but the carcinogenic response in lung was still strongly enhanced.