Evidence for estradiol promotion of neoplastic lesions in the rat vagina after initiation with N-methyl-N-nitrosourea.
The hypothesis that estrogens are tumor promoters was tested by tumor induction in the rat vagina. Ovariectomized rats were given a single dose of N-methyl-N-nitrosourea (MNU) by vaginal instillation, followed one week later by long-term release Silastic implants containing estradiol (E2). After 16 months, a significant incidence (4/9) of benign vaginal stromal polyps was found in the MNU-E2 group, but no vaginal polyps were seen in groups given either MNU or E2 alone. A number of non-neoplastic changes were also seen and were due to E2 treatment either with or without MNU. The incidence of stromal polyps and their restriction to animals receiving the initiator-promoter regimen alone suggests that estrogens promote tumorigenesis in the rat vagina.
D000818:Animals; D002369:Castration; D004958:Estradiol / Q000009:adverse effects*; D005260:Female; D008770:Methylnitrosourea / Q000633:toxicity*; D009374:Neoplasms, Experimental / Q000139:chemically induced; D009607:Nitrosourea Compounds / Q000633:toxicity*; D051381:Rats; D014599:Uterus / Q000187:drug effects; D014625:Vaginal Neoplasms / Q000139:chemically induced* / Q000473:pathology
D009607:Nitrosourea Compounds; D004958:Estradiol; D008770:Methylnitrosourea