Induction of endometrial adenocarcinomas in persistent estrous Donryu rats by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine.
Induction of endometrial adenocarcinomas in persistent estrous Donryu rats by a single intra-uterine administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) was examined. Female Donryu rats were divided into four groups at 7 weeks of age. Rats in Croup 1 were controls under a 12-h light/12-h dark regimen while Groups 2-4 were persistent estrous animals maintained under 24-h light conditions. At 10 weeks of age, rats in Group 1 and 2 were given a single intra-uterine administration of polyethylene glycol(PEG), and those in Groups 3 and 4 received ENNG(20 mg/kg body weight), dissolved in PEG, in the same manner. Group 4 rats also received an s.c. 17 beta-estradiol(E2) implant one week thereafter. At the termination of the experiment (week 42 after the ENNG-treatment), all surviving rats were killed and the development of uterine proliferative lesions assessed. All groups demonstrated hyperplasias, the incidence and severity being higher in ENNG-treated animals. The incidence of uterine adenocarcinomas in Group 2(2/20, 10%) was slightly higher than that in Group 1(0/16, 0%), although this difference was not significant. In Groups 3(7/19, 37%) and 4(6/20, 30%) statistically significant induction of adenocarcinomas was noted, two lesions in the latter case being very large with prominent invasion of tumor cells into the perimetrium. At 10 and 25 weeks after ENNG-treatment, the E2-progesterone(E2:P) ratios in Groups 2, 3 and 4 were significantly higher than in Group 1.(ABSTRACT TRUNCATED AT 250 WORDS)
Takahashi
M
M
Department of Pathology, Sasaki Institute, Tokyo, Japan.
Ando-Lu
J
J
Iijima
T
T
Ishihara
R
R
Imai
S
S
Kitamura
T
T
Wakabayashi
K
K
Maekawa
A
A
D000230:Adenocarcinoma / Q000139:chemically induced* / Q000473:pathology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002273:Carcinogens / Q000633:toxicity*; D016889:Endometrial Neoplasms / Q000139:chemically induced* / Q000473:pathology; D004958:Estradiol / Q000097:blood; D004971:Estrus; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood; D008769:Methylnitronitrosoguanidine / Q000031:analogs & derivatives* / Q000633:toxicity; D009929:Organ Size / Q000187:drug effects; D010053:Ovary / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000097:blood; D051381:Rats; D014599:Uterus / Q000187:drug effects
D002273:Carcinogens; D008769:Methylnitronitrosoguanidine; C013525:ENNG; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone