Mammary carcinogenic effect of low-dose fission radiation in Wistar/Furth rats and its dependency on prolactin
- Hiroshima Univ., Japan
The mammary carcinogenic effect in rats of low-dose fission radiation and its dependency on prolactin were studied. A total of 141 female W/Fu rats were exposed to 4.8, 8.9, or 19.5 rads of fission radiation that had both fission neutrons of 2.0 million electron volts (MeV) and gamma ray components similar to those produced by the Hiroshima bomb. Only 1 of 48 rats (2.0%) developed mammary tumor (MT) after irradiation alone, whereas 20 of 48 rats (41.6%) developed MT's if prolactin was supplied shortly after irradiation by means of grafting of the prolactin-secreting pituitary tumor. Furthermore, MT's occurred in 11 of 45 rats (24.4%) treated wit prolactin as late as 12 months after irradiation, which suggested the long-term survival of radiation-induced dormant MT cells. A correlation was found between the development of MT and the elevation of serum prolactin level; most MT's appeared shortly after the grafted mammotropic pituitary tumor became palpable. The growth of MT's appeared to be promoted by prolactin in collaboration with ovarian hormones; the growth of adenocarcinomas was dependent on prolactin and ovarian hormones, whereas the growth of fibroadenomas appeared to be less hormone-dependent. Much higher bioiogic effectiveness, especially in the low-dose range, was found with 2.0-MeV fission neutrons compared with 14.1-MeV fast neutrons or 180-kilovolt peak X-rays in rat mammary carcinogenesis.
- OSTI ID:
- 5179225
- Journal Information:
- J. Natl. Cancer Inst.; (United States), Vol. 64:6
- Country of Publication:
- United States
- Language:
- English
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ADENOMAS
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CARCINOMAS
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CARCINOGENESIS
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MAMMARY GLANDS
BIOLOGICAL RADIATION EFFECTS
COMPARATIVE EVALUATIONS
FISSION PRODUCTS
GRAFTS
LTH
RADIATION DOSES
RADIOSENSITIVITY EFFECTS
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FERMIONS
GLANDS
GONADOTROPINS
HADRONS
HORMONES
IONIZING RADIATIONS
IRRADIATION
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PATHOGENESIS
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560152* - Radiation Effects on Animals- Animals