ENDOCRINOLOGIC MILIEU AND SUSCEPTIBILITY OF THE RAT MAMMARY-GLAND TO CARCINOGENESIS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 109  (1) , 47-56
Abstract
The incidence of DMBA[7,12-dimethylbenz(a)anthracene]-induced mammary carcinomas in Sprague-Dawley rats depends upon their previous reproductive histories. Young virgin rats (YV) are highly susceptible to the carcinogen, while old virgin rats (OV) are less susceptible, and parous rats (P) are resistant. Endocrinologic studies were performed in these 3 groups of rats in order to determine whether the different susceptibility to carcinogenesis, according to the reproductive history, is or is not related to the hormonal milieu. The pituitary, the ovaries, the adrenals and the mammary glands were processed for light microscopy. Pituitary prolactin (PRL), FSH and luteinizing hormone cells were immunostained by peroxidase-antiperoxidase and quantitated with an image analyzer. Radioimmunoassays of serum and pituitary PRL and serum estradiol were also done. There were no differences in the hormonal milieu of YV, OV and P rats at the time of carcinogen treatment. Several changes were observed after DMBA administration, the most conspicuous being hyperplasia of pituitary PRL cells, high serum PRL levels, nodular hyperplasia of the adrenal cortex, high serum estradiol levels and lack of adrenal necrosis in P rats and some OV rats. These modifications did not correlate with the degree of susceptibility of YV, OV and P rats to carcinogenesis, supporting the concept of the importance of the mammary gland differentiation at the moment of carcinogen administration.