Effects of Exogenous Hormones on Growth Characteristics and Morphology of Transplanted Mammary Fibroadenoma of the Rat

Abstract

THE description of a line of transplanted mammary fibroadenomata in rats was presented in a preceding paper from this laboratory (Millar and Noble, 1954).Observations by us and others have shown that this type of tumour is more easily propagated, grows more rapidly and usually shows greater epithelial development in the female host than in the male. In addition, castration in males and females increases and decreases respectively the growth energy of transplanted mammary fibroadenomata in rats. In order to elucidate further the nature of the hormonal control of these benign tumours, experiments have been carried out to determine the effect of administered pituitary, adrenal and sex hormones on their growth and morphology.The effect of estrogens on the growth of mammary fibroadenomata in rats has been studied by several workers with somewhat conflicting results. Heiman and Krehbiel (1936) found no consistent tumour response to administered estrogens. However, estrogen (theelin) plus growth hormone (Antuitrin S) or gonadotrophic hormone (Antuitrin G) increased the number of tumour takes in intact rats, although none of the individual preparations were active. Antuitrin S alone was effective in increasing the takes in castrated males and females, while estrogen and growth hormone were again effective only when injected simultaneously. In these experiments tumours of the 13th to 22nd generations were used.Estrogen administration to rats bearing auto-and homo-transplants of spontaneous tumours produced marked tumour epithelial proliferation and increased growth rate (Heiman, 1940b). Mohs (1940)

Hormonal Influences on Mammary Tumors of the Rat

“…Crude extracts of the pituitary accelerated the growth of the tumor, but a refined preparation of growth hormone did not alter its growth rate (15). When chorionic gonadotrophin was injected with estrone in gonadectomized rats the growth rate of the tumor was enhanced but neither hormone was effective when administered separately (10).…”

“…daily) of estrogenic substances have no effect on the tumor in female rats. The estrogens employed were estrone (13,14), diethylstilbestrol (15), and estradiol (15). Mohs (11), on the contrary, stated that estrone increased the number of successful transplants.…”

“…Large doses of diethylstilbestrol (100 to 200 /~g. daily) caused retardation or arrest of tumor growth (15); this inhibition of growth was not related to the decreased intake of food induced by estrogenic substances since the growth rate of the tumor was not depressed by underfeeding (16).…”

“…It has been stated that progesterone in small amounts retarded the growth of the tumor (17) while in larger dosage it exerted no effect (15).…”

On the Occurrence and Morphology of Spontaneous Tumours in the Pituitary, Adrenals, Gonads and Mammary Glands in Rats Before and After Gonadectomy, Irradiation and Treatment with Oestrogen or Progesterone

“…Observations on transplanted mammary fibroadenomata in rats (Millar and Noble, 1954) have shown that such transplants grow more quickly in female hosts. If the male or female host is gonadectomized, the growth of the adenomatransplant is increased or decreased, respectively.…”