Potentiation of Effect of Prolactin by Adrenocorticotropic and Growth Hormones Upon Weight and Nucleic Acids Contents of Female Rat Mammary Gland

Effects of prolactin, adrenocorticotropic hormone, growth hormone, adrenaleetomy, adrenalectomy and corticoids, and adrenalectomy plus prolactin or growth hormone upon the adult female rat mammary gland were investigated.Endogenous hormone effects were studied in rats bearing a transplantable pituitary mammotropic tumor which secretes large quantities of adrenocorticotropic hormone and prolactin.In 40 days the tumor produced a 380% weight increase and 460% increase in deoxyribonucleic acid content of mammary glands in intact rats in contrast to 95% and 297% increase in adrenalectomized rats (10 days after the rats were adrenaleetomized).Inhibitory effects of adrenalectomy were prevented by administration of hydrocorticosterone but not by deoxycorticosterone.Administration of growth hormone elicited an increase in gland weight and deoxyribonucleic acid content (70% and 110%) in intact tumor bearing females but not in adrenalectomized animals ( --50% and --10%).Prolactin produced mammogenic effects in normal adrenalectomized female rats.Adrenocortieotropic hormone or growth hormone administered separately did not produce any noticeable change in the mammary gland, but effects of prolactin on mammary gland weight and deoxyribonueleie aeid content were greatly potentiated by simultaneous injections of adreooeorticotropie hormone and/or growth hormone.