Inhibitory effects of potassium thiocyanate on normal and neoplastic mammary development in female mice

Effects of potassium thiocyanate (KSCN) on normal and neoplastic mammary development in female mice were studied. Administration of KSCN as drinking water (0.1 or 0.3%) for 12 weeks to 8-week-old SHN female mice resulted in the dose-related inhibition of development of normal mammary lobulo-alveolar system, hyperplastic alveolar nodules and spontaneous mammary tumors associated with marked decrease in plasma levels of triiodothyronine and thyroxine. On the other hand, the treatment affected little estrous cycles, ovarian structures, plasma prolactin levels and weights of body, anterior pituitary and adrenals. The incidence and number of pregnancy-dependent mammary tumors in GR/A female mice were also significantly suppressed by the similar treatment with KSCN with no influence on reproductivity as well as pituitary levels of prolactin and growth hormone. These results suggest that KSCN does not affect the secretion of pituitary and ovarian mammotropic hormones and that thyroid hormones are principally involved in normal and neoplastic development of mammary glands.