Rat mammary gland atypia produced by iodine blockade with perchlorate

Prior published work from our laboratory concluded that there was a need for appropriate metabolic activity of iodine in breast tissue for normal growth and development. Results from studies in rats that were made iodine deficient showed histological changes in the breasts that were atypical and dysplastic. These tissue findings were further affected by the presence of estrogen and thyroxine. These changes parallel the iodine uptake of the tissues, thus representing a difference in the utilization of iodine by the mammary glands. Using an ion blockade agent, sodium perchlorate, breast tissues lacking iodine were evaluated by both endocrine and histological techniques. A dose-response series was completed that showed that perchlorate therapy for 8 weeks at 400 mg/100 ml produced breast blockade by a reduction in iodine uptake of greater than 52% of the control. At these levels, the histological experimentation showed atypia and some pleomorphism of the cells, particularly in the glands of the lobules. Blockade was less effective in estrogen-treated groups. It is especially notable that both histological changes and uptake reduction were greatest in those breasts that had been rendered euthyroid by thyroxine replacement, thus clearly indicating the necessity of iodine itself for maintenance of normal breast development. By this blockade the responses of iodine inadequacy in the breast were shown to cause abnormal tissue changes relative to the percentage of the block obtained.