Parathyroid Glands and Lactation in the Rat

Abstract

REMOVAL of the thyroid gland together with the associated parathyroid tissue was reported by Nelson and Tobin¹ to have no deleterious effect.on lactation, as measured by the growth-rates of litters, in the rat. Contrary results were, however, reported by Folley² who, moroever, failed to improve lactation in thyroidectomized rats by injections of thyroxine and small doses of parathyroid extract. Nelson³ has since confirmed the original findings of Nelson and Tobin. A re-examination of the question in this laboratory, partly in collaboration with Miss H. M. Scott Watson, has reaffirmed the almost total failure of thyroidectomized rats to rear their young and has also shown that administration of much higher doses of parathyroid extract than were previously used results in a significant improvement in lactational performance, which however is still below normal. Typical results are shown in the accompanying table.