Effect of thyroparathyroidectomy on uterine sensitivity to estrogen in ovariectomized rats

¹ Department of Physiology, University of Pittsburgh School of Dentistry, Pittsburgh, Pennsylvania

Evidence has been presented previously indicating that uterine sensitivity of ovariectomized rats to estrogen increased with age up to about 46 days when the animals, if intact, would have reached puberty. With further increase in age, uterine sensitivity to estrogen decreased markedly. The present experiments demonstrate that thyroparathyroidectomy of ovariectomized immature rats did not affect maximal uterine sensitivity to estrogen at about the age of expected puberty. However, thyroparathyroidectomy of ovariectomized rats prevented the marked decrease in uterine sensitivity to estrogen with further increase in age (66–156 days), possibly by decreasing metabolism of administered estrogen after complete depletion of the thyroid hormone.