The Different Effects of Thyroidectomy, KC1O4and Propylthiouracil on Insulin Secretion and Glucose Uptake in the rat

A comparable degree of hypothyroidismwas induced in male Wistar rats by thyroidectomy, KC1O4, or propylthiouracil (PTU) treatment. Their plasma PBI, body weight gain, and growth hormone-like content in the pituitary were very similar. A 200 mg/100 g body weight ip injection of 20% glucose was administered to the rats. The removal rate of plasma glucose was lower in the thyroidectomized (thyx) and KClO4-treated rats than in those given PTU. Glucose tolerance in the PTU-treated rats resembled that in normal animals. Differences in the rise of plasma insulin in response to the glucose load were also observed among the groups. The administration of an ip 3 mg/100 g body weight dose of PTU decreased the plasma glucose concentration in normal, adrenalectomized (adx), or hypophysectomized (hypx) rats. PTU increased the plasma insulin concentration in all groups of rats and had its greatest effect in adrenalectomized animals. The results indicate that neither the adrenal glands nor the pituitary gland are necessary for the PTU-induced stimulation of pancreatic insulin secretion in the rat. (Endocrinology94: 1502, 1974)