Endocrinology, Vol 114, 1358-1363, Copyright © 1984 by Endocrine Society

ARTICLES

Decreased beta-adrenergic receptors in rat heart in streptozotocin- induced diabetes: role of thyroid hormones

PR Sundaresan, VK Sharma, SI Gingold and SP Banerjee

The effect of streptozotocin-induced diabetes on the beta-adrenergic receptor-coupled adenylate cyclase was studied in rat heart particulate fractions. Streptozotocin treatment decreased the number of myocardial beta-adrenergic receptors by 34% with no change in the apparent affinity of these receptors for [3H]dihydroalprenolol. The maximal isoproterenol-activated accumulation of cAMP in streptozotocin-treated rat hearts was decreased by only 10%. Insulin administration to streptozotocin-treated rats increased the number of myocardial beta- adrenergic receptors to near or above control levels. Administration of L-T4 to streptozotocin-treated rats had the same effect. Total T4, free T4, and total T3 levels were all significantly decreased in the diabetic animals. Administration of insulin to streptozotocin-treated rats increased the serum thyroid hormone levels toward or above the levels found in control animals. Streptozotocin-induced diabetes had no significant effect on cardiac beta-adrenergic receptor number in thyroidectomized rats. Insulin did not elevate cardiac beta-adrenergic receptor number in thyroidectomized diabetic rats. The decrease in the number of myocardial beta-adrenergic receptors occurring in diabetes mellitus is probably mediated through thyroid hormones.