title: Decreased beta-adrenergic receptors in rat heart in streptozotocin-induced diabetes: role of thyroid hormones.
abstract: 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.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004082:Dihydroalprenolol / Q000378:metabolism; D006321:Heart / Q000187:drug effects / Q000503:physiopathology*; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013965:Thyroidectomy; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology*; D014284:Triiodothyronine / Q000097:blood
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008565:Membrane Proteins; D011943:Receptors, Adrenergic, beta; D014284:Triiodothyronine; D004082:Dihydroalprenolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D013974:Thyroxine