Iodothyronines and iodotyrosines as hypothetical receptors for catecholamines and opiates.
The signs and symptoms of hyperthyroidism are similar to those of phaeochromocytoma and adrenergic stimulation. These changes have been attributed to increased beta receptor numbers in hyperthyroidism, resulting in adrenergic supersensitivity. Beta blockers are used in treatment of hyperthyroidism and inoperable phaeochromocytomas. Beta receptor numbers increase in direct proportion to the dose of thyroid hormone given. Hypothyroidism decreases the number of alpha and beta receptors with greater reduction in beta receptor numbers. Beta responses predominate in hyperthyroidism and alpha responses in hypothyroidism. Hypothyroid patients show increased sensitivity to opiates while hyperthyroid patients are tolerant to opiates. In the present paper it is proposed that the various iodothyronine amino acids are incorporated into the various catecholamine and opiate receptors, providing the phenyl binding sites in the receptors. T3 and T4 are proposed as part of beta 1 chronotropic and inotropic receptors and those mediating vasodilation. T2 and rT3 are proposed as part of alpha 1 and alpha 2 receptors and dopamine and opiate receptors. T2 is probably incorporated into beta 2 receptors causing bronchodilation. The different structural features of the various amino acids would account in part for the selectivity of various drugs for various receptors.
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D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D006860:Hydrogen Bonding; D007467:Iodoproteins; D008956:Models, Chemical; D007470:Monoiodotyrosine; D051381:Rats; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D011954:Receptors, Dopamine; D011957:Receptors, Opioid; D013970:Thyronines
D007467:Iodoproteins; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D011954:Receptors, Dopamine; D011957:Receptors, Opioid; D013970:Thyronines; D007470:Monoiodotyrosine