Thermogenic responses to selective and nonselective beta-adrenerg agonists in hypothyroidism of Sprague-Dawley rats.
Resting oxygen consumption (VO2) and mitochondrial GDP binding were measured in hypothyroid and euthyroid rats after administration of selective and nonselective beta-adrenoceptor agonists (BRL 35135A and Isoprenaline--BRL, ISO). Resting VO2, VO2 increment and mitochondrial GDP binding after beta-agonists were lower in hypothyroid rats than in the euthyroid group. The reduced response was more marked for ISO than for BRL. These results suggest that BRL is acting on a beta-adrenoceptor which differs from beta-1 and beta-2 adrenoceptors, responsible for the effect of ISO. Activation of thermogenesis via this beta-3 adrenoceptor seems to be less dependent on permissive levels of thyroid hormones than on activation via beta-1 and/or beta-2 adrenoceptors.
Department of Pediatrics, University Medical School Debrecen, Hungary.
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D000273:Adipose Tissue / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001835:Body Weight; D004195:Disease Models, Animal; D006153:Guanosine Diphosphate / Q000378:metabolism; D007037:Hypothyroidism / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008713:Methimazole; D010101:Oxygen Consumption / Q000187:drug effects*; D010627:Phenethylamines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013823:Thermoreceptors; D013965:Thyroidectomy
D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; D006153:Guanosine Diphosphate; D008713:Methimazole; C063157:BRL 35135; D007545:Isoproterenol