title: Independent regulation of beta 1- and beta 2-adrenoceptors.
abstract: 1 The down-regulation of beta-adrenoceptors has been postulated as a biochemical marker of antidepressant efficacy. Here we demonstrate that chronic treatment with desipramine down-regulates beta 1-adrenoceptors in rat cerebral cortex and that beta-adrenoceptor subtypes can be independently regulated by treatment with different beta-adrenoceptor agonists. 2 Desipramine, (+/-)-clenbuterol, prenalterol, corwin (20 mg kg-1 daily) and corwin (10 mg kg-1 daily) were administered to male, Sprague-Dawley rats, over eight days, by means of osmotic Alzet pumps placed subcutaneously and removed 24 h before analysis. Control rats received vehicle only. The beta 1- and beta 2-adrenoceptor populations were measured in cerebral cortex by a modified (-)-[125I]-pindolol receptor binding assay. 3 The conventional antidepressant, desipramine, preferentially down-regulated beta 1-adrenoceptors whereas the non-selective beta-adrenoceptor agonist (+/-)-clenbuterol preferentially down-regulated beta 2-adrenoceptors. The beta 1-selective partial agonist, prenalterol, up-regulated beta 1-adrenoceptors perhaps acting more as an antagonist than as an agonist. Finally, neither dose of corwin had any significant effect on beta-adrenoceptor number.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D002976:Clenbuterol / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D010869:Pindolol / Q000378:metabolism; D011294:Prenalterol / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D017307:Xamoterol
chemical_list: D000318:Adrenergic beta-Agonists; D007457:Iodine Radioisotopes; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D017307:Xamoterol; D010869:Pindolol; D011294:Prenalterol; D003891:Desipramine; D002976:Clenbuterol