title: Effect of the tricyclic antidepressant desipramine on beta-adrenergic receptors in cultured rat glioma C6 cells.
abstract: Rat glioma C6 cells, cultured in the presence of the tricyclic antidepressant desipramine, lost a significant number of beta-adrenergic receptors in a time- and dose-dependent manner. A similar loss was observed whether binding was determined on intact cells with the hydrophilic beta-adrenergic antagonist (+/-)-[3H]4-(3-tert-butylamino-2-hydroxypropoxyl)benzimidazole-2-o n HCl ([3H]CGP-12177) or on cell lysates with the more hydrophobic antagonists [125I]iodocyanopindolol or [3H]dihydroalprenolol. When stimulated with the agonist isoproterenol, desipramine-treated cells accumulated less cyclic AMP than control cells. The affinity of the beta-adrenergic receptors for either antagonist or agonist was unchanged after desipramine treatment. Desipramine interacted only weakly with the receptors and competed for [125I]iodocyanopindolol binding with a Ki of 30 microM. The presence in the culture medium of alprenolol or propranolol, potent beta-adrenergic antagonists, however, did not prevent the reduction in receptors by desipramine. Desipramine also caused a loss of beta-adrenergic receptors from cells maintained in serum-free medium and the cells themselves did not contain or secrete endogenous catecholamines. Although desipramine is a potent inhibitor of catecholamine uptake, it appears unlikely that the observed loss of beta-adrenergic receptors in rat glioma C6 cells exposed to the drug is due to an increase in extracellular catecholamine levels or to a direct interaction with the receptors.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000526:Alprenolol / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D003891:Desipramine / Q000494:pharmacology*; D005910:Glioma / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
chemical_list: D011943:Receptors, Adrenergic, beta; D000526:Alprenolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D003891:Desipramine