title: beta-Adrenergic dependent downregulation of insulin binding in rat adipocytes.
abstract: In order to study factors regulating insulin binding to rat adipocytes short- and long-term incubations were performed in the presence or absence of noradrenaline (NA) at a concentration of 3 microM. Culture with NA for 24 hours resulted in a significant decrease (30%) of insulin binding due to a reduced number of binding sites. This reduction was dose-dependent and completely prevented by the addition of timolol, a beta-adrenergic blocking agent, but not by the alpha-blocking agent phentolamine. Addition of 1.0 mM db cAMP to the culture medium resulted in a similar reduction in insulin binding. Also short-term incubations with NA resulted in a downregulation of insulin binding; reproducible reductions seen already after 20 min and about 30% reduction achieved after 2 hours' preincubation. Thus, beta-adrenergic stimulation and subsequent cAMP elevation results in a rapid reduction in the number of insulin binding sites.
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D002395:Catecholamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000187:drug effects / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects
chemical_list: D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D011972:Receptor, Insulin