Expression of beta3-adrenoceptors with low lipolytic action in human subcutaneous white adipocytes.

Expression of beta3-adrenoceptors with low lipolytic action in human subcutaneous white adipocytes.

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Beta3-Adrenoceptors are involved in the control of catecholamine-induced lipolysis in rodent adipose tissues.The expression and function of human beta3-adrenoceptors were investigated in subcutaneous white adipocytes of young healthy women.In these cells, beta3-adrenoceptor mRNAs represent 20% of total amount of beta-adrenoceptor transcripts and less than half of beta1-adrenoceptor transcripts.Among beta3-agonists known to stimulate beta3-adrenoceptor-mediated lipolysis in rodent fat cells, only CGP12177 was able to mediate such activity in human fat cells.In in vitro lipolysis experiments and jeff rosenstock buffalo in situ microdialysis studies, CGP12177 had a 4- to 5-times lower lipolytic efficacy than isoprenaline, a nonselective beta-adrenoceptor agonist.

CGP12177-induced lipolysis was here antagonized in vitro by bupranolol, a beta-adrenergic antagonist potent on rodent beta3-adrenoceptors but not by nadolol, a beta1- and beta2-adrenoceptor antagonist.The in vitro blockade of isoprenaline-stimulated lipolysis by nadolol showed that the agonist acted solely via beta1- and beta2-adrenoceptors.Isoprenaline and CGP12177 were able to increase the nutritive blood flow suggesting an interaction of these molecules with receptors present in adipose tissue vessels.In conclusion, beta3-adrenoceptors are expressed in human subcutaneous white adipocytes but do not significantly contribute to isoprenaline-induced lipolysis.