Stimulatory effect of octopamine on beta 3-adrenoceptors to lower the uptake of [14C]-deoxy-D-glucose into rat adipocytes in vitro.
1. The effect of octopamine on beta 3-adrenoceptors has been studied in isolated adipocytes of Wistar rats using uptake of [14C]-deoxy-D-glucose as the indicator. 2. Octopamine (0.1-1 nmol 1-1) induced a concentration-dependent decrease of [14C]-deoxy-D-glucose uptake into the adipocytes and this inhibition was not influenced by haloperidol at concentrations sufficient to block dopaminergic receptors. 3. Pindolol and propranolol reversed this inhibition of octopamine in a concentration-dependent manner. The effect of octopamine was reduced in the presence of Rp-cyclic AMPS triethylamine, the membrane-permeable antagonist of cyclic AMP (cAMP), indicating the mediation of cAMP in this inhibition. 4. A direct effect of octopamine on beta 3-adrenoceptors was proved using the application of antibodies. In the presence of an antibody for beta 3-adrenoceptors, the actions of octopamine were concentration-dependently reduced in a manner similar to the decrease of BRL37344-induced inhibitions. 5. The same degree of diminished activities for octopamine as that of BRL37344, the well-known specific agonist of beta 3-adrenoceptors, was also obtained in isoprenline-desensitized adipocytes. Insulin-stimulated uptake of [14C]-deoxy-D-glucose into adipocytes was not modified by isoprenaline induced desensitization. 6. These results suggest that octopamine can activate beta 3-adrenoceptors to lower the glucose uptake through an increase of cAMP in rat white adipocytes.
Yen
S T
ST
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan City, Taiwan, Republic of China.
Li
M H
MH
Hsu
C T
CT
Lee
T L
TL
Cheng
J T
JT
D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002250:Carbon Radioisotopes; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006220:Haloperidol / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009655:Octopamine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D022702:Receptors, Adrenergic, beta-3; D013873:Thionucleotides / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D002250:Carbon Radioisotopes; D004791:Enzyme Inhibitors; D011943:Receptors, Adrenergic, beta; D022702:Receptors, Adrenergic, beta-3; D013873:Thionucleotides; D009655:Octopamine; C016957:adenosine-3',5'-cyclic phosphorothioate; D003847:Deoxyglucose; D000242:Cyclic AMP; D005947:Glucose; D006220:Haloperidol; D007545:Isoproterenol