Anti-leptin receptor antibody mimics the stimulation of lipolysis induced by leptin in isolated mouse fat pads.
An anti-leptin receptor polyclonal antibody (receptor antibody), as well as leptin, stimulated the release of free fatty acids from isolated mouse fat pads in a time-dependent manner. Following a 90-min incubation, maximal lipolysis was observed at 6 microg/ml receptor antibody and 0.1 nM leptin. The receptor antibody did not show any additive effect to the stimulation of lipolysis induced by leptin, suggesting that they exert their actions through a similar mechanism involving the leptin receptor. N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), quin 2-AM, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), and neomycin sulfate (neomycin) all potently inhibited the stimulation of lipolysis by the receptor antibody and leptin. Short-term incubation of the fat pads with the receptor antibody or leptin showed a transient increase in the cellular content of cAMP and myo-inositol 1,4,5-trisphosphate (IP3) in similar concentrations to the free fatty acid release. Quin 2-AM and W-7 also inhibited the increase in cAMP content, suggesting that a Ca(2)+/calmodulin-dependent process may be involved in a part of the mechanism in which the receptor antibody and leptin exert their effects. The increase in cellular IP3 content via phosphoinositide-specific phospholipase C (PLC) sensitive to neomycin appears to be a primary step to initiate intracellular events. Both the receptor antibody and leptin may stimulate the lipolysis through mechanisms involving a transient increase in the cellular IP3 content followed by cAMP production, which leads to the activation of cAMP-dependent protein kinase.
Kawaji
N
N
Department of Biochemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan.
Yoshida
A
A
Motoyashiki
T
T
Morita
T
T
Ueki
H
H
D000273:Adipose Tissue / Q000187:drug effects*; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology*; D002352:Carrier Proteins / Q000819:agonists* / Q000276:immunology*; D002614:Chelating Agents / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D020738:Leptin / Q000494:pharmacology*; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D051379:Mice; D009355:Neomycin / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors
D000634:Aminoquinolines; D000906:Antibodies; D002352:Carrier Proteins; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D020738:Leptin; D011500:Protein Synthesis Inhibitors; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D013449:Sulfonamides; C515447:leptin receptor, mouse; C017967:W 7; C035738:Quin2-acetoxymethyl ester; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D009355:Neomycin; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide