title: Non-steroidal anti-inflammatory drugs activate NADPH oxidase in adipocytes and raise the H2O2 pool to prevent cAMP-stimulated protein kinase a activation and inhibit lipolysis.
abstract: BACKGROUND
  Non-steroidal anti-inflammatory drugs (NSAIDs) -aspirin, naproxen, nimesulide, and piroxicam- lowered activation of type II cAMP-dependent protein kinase A (PKA-II) in isolated rat adipocytes, decreasing adrenaline- and dibutyryl cAMP (Bt2cAMP)-stimulated lipolysis. The molecular bases of insulin-like actions of NSAID were studied.
  
  
  RESULTS
  Based on the reported inhibition of lipolysis by H2O2, catalase was successfully used to block NSAID inhibitory action on Bt2cAMP-stimulated lipolysis. NSAID, at (sub)micromolar range, induced an H2O2 burst in rat adipocyte plasma membranes and in whole adipocytes. NSAID-mediated rise of H2O2 was abrogated in adipocyte plasma membranes by: diphenyleneiodonium, an inhibitor of NADPH oxidase (NOX); the NOX4 antibody; and cytochrome c, trapping the NOX-formed superoxide. These three compounds prevented the inhibition of Bt2cAMP-stimulated lipolysis by NSAIDs. Inhibition of aquaporin-mediated H2O2 transport with AgNO3 in adipocytes allowed NOX activation but prevented the lipolysis inhibition promoted by NSAID: i.e., once synthesized, H2O2 must reach the lipolytic machinery. Since insulin inhibits adrenaline-stimulated lipolysis, the effect of aspirin on isoproterenol-stimulated lipolysis in rat adipocytes was studied. As expected, isoproterenol-mediated lipolysis was blunted by both insulin and aspirin.
  
  
  CONCLUSIONS
  NSAIDs activate NOX4 in adipocytes to produce H2O2, which impairs cAMP-dependent PKA-II activation, thus preventing isoproterenol-activated lipolysis. H2O2 signaling in adipocytes is a novel and important cyclooxygenase-independent effect of NSAID.
authors.affiliation: Departamento de Bioquímica, Universidad Nacional Autónoma de México, México, México. hvazquez@bq.unam.mx
authors.forename: Héctor
authors.initials: H
authors.lastname: Vázquez-Meza
authors.forename: Martha Zentella
authors.initials: MZ
authors.lastname: de Piña
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Pardo
authors.forename: Héctor
authors.initials: H
authors.lastname: Riveros-Rosas
authors.forename: Rafael
authors.initials: R
authors.lastname: Villalobos-Molina
authors.forename: Enrique
authors.initials: E
authors.lastname: Piña
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D020346:Aquaporins / Q000494:pharmacology; D054746:Cyclic AMP-Dependent Protein Kinase Type II / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012835:Silver Nitrate / Q000494:pharmacology
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D020346:Aquaporins; D012835:Silver Nitrate; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D054746:Cyclic AMP-Dependent Protein Kinase Type II