Caloric restriction induces H(2)O(2) formation as a trigger of AMPK-eNOS-NO pathway in obese rats: role for CAMKII


  • C.F. García-Prieto
  • M. Gil-Ortega
  • A. Plaza
  • F.J. Manzano-Lista
  • R. González-Blázquez
  • M. Alcalá
  • P. Rodríguez-Rodríguez
  • M. Viana
  • I. Aranguez
  • M. Gollasch
  • B. Somoza
  • M.S. Fernández-Alfonso


  • Free Radical Biology and Medicine


  • Free Radic Biol Med 139: 35-45


  • Caloric restriction (CR) improves endothelial function through the upregulation of adenosine monophosphate-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS). Moreover, hydrogen peroxide (H(2)O(2)) is upregulated in yeast subjected to CR. Our aim was to assess if mild short-term CR increases vascular H(2)O(2) formation as a link with AMPK and eNOS activation. Twelve-week old Zucker obese (fa/fa) and control Zucker lean male rats were fed a standard chow either ad libitum (AL, n=10) or with a 20% CR (CR, n=10) for two weeks. CR significantly improved relaxation to ACh in fa/fa rats because of an enhanced endogenous production of H(2)O(2) in aortic rings (H2O2 levels (fa/faAL)=0.5 ± 0.05 nmol/mg vs. H(2)O(2) levels (fa/faCR)=0.76 ± 0.07 nmol/mg protein; p<0.05). Expression of mitochondrial superoxide dismutase (Mn-SOD) and total SOD activity were increased in aorta from fa/fa animals after CR. In cultured aortic endothelial cells, serum deprivation or 2-deoxy-dD-glucose induced a significant increase in: i) superoxide anion and H(2)O(2) levels, ii) p-AMPK/AMPK and p-eNOS/eNOS expression and iii) nitric oxide levels. This effect was reduced by catalase and strongly inhibited by Ca(2+)/calmodulin-dependent kinase II (CamkII) silencing. In conclusion, we propose that mild short-term CR might be a trigger of mechanisms aimed at protecting the vascular wall by the increase of H(2)O(2), which then activates AMPK and nitric oxide release, thus improving endothelium-dependent relaxation. In addition, we demonstrate that CAMKII play a key role in mediating CR-induced AMPK activation through H(2)O(2) increase.