title: AMP-activated kinase and the endogenous endocannabinoid system might contribute to antinociceptive effects of prolonged moderate caloric restriction in mice.
abstract: Caloric restriction is associated with broad therapeutic potential in various diseases and an increase in health and life span. In this study, we assessed the impact of caloric restriction on acute and inflammatory nociception in mice, which were either fed ad libitum or subjected to caloric restriction with 80% of the daily average for two weeks.
  
  
  
  The behavioral tests revealed that inflammatory nociception in the formalin test and in zymosan-induced mechanical hypersensitivity were significantly decreased when mice underwent caloric restriction. As potential mediators of the diet-induced antinociception, we assessed genes typically induced by inflammatory stimuli, AMP-activated kinase, and the endocannabinoid system which have all already been associated with nociceptive responses. Zymosan-induced inflammatory markers such as COX-2, TNFα, IL-1β, and c-fos in the spinal cord were not altered by caloric restriction. In contrast, AMPKα2 knock-out mice showed significant differences in comparison to C57BL/6 mice and their respective wild type littermates by missing the antinociceptive effects after caloric restriction. Endocannabinoid levels of anandamide and 2-arachidonyl glyceroldetermined in serum by LC-MS/MS were not affected by either caloric restriction alone or in combination with zymosan treatment. However, cannabinoid receptor type 1 expression in the spinal cord, which was not altered by caloric restriction in control mice, was significantly increased after caloric restriction in zymosan-induced paw inflammation. Since increased cannabinoid receptor type 1 signaling might influence AMP-activated kinase activity, we analyzed effects of anandamide on AMP-activated kinase in cell culture and observed a significant activation of AMP-activated kinase. Thus, endocannabionoid-induced AMP-activated kinase activation might be involved in antinociceptive effects after caloric restriction.
  
  
  
  Our data suggest that caloric restriction has an impact on inflammatory nociception which might involve AMP-activated kinase activation and an increased activity of the endogenous endocannabinoid system by caloric restriction-induced cannabinoid receptor type 1 upregulation.
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Tanya Sarah
authors.initials: TS
authors.lastname: King-Himmelreich
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Christine Verena
authors.initials: CV
authors.lastname: Möser
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Miriam Christina
authors.initials: MC
authors.lastname: Wolters
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Julia
authors.initials: J
authors.lastname: Schmetzer
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Moritz
authors.initials: M
authors.lastname: Möller
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Yannik
authors.initials: Y
authors.lastname: Schreiber
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Nerea
authors.initials: N
authors.lastname: Ferreirós
authors.affiliation: pharmazentrum frankfurt/ZAFES.
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
authors.forename: Ellen
authors.initials: E
authors.lastname: Niederberger
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D031204:Caloric Restriction / Q000379:methods; D063388:Endocannabinoids / Q000494:pharmacology*; D007249:Inflammation / Q000188:drug therapy*; D008297:Male; D008810:Mice, Inbred C57BL; D059225:Nociception / Q000187:drug effects*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology*
chemical_list: D000700:Analgesics; D001095:Arachidonic Acids; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D055372:AMP-Activated Protein Kinases; C078814:anandamide