title: Dietary supplementation with arachidonic acid increases arachidonic acid content in paw, but does not affect arthritis severity or prostaglandin E2 content in rat adjuvant-induced arthritis model.
abstract: BACKGROUND
  Arachidonic acid (ARA) is an essential fatty acid and a major constituent of biomembranes. It is converted into various lipid mediators, such as prostaglandin E2 (PGE2), which is involved in the development of rheumatoid arthritis (RA). However, the effects of dietary ARA on RA are unclear. Our objective was to clarify the effects of dietary ARA on an experimental rat arthritis model.
  
  
  METHODS
  Lew rats were fed three contents of ARA diet (0.07%, 0.15% or 0.32% ARA in diet (w/w)), a docosahexaenoic acid (DHA) diet (0.32% DHA), or a control diet. After 4 weeks, arthritis was induced by injection of Freund's complete adjuvant into the hind footpad. We observed the development of arthritis for another 4 weeks, and evaluated arthritis severity, fatty acid and lipid mediator contents in the paw, and expression of genes related to lipid mediator formation and inflammatory cytokines. Treatment with indomethacin was also evaluated.
  
  
  RESULTS
  The ARA content of phospholipids in the paw was significantly elevated with dietary ARA in a dose-dependent manner. Dietary ARA as well as DHA did not affect arthritis severity (paw edema, arthritis score, and bone erosion). PGE2 content in the paw was increased by arthritis induction, but was not modified by dietary ARA. Dietary ARA did not affect the contents of other lipid mediators and gene expression of cyclooxygenase (COX)-1, COX-2, lipoxgenases and inflammatory cytokines. Indomethacin suppressed arthritis severity and PGE2 content in the paw.
  
  
  CONCLUSIONS
  These results suggest that dietary ARA increases ARA content in the paw, but has no effect on arthritis severity and PGE2 content of the paw in a rat arthritis model.
authors.affiliation: Institute for Health Care Science, Suntory Wellness Ltd., 1-1-1 Wakayamadai, Shimamoto, Osaka, 6188503, Japan. Norifumi_Tateishi@suntory.co.jp.|Department of physiology and pharmacology, School of advanced science and engineering, Waseda University, Tokyo, Japan. Norifumi_Tateishi@suntory.co.jp.
authors.forename: Norifumi
authors.initials: N
authors.lastname: Tateishi
authors.affiliation: Institute for Health Care Science, Suntory Wellness Ltd., 1-1-1 Wakayamadai, Shimamoto, Osaka, 6188503, Japan. yoshihisa_kaneda@suntory.co.jp.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kaneda
authors.affiliation: Institute for Health Care Science, Suntory Wellness Ltd., 1-1-1 Wakayamadai, Shimamoto, Osaka, 6188503, Japan. saki_kakutani@suntory.co.jp.
authors.forename: Saki
authors.initials: S
authors.lastname: Kakutani
authors.affiliation: Institute for Health Care Science, Suntory Wellness Ltd., 1-1-1 Wakayamadai, Shimamoto, Osaka, 6188503, Japan. hiroshi_kawashima@suntory.co.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawashima
authors.affiliation: Institute for Health Care Science, Suntory Wellness Ltd., 1-1-1 Wakayamadai, Shimamoto, Osaka, 6188503, Japan. hiroshi_shibata@suntory.co.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shibata
authors.affiliation: Department of Cellular Physiological Chemistry, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. morita.cell@tmd.ac.jp.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Morita
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use*; D001169:Arthritis, Experimental / Q000097:blood / Q000188:drug therapy* / Q000473:pathology*; D001842:Bone and Bones / Q000187:drug effects / Q000473:pathology; D019587:Dietary Supplements; D015232:Dinoprostone / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D007975:Leukotriene B4 / Q000378:metabolism; D044045:Lipoxins / Q000378:metabolism; D008297:Male; D011917:Rats, Inbred Lew; D013997:Time Factors
chemical_list: D044045:Lipoxins; C040527:lipoxin A4; D007975:Leukotriene B4; D016718:Arachidonic Acid; D015232:Dinoprostone