title: Docosahexaenoic acid potentiates interleukin-1beta induction of nitric oxide synthase through mechanism involving p44/42 MAPK activation in rat vascular smooth muscle cells.
abstract: The effect of docosahexaenoic acid (DHA) on nitric oxide (NO) production and inducible NO synthase (iNOS) expression induced by interleukin (IL)-1beta, and whether the effect of DHA is related to its effect on mitogen-activated protein kinase (MAPK) activation were investigated in cultured rat vascular smooth muscle cells (VSMCs). DHA and eicosapentaenoic acid (EPA), although less potent, increased the NO production induced by IL-1beta (3 ng ml(-1)) in a concentration-dependent manner (3 - 30 microM) Arachidonic acid had no significant effect. The stimulatory effect of DHA (30 microM) on the NO production was more obvious at lower concentrations of IL-1beta. IL-1beta induced iNOS protein and mRNA expressions, which were significantly potentiated by DHA. EPA (30 microM) had a tendency to increase the iNOS protein and mRNA expressions, but arachidonic acid had no effect. IL-1beta-induced iNOS protein expression was significantly inhibited by PD 98059 (10 microM), a selective inhibitor of p44/42 MAPK kinase, both in the absence and the presence of DHA. SB 203580 (10 microM), a selective inhibitor of p38 MAPK activity, had no significant effect, although had a tendency to inhibit slightly. IL-1beta increased the phosphorylation of p44/42 MAPK, while it did not apparently increase the phosphorylation of p38 MAPK. DHA significantly potentiated the IL-1beta-induced phosphorylation of p44/42 MAPK, while it had no significant effect on the phosphorylation of p38 MAPK. These results suggest that DHA increases NO production by potentiating iNOS expression induced by IL-1beta through mechanism involving p44/42 MAPK signalling cascade in rat VSMCs. The present study may contribute to the understanding of basic mechanisms underlying the beneficial effects of DHA on various cardiovascular disorders.
authors.affiliation: Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. hirafuji@hoku-iryo-u.ac.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirafuji
authors.forename: Takuji
authors.initials: T
authors.lastname: Machida
authors.forename: Marito
authors.initials: M
authors.lastname: Tsunoda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyamoto
authors.forename: Masaru
authors.initials: M
authors.lastname: Minami
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D015118:Eicosapentaenoic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011921:Rats, Inbred WKY; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D009569:Nitric Oxide; D015118:Eicosapentaenoic Acid; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases