Inhibitory effect of fucoidan on nitric oxide production in lipopolysaccharide-activated primary microglia.
1. Microglial activation plays an important role in the pathogenesis of neurodegenerative diseases by producing various pro-inflammatory cytokines. Microglia-derived nitric oxide (NO) is critical for the lipopolysaccharide (LPS)-induced selective loss of dopaminergic neurons. 2. Fucoidan is a sulphated polysaccharide extracted from brown seaweeds. It has a variety of biological actions, including anticoagulant, antiviral and anti-inflammatory effects. The aim of the present study was to investigate the effects of fucoidan on LPS-induced cellular activation in microglia and to evaluate the inhibitory mechanisms involved. 3. To investigate the effects of fucoidan on LPS-induced cellular activation in microglia, primary microglial cells were preincubated with fucoidan (31.25, 62.5 and 125 microg/mL) for 10 min, followed by stimulation with LPS (0.01 microg/mL). Then, cell shape and NO production were determined 24 h after LPS stimulation, whereas inducible nitric oxide synthase (iNOS) mRNA and protein expression were determined at 6 and 18 h after LPS stimulation, respectively. To evaluate the inhibitory mechanisms involved, mitogen-activated protein kinase (MAPK) activation was also evaluated. 4. Lipopolysaccharide transformed cells into an amoeboid shape, whereas 62.5 microg/mL fucoidan inhibited this activation. Moreover, 125 microg/mL fucoidan significantly inhibited microglial NO production to 75% of that in LPS-treated group and also significantly diminished the expression of iNOS mRNA and protein by nearly 50%. Fucoidan (125 microg/mL) also suppressed phosphorylation of p38 and extracellular signal-regulated kinase (ERK) by approximately 50%, but not that of c-Jun N-terminal kinase. 5. The results provide the first evidence that fucoidan has a potent inhibitory effect against LPS-induced NO production by microglia. The results also suggest that this inhibitory action of fucoidan involves suppression of p38 and ERK phosphorylation.
Cui
Yan-Qiu
YQ
Key Laboratory of Neurodegenerative Diseases of Ministry of Education, Capital Medical University, Beijing, China.
Zhang
Li-Juan
LJ
Zhang
Ting
T
Luo
Ding-Zhen
DZ
Jia
Yan-Jun
YJ
Guo
Zi-Xuan
ZX
Zhang
Quan-Bin
QB
Wang
Xuan
X
Wang
Xiao-Min
XM
D000818:Animals; D000831:Animals, Newborn; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D008070:Lipopolysaccharides / Q000633:toxicity*; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000188:drug therapy / Q000503:physiopathology; D018696:Neuroprotective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012624:Seaweed / Q000737:chemistry; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D008070:Lipopolysaccharides; D018696:Neuroprotective Agents; D011134:Polysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; C007789:fucoidan; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases