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.
Key Laboratory of Neurodegenerative Diseases of Ministry of Education, Capital Medical University, Beijing, China.
Yan-Qiu
YQ
Cui
Li-Juan
LJ
Zhang
Ting
T
Zhang
Ding-Zhen
DZ
Luo
Yan-Jun
YJ
Jia
Zi-Xuan
ZX
Guo
Quan-Bin
QB
Zhang
Xuan
X
Wang
Xiao-Min
XM
Wang
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