Inhibition of inducible nitric oxide synthase by Acanthopanax senticosus extract in RAW264.7 macrophages.
OBJECTIVE
The herb Acanthopanax senticosus (Siberian ginseng) has long been used as a traditional medicine. However, little is known about anti-inflammatory effects and its mechanisms of action. Excess production of nitric oxide (NO) is one of the characteristics of inflammation. In this study we examined the effects of A. senticosus extract (ASE) on NO production and inducible nitric oxide synthase (iNOS) gene expression in lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma)-stimulated RAW264.7 macrophages and investigated its mechanisms of anti-inflammatory activity.


METHODS
RAW264.7 macrophages were treated with 10 microg/ml LPS plus 20U/ml IFN-gamma in the presence or absence of ASE. NO production and iNOS gene expression were investigated. We further evaluated the effect of ASE on oxidative stress-sensitive transcription nuclear factor-kappa B (NF-kappaB) activation.


RESULTS
ASE significantly suppressed NO production and iNOS gene expression in a dose-dependent manner. ASE also reduced DNA-binding activity of NF-kappaB in LPS plus IFN-gamma stimulated RAW264.7 macrophages. Further studies indicated that LPS plus IFN-gamma-induced inhibitory factor-kappa B alpha (I-kappaBalpha) degradation and p65 nuclear translocation were inhibited in RAW264.7 macrophages exposed to ASE. Moreover, ASE inhibited the LPS plus IFN-gamma mediated increase in intracellular peroxides production.


CONCLUSIONS
These results suggest ASE suppresses iNOS gene expression through the inhibition of intracellular peroxides production, which has been implicated in the activation of NF-kappaB.
Lin
Qiu-Ye
QY
Department of Bioscience and Biotechnology, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian, Liaoning 116024, People's Republic of China.
Jin
Li-Ji
LJ
Cao
Zhen-Hui
ZH
Xu
Yong-Ping
YP
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D028001:Eleutherococcus / Q000737:chemistry*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007249:Inflammation / Q000188:drug therapy* / Q000503:physiopathology; D007371:Interferon-gamma; D008070:Lipopolysaccharides; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008516:Medicine, Chinese Traditional; D051379:Mice; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors*; D018384:Oxidative Stress / Q000187:drug effects; D010545:Peroxides / Q000378:metabolism; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*
D000893:Anti-Inflammatory Agents; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010545:Peroxides; D010936:Plant Extracts; D009569:Nitric Oxide; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II