Interaction between COX-2 and iNOS aggravates vascular lesion and antagonistic effect of ginsenoside.
OBJECTIVE
Ginseng, the root of Panax ginseng C.A.Meyer (Araliaceae), is one of the most widely used Chinese herbs with hypotensive and cardiotonic actions for thousands of years, but the underlying mechanisms have not been well determined. Ginsenoside, the effective components of ginseng, has anti-inflammatory and anti-oxidative effects. Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are key enzymes in inflammation and oxidative stress, respectively, which have close interaction, aggravating their damaging effects. This study investigated whether COX-2 interacted with iNOS in vascular endothelial lesion and the protective effect of ginsenoside.


METHODS
SD male rats were fed with high l-methionine (3%, w/w) to induce vascular endothelial lesion, and the rats in ginsenoside group were fed ginsenoside solution (0.8 mg kg(-1)d(-1)). The mRNA expression and protein contents of COX-2 and iNOS were detected by RT-PCR and Western blotting, respectively. The interaction between COX-2 and iNOS was analyzed by co-immunoprecipitation and laser confocal microscopy. The content of NT, a specific marker of peroxynitrite, was evaluated by Western blotting. The morphological changes of vascular endothelium were observed.


RESULTS
Compared with control group, the transcription and protein levels of both COX-2 and iNOS increased obviously and their interaction enhanced significantly in model group, in accord with the increased NT content and the pathological alterations of aorta. In ginsenoside group, all these alterations were attenuated significantly (P < 0.01 or P < 0.05).


CONCLUSIONS
It is proved that there exists interaction between COX-2 and iNOS, aggravating endothelial lesion through peroxynitrite and ginsenoside might antagonize their interaction, playing a protective role.
Li
Yan-Ning
YN
Department of Biochemistry, Hebei Medical University, Shijiazhuang City 050017, Hebei, PR China.
Wu
Yi-Ling
YL
Jia
Zhen-Hua
ZH
Qi
Jin-Sheng
JS
D000818:Animals; D015153:Blotting, Western; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D036145:Ginsenosides / Q000302:isolation & purification / Q000494:pharmacology*; D047468:Immunoprecipitation; D008297:Male; D008516:Medicine, Chinese Traditional; D018613:Microscopy, Confocal; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D005894:Panax / Q000737:chemistry*; D030421:Peroxynitrous Acid / Q000378:metabolism; D018517:Plant Roots; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D036145:Ginsenosides; D012333:RNA, Messenger; D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2