Kim Nak Doo, Kim Eun Mi, Kang Keon Wook, Cho Min Kyung, Choi So Yeon, Kim Sang Geon
College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Sillim-dong, Kwanak-gu, Seoul 151-742, South Korea.
Br J Pharmacol. 2003 Oct;140(4):661-70. doi: 10.1038/sj.bjp.0705490.
Ginsenoside Rg3 (Rg3) isolated from Panax ginseng relaxes vessels and exerts a cytoprotective effect. In view of the fact that nitric oxide (NO) is involved in vascular hyporeactivity and immunostimulation, the effects of total ginsenosides (GS) and Rg3 on the vascular responses and the expression of inducible nitric oxide synthase (iNOS) were investigated. Vasocontraction of endothelium-denuded aortic ring was induced by phenylephrine with or without GS or Rg3. The expression of iNOS was assessed by Western blot and RT-PCR analyses. NF-kappaB activation was monitored by gel shift, immunoblot and immunocytochemical analyses. Incubation of the endothelium-denuded aortic ring with GS or Rg3 inhibited phenylephrine-induced vasocontraction, which was abrogated by NOS inhibition. GS or Rg3 increased NO production in aortic rings, but Rb1, Rc, Re and Rg1 had no effect. Aortic rings obtained from rats treated with GS or Rg3 responded to phenylnephrine to a lesser extent, while producing NO to a larger extent, than those from control animals. GS or Rg3 induced iNOS in vascular smooth muscle. Rg3 induced iNOS with increase in NO production in Raw264.7 cells. Rg3 increased NF-kappaB DNA binding, whose band was supershifted with anti-p65 and anti-p50 antibodies, and elicited p65 nuclear translocation, which was accompanied by phosphorylation and degradation of I-kappaBalpha. PKC regulated iNOS induction by Rg3. In conclusion, Rg3 relaxes vessels as a consequence of NO production, to which iNOS induction contributes, and iNOS induction by Rg3 accompanied NF-kappaB activation, which involves phosphorylation and degradation of I-kappaBalpha and nuclear translocation of p65.
从人参中分离出的人参皂苷Rg3（Rg3）可舒张血管并发挥细胞保护作用。鉴于一氧化氮（NO）参与血管反应性降低和免疫刺激，本研究探讨了总人参皂苷（GS）和Rg3对血管反应及诱导型一氧化氮合酶（iNOS）表达的影响。采用苯肾上腺素诱导去内皮主动脉环收缩，同时加入或不加入GS或Rg3。通过蛋白质免疫印迹法和逆转录聚合酶链反应分析评估iNOS的表达。通过凝胶迁移、免疫印迹和免疫细胞化学分析监测核因子κB（NF-κB）的激活情况。用GS或Rg3孵育去内皮主动脉环可抑制苯肾上腺素诱导的血管收缩，而一氧化氮合酶抑制可消除这种作用。GS或Rg3可增加主动脉环中NO的生成，但Rb1、Rc、Re和Rg1无此作用。与对照组动物相比，用GS或Rg3处理的大鼠的主动脉环对苯肾上腺素的反应较小，而产生的NO较多。GS或Rg3可诱导血管平滑肌中iNOS的表达。Rg3可诱导Raw264.7细胞中iNOS的表达并增加NO的生成。Rg3可增加NF-κB与DNA的结合能力，其条带可被抗p65和抗p50抗体超迁移，并引发p65核转位，同时伴有I-κBα的磷酸化和降解。蛋白激酶C调节Rg3诱导的iNOS表达。综上所述，Rg3通过产生NO舒张血管，iNOS的诱导对此有贡献，Rg3诱导iNOS的过程伴有NF-κB的激活，这涉及I-κBα的磷酸化和降解以及p65的核转位。
