| Objective:To investigate the effects of Ginsenoside Rb1 (Rb1) on the proliferation and cell cycle of rat vascular smooth muscle cells (VSMCs) induced by PDGF-BB, and explore its mechanisms.Methods:VSMCs from the thoracic aorta of SD rats were cultured by tissue explant method. MTT assay was used to evaluate the effects of Rb1 (25μg/ml,50μg/ml,100μg/ml) on PDGF-BB-induced (25ng/ml) proliferation, and the flow cytometry was used to analyse the cell cycle; For probing the mechanisms deeply, the contents of nitric oxide (NO) in cell supernatant were measured by nitric oxide kit. The expressions of Cyclin A, Cyclin E, CDK2, CaN, iNOS and eNOS mRNA in the VSMCs were detected by real-time quantitative reverse transcription-polymerase chain reaction (Real-time RT-PCR).Results:In normal cultured VSMCs, Rb1 100μg/ml had no any effect on the growth and proliferation of normal VSMCs (P>0.05). Contrarily, PDGF-BB could significantly increase the optical density of MTT assay for VSMCs (P<0.01) and the percentage of the S phase cells, but decrease the G0/G1 phase cell percentage in the cell cycle analysis by flow cytometry (P<0.01); PDGF-BB could also reduce the contents of NO in the cell supernatant (P<0.01). At the same time, PDGF-BB could up-regulate Cyclin A, Cyclin E, CDK2, CaN and iNOS mRNA expressions, but down-regulate the eNOS mRNA expression (P<0.01). Treatments with Rb1 (25μg/ml,50μg/ml,100μg/ml) could inhibit the PDGF-BB-induced proliferation of VSMCs, decrease the S phase percentage and upgrade the G0/G1 phase percentage in the cell cycle; Rb1 could also depress the expressions of Cyclin A,Cyclin E,CDK2 and CaN mRNA(P<0.01). Furthermore, Rb1100μg/ml could decrease the expression of iNOS mRNA and increase the expression of eNOS mRNA in PDGF-treated VSMCs (P<0.01), but no change in NO content was found in this group; Rb1 50 and 25μg/ml tended to decrease the iNOS and increase the eNOS expression, and elevated significantly the NO content in the supernatant(P<0.05).Conclusions:Rb1 could inhibit the VSMC proliferation induced by PDGF-BB.The mechanisms may be related to restricting the progression of G0/G1 phase to S phase in cell cycle by down-regulated the expressions of Cyclin A,CyclinE and CDK2. Its down-regulation action on CaN mRNA expression may be one of the molecular mechanisms for the Objective:To observe the effects of ginsenoside Rb1 (Rb1) on vascular intimal hyperplasia in balloon-injured carotid artery of rats and explore the mechanisms.Methods:The balloon-injured carotid artery of rats model was established. Animals were then injected (ip) with distilled water (sham operation group and model group) or Rb1 (10 mg/kg/d,30 mg/kg/d). After 14 days of endothelia rubbing, the neointimal hyperplasia level and the degree of vascular smooth muscle cell (VSMC) proliferation were evaluated by calculating the neointimal area (NIA) and the NIA/media area(MA) ratio (NIA/MA),as well as by calculating the proliferating cell nuclear antigen (PCNA) positive expression percentage. Plasma superoxide dismutase (SOD) activities, cGMP contents, and maleic dialdehyde (MDA) levels were detected; and the expression of PCNA, phosphorylation extracellular signal-regulated kinase 1/2 (pERKl/2) and smooth muscle a-actin (SM a-actin) were examined by immunohistochemistry and analyzed with Image-Pro Plus.The expression of proto-oncogene (c-myc), SM a-actin, SM-emb (nonmuscle B myosin heavy chain) and p38 MAPK mRNA levels were detected by Real-Time PCR.Results:Compared with endothelia rubbing model group, Rb1 10 mg/kg/d and 30 mg/kg/d medication significantly decreased the elevated NIA, NIA/MA and PCNA positive percentage(P<0.01); also, the medication could reduce the increased MDA levels(P<0.01 or P<0.05), and increase the SOD activity and the content of cGMP in plasma(P<0.01 or P<0.05). In immunohistochemistry and Real-Time PCR assays, Rbi medication was found to decrease significantly the elevated protein expression of pERK1/2 and the mRNA expression of c-myc(P<0.01 or P<0.05), but no remarkable effect on the expression of p38 MAPK mRNA(P>0.05). Further more, Rb1 could also down-regulate the high SM-emb mRNA expression induced by balloon-injury, and when its dose at 30 mg/kg/d, it could increase the low expression of SM a-actin mRNA transcription(P<0.05). Conclusion:1. Rb1 can significantly attenuate the vascular intimal hyperplasia induced by ballon-injury in rats, and the effect may be through suppressing the VSMC proliferation and migration; 2. The anti-proliferative effect of Rb1 appears to be due, at least in part, to the increasings of SOD activity and cGMP content, and the decreasing of MDA level; 3. Its anti-proliferative effect may be related to its inhibition on VSMC phenotype modulation; 4. The molecular mechanisms may be involved in the suppressions of pERK1/2 protein and c-myc mRNA over expression induced by balloon-injury. |
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