Icariin is a flavonoid isolated from the traditional Chinese herbal medicine Epimedium brevicornum Maxim and has been reported to be effective for the treatment of a variety of cardiovascular diseases. The aim of the present study was to investigate the effect and mechanism of icariin on atherosclerosis (AS) using a high-cholesterol diet (HCD)-induced rat model. Seventy male Wistar rats were divided into five groups: 20 in the control group, 20 in the AS group, 10 in the simvastatin group, 10 in the low-dose icariin group, and 10 in the high-dose icariin group. A HCD and vitamin D3 were administered to establish AS rat model. The five groups of rats received daily intragastric administration of normal saline, simvastatin, or icariin (30 mg/kg/d, 60 mg/kg/d) for 4 weeks. The levels of blood lipids, superoxide dismutase (SOD), and malonaldehyde (MDA) were measured. The mRNA levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were analyzed by real-time RT-PCR, and the serum levels of IL-6 and TNF-α were measured using ELISA kit. In addition, the expression of phosphorylated p38 (p-p38) MAPK was detected by Western blot analysis. The results indicated that AS rat models were successfully constructed. In the AS group, the levels of blood lipids including total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), and MDA were significantly increased, while high-density lipoprotein-cholesterol (HDL-C) and SOD were significantly decreased, compared with those in the control group. However, icariin succeeded in improving these biochemical parameters towards the normal values in the control group. In the simvastatin group and the icariin groups, the serum levels of IL-6 and TNF-α and the related tissue mRNA levels, as well as the expression of p-p38 MAPK, were markedly reduced compared with the AS group. In conclusion, the present study indicated that icariin inhibited the HCD-induced dyslipidemia in rats, the mechanisms may be associated with the anti-inflammation, anti-oxidative stress, and downregulation of p-p38 MAPK by icariin.

Icariin, a flavonoid isolated from the traditional Chinese herbal medicine Epimedium brevicornum Maxim, has been shown to possess anti-inflammatory, anti‑oxidant and anti-atherosclerotic activities in vivo and in vitro. The aim of the present study was to investigate the effects of icariin on oxidized low‑density lipoprotein (ox-LDL)-induced proliferation of vascular smooth muscle cells (VSMCs) and the possible underlying mechanism. VSMCs were cultured and pre‑treated with various concentrations of icariin (0, 10, 20 or 40 µm) prior to stimulation by ox‑LDL (50 µg/ml). Cell proliferation was evaluated by an MTT assay. Flow cytometry was used to study the influence of icariin on the cell cycle. Proliferating cell nuclear antigen (PCNA) expression and phosphorylation levels of extracellular signal-regulated kinase (ERK)1/2 were detected by western blot analysis. The results indicated that icariin significantly inhibited ox‑LDL‑induced proliferation of VSMCs and phosphorylation of ERK1/2. Furthermore, icariin also blocked the ox‑LDL‑induced cell‑cycle progression at G1/S‑interphase and downregulated the expression of PCNA in VSMCs. In conclusion, the present study indicated for the first time that icariin reduced the amount of ox‑LDL‑induced proliferation of VSMCs through suppression of PCNA expression and inactivation of ERK1/2.

ABSTRACT. The development of age-related cardiovascular disease is associated with the senescence of vascular cells. This study aimed to investigate the effect of ginsenoside Rg1 on vascular smooth muscle cell (VSMC) senescence. Primary VSMCs were cultured and divided into control, D-galactose (D-gal), Rg1-L, and Rg1-H groups, which were cultured without and with D-gal, and with low-and highconcentrations of Rg1, respectively. D-gal-induced cellular senescence was identified by b-galactosidase staining, and ultrastructural changes within the cells were observed. The expression of p16, p21, and p53 in the four groups of VSMCs was determined by western blotting, and the cell cycle was investigated by flow cytometry. Compared with the control group, there was an obvious change in the ultrastructure of VSMCs in the D-gal group, and the proportion of b-galactosidasepositive cells was significantly increased (P < 0.05). In addition, p16, p21, and p53 expression was significantly increased (P < 0.05) and the cell cycle was arrested in the G0/G1 phase. Compared with the D-gal group, the percentage of positive cells was significantly reduced (P < 0.05) in the Rg1 groups, the expression of p16, p21, and p53 was significantly reduced (P < 0.05), and the number of cells in the G0/G1 phase decreased (P < 0.05). Ginsenoside Rg1 can inhibit VSMC senescence, and the mechanisms may be related to its partial inhibition of the p16 INK4a /Rb and p53-p21Cip1/Waf1 signaling pathways during the cell cycle.

This paper was aimed to study the effects of icariin (ICA) on the proliferation of vascular smooth muscle cell (VSMC) induced by oxidized low density lipoprotein (ox-LDL), and the molecular mechanism of the expression of proliferating cell nuclear antigen (PCNA) and MAPK signaling pathway. In this study, VSMC was induced by ox-LDL (50 mg•L⁻¹),the effect of ICA on the proliferation of VSMC was detected by MTT assay, Western blot and Real-time PCR. The results showed that after stimulation of ox-LDL, the proliferation activity of VSMC was increased, S phase, G₂/M phase cells were increased, G₀/G₁ phase cells were decreased, PCNA protein expression was enhanced; ICA (40, 20, 10 μmol•L⁻¹) could effectively inhibit ox-LDL-induced VSMC proliferation, S phase and G₂/M phase cells were decreased, the percentage of cells in G₀/G₁ phase were increased, PCNA expression was decreased, p38MAPK and ERK1/2 activation were inhibited. These results indicate that ICA can inhibit the proliferation of VSMC by reducing the expression of PCNA and blocking the p38MAPK and ERK1/2 signaling pathway.