RESUMO
Objective: To explore the mechanism of the effect of cadmium exposure on TopBP1-induced mitochondrial DNA damage in atherosclerotic rats to affect oxidative stress. Methods: 50 rats were established atherosclerotic model, and they were divided into model control group (MC group), low-dose cadmium exposure group (LD group), medium-dose cadmium exposure group (MD group), high-dose cadmium exposure group (HD group), and positive control group, with 10 rats in each group. Rats in the LD group, MD group, and HD group were intraperitoneally injected with different doses of cadmium acetate solution for intervention, rats in the PC group were intraperitoneally injected with oxidized banking solution, and those in the MC group were injected with normal saline. 10 rats were taken as the normal control group (NC group). Human umbilical vein endothelial cells were taken for cell experiments, normal saline was added as the blank control group (group A), cadmium acetate solution was added (group B), oxidized bankning solution was added (Group C), and oxidized bankning solution and cadmium acetate solution were added (Group D). Western blot and fluorescence quantitative PCR were used to detect the protein and mRNA expressions respectively. ROS, MDA, and SOD were detected by ELISA, apoptosis of endothelial cells was detected by flow cytometry, and arterial plaque damage was observed by oil red O staining. Results: The relative expressions of TopBP, Bax, and Bcl-2 proteins in rat aortic tissues in each group were significantly different (all P < .05). The relative expressions of TopBP1 and Bcl-2 proteins in the aortic tissues of rats in NC group, MC group, LD group, MD group, HD group, and PC group decreased (all P < .05), while the relative expressions of Bax protein in those groups were increased (all P < .05). Similarly, the relative expression levels of Topbp1mRNA, BaxmRNA, and Bcl-2mRNA in the aortic tissues of rats in each group were significantly different (all P < .05). There were statistically significant differences in the expression levels of ROS, MDA, SOD, and mtDNA expression levels in the aortic tissues of rats in each group. There were statistically significant differences in TopBP1, Topbp1mRNA, and mtDNA among groups (all P < .05); while the relative expression of TopBP1 and Topbp1mRNA in groups A, B, C, and D decreased (all P < .05), the expression levels of mtDNA in those group increased (all P < .05), and the apoptosis rates of endothelial cells were also increased (all P < .05). Conclusion: Cadmium exposure can down-regulate the expression of TopBP1 in atherosclerotic rats, aggravate mitochondrial DNA damage, promote oxidative stress response, and then induce the development of atherosclerosis.
RESUMO
AIM: Total flavones of Hippophae rhamnoides L. (TFH) have a clinical use in the treatment of cardiac disease. The pharmacological effects of TFH are attributed to its major flavonoid components, isorhamnetin, kaempferol, and quercetin. However, poor oral bioavailability of these flavonoids limits the clinical applications of TFH. This study explores phytic acid (IP6) enhancement of the oral absorption in rats of isorhamnetin, kaempferol, and quercetin in TFH. METHODS: In vitro Caco-2 cell experiments and in vivo pharmacokinetic studies were performed to investigate the effects of IP6. The aqueous solubility and lipophilicity of isorhamnetin, quercetin, and kaempferol were determined with and without IP6, and mucosal epithelial damage resulting from IP6 addition was evaluated by MTT assays and morphology observations. RESULTS: The Papp of isorhamnetin, kaempferol, and quercetin was improved 2.03-, 1.69-, and 2.11-fold in the presence of 333 µg/mL of IP6, respectively. Water solubility was increased 22.75-, 15.15-, and 12.86-fold for isorhamnetin, kaempferol, and quercetin, respectively, in the presence of 20mg/mL IP6. The lipophilicity of the three flavonoids was slightly decreased, but their hydrophilicity was increased after the addition of IP6 in the water phase as the logP values of isorhamnetin, kaempferol, and quercetin decreased from 2.38±0.12 to 1.64±0.02, from 2.57±0.20 to 2.01±0.04, and from 2.39±0.12 to 1.15±0.01, respectively. The absorption enhancement ratios were 3.21 for isorhamnetin, 2.98 for kaempferol, and 1.64 for quercetin with co-administration of IP6 (200 mg/kg) in rats. In addition, IP6 (200 mg/kg, oral) caused neither significant irritation to the rat intestines nor cytotoxicity (400 µg/mL) in Caco-2 cells. CONCLUSIONS: The oral bioavailability of isorhamnetin, kaempferol, and quercetin in TFH was enhanced by the co-administration of IP6. The main mechanisms are related to their enhanced aqueous solubility and permeability in the presence of IP6. In summary, IP6 is a potential absorption enhancer for pharmaceutical formulations that is both effective and safe.