RESUMO
BACKGROUND: Oxidative stress plays a pivotal role in the progress of severe acute pancreatitis (SAP). Vitamin C (VC) is the most important antioxidant in plasma. However, the effects of an intravenous administration of high-dose VC and the mechanisms by which it exerts its antioxidant function in an experimental model of SAP have not been determined. METHODS: Sodium taurocholate was used to induce rat pancreatic injury and AR42J cells injury. After the establishment of SAP model, SAP rat and injured AR42J cells were treated with VC. For the injured AR42J cells, small interfering RNA-mediated knockdown of NRF2 was conducted after VC treatment. The histopathological characteristics, the apoptosis of pancreatic acinar cells, oxidative stress markers and levels of enzymes, biochemical indicators, and inflammatory cytokines were examined in vivo and in vitro. Furthermore, the mortality of rats was assessed. RESULTS: In vivo and in vitro results demonstrated that VC treatment ameliorated apoptosis of pancreatic acinar cells, as evidenced by the increase in Bcl-2, Bcl-XL, and MCL-1 expressions and decrease in Bax and cleaved caspase-3 expression along with decreased TUNEL-positive cells. Also, we found that the elevation of MDA and decrease of SOD, GPx, GSH/GSSG, and T-AOC induced by SAP were reversed by VC treatment in vivo and in vitro, and VC treatment increased expressions of Nrf2, NQO1, and HO-1 in SAP model at protein and gene level, indicating that VC attenuated oxidative stress via the NRF2/NQO1/HO-1 pathway. Meanwhile, it was found that sodium taurocholate significantly induced the release of amylase, lipase, IL-1ß, and IL-6 in rat plasma and AR42J cells, which were declined by VC treatment. In vitro results also revealed that these alterations in sodium taurocholate-injured AR42J cells due to VC treatment was attenuated by NRF2 knockdown. In addition, VC at a dose of 500 mg/kg decreased the levels of lactic acid, Cre, NGAL, AST, and ALT in the plasma of SAP rats, suggesting the improvement of renal and pancreatic injury and liver function of SAP rats. Furthermore, the mortality of SAP rats was 50%, which declined to 30% after VC treatment. CONCLUSIONS: The present study suggests that high-dose of VC ameliorate pancreatic injury of SAP via the NRF2/NQO1/HO-1 pathway to inhibit oxidative stress.
RESUMO
To investigate the effect of intravenous Vitamin C (VC) on hemorrhagic shock (HS)-associated rat renal injury and the involved mechanism. Thirty SD rats were randomly assigned to the sham surgery (sham), hemorrhagic shock (HS), HS+100 mg/kg VC (H + VL), HS+500 mg/kg VC (H + VH) and HS+100 mg/kg VC + EX527 (H + VL + E) groups. Tissue and blood samples were collected 6 h after surgery. Kidney pathological changes were scored. Creatinine (CRE), blood urea nitrogen (BUN), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels in serum and Vitamin C levels and superoxide dismutase (SOD) activity and the ability to suppress hydroxyl radical (RAFHR) in plasma were measured. The expression of Sirtuin1 (SIRT1), Acetyl-NF-κB (Ace-NF-κB), heme oxygenase-1 (HO-1), TNF-α, and IL-1ß in tissues was analyzed by ELISA or western-blot. In the HS group, the kidney pathological score and CRE, BUN, TNF-α, and IL-1ß levels in serum were significantly higher than in the Sham group (Pâ¯<â¯0.05), while SOD and RAFHR were significantly decreased in the plasma (Pâ¯<â¯0.05). SOD activity and SIRT1 expression were remarkably lower in the kidney in the HS group than in the Sham group (Pâ¯<â¯0.05), while MDA, TNF-α, and IL-1ß concentrations and Acetyl-NF-κB andHO-1 expression in the kidney showed a noteworthy increase compared to the Sham group (Pâ¯<â¯0.05). Compared to the HS group, VC treatment led to a remarkable reduction in the kidney pathological score and CRE,BUN,TNF-α, and IL-1ß levels (Pâ¯<â¯0.05), and a significant increase in Vitamin C, SOD, and RAFHR levels in the plasma (Pâ¯<â¯0.05). Additionally, MDA, TNF-α, IL-1ß and Acetyl-NF-κB expression levels were decreased in the kidney (P < 0.05), while SOD, SIRT1 and HO-1 levels were notably enhanced. There were no differences between the H + VL and H + VH groups aside from plasma Vitamin C levels. The effect of Vitamin C was decreased after the addition of EX527, which inhibits SIRT1. Intravenous Vitamin C might attenuate HS-related renal injury via the SIRT1 pathway, and it appears that there were no differences in the effects between the high and low doses.
