Development of a novel method for monitoring the antioxidative effect of ascorbic acid in rat blood

Quantitative and antioxidative behavior of Trolox in rats' blood and brain by HPLC-UV and SMFIA-CL methods

Trolox, a water-soluble vitamin E analogue has been used as a positive control in Trolox equivalent antioxidant capacity and oxygen radical antioxidant capacity assays due to its high antioxidative effect. In this study, the ex vivo antioxidative effects of Trolox and its concentration in blood and brain microdialysates from rat after administration were evaluated by newly established semi-microflow injection analysis, chemiluminescence detection and HPLC-UV. In the administration test, the antioxidative effect of Trolox in blood and brain microdialysates after a single administration of 200 mg/kg of Trolox to rats could be monitored. The antioxidative effects in blood (12.0 ± 2.1) and brain (8.4 ± 2.1, × 10(3) antioxidative effect % × min) also increased. Additionally, the areas under the curve (AUC)s0-360 (n = 3) for blood and brain calculated with quantitative data were 10.5 ± 1.2 and 9.7 ± 2.5 mg/mL × min, respectively. This result indicates that Trolox transferability through the blood-brain barrier is high. The increase in the antioxidative effects caused by Trolox in the blood and brain could be confirmed because good correlations between concentration and antioxidative effects (r ≥ 0.702) were obtained. The fact that Trolox can produce an antioxidative effect in rat brain was clarified.

Vagal stimulation triggers peripheral vascular protection through the cholinergic anti-inflammatory pathway in a rat model of myocardial ischemia/reperfusion

Myocardial ischemia/reperfusion (I/R) induces inflammatory response that may lead to remote vascular injury. Vagal nerve elicits the cholinergic anti-inflammatory pathway by activating α7 nicotinic acetylcholine receptors (α7nAChR). Nevertheless, the role of vagal nerve-mediated anti-inflammatory pathway in the vasculature has not been studied previously. Therefore, we aimed to clarify the potential role of vagal stimulation (VNS) in regulating remote vascular injury after myocardial I/R. Adult male Sprague-Dawley rats were subjected to VNS starting 15 min prior to ischemia until the end of reperfusion. VNS not only reduced infarct size and improved cardiac function, but also ameliorated myocardial I/R-induced dysfunctional vasoconstriction and vasodilatation and degradation of endothelial structure in mesenteric arteries. VNS decreased serum and vascular levels of tumor necrosis factor-α and IL-1β. Interestingly, in vivo microdialysis studies demonstrated that VNS increased ACh concentration in the mesenteric circulation. Furthermore, VNS up-regulated expressions of muscarinic ACh receptors-3 (M3AChR) and α7nAChR in mesenteric arteries. Preserved endothelial relaxations by VNS were inhibited by atropine or methyllycaconitine, indicating that functional protection was associated with M3 and α7nAChR activation. Finally, VNS increased STAT3 phosphorylation and inhibited NF-κB activation in mesenteric arteries, and these effects were abolished by α7nAChR shRNA treatment, indicating VNS-mediated anti-inflammatory effect mainly involved α7nAChR. These results demonstrated for the first time that VNS protected against remote vascular dysfunction, through the cholinergic anti-inflammatory pathway which is dependent on α7nAChR. Our findings represent a significant addition to the understanding of vagal nerve-mediated pathways and the potential roles they play in regulating the vasculature.