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Objective To investigate the protection effect of dexmedetomidine against H2O2 injury in Human renal tubular epithelial cells(HK-2 cells). Methods HK-2 cells cultured in vitro were randomly divided into four groups(n = 24): control group, dexmedetomidine pretreatment group, H2O2 injury group, H2O2 injury +dexmedetomidine pretreatment group. Cell viabilities were measured by MTS assay, cell apoptosis were detected using flow cytometry, and expression of HIF-1α protein was quantified by western blot. HK-2 cells were divided into 8 groups by combining with three treatment factors such as PI3K inhibitor LY294002, dexmedetomidine and H2O2 injury. MTS assay was used to detect cell viability and western blot was used to quantify protein expression of HIF-1α,Bcl-2 and Bax after treatment in each group. Results Dexmedetomidine significantly increased the level of HIF-1α、 Bcl-2 in HK-2 cells after H2O2 injury, thus improved viabilities and reduced apotosis of cells. Moreover, effect on H2O2 injury cells of Dexmedetomidine was reversed by PI3K inhibitor LY294002. Conclusion Dexmedetomidine could protect against H2O2 injury by up-regulating HIF-1α expression through activating PI3K/Akt/mTOR signaling pathway in HK-2 cells.
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Objective To evaluate the role of mammalian target of rapamycin (mTOR) signaling pathway in dexmedetomidine-induced reduction of renal ischemia-reperfusion (I/R) injury in rats and the relationship with hypoxia-inducible factor 1 (HIF-1α).Methods Seventy-two male Sprague-Dawley rats, aged 10-12 weeks, weighing 220-260 g, were randomly divided into 4 groups (n=18 each) using a random number table: sham operation group (group S), group I/R, dexmedetomidine group (group Dex) ,and rapamicyn + dexmedetomidine group (group Rpm+Dex).Renal I/R was produced by occlusion of bilateral renal pedicles for 35 min follow by reperfusion in anesthetized rats in I/R, Dex and Rpm+Dex groups.Bilateral renal pedicles were only exposed, and then the abdominal cavity was closed in group S.Dexdetomidine 50 μg/kg was injected intraperitoneally at 30 min before I/R in group Dex.In group Rpm+Dex, rapamicyn 1.5 mg/kg and dexdetomidine 50 μg/kg were injected intraperitoneally, and renal I/R model was established 30 min later.Immediately after onset of reperfusion, and at 4 and 24 h of reperfusion (T1-3) , blood samples were collected from the caudal vein for measurement of serum creatinine and blood urea nitrogen (BUN) concentrations.After blood sampling at T1-3, the rats were sacrificed, and the renal specimens were obtained for detection of HIF-1αt, erythropoietin (EPO) and mTOR expression by Western blot.Their kidneys were removed at T3, and cut into sections which were stained with haematoxylin and eosin and examined under microscope.Acute renal tubular necrosis was scored.The cell apoptosis in renal tissues was detected by TUNEL assay, and apoptosis index (AI) was calculated.Results Compared with group S,the concentrations of serum creatinine and BUN, expression of HIF-1α, EPO and mTOR at T2,3 , AI at T3 and acute renal tubular necrosis score were significantly increased in the other three groups (P＜ 0.05).Compared with group I/R, the concentrations of serum creatinine and BUN were significantly decreased, and the expression of HIF-1α, EPO and mTOR was up-regulated at T2,3 , and AI and acute renal tubular necrosis score were decreased in group Dex (P＜0.05) , and no significant change was found in the parameters mentioned above in group Rpm + Dex (P ＞ 0.05).Conclusion The mTOR signaling pathway is involved in dexmedetomidine-induced reduction of renal I/R injury, which may be related to dexmedetomidine-produced up-regulation of HIF-1α expression in renal tissues of rats.
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<p><b>BACKGROUND</b>Atherosclerosis is a kind of disease with multiple risk factors, of which hyperlipidemia is a major classical risk factor resulting in its pathogenesis and development. The aim of this study was to determine the effects of short-term intensive atorvastatin (IA) therapy on vascular endothelial function and explore the possible mechanisms that may help to explain the clinical benefits from short-term intensive statin therapy.</p><p><b>METHODS</b>After exposure to high-fat diet (HFD) for 8 weeks, the animals were, respectively, treated with IA or low-dose atorvastatin (LA) for 5 days. Blood lipids, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO), endothelin-1 (ET-1), and endothelium-dependent vasorelaxation function were, respectively, measured. mRNA and protein expression of CRP, TNF-α, IL-6, macrophage chemoattractant protein-1 (MCP-1), and 5-lipoxygenase (5-LO) were also evaluated in pericarotid adipose tissue (PCAT) and cultured adipocytes.</p><p><b>RESULTS</b>HFD increased serum inflammatory factor levels; induced significant hyperlipidemia and endothelial dysfunction, including imbalance between NO and ET-1; enhanced inflammatory factors and 5-LO expression; and promoted macrophage infiltration into adipose tissue. Five-day IA therapy could significantly decrease serum inflammatory factor levels and their expression in PCAT; restore the balance between NO and ET-1; and improve endothelial function and macrophage infiltration without significant changes in blood lipids. However, all of the above were not observed in LA therapy. In vitro experiment found that lipopolysaccharide (LPS) enhanced the expression of inflammatory factors and 5-LO in cultured adipocytes, which could be attenuated by short-time (6 hours) treatment of high-dose (5 µmol/L) but not low-dose (0.5 µmol/L) atorvastatin. In addition, inhibiting 5-LO by Cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC, a potent and direct 5-LO inhibitor) could significantly downregulate the above-mentioned gene expression in LPS-treated adipocytes.</p><p><b>CONCLUSION</b>Short-term IA therapy could significantly ameliorate endothelial dysfunction induced by HFD, which may be partly due to attenuating inflammation of PCAT through inhibiting 5-LO pathway.</p>