Dexmedetomidine protects against ischemia–reperfusion injury in rat skeletal muscle

Background

Dexmedetomidine (DEX) has been shown to decrease ischemia–reperfusion (I/R) injury in kidney and brain tissues. In this study, the effects of DEX were evaluated in skeletal muscle during I/R injury.

Materials and methods

Animals were divided into four groups: sham-operated (sham group), saline + I/R, DEX + I/R, and α-tocopherol + I/R groups. Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4 h of ischemia, the clamp was removed and the animals underwent 2 h of reperfusion. Animals in the drug treatment group received DEX or α-tocopherol by intraperitoneal injection 1 h before reperfusion. We measured plasma concentrations of interleukin 1β and tumor necrosis factor α levels using an enzyme-linked immunosorbent assay. The right gastrocnemius muscle was harvested and immediately stored at −80°C for the assessment of superoxide dismutase (SOD) and catalase (CAT) activities as well as glutathione (GSH), malondialdehyde (MDA), and protein oxidation (PO) levels. DEX (25 μg/kg) and normal saline (10 mL/kg) were administered by intraperitoneal injection 1 h before reperfusion.

Results

Plasma tumor necrosis factor α or interleukin 1β levels increased significantly in the I/R group (P < 0.01 compared with sham group) and decreased significantly in the DEX group (P < 0.01 compared with I/R group). Muscle tissues of the I/R group had significantly decreased SOD, GSH, and CAT activities and increased levels of MDA and PO content compared with the sham group. The activity of antioxidant enzymes in the DEX + I/R group was greatly elevated compared with that in the I/R group (SOD, 1.068 ± 0.120 versus 0.576 ± 0.072 U/mg protein; GSH, 2.436 ± 0.144 versus 1.128 ± 0.132 μmol/g; and CAT, 69.240 ± 6.456 versus 31.884 ± 6.312 U/mg protein; P < 0.01), whereas the levels of MDA and PO content were clearly reduced (23.268 ± 3.708 versus 53.604 ± 5.972 nmol/g protein and 1.908 ± 0.192 versus 5.208 ± 0.612 nmol/mg protein, respectively; P < 0.01). Moreover, DEX exhibited more potent antioxidant activity than vitamin E in the skeletal muscle I/R.

Conclusions

We found that DEX exhibits protective effects against skeletal muscle I/R injury. These results underscore the necessity of human studies with DEX to determine if it is beneficial for preventing skeletal muscle I/R injury.     

Dexmedetomidine protects against lung ischemia–reperfusion injury by the PI3K/Akt/HIF-1α signaling pathway

Purpose

To evaluate the role of the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway in the protection by dexmedetomidine against lung ischemia–reperfusion injury (IRI) in rats.

Methods

Forty-eight male Sprague–Dawley rats weighing 250–350 g were randomly divided into six groups (n = 8 each group): sham group, IRI group, low-dose dexmedetomidine group (LD group), high-dose dexmedetomidine group (HD group), combined low-dose dexmedetomidine and LY294002 group (LDL group), and combined high-dose dexmedetomidine and LY294002 group (HDL group). A 30-min ischemia was induced by occluding the hilum of the left lung, followed by a 120-min reperfusion by removing occlusion of the hilum. After the left lung was removed, the wet/dry weight ratio (W/D) of the lung tissues was determined. Pathological changes of lung tissues were evaluated by light and electron microscopes and the expression of p-Akt and HIF-1α in the lung tissues was determined by western blotting.

Results

Compared with the sham group, both the W/D ratio and lung injury were significantly increased, the p-Akt expression was down-regulated and HIF-1α expression was up-regulated in the five experimental groups. Compared with the LD and LDL groups, both the W/D ratio and lung injury were decreased, but the expression of p-Akt and HIF-1α was increased in the HD and HDL groups.

Conclusions

Administration of dexmedetomidine before ischemia can provide a protection against lung IRI by re-installing the PI3K/Akt/HIF-1α signaling pathway.

     

miR-21调控PTEN/PI3K/Akt通路抑制增生性瘢痕形成的机制研究

目的:探讨miR-21对增生性瘢痕中PTEN表达和成纤维细胞增殖的影响,以期为增生性瘢痕的临床诊断和治疗提供新靶点。方法:分别用qPCR和Westernblot检测增生性瘢痕(HTS)组织和细胞中miR-21及PTEN的表达;双荧光素酶报告基因检测验证miR-21与PTEN的调控关系;Westernblot检测miR-21对增生性瘢痕成纤维细胞(HSF)中PTEN蛋白表达影响;MTT检测细胞增殖能力变化。结果:HTS组织中miR-21高表达,PTEN低表达;双荧光素酶报告实验和Westernblot证实了miR-21对PTEN的靶向调控作用;下调miR-21可增加PTEN的表达,从而可抑制PI3K/Akt通路活性,抑制HSF细胞增殖。结论:本研究证实了miR-21具有诊断和治疗HTS的潜能,并为临床提供可能的新靶点。     

Photobiomodulation enhances facial nerve regeneration via activation of PI3K/Akt signaling pathway–mediated antioxidant response

Lasers in Medical Science - Facial nerve dysfunction is a common clinical condition that leads to disfigurement and emotional distress in the affected individuals. This study aimed to evaluate...     

Uric acid induces inflammatory injury in HK-2 cells via PI3K/AKT/NF-κB signaling pathway

Objective To investigate the effects and underlying mechanisms of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/NF-κB signaling pathway in human kidney-2 (HK-2) cells of hyperuricemic nephropathy. Methods HK-2 cells were cultured in vitro and randomly divided into control group and experimental group. The experimental group was induced by high uric acid (720 μmol/L) immersion for 48 h to establish a cell model of hyperuricemic nephropathy in vitro and subsequently divided into hyperuricemic group, overexpressed protease activated receptor 2 (PAR2) and knockdown PAR2 group. The expressions of PAR2, PI3K, AKT, NF-κB mRNA were measured by real-time PCR. The expressions of PAR2, PI3K, AKT and NF-κB protein were measured by Western blotting. The expressions of tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1), interleukin-6 (IL-6), pro-interleukin-1β (pro-IL-1β), interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) were detected by enzyme linked immunosorbent assay (ELISA). Results (1) Compared with the control group, the expressions of PAR2, PI3K, AKT and NF-κB mRNA and protein in hyperuricemic group were significantly increased (all P＜0.05), the expressions of TNF-α, MCP-1, IL-6, pro-IL-1β, IL-1β and TGF-β1 in the supernatant in hyperuricemic group were significantly increased (all P＜0.01). (2) Compared with the hyperuricemic group, the expressions of PAR2, PI3K, AKT and NF-κB mRNA and protein in overexpressed PAR2 group were significantly increased (all P＜0.05), the expressions of TNF-α, MCP-1, IL-6, IL-1β and TGF-β1 in the supernatant were significantly increased (all P＜0.05). (3) Compared with the hyperuricemic group, the expression of PAR2, PI3K, AKT and NF-κB mRNA and protein in knockdown PAR2 group were significantly decreased (all P＜0.05), the expressions of IL-6, pro-IL-1β, IL-1β and TGF-β1 in the supernatant were significantly decreased (all P＜0.05). Conclusions In the process of uric acid-induced HK-2 cell damage, uric acid significantly up-regulates the expression of PI3K/AKT/NF-κB signaling pathway by activating PAR2, leading to a marked increase in inflammatory damage. Knocking down PAR2 inhibits the expression of PI3K/AKT/NF-κB signaling pathway, which can effectively reduce the inflammatory damage of HK-2 cells.     

Loss of Cbl–PI3K interaction in mice prevents significant bone loss following ovariectomy

Cbl and Cbl-b are E3 ubiquitin ligases and adaptor proteins, which perform regulatory roles in bone remodeling. Cbl −/− mice have delayed bone development due to decreased osteoclast migration. Cbl-b −/− mice are osteopenic due to increased bone resorbing activity of osteoclasts. Unique to Cbl, but not present in Cbl-b, is tyrosine 737 in the YEAM motif, which upon phosphorylation provides a binding site for the regulatory p85 subunit of PI3K. Substitution of tyrosine 737 with phenylalanine (Y737F, CblYF/YF mice) prevents Y737 phosphorylation and abrogates the Cbl–PI3K interaction. We have previously reported that CblYF/YF mice had increased bone volume due to defective bone resorption and increased bone formation. Here we show that the lumbar vertebra from CblYF/YF mice did not have significant bone loss following ovariectomy. Our data also suggests that abrogation of Cbl–PI3K interaction in mice results in the loss of coupling between bone resorption and formation, since ovariectomized CblYF/YF mice did not show significant changes in serum levels of c-terminal telopeptide (CTX), whereas the serum levels of pro-collagen type-1 amino-terminal pro-peptide (P1NP) were decreased. In contrast, following ovariectomy, Cbl −/− and Cbl-b −/− mice showed significant bone loss in the tibiae and L2 vertebrae, concomitant with increased serum CTX and P1NP levels. These data indicate that while lack of Cbl or Cbl-b distinctly affects bone remodeling, only the loss of Cbl–PI3K interaction protects mice from significant bone loss following ovariectomy.     

STAT3及其下游miR-92a/KLF4/PI3K/Akt轴在先天性巨结肠病变组织中的表达

背景与目的:信号传导与转录激活因子(STAT)蛋白家族在多种遗传性疾病中异常表达,然而STAT3在先天性巨结肠(HD)进程中的表达及意义如何?为此,本研究探讨STAT3及其下游miR-92a/KLF4/PI3K/Akt信号轴在HD病变组织中的表达,以期为临床该病的治疗提供新靶点.方法:采用S-P免疫组化染色法观察68例...     

microRNA-29b prevents renal fibrosis by attenuating renal tubular epithelial cell–mesenchymal transition through targeting the PI3K/AKT pathway

International Urology and Nephrology - This study aimed to investigate the effects of miR-29b on renal interstitial fibrosis in the obstructed kidney of mouse with unilateral ureteral obstruction...     

Hydrogen sulfide attenuates lung ischemia–reperfusion injury through SIRT3-dependent regulation of mitochondrial function in type 2 diabetic rats

BackgroundLung ischemia–reperfusion injury is a complex pathophysiologic process associated with high morbidity and mortality. We have demonstrated elsewhere that diabetes mellitus aggravated ischemia-induced lung injury. Oxidative stress and mitochondrial dysfunction are drivers of diabetic lung ischemia-reperfusion injury; however, the pathways that mediate these events are unexplored. In this study using a high-fat diet–fed model of streptozotocin-induced type 2 diabetes in rats, we determined the effect of hydrogen sulfide on lung ischemia-reperfusion injury with a focus on Sirtuin3 signaling.MethodsRats with type 2 diabetes were exposed to GYY4137, a slow release donor of hydrogen sulfide with or without administration of the Sirtuin3 short hairpin ribonucleic acid plasmid, and then subjected to a surgical model of ischemia–reperfusion injury of the lung (n = 8). Lung function, oxidative stress, inflammation, cell apoptosis, and mitochondrial function were measured.ResultsCompared with nondiabetic rats, animals with type 2 diabetes at baseline exhibited significantly decreased Sirtuin3 signaling in lung tissue and increased oxidative stress, apoptosis, inflammation, and mitochondrial dysfunction (P < .05 each). In addition, further impairment in Sirtuin3 signaling was found in diabetic rats subjected to this model of lung ischemia–reperfusion. Simultaneously, the indexes showed further aggravation. Treatment with hydrogen sulfide restored Sirtuin3 expression and decreased lung ischemia–reperfusion injury in animals with type 2 diabetes mellitus by improving lung functional recovery, decreasing oxidative damage, suppressing inflammation, ameliorating cell apoptosis, and preserving mitochondrial function (P < .05). Conversely, these protective effects were largely reversed in Sirtuin3 knockdown rats.ConclusionImpaired lung Sirtuin3 signaling associated with type 2 diabetic conditions was further attenuated by an ischemia-reperfusion insult. Hydrogen sulfide ameliorated reperfusion-induced oxidative stress and mitochondrial dysfunction via activation of Sirtuin3 signaling, thereby decreasing lung ischemia-reperfusion damage in rats with a model of type II diabetes.     

miR-155靶向调节PIK3R1对类风湿关节炎大鼠模型PI3K/Akt/mTOR信号通路的影响

目的 探讨miR-155靶向调节PIK3R1对类风湿关节炎（rheumatoid arthritis,RA）大鼠PI3K/Akt/mTOR信号通路的影响。方法 SD大鼠随机分为对照组、模型组、miR-155 agomir组、miR-155 antagomir组、miR-155阴性对照组,诱导RA模型,分组处理后,观察关节症状,检测关节炎指数及后足趾容积;HE染色观察大鼠关节组织病理形态;使用试剂盒检测大鼠关节组织炎性因子IL-6、IL-17及IL-18水平;免疫印迹检测大鼠关节组织PI3K/Akt/mTOR信号通路蛋白表达;qRT-PCR实验检测大鼠关节组织miR-155及PIK3R1 mRNA水平;双荧光素酶报告基因实验检测miR-155对PIK3R1的靶向调控作用。结果 与对照组比较,模型组大鼠关节炎症状明显,关节炎指数、后足趾容积、关节组织炎性因子IL-6、IL-17及IL-18水平、关节组织p-PI3K/PI3K、p-Akt/Akt及p-mTOR/mTOR水平、关节组织miR-155水平明显升高（P＜0.05）,PIK3R1 mRNA水平明显降低（P＜0.05）。与模型组、miR-155阴性对照组比较,miR-155 antagomir组大鼠上述指标得到明显改善（P＜0.05）;miR-155 agomir组与miR-155 antagomir组趋势相反（P＜0.05）。结论 miR-155可靶向下调PIK3R1的表达,激活PI3K/Akt/mTOR信号,加重RA大鼠关节炎症损伤,下调miR-155表达,可抑制PI3K/Akt/mTOR信号激活及炎症反应发生发展,改善关节炎症状。     

Hypoxia preconditioning protects neuronal cells against traumatic brain injury through stimulation of glucose transport mediated by HIF-1α/GLUTs signaling pathway in rat

Neurosurgical Review - Hypoxia preconditioning (HPC), a well-established preconditioning model, has been shown to protect the brain against severe hypoxia or ischemia caused by traumatic brain...     

Role of tea polyphenols in delaying hyperglycemia-induced senescence in human glomerular mesangial cells via miR-126/Akt–p53–p21 pathways

International Urology and Nephrology - The aim of this study was to investigate the effects and possible mechanism of tea polyphenols (TPs) on the senescence of human glomerular mesangial cells...     

Fish-oil emulsion (omega-3 polyunsaturated fatty acids) attenuates acute lung injury induced by intestinal ischemia–reperfusion through Adenosine 5′-monophosphate-activated protein kinase–sirtuin1 pathway

Background

Activated macrophage infiltration into the lungs is paramount in the pathogenesis of acute lung injury (ALI) induced by intestinal ischemia–reperfusion (I/R). Omega-3 polyunsaturated fatty acid (ω-3 PUFA) is a potent activator of the Adenosine 5′-monophosphate-activated protein kinase–sirtuin1 (AMPK/SIRT1) pathway against macrophage inflammation. We aimed to evaluate whether ω-3 PUFAs may protect against ALI induced by intestinal I/R via the AMPK/SIRT1 pathway.

Methods

Ischemia in male Wistar rats was induced by superior mesenteric artery occlusion for 60 min and reperfusion for 240 min. One milliliter per day of fish-oil emulsion (FO emulsion, containing major ingredients as ω-3 PUFAs) or normal saline (control) was administered by intraperitoneal injection for three consecutive days to each animal. All animals were sacrificed at the end of reperfusion. Blood and tissue samples were collected for analysis.

Results

Intestinal I/R caused intestinal and lung injury, evidenced by severe lung tissue edema and macrophage infiltration. Pretreatment with FO emulsion improved the integrity of microscopic structures in the intestine and lungs. Intestinal I/R induced the expression of macrophage-derived mediators (macrophage migration inhibitory factor and macrophage chemoattractant protein-1), inflammatory factors (nuclear factor κB, tumor necrosis factor α, interleukin 6, and interleukin 1β), and proapoptosis factor p66shc. There was a decrease in the expression of AMPK, SIRT1, and claudin 5. FO emulsion significantly inhibited macrophage infiltration into the lungs, inflammatory factor expression, and p66shc phosphorylation. Importantly, FO emulsion restored AMPK, SIRT1, and claudin 5 in the lungs.

Conclusions

Pretreatment with ω-3 PUFAs effectively protects intestinal and lung injury induced by intestinal I/R, reduces macrophage infiltration, suppresses inflammation, inhibits lung apoptosis, and improves the lung endothelial barrier after intestinal I/R in a manner dependent on AMPK/SIRT1. Thus, there is a potential for developing AMPK/SIRT1 as a novel target for patients with intestinal I/R–induced ALI.     

PLXND1/SEMA3E Promotes Epithelial–Mesenchymal Transition Partly via the PI3K/AKT-Signaling Pathway and Induces Heterogenity in Colorectal Cancer

Annals of Surgical Oncology - Colorectal cancer (CRC) is a major cause of cancer-related deaths. Metastasis is enhanced through epithelial-mesenchymal transition (EMT), a process primarily induced...