u-0126 and Ischemia

Testicular torsion is a urological emergency. However, surgical detorsion of the torsed spermatic cord can cause testicular reperfusion injury. Although remote ischemic preconditioning (RIPC) has been convincingly shown to protect organs against ischemia/reperfusion (I/R) injury, little is known regarding the effect of RIPC on testicular torsion/detorsion-induced reperfusion injury. Therefore, we aimed to evaluate the effect of RIPC on testes after testicular I/R injury in a rat model in vivo. Male Sprague-Dawley rats were randomly classified into 4 groups: sham-operated (sham), testicular I/R (TI/R), or remote liver (RIPC liver) and limb (RIPC limb) ischemic preconditioning groups. Testis I/R was induced by 3 h of right spermatic cord torsion (720° clockwise), and reperfusion was allowed for 3 hours. In the RIPC group, four cycles of 5 min of ischemia and 5 min of reperfusion were completed 30 min prior to testicular torsion. The ERK1/2 inhibitor U0126 was administered intravenously at the beginning of reperfusion (1 mg/kg). The testes were taken for the oxidative stress evaluations, histology, apoptosis, immunohistochemical and western blotting analysis. Remote liver and limb ischemic preconditioning attenuated ipsilateral and contralateral testicular damage after testicular I/R injury. For example. RIPC reduced testicular swelling and oxidative stress, lessened structural damage, and inhibited the testicular inflammatory response and apoptosis. Furthermore, RIPC treatment enhanced testicular ERK1/2 phosphorylation postI/R. Inhibition of ERK1/2 activity using U0126 eliminated the protection offered by RIPC. Our data demonstrate for the first time that RIPC protects testes against testicular I/R injury via activation of the ERK1/2 signaling pathway.

Topics: Animals; Humans; Ischemia; Male; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Spermatic Cord Torsion; Testis

Cooling following cardiac arrest can improve survival significantly. However, delays in achieving target temperature may decrease the overall benefits of cooling. Here, we test whether lipid emulsion, a clinically approved drug reported to exert cardioprotection, can rescue heart contractility in the setting of delayed cooling in stunned mouse cardiomyocytes.. Cell culture study.. Academic research laboratory.. Cardiomyocytes isolated from 1- to 2-day-old C57BL6 mice.. Cardiomyocytes were exposed to 30 minutes of ischemia followed by 90 minutes of reperfusion and 10 minutes of isoproterenol with nine interventions: 1) no additional treatment; 2) intraischemic cooling at 32 °C initiated 10 minutes prior to reperfusion; 3) delayed cooling started 20 minutes after reperfusion; 4) lipid emulsion + delayed cooling; 5) lipid emulsion (0.25%) administered at reperfusion; 6) lipid emulsion + intraischemic cooling; 7) delayed lipid emulsion; 8) lipid emulsion + delayed cooling + Akt inhibitor (API-2, 10 µM); and 9) lipid emulsion + delayed cooling + Erk inhibitor (U0126, 10 µM). Inhibitors were given to cells 1 hour prior to ischemia.. Contractility was recorded by real-time phase-contrast imaging and analyzed with pulse image velocimetry in MATLAB (Mathworks, Natick, MA). Ischemia diminished cell contraction. The cardioprotective effect of cooling was diminished when delayed but was rescued by lipid emulsion. Further, lipid emulsion on its own improved recovery of the contractility to a greater extent as intraischemic cooling. However, cotreatment of lipid emulsion and intraischemic cooling did not further improve the recovery compared to either treatment alone. Furthermore, Akt and Erk inhibitors blocked lipid emulsion-induced protection.. Lipid emulsion improved contractility and rescued contractility in the context of delayed cooling. This protective effect required Akt and Erk signaling. Lipid emulsion might serve as a treatment or adjunct to cooling in ameliorating myocardial ischemia/reperfusion injury.

Topics: Animals; Butadienes; Cardiotonic Agents; Chlorpropamide; Disease Models, Animal; Hypothermia, Induced; Ischemia; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Muscle Contraction; Myocardial Reperfusion Injury; Myocytes, Cardiac; Nitriles; Proto-Oncogene Proteins c-akt; Time Factors

Apoptotic death of endothelial cells (EC) plays a crucial role for the development of ischemic injury. In the present study we investigated the impact of extracellular Adenosine-5'-triphosphate (ATP), either released from cells or exogenously added, on ischemia-induced apoptosis of human EC.. To simulate ischemic conditions, cultured human umbilical vein endothelial cells (HUVEC) were exposed to 2 h of hypoxia (Po(2)<4mm Hg) in serum-free medium. Ischemia led to a 1.7-fold (+/-0.4; P<0.05) increase in EC apoptosis compared to normoxic controls as assessed by immunoblotting and immunocytochemistry of cleaved caspase-3. Ischemia-induced apoptosis was accompanied by a 2.3-fold (+/-0.5; P<0.05) increase of extracellular ATP detected by using a luciferin/luciferase assay. Addition of the soluble ecto-ATPase apyrase, enhancing ATP degradation, increased ischemia-induced caspase-3 cleavage. Correspondingly, inhibition of ATP breakdown by addition of the selective ecto-ATPase inhibitor ARL67156 significantly reduced ischemia-induced apoptosis. Extracellular ATP acts on membrane-bound P2Y- and P2X-receptors to induce intracellular signaling. Both, ATP and the P2Y-receptor agonist UTP significantly reduced ischemia-induced apoptosis in an equipotent manner, whereas the P2X-receptor agonist αβ-me-ATP did not alter caspase-3 cleavage. The anti-apoptotic effects of ARL67156 and UTP were abrogated when P2-receptors were blocked by Suramin or PPADS. Furthermore, extracellular ATP led to an activation of MEK/ERK- and PI3K/Akt-signaling pathways. Accordingly, inhibition of MEK/ERK-signaling by UO126 or inhibition of PI3K/Akt-signaling by LY294002 abolished the anti-apoptotic effects of ATP.. The data of the present study indicate that extracellular ATP counteracts ischemia-induced apoptosis of human EC by activating a P2Y-receptor-mediated signaling reducing caspase-3 cleavage.

Topics: Adenosine Triphosphate; Apoptosis; Butadienes; Caspase 3; Cells, Cultured; Chromones; Cytoprotection; Enzyme Inhibitors; Human Umbilical Vein Endothelial Cells; Humans; Ischemia; MAP Kinase Kinase Kinases; Morpholines; Nitriles; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Purinergic P2Y Receptor Agonists; Receptors, Purinergic P2Y

Previously we demonstrated benefits of inhibiting the extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathway in spinal cord ischemia/reperfusion (I/R) injury. To further identify the underlying mechanisms, we investigated the impact of ERK inhibition on apoptosis and cellular protective mechanisms against cell death. Spinal cord I/R injury induced ERK1/2 phosphorylation, followed by neuronal loss through caspase 3-mediated apoptosis. Pre-treatment with U0126, a specific inhibitor of MAPK/ERK kinases 1/2 (MEK1/2), inhibited ERK1/2 phosphorylation, and significantly attenuated apoptosis and increased neuronal survival. MEK/ERK inhibition also induced I-kappaB phosphorylation and enhanced nuclear factor (NF)-kappaB/DNA binding activity, leading to expression of cellular inhibitors of apoptosis protein 2 (c-IAP2), a known nuclear factor-kappaB (NF-kappaB)-regulated endogenous anti-apoptotic molecule. Pyrrolidine dithiocarbamate, an NF-kappaB inhibitor, by blocking I-kappaB phosphorylation, NF-kappaB activation, and c-IAP2 synthesis, abolished the protective effects of U0126. The MEK/ERK pathway appears to mediate cellular death following I/R injury. The U0126 neuroprotection appears related to NF-kappaB-regulated transcriptional control of c-IAP2. MEK/ERK inhibition at the initial stage of I/R injury may cause changes in c-IAP2 gene expression or c-IAP2/caspase 3 interactions, resulting in long lasting therapeutic effects. Future research should focus on the possible cross-talk between the MEK/ERK pathway and the NF-kappaB transcriptional cascade.

Topics: Animals; Apoptosis; Butadienes; Caspase 3; Cell Survival; Enzyme Activation; I-kappa B Proteins; Inhibitor of Apoptosis Proteins; Ischemia; Male; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurons; Neuroprotective Agents; NF-kappa B; Nitriles; Phosphorylation; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; Spinal Cord

High mobility group box-1 (HMGB1), a non-histone DNA-binding protein, is massively released into the extracellular space from neuronal cells after ischemic insult and exacerbates brain tissue damage in rats. Minocycline is a semisynthetic second-generation tetracycline antibiotic which has recently been shown to be a promising neuroprotective agent. In this study, we found that minocycline inhibited HMGB1 release in oxygen-glucose deprivation (OGD)-treated PC12 cells and triggered the activation of p38mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK1/2). The ERK kinase (MEK)1/2 inhibitor U-0126 and p38MAPK inhibitor SB203580 blocked HMGB1 release in response to OGD. Furthermore, HMGB1 triggered cell death in a dose-dependent fashion. Minocycline significantly rescued HMGB1-induced cell death in a dose-dependent manner. In light of recent observations as well as the good safety profile of minocycline in humans, we propose that minocycline might play a potent neuroprotective role through the inhibition of HMGB1-induced neuronal cell death in cerebral infarction.

Topics: Animals; Apoptosis; Butadienes; Cattle; Enzyme Inhibitors; Glucose; HMGB1 Protein; Ischemia; Minocycline; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurons; Nitriles; Oxygen; p38 Mitogen-Activated Protein Kinases; PC12 Cells; Rats

A previous exposure to a non-harmful ischemic insult (preconditioning) protects the brain against subsequent harmful ischemia (ischemic tolerance). In contrast to delayed gene-mediated ischemic tolerance, little is known about the molecular mechanisms that regulate rapid ischemic tolerance, which occurs within 1 h following preconditioning. Here we have investigated the degradation of the pro-apoptotic Bcl-2 family member Bim as a mechanism of rapid ischemic tolerance. Bim protein levels were reduced 1 h following preconditioning and occurred concurrent with an increase in Bim ubiquitination. Ubiquitinated proteins are degraded by the proteasome, and inhibition of the proteasome with MG132 (a proteasome inhibitor) prevented Bim degradation and blocked rapid ischemic tolerance. Inhibition of p42/p44 mitogen-activated protein kinase activation by U0126 reduced Bim ubiquitination and Bim degradation and blocked rapid ischemic tolerance. Finally, inhibition of Bim expression using antisense oligonucleotides also reduced cell death following ischemic challenge. Our results suggest that following preconditioning ischemia, Bim is rapidly degraded by the ubiquitin-proteasome system, resulting in rapid ischemic tolerance. This suggests that the rapid degradation of cell death-promoting proteins by the ubiquitin-proteasome pathway may represent a novel therapeutic strategy to reduce cell damage following neuropathological insults, e.g. stroke.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Butadienes; Cell Death; Cells, Cultured; Cyclin-Dependent Kinase Inhibitor p21; Immunoblotting; Immunohistochemistry; In Situ Nick-End Labeling; Ischemia; Ischemic Preconditioning; Leupeptins; Membrane Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neurons; Nitriles; Oligonucleotides, Antisense; Phosphorylation; Propidium; Proteasome Endopeptidase Complex; Proto-Oncogene Proteins; Rats; Rats, Sprague-Dawley; Time Factors; Ubiquitin