Protective effects of adenosine on the diabetic myocardium against ischemia–reperfusion injury: Role of calpain

Myocardial ischemia/reperfusion injury (I/RI) is the principal cause of mortality and morbidity in diabetic patients undergoing cardiac surgery. However, there is no specific measure available to protect diabetic hearts in this clinical setting. Our clinical studies showed that adenosine pre-treatment or post-treatment and adding adenosine to cardioplegia solution had significant myocardial protective effects in patients undergoing cardiac surgery. However, the specific protective effects and mechanisms of adenosine in diabetic myocardial I/RI are not clear. Calpain is an important proteolytic enzyme in the myocardium. Studies show that the activation of calpain is an injury factor in not only the diabetic myocardium but also myocardial I/RI progression. We therefore hypothesize that adenosine play a protective role in diabetic myocardial I/RI through the inhibition of calpain.     

Emulsified isoflurane postconditioning produces cardioprotection against myocardial ischemia–reperfusion injury in rats

Emulsified isoflurane (EIso) preconditioning can induce cardioprotection. We investigated whether EIso application after ischemia protects hearts against reperfusion injury and whether it is mediated by the inhibition of apoptosis. Rats were subjected to 30-min coronary occlusion followed by 180-min reperfusion. At the onset of reperfusion, rats were intravenously administered saline (sham, control group), 30 % intralipid (IL group) or 2 ml kg^?1 EIso (EIso group) for 30 min. After reperfusion, infarct sizes, myocardial apoptosis and expression of Bcl-2, Bax and caspase-3 proteins were determined. Hemodynamic parameters were not different among groups. Compared with control and intralipid group, EIso limited infarct size, inhibited apoptosis, increased the expression of Bcl-2, decreased the expression of Bax, cleaved caspase-3, and enhanced Bcl-2/Bax ratio. EIso protects hearts against reperfusion injury when administered at the onset of reperfusion, which may be mediated by the inhibition of apoptosis via modulation of the expression of pro- and anti-apoptotic proteins.     

Comparison of cardioprotective and anti-inflammatory effects of ischemia pre- and postconditioning in rats with myocardial ischemia–reperfusion injury

Objective  

To compare cardioprotective and anti-inflammatory effects of ischemia preconditioning (IPC) and ischemia postconditioning (IPOC) in a rat myocardial ischemia–reperfusion injury (IRI) model.     

Activation of big conductance Ca2+-activated K+ channels (BK) protects the heart against ischemia–reperfusion injury

Activation of the large-conductance Ca²⁺-activated K⁺ channel (BK) in the cardiac inner mitochondrial membrane has been suggested to protect the heart against ischemic injury. However, these findings are limited by the low selectivity profile and potency of the BK channel activator (NS1619) used. In the present study, we address the cardioprotective role of BK channels using a novel, potent, selective, and chemically unrelated BK channel activator, NS11021. Using electrophysiological recordings of heterologously expressed channels, NS11021 was found to activate BK α + β1 channel complexes, while producing no effect on cardiac K_ATP channels. The cardioprotective effects of NS11021-induced BK channel activation were studied in isolated, perfused rat hearts subjected to 35 min of global ischemia followed by 120 min of reperfusion. 3 μM NS11021 applied prior to ischemia or at the onset of reperfusion significantly reduced the infarct size [control: 44.6 ± 2.0%; NS11021: 11.4 ± 2.0%; NS11021 at reperfusion: 19.8 ± 3.3% (p < 0.001 for both treatments compared to control)] and promoted recovery of myocardial performance. Co-administration of the BK-channel inhibitor paxilline (3 μM) antagonized the protective effect. These findings suggest that tissue damage induced by ischemia and reperfusion can be reduced by activation of cardiac BK channels.     

Anandamide enhances expression of heat shock protein 72 to protect against ischemia–reperfusion injury in rat heart

Anandamide (AEA), one of endocannabinoids, has been reported to exhibit a cardioprotective ability to limit the damage produced by ischemia–reperfusion injury. AEA reportedly enhanced heat shock protein 72 (HSP72) and HSP25 expression in lungs to protect against lung inflammation. This study tested the hypothesis that intravenously injected AEA would induce HSP72 in the heart and thus render cardioprotection against ischemia–reperfusion injury in rats. Cardiac expression of HSPs was quantitatively evaluated in rats by Western blot analysis. That intravenously injected AEA 1 mg/kg in vivo induced expression of HSP72, which peaked at 24 h after administration. The enhancement of HSP72 by AEA was blocked by cannabinoid 2 (CB₂) receptor antagonist AM630, but not cannabinoid 1 (CB₁) receptor antagonist AM251. Therefore, the rats were induced with a 30-min coronary occlusion followed by a 120-min reperfusion in vivo at 24 h after administration of drugs or vehicle, and then the infarct size was measured. AEA reduced myocardial infarct size compared to control group. Pretreatment with AM630 but not AM251 abolished the infarct size-limiting effect of AEA. Further study demonstrated pretreatment with phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin, Akt inhibitor MK-2206 and AM630 attenuated phosphorylation of Akt and AEA-induced HSP72 expression. The results suggest that AEA is cardioprotective against ischemia–reperfusion insult through its induction of HSP72, which might be mediated by the PI3K/Akt signaling pathway. These effects were mediated by CB₂ but not CB₁ receptors.     

Nerve growth factor protects retinal ganglion cells against injury induced by retinal ischemia–reperfusion in rats

Abstract

In this study, we investigated the protective effect of mouse nerve growth factor (NGF) on retinal ganglion cell (RGC) injury induced by retinal ischemia–reperfusion (RIR) in rats and explored its possible mechanisms of action. RIR caused a significant injury to RGCs and an obvious impairment of the inner retina functions, which could be seen from flash electroretinogram and flash visual evoked potential recordings. RIR also increased the expression of the apoptotic protein Bax while decreasing the expression of Bcl-2 and the phosphorylation of protein kinase B (Akt) in RGCs. Preinjection (i.m.) of NGF for 22 d reversed the injury induced by RIR and ameliorated the inner retina functions. NGF also reduced the expression of Bax and reversed the reduction of Bcl-2 and the phosphorylated Akt induced by RIR. These results indicate that NGF produces a neuroprotective effect on RGCs against RIR injury and the protective effect of NGF is mainly mediated by the PI-3K/Akt signaling pathway.     

The effect of erythropoietin on endometrial edema during ischemia–reperfusion injury in rats

This experimental study examined the effect of erythropoietin (Epo) in a rat model and particularly in an ischemia–reperfusion protocol. The potential beneficial effect of Epo was studied pathologically using endometrial edema (EE) lesions. Endometrial edema was evaluated 60 min after reperfusion (Groups A and C) and 120 min after reperfusion (Groups B and D) in rats. Epo was administered only in Groups C and D. Epo administration non-significantly increased the EE scores by 0.05 (p = 0.9315). Reperfusion non-significantly increased the EE scores by 0.15 (p = 0.6508). Epo administration and reperfusion together non-significantly increased the EE scores by 0.027 (p = 0.8898). Epo administration, reperfusion, and their interaction reduced the EE scores from significant to non-significant levels. Perhaps a study time longer than 2 h or a higher Epo dose could result in complete resolution of the endometrial edema formed as a result of the ischemia–reperfusion injury in this rat model.     

Hydrogen rich water protects against myocardial ischemia/reperfusion injury in rats北大核心

BACKGROUND: Increasing evidence has indicated that low-concentration hydrogen or hydrogen rich water or hydrogen saturated saline exerts a protective effect on various diseases, such as myocardial ischemia/reperfusion injury. OBJECTIVE: To explore the protective effect of hydrogen rich water on myocardial ischemia/reperfusion injury. METHODS: Forty-eight Wistar rats were equally randomized into control and hydrogen-rich groups, and then subdivided into ischemic preconditioning, ischemia, and ischemia/reperfusion groups (n=8 rats in each subgroup). The myocardial ischemia/reperfusion model was established in the heart of each rat by the following procedures: reverse perfusion for 10 minutes, room temperature for 20 minutes, and reperfusion for 20 minutes. The control rats was perfused with pre-oxygenated (95% O2 plus 5% CO2) 37 ℃ K-R solution and the hydrogen-rich group was perfused with pre-oxygen-equilibrated (95% O2 plus 5% CO2) 37 ℃ K-R solution plus hydrogen-rich water (0.6 mmol/L, pH=7.3). Subsequently, the heart was removed, the pathological changes of the myocardial tissues were observe by hematoxylin-eosin staining, the activities of lactic dehydrogenase and creatine kinase in the myocardial tissues were determined, and the levels of tumor necrosis factor-α and interleukin-1β were detected by ELISA. RESULTS AND CONCLUSION: In the control group, the activity of lactic dehydrogenase at the ischemic and ischemia/reperfusion stages was significantly higher than that at the ischemic preconditioning stage (P < 0.05), and the activity of creatine kinase at the ischemia/reperfusion stage was significantly higher than that at the ischemic preconditioning and ischemic stages (P < 0.05). In the hydrogen-rich group, there was no significant difference in the activities of lactic dehydrodenase and creatine kinase at each stage, but the activities of at the ischemia/reperfusion stage was significantly lower than those in the control group (P < 0.05). In the two groups, the order of the levels of tumor necrosis factor-α and interleukin-1β was as follows: the ischemia/reperfusion stage > ischemic stage > ischemic preconditioning stage (P < 0.05). The levels of above factors in the hydrogen-rich group were significantly lower than those in the control group (P < 0.05). Our findings imply that hydrogen rich water has protective effect on myocardial ischemia/reperfusion injury of the rat hearts in vitro, which may be by reducing the expression of tumor necrosis factor-α and interleukin-1β, and further alleviating the inflammatory response. © 2018, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Protective effects of N-acetylcysteine on myocardial injury induced by hindlimb ischaemia–reperfusion: a histological study in a rat model

This study evaluated the effects of N-acetylcysteine as a scavenger of radical oxygen species on myocardial injury as a remote organ after skeletal muscle ischaemia–reperfusion. Twenty male Wistar rats were allocated randomly into two experimental groups: ischaemia–reperfusion and ischaemia–reperfusion?+?N-acetylcysteine. All animals underwent 2 h of ischaemia by occlusion of the femoral artery followed by 24 h of reperfusion. Rats treated with N-acetylcysteine were given an intravenous dose of 150 mg/kg, immediately before reperfusion. After the reperfusion period, animals were euthanized and hearts harvested for histopathological analysis under light microscopy. In the ischaemia–reperfusion group, tissues showed histological changes with interstitial oedema, neutrophil infiltration and adhesion of neutrophils to the endothelium, haemorrhage and coagulative necrosis. Histopathologically, there was a significant difference (P?N-acetylcysteine significantly decreased myocardial injury induced by skeletal muscle ischaemia–reperfusion according to our histological findings.     

Hyperbaric oxygen preconditioning reduces ischemia–reperfusion injury by inhibition of apoptosis via mitochondrial pathway in rat brain

This study examined the hypothesis that apoptotic inhibition via mitochondrial pathway was involved in hyperbaric oxygen preconditioning (HBO-PC)–induced neuroprotection on ischemia–reperfusion injury in rat brain. Male Sprague–Dawley rats (250∼280 g, n=144) were divided into control, middle cerebral artery occlusion (MCAO) for 90 min, and HBO-PC plus MCAO groups. HBO-PC was conducted four times by giving 100% oxygen at 2.5 atm absolute (ATA), for 1 h at 12 h intervals for 2 days. At 24 h after the last HBO-PC, MCAO was performed and at 24 h after MCAO, neurological function, brain water content, infarct volume, and cell death were evaluated. Enzymatic activity of capase-3 and −9, and expression of cytochrome c, Bcl-2 and Bax proteins were performed in the samples from hippocampus, ischemic penumbra and core of the brain cortex, respectively. HBO-PC reduced brain edema, decreased infarction volume, and improved neurological recovery. HBO-PC reduced cytoplasm cytochrome c levels, decreased caspase enzyme activity, upregulated the ratio of Bcl-2 and Bax expression, and abated the apoptosis of ischemic tissue. HBO-PC protects brain tissues from ischemia–reperfusion injury by suppressing mitochondrial apoptotic pathways.     

Higenamine regulates Nrf2-HO-1-Hmgb1 axis and attenuates intestinal ischemia–reperfusion injury in mice

Inflammation Research - Intestinal ischemia and reperfusion (IR) syndrome is a life-threatening dilemma caused by diverse events. Higenamine (HG), an active ingredient of Aconiti Lateralis Radix...     

Xanthohumol suppresses inflammatory response to warm ischemia–reperfusion induced liver injury

Liver ischemia/reperfusion (I/R) leads to formation of reactive oxygen species (ROS), which cause hepatic injury and initiate an inflammatory response, which is a critical problem after liver surgery and transplantation. Xanthohumol, the major prenylated chalcone found in hops, has been discussed for its anti-inflammatory and ROS-scavenging properties, and thus, we aimed to investigate the effect of xanthohumol in a model of warm I/R liver injury. Xanthohumol was applied to BALB/c mice orally at a dose of 1 mg/g body weight for 5 days before I/R-injury was induced by clamping the vascular blood supply to the median and left lateral liver lobe for 1 h followed by a 6 h period of reperfusion. At this time, HPLC analysis revealed hepatic xanthohumol levels of approximately 2 μM, a concentration which has been shown to inhibit inflammatory effects in vitro. Assessment of hepatic HMOX1 expression, hepatic glutathione content and immunohistochemical analysis for proteins conjugated with the reactive aldehyde 4-hydroxynonenal indicated that I/R-induced oxidative stress was significantly inhibited in xanthohumol-fed compared to control mice. Histological analysis, TUNEL staining and determination of transaminase serum levels revealed no significant effects of xanthohumol on acute hepatocellular injury. However, at the same time point, pretreatment with xanthohumol almost completely blunted the I/R-induced AKT and NFκB activation and the expression of the proinflammatory genes IL-1alpha, IL-6, MCP-1 and ICAM-1, which are known to play a crucial role in the subacute phase of I/R-induced liver damage. In conclusion, these data indicate the potential of xanthohumol application to prevent adverse inflammatory responses to I/R-induced liver damage such as after surgical liver resection or transplantation.     

Protective effects of hyperbaric oxygen treatment against spinal cord injury in rats via toll-like receptor 2/nuclear factor-κB signaling

Spinal cord injury (SCI) is a serious medical problem with high mortality and disability rates. Hyperbaric oxygen (HBO) treatment is beneficial for neurological recovery after SCI, but the underlying mechanisms await characterization. This study examined whether HBO treatment following SCI in rats exerts a neuroprotective effect through activation of the toll-like receptor (TLR) 2/nuclear factor (NF)-κB signaling pathway. The SC of rats was injured via T10 laminectomy. Experimental animals (n = 144) were divided into four groups: sham-operated (SH), SH + HBO, SCI, and SCI + HBO. Each group was subdivided into six subgroups (n = 6 per group) that were examined at 12 h, and 1, 2, 3, 7, and 14 days post-injury. Functional recovery in the hind limb was evaluated using the Basso, Beattie, and Bresnahan (BBB) scoring system. The expression of TLR2 and NF-кB was assessed by real-time polymerase chain reaction and Western blotting, while interleukin-1 (IL)-1β and tumor necrosis factor (TNF)-α levels were measured by enzyme-linked immunosorbent assay. TLR2 and NF-кB levels and histological scores were higher in the SCI than in the SH and SH + HBO groups at various time points. HBO treatment decreased TLR2 and NF-кB expression and histological scores as well as IL-1β and TNF-α levels compared to the SCI group at early post-injury stages. In addition, BBB scores were improved in the SCI + HBO relative to the SCI group at 7 and 14 days. HBO treatment may mitigate secondary injury to the SC by inhibiting inflammatory responses induced by TLR2/NF-кB signaling, thereby promoting functional recovery and improving neurological outcome.     

Sevoflurane pretreatment enhance HIF-2α expression in mice after renal ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury often occurs, which is one of the major causes of acute kidney injury, thus increasing in-hospital mortality. HIF-2α has a protective role against ischemia of the kidney. Renal ischemia/reperfusion under sevoflurane anesthesia resulted in drastic improvements in renal function. We hypothesized that underlying mechanism responsible for renal protection from sevoflurane pretreatment involves the upregulation of HIF-2α. Sevoflurane pretreatment were performed on WT and HIF-2α knockout mice before renal ischemia/reperfusion. Levels of blood urea nitrogen (BUN) and serum creatinine (Cr) were determined with a standard clinical automatic analyzer. The left kidneys were taken for morphological examination. Expression of HIF-2α in kidney tissue was examined by western blotting. In WT mice, group I/R injury had significantly higher BUN and Cr levels than group control, whereas group I/R + Sev had significantly lower BUN and Cr levels than group I/R injury. Renal HIF-2α expression levels were significantly higher in WT mice of group I/R + Sev than group control and group I/R. In HIF-2α^-/- mice, group I/R + Sev showed much higher BUN and Cr levels and severer histological damage than group I/R and group control. Renal HIF-2α expression levels were significantly higher in WT mice of group I/R + Sev than group control and group I/R. Our findings suggested that HIF-2α might contribute to the beneficial effect of sevoflurane in renal ischemia/reperfusion injury.     

Quercetin ameliorates peripheral nerve ischemia–reperfusion injury through the NF-kappa B pathway

This study aimed to investigate the protective effect of quercetin against ischemia–reperfusion (IR) injury induced in the sciatic nerve of the rat. Quercetin (20 mg/kg) was given during ischemia just before reperfusion. Four groups of rats (Q+IR3, Q+IR7, Q+IR14, and Q+IR28) received 3, 7, 14, and 28 days of reperfusion, respectively, after the intraperitoneal injection of quercetin. After reperfusion, a behavioral test was performed and the sciatic functional index was calculated. Each sciatic nerve was stained to check for edema and ischemic fiber degeneration. Immunohistochemical staining was performed to detect TNF-alpha and NF-kappa B, and TUNEL staining was carried out to detect apoptosis. The Q+IR3, Q+IR7, and Q+IR14 groups showed significantly increased behavioral scores and ameliorated sciatic functional index values compared to IR-injured rats that received vehicle alone during ischemia and then the same period of reperfusion. The Q+IR3, Q+IR7, Q+IR14, and Q+IR28 groups presented significant ischemic fiber degeneration (IFD), TNF-alpha expression, and apoptosis as compared with the IR-injured and perfused rats that did not receive quercetin. The Q+IR3, Q+IR7, and Q+IR28 groups also exhibited significantly decreased NF-kappa B expression (p < 0.001, p = 0.001, p = 0.026) as compared with the IR-injured rats that were perfused but did not receive quercetin. These results imply that quercetin may be beneficial in the treatment of sciatic IR injury because of its antiapoptotic and antiinflammatory effects and its ability to decrease the expression of NF-kappa B.     

The opposite roles of nNOS in cardiac ischemia–reperfusion-induced injury and in ischemia preconditioning-induced cardioprotection in mice

The role of neuronal nitric oxide synthase (nNOS) in cardiac ischemia–reperfusion (IR) and ischemia preconditioning (IP) is still controversial. Here, we focused on the possible roles of nNOS in cardiac IR and IP. Wild type C57BL/6 (WT) mice were subjected to coronary artery occlusion for 30 min followed by 24-h reperfusion (IR). Cardiac injury (infarct size and apoptotic cell number) was increased, associated with elevation of oxidative stress (lipid peroxidation) and nitrative stress (nitrotyrosine formation). A potent nNOS inhibitor, L-VNIO, and a superoxide dismutase mimetic and peroxynitrite scavenger, MnTBAP, significantly reduced IR-induced increases of oxidative/nitrative stress and cardiac injury. IR-induced cardiac injury in nNOS^−/− (KO) mice was significantly lower than that in WT mice. MnTBAP markedly reduced IR-induced cardiac injury by suppression of oxidative/nitrative stress in KO mice. Cardiac IP was performed by three cycles of 5-min IR before 30-min ischemia followed by 24-h reperfusion. IP attenuated IR-induced cardiac injury in WT mice associated with reductions of oxidative/nitrative stress. IP-induced reduction of cardiac injury and oxidative/nitrative stress were eliminated by pretreatment with L-VNIO. In contrast with WT mice, IP had no protective effects in nNOS KO mice. In conclusion, nNOS played a dual role during cardiac IR and IP; nNOS exacerbated IR-induced injury by increasing oxidative/nitrative stress and contributed to IP-induced protection by inhibition of oxidative/nitrative stress.