Activation of protein kinase C delta reduces hepatocellular damage in ischemic preconditioned rat liver.

BACKGROUND: Liver ischemic preconditioning (IPC), pre-exposure of the liver to transient ischemia, has been applied as a useful surgical method to prevent liver ischemia and reperfusion (I/R) injury. Although activation of protein kinase C (PKC), especially novel PKCs, has been known as central signaling responsible for the liver protection of IPC, determination of the involved isozyme in strong protection afforded by IPC has not been elucidated. MATERIALS AND METHODS: Rats were subjected to 90 min of partial liver ischemia followed by 3, 6, and 24 h of reperfusion. IPC was induced by 10 min of ischemia after 10 min of reperfusion before sustained ischemia. Rottlerin, a PKC-δ selective inhibitor; PKC-εV1-2 peptide, a selective PKC-ε inhibitor; and 3,7-dimethyl-1-[2-propargyl] xanthine, an adenosine A2 receptor antagonist, were intravenously injected before IPC. N-acetyl-L-cysteine, a strong antioxidant, and Nω-nitro-L-arginine methyl ester, a nonselective nitric oxide synthase inhibitor, were injected intraperitoneally before IPC. RESULTS: IPC resulted in strong protection against liver I/R injury as evidenced by biochemical and histologic analyses. Inhibition of PKC-δ strongly attenuated the IPC-induced liver protection, whereas PKC-ε inhibition did not exert any effect on IPC-induced protection. Although inhibition of reactive oxygen species, adenosine, and nitric oxide attenuated the beneficial effects of IPC, inhibition of adenosine only attenuated PKC-δ and -ε translocation. CONCLUSIONS: Our findings suggest that IPC protects against I/R-induced hepatic injury through activation of PKC-δ.

Protective effects of hyperoside against carbon tetrachloride-induced liver damage in mice.

In this study, the hepatoprotective effects of hyperoside (1), a flavonoid glycoside isolated from Artemisia capillaris, have been examined against carbon tetrachloride (CCl4)-induced liver injury. Mice were treated intraperitoneally with vehicle or 1 (50, 100, and 200 mg·kg(-1)) 30 min before and 2 h after CCl4 (20 µL·kg(-1)) injection. Levels of serum aminotransferases were increased 24 h after CCl4 injection, and these increases were attenuated by 1. Histological analysis showed that 1 prevented portal inflammation, centrizonal necrosis, and Kupffer cell hyperplasia. Lipid peroxidation was increased and hepatic glutathione content was decreased significantly after CCl4 treatment, and these changes were reduced by administration of 1. Protein and mRNA expression of tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and heme oxygenase-1 (HO-1) and nuclear protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) significantly increased after CCl4 injection. Compound 1 suppressed TNF-α, iNOS, and COX-2 protein and mRNA expression and augmented HO-1 protein and mRNA expression and Nrf2 nuclear protein expression. These results suggest that 1 has protective effects against CCl4-induced acute liver injury, and this protection is likely due to enhancement of the antioxidative defense system and suppression of the inflammatory response.

Robot-assisted gait training effectively improved lateropulsion in subacute stroke patients: a single-blinded randomized controlled trial.

BACKGROUND: Some stroke patients are known to use nonparetic extremities to push toward the paretic side, a movement known as lateropulsion. Lateropulsion impairs postural balance and interferes with rehabilitation. AIM: The aim of the present study was to investigate the effect of robot-assisted gait training (RAGT) on recovery from lateropulsion compared with conventional physical therapy (CPT). DESIGN: This was a single-blinded, randomized controlled trial. SETTING: Participants were recruited from a rehabilitation department of a tertiary hospital. POPULATION: Patients diagnosed with lateropulsion after a stroke. METHODS: Thirty-six subacute stroke patients with lateropulsion were recruited. RAGT was performed in the experimental group (N.=18), and CPT was performed in the control group (N.=18). The participants received treatment for 3 weeks, 30 minutes per day, 5 days per week. Outcomes were assessed before the intervention (T0), immediately after the intervention (T1), and 4 weeks after the intervention (T2). The Burke Lateropulsion Scale (BLS) was evaluated as a primary outcome to assess the severity of lateropulsion. The secondary outcome measures were the Berg Balance Scale (BBS), the Postural Assessment Scale for Stroke (PASS), and Somatosensory Evoked Potentials (SSEP). RESULTS: After intervention, the experimental group showed greater improvement in the BLS score at T1 (experimental group: Δ=-1.9, control group: Δ=-1.1, P=0.032) and T2 (experimental group: Δ=-2.8, control group: Δ=-6.5, P<0.001) than the control group. In addition, the BBS was significantly improved in the experimental group at T1 (experimental group: Δ=+7.1, control group: Δ=+1.9, P<0.001) and T2 (experimental group: Δ=+13.0, control group: Δ=+6.1, P<0.001). There were significant between-group differences in the PASS at T1 (experimental group: Δ=+3.2, control group: Δ=+1.6, P=0.014) and T2 (experimental group: Δ=+8.8, control group: Δ=+4.3, P<0.001). CONCLUSIONS: RAGT ameliorated lateropulsion and balance function more effectively than CPT in subacute stroke patients. CLINICAL REHABILITATION IMPACT: Early RAGT may be recommended for patients with lateropulsion after stroke.

Impaired autophagy contributes to hepatocellular damage during ischemia/reperfusion: heme oxygenase-1 as a possible regulator.

Liver ischemia and reperfusion (I/R) injury is characterized by oxidative stress that is accompanied by alterations of the endogenous defensive system. Emerging evidence suggests a protective role for autophagy induced by multiple stressors including reactive oxygen species. Meanwhile, heme oxygenase-1 (HO-1) has long been implicated in cytoprotection against oxidative stress in vitro and in vivo. Therefore, we investigated the impact of autophagy in the pathogenesis of liver I/R and its molecular mechanisms, particularly its linkage to HO-1. By using transmission electron microscopic analysis and biochemical autophagic flux assays with microtubule-associated protein 1 light chain 3-II, and beclin-1, representative autophagy markers, and p62, a selective substrate for autophagy, we found that reperfusion reduced autophagy both in the rat liver and in primary cultured hepatocytes. When autophagy was further inhibited with chloroquine or wortmannin, I/R-induced hepatocellular injury was aggravated. While livers that underwent I/R showed increased levels of mammalian target of rapamaycin and calpain 1 and 2, inhibition of calpain 1 and 2 induced an autophagic response in hepatocytes subjected to hypoxia/reoxygenation. HO-1 increased autophagy, and HO-1 reduced I/R-induced calcium overload in hepatocytes and prevented calpain 2 activation both in vivo and in vitro. Taken together, these findings suggest that the impaired autophagy during liver I/R, which is mediated by calcium overload and calpain activation, contributes to hepatocellular damage and the HO-1 system protects the liver from I/R injury through enhancing autophagy.

Protective Effect of Flos Lonicerae against Experimental Gastric Ulcers in Rats: Mechanisms of Antioxidant and Anti-Inflammatory Action.

Flos Lonicerae is one of the oldest and most commonly prescribed herbs in Eastern traditional medicine to treat various inflammatory diseases. In the present study, we investigated the effects of ethyl acetate fraction of Flos Lonicerae (GC-7101) on experimental gastric ulcer models and its mechanisms of action in gastric ulcer healing. The pharmacological activity of GC-7101 was investigated in rats on HCl/EtOH, indomethacin, water immersion restraint stress induced acute gastric ulcer, and acetic-acid-induced subchronic gastric ulcer. To determine its gastroprotective mechanisms, gastric wall mucus secretion, mucosal PGE2, mucosal NO content, nuclear translocation of NF-κB, mRNA expression of inflammatory cytokines, lipid peroxidation and glutathione content, and superoxide dismutase and catalase activities were measured. GC-7101 significantly attenuated development of acute gastric ulcer and accelerated the healing of acetic-acid-induced subchronic gastric ulcer. In HCl/EtOH-induced gastric ulcer, GC-7101 markedly enhanced gastric wall mucus content which was accompanied by increased mucosal PGE2 and NO production. Furthermore, treatment of GC-7101 exhibited anti-inflammatory and antioxidant activities as evidenced by decreased myeloperoxidase activity, NF-κB translocation, inflammatory cytokines mRNA expression, and lipid peroxidation and increased glutathione content and superoxide dismutase and catalase activities. These results demonstrated that GC-7101 possesses strong antiulcerogenic effect by modulating oxidative stress and proinflammatory mediators.

Protective effects of chlorogenic acid against ischemia/reperfusion injury in rat liver: molecular evidence of its antioxidant and anti-inflammatory properties.

Hepatic ischemia and reperfusion injury (I/R) is accompanied by excessive reactive oxygen species and resultant sterile inflammation. Chlorogenic acid (CGA), one of the most abundant polyphenols in the human diet, has been shown to exert potent anti-inflammatory, antibacterial and antioxidant activities. Thus, the purpose of the present study was to investigate protective effects of CGA and its molecular mechanisms against hepatic I/R injury. Rats were subjected to 60 min of partial hepatic ischemia followed by 5 h of reperfusion. CGA (2.5, 5 and 10 mg/kg, ip) was administered twice: 10 min prior to ischemia and 10 min before reperfusion. CGA treatment resulted in marked improvement of hepatic function and histology, and suppressed oxidative stress, as indicated by hepatic lipid peroxidation and glutathione level. Levels of serum tumor necrosis factor-α, inducible nitric oxide synthase and cyclooxygenase-2 protein and mRNA expressions were up-regulated after I/R; these effects were attenuated by CGA. Immunoblot results showed that CGA reduced I/R-induced toll-like receptor 4 overexpression, nuclear translocation of nuclear factor kappa B and interferon regulatory factor-1, high-mobility group box-1 release into extracellular milieu, and enhanced heme oxygenase-1 expression and nuclear translocation of nuclear factor erythroid 2-related factor 2. Our results suggest that CGA alleviates I/R-induced liver injury and that this protection is likely due to inhibition of inflammatory response and enhancement of antioxidant defense systems. Therefore, CGA might have potential as an agent for use in clinical treatment of hepatic I/R injury.

Differential consequences of protein kinase C activation during early and late hepatic ischemic preconditioning.

Activation of protein kinase C (PKC) has been implicated in the protection of ischemic preconditioning (IPC), but the exact role of PKC in early and late hepatic IPC is still unclear. The present study was conducted in order to investigate the differential role of PKC during early and late hepatic IPC. Rats were subjected to 90 min of partial hepatic ischemia followed by 3 (early IPC) and 24 h (late IPC) of reperfusion. IPC was induced by 10 min of ischemia following 10 min of reperfusion prior to sustained ischemia, and chelerythrine, a PKC inhibitor, was injected 10 min before IPC (5 mg/kg, i.v.). Chelerythrine abrogated the protection of early IPC, as indicated by increased serum aminotransferase activities and decreased hepatic glutathione content. While the IPC-treated group showed a few apoptotic cell deaths during both phases, chelerythrine attenuated these changes only at late IPC and limited IPC-induced inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) overexpression. Membrane translocation of PKC-δ and -ε during IPC was blocked by chelerythrine. Our results suggest that PKC might play a differential role in early and late IPC; activation of PKC-δ and -ε prevents necrosis in early IPC through preservation of redox state and prevents apoptosis in late IPC with iNOS and HO-1 induction. Therefore, PKC represents a promising target for hepatocyte tolerance to ischemic injury, and understanding the differential role of PKC in early and late IPC is important for clinical application of IPC.

Protective role of heme oxygenase-1 against liver damage caused by hepatic ischemia and reperfusion in rats.

This study investigated the time course of heme oxygenase (HO)-1 expression and the role of endogenous HO-1 in hepatic ischemia and reperfusion (I/R). Rats were pretreated with hemin, an HO-1 inducer, and zinc protoporphyrin (ZnPP), an HO-1 inhibitor. Hepatic HO activity increased at 1 h after reperfusion, reaching a maximum at 6 h after reperfusion and then declined. HO-1 mRNA and protein expression in I/R liver were upregulated prior to reperfusion and highly induced again by reperfusion. The ALT level was upregulated at all time points, with a peak at 4-6 h. This increase was augmented by ZnPP but attenuated by hemin. Lipid peroxidation and serum HMGB1 release significantly increased at 1 h after reperfusion and remained elevated throughout the 24 h of reperfusion period, whereas the glutathione content decreased markedly at 4-6 h after reperfusion. These changes were attenuated by hemin but augmented by ZnPP. The levels of serum TNF-α, iNOS, and COX-2 protein and mRNA expressions were upregulated after reperfusion, further enhanced by ZnPP, and suppressed by hemin. HO-1 overexpression protects the liver against I/R injury by modulating oxidative stress and proinflammatory mediators.

Protective effect of Aloe vera on polymicrobial sepsis in mice.

Sepsis is an acute life-threatening clinical condition and remains the major cause of death in intensive care units. The primary pathophysiologic event central to the septic response is an overwhelming activation of the inflammatory system and countervailing response from the anti-inflammatory system. However, the cause of this perturbation has yet to be elucidated. In this study, we report that Aloe vera therapeutically reverses the lethality induced by cecal ligation and puncture (CLP), a clinically relevant model of sepsis. The administration of Aloe vera ameliorated the multiple organ dysfunction syndrome, as evidenced by the serum levels of biochemical parameters and histological changes. In order to investigate the pharmacological mechanism of Aloe vera, the levels of the cytokines, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were determined by ELISA at various time points. The increases in the levels of TNF-alpha, IL-1beta, and IL-6 were attenuated by Aloe vera.In vivo administration of Aloe vera also markedly enhanced bacterial clearance. Our findings suggest that Aloe vera could be a potential therapeutic agent for the clinical treatment of sepsis.

Protective effect of a mixture of Aloe vera and Silybum marianum against carbon tetrachloride-induced acute hepatotoxicity and liver fibrosis.

The hepatoprotective effects of ACTIValoe N-931 complex, a mixture of Aloe vera and Silybum marianum, against acute and chronic carbon tetrachloride (CCl(4))-induced liver injuries were investigated. Acute hepatotoxicity was induced by intraperitoneal injection of CCl(4) (50 microl/kg), and ACTIValoe N-931 complex at 85, 170, and 340 mg/kg was administered orally 48, 24, and 2 h before and 6 h after injection of CCl(4). Hepatotoxicity was assessed 24 h after CCl(4) treatment. Liver fibrosis was induced by intraperitoneal injection of CCl(4) for 8 weeks (0.5 ml/kg, twice per week), and mice were treated with ACTIValoe N-931 complex at 85, 170, or 340 mg/kg once a day (p.o.). In both acute hepatotoxicity and liver fibrosis, serum aminotransferase levels and lipid peroxidation were increased and the hepatic glutathione content was decreased. These changes were prevented by ACTIValoe N-931 complex. The ACTIValoe N-931 complex attenuated the increase in tumor necrosis factor-alpha (TNF-alpha), and inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), mRNA expressions in acute hepatotoxicity. In antifibrotic experiments, tissue inhibitor of metalloprotease-1 (TIMP-1) mRNA expression was attenuated by treatment with ACTIValoe N-931 complex. The ACTIValoe N-931 complex decreased the hepatic hydroxyproline content and the transforming growth factor-beta1 levels. Our results suggest that the ACTIValoe N-931 complex has hepatoprotective effects in both acute and chronic liver injuries induced by CCl(4).