Lichao Hou

Preconditioning with isoflurane produces dose-dependent neuroprotection via activation of adenosine triphosphate-regulated potassium channels after focal cerebral ischemia in rats.

In this study, we determined whether repeated brief isoflurane (Iso) anesthesia induces ischemic tolerance to focal cerebral ischemia in a dose-response manner and whether the effect is dependent on adenosine triphosphate-regulated potassium channels. In Experiment 1, 40 rats were randomly assigned to 4 groups: control animals received 100% oxygen 1 h/d for 5 days, whereas the isoflurane (Iso)1, Iso2, and Iso3 groups received 0.75%, 1.5%, or 2.25% Iso in oxygen 1 h/d for 5 days. In Experiment 2, 36 rats were randomly assigned to 4 groups: controls received 100% oxygen 1 h/d for 5 days; animals in the Iso and I+G (Iso+glibenclamide) groups received 2% Iso in oxygen 1 h/d for 5 days, and the I+G group received glibenclamide (GLB) (5 mg/kg intraperitoneally) before each Iso pretreatment. Animals in the GLB group received GLB (5 mg/kg intraperitoneally) once a day for 5 days. Twenty-four hours after the last pretreatment, the right middle cerebral artery was occluded for 120 min. Neurologic deficit scores (NDS) and brain infarct volumes were evaluated at 24 h. The NDS and infarct volumes of Iso2 and Iso3 were less than those of the controls (P < 0.05). The infarct volume in Iso3 was smaller than in Iso2 (P < 0.05). The NDS and infarct volume in the Iso group were less than in the control and I+G groups (P < 0.05). There was no statistical difference among the control, I+G, and GLB groups. The study demonstrated that repeated Iso anesthesia induces ischemic tolerance in rats in a dose-response manner. GLB, an adenosine triphosphate-regulated potassium channel blocker, abolished the tolerance induced by Iso.

Preconditioning with hyperbaric oxygen and hyperoxia induces tolerance against spinal cord ischemia in rabbits.

Background The aim of this study was to determine if the ischemic tolerance could be induced in the spinal cord by pretreatment with hyperbaric oxygen (HBO) and what components of HBO (hyperoxia, hyperbaricity, and combination of these two) were critical in the induction of tolerance against ischemic injury. Methods In experiment 1, 21 rabbits were randomly assigned to one of three groups (n = 7 each): animals in the control group received no HBO before spinal cord ischemia; animals in the HBO-1 and HBO-2 groups received HBO (2.5 atmosphere absolute [ATA], 100% O2) pretreatment 1 h/day for 3 and 5 days before ischemia, respectively. In experiment 2, 48 rabbits were randomly assigned to one of four groups (n = 12 each): the control group received no HBO (21% O2, 1 ATA, 1 h/day, 5 days) before spinal cord ischemia; the HB group received 1-h treatment in 21% O2 at 2.5 ATA each day for 5 days; the HO group received 1-h treatment in 100% oxygen at 1 ATA each day for 5 days; and the HBO group received HBO (2.5 ATA, 100% O2) treatment 1 h/day for 5 days. Twenty-four hours after the last treatment, spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min. Forty-eight hours after reperfusion, hind-limb motor function and histopathology of the spinal cord were examined in a blinded fashion. Results In experiment 1, the neurologic outcome in the HBO-2 group was better than that of the control group (P = 0.004). The number of normal neurons in the anterior spinal cord in the HBO-2 group was more than that of the control group (P = 0.021). In experiment 2, the neurologic and histopathologic outcomes in the HBO group were better than that of the control group (P < 0.01). The histopathologic outcome in the HO group was better than that in the control group (P < 0.05). Conclusions Serial exposure to high oxygen tension induced ischemic tolerance in spinal cord of rabbits. Simple hyperbaricity (2.5 ATA, 21% O2) did not induce ischemic tolerance.

PROTECTIVE EFFECTS OF HYDROGEN GAS ON MURINE POLYMICROBIAL SEPSIS VIA REDUCING OXIDATIVE STRESS AND HMGB1 RELEASE

Despite recent advances in antibiotic therapy and intensive care, sepsis is still considered to be the most common cause of death in intensive care units. Excessive production of reactive oxygen species plays an important role in the pathogenesis of sepsis. Recently, it has been suggested that molecular hydrogen (H2) exerts a therapeutic antioxidant activity by selectively reducing hydroxyl radicals (•OH, the most cytotoxic reactive oxygen species) and effectively protects against organ damage induced by I/R. Therefore, we hypothesized that H2 treatment had a beneficial effect on sepsis. In the present study, we found that H2 inhalation starting at 1 and 6 h after cecal ligation and puncture (CLP) or sham operation significantly improved the survival rate of septic mice with moderate or severe CLP in a concentration- and time-dependent manner. Furthermore, moderate or severe CLP mice showed significant multiple organ damage characterized by the increases of lung myeloperoxidase activity, wet-to-dry weight ratio, protein concentration in bronchoalveolar lavage, serum biochemical parameters, and organ histopathologic scores at 24 h after CLP operation, which was significantly attenuated by 2% H2 treatment. In addition, we found that the beneficial effects of H2 treatment on sepsis and sepsis-associated organ damage were associated with the decreased levels of oxidative product, increased activities of antioxidant enzymes, and reduced levels of high-mobility group box 1 in serum and tissue. Thus, H2 inhalation may be an effective therapeutic strategy for patients with sepsis.ABBREVIATIONS-ALI-acute lung injury; ALT-alanine aminotransferase; AST-aspartate aminotransferase; BAL-bronchoalveolar lavage; BUN-blood urea nitrogen; CAT-catalase; CLP-cecal ligation and puncture; Cr-creatinine; H2-hydrogen; H2O2-hydrogen peroxide; HMGB1-high-mobility group box 1; 8-iso-PGF2&agr;-8-iso-prostaglandin F2&agr;; MPO-myeloperoxidase; •OH-hydroxyl radicals; ROS-reactive oxygen species; SOD-superoxide dismutase; W/D-wet-to-dry

Molecular hydrogen ameliorates lipopolysaccharide-induced acute lung injury in mice through reducing inflammation and apoptosis.

Acute lung injury (ALI) is still a leading cause of morbidity and mortality in critically ill patients. Recently, our and other studies have found that hydrogen gas (H2) treatment can ameliorate the lung injury induced by sepsis, ventilator, hyperoxia, and ischemia-reperfusion. However, the molecular mechanisms by which H2 ameliorates lung injury remain unclear. In the current study, we investigated whether H2 or hydrogen-rich saline (HS) could exert protective effects in a mouse model of ALI induced by intratracheal administration of lipopolysaccharide (LPS) via inhibiting the nuclear factor &kgr;B (NF-&kgr;B) signaling pathway–mediated inflammation and apoptosis. Two percent of H2 was inhaled for 1 h beginning at 1 and 6 h after LPS administration, respectively. We found that LPS-challenged mice exhibited significant lung injury characterized by the deterioration of histopathology and histologic scores, wet-to-dry weight ratio, and oxygenation index (PaO2/FIO2), as well as total protein in the bronchoalveolar lavage fluid (BALF), which was attenuated by H2 treatment. Hydrogen gas treatment inhibited LPS-induced pulmonary early and late NF-&kgr;B activation. Moreover, H2 treatment dramatically prevented the LPS-induced pulmonary cell apoptosis in LPS-challenged mice, as reflected by the decrease in TUNEL (deoxynucleotidyl transferase dUTP nick end labeling) staining–positive cells and caspase 3 activity. Furthermore, H2 treatment markedly attenuated LPS-induced lung neutrophil recruitment and inflammation, as evidenced by downregulation of lung myeloperoxidase activity, total cells, and polymorphonuclear neutrophils in BALF, as well as proinflammatory cytokines (tumor necrosis factor &agr;, interleukin 1&bgr;, interleukin 6, and high-mobility group box 1) and chemokines (keratinocyte-derived chemokine, macrophage inflammatory protein [MIP] 1&agr;, MIP-2, and monocyte chemoattractant protein 1) in BALF. In addition, i.p. injection of 10 mL/kg hydrogen-rich saline also significantly attenuated the LPS-induced ALI. Collectively, these results demonstrate that molecular hydrogen treatment ameliorates LPS-induced ALI through reducing lung inflammation and apoptosis, which may be associated with the decreased NF-&kgr;B activity. Hydrogen gas may be useful as a novel therapy to treat ALI. ABBREVIATIONS ALI—acute lung injury; ARDS—acute respiratory distress syndrome; BALF—bronchoalveolar lavage fluid; ELISA—enzyme-linked immunosorbent assay; H2—hydrogen gas; HMGB1—high-mobility group box 1; HS—hydrogen-rich saline; i.t.—intratracheal; KC—keratinocyte-derived chemokine; LPS—lipopolysaccharide; MCP-1—monocyte chemoattractant protein 1; MIP-1&agr;—macrophage inflammatory protein 1&agr;; MIP-2—macrophage inflammatory protein 2; MPO—myeloperoxidase; PBS—phosphate-buffered saline; PMNs—polymorphonuclear neutrophils; TUNEL—deoxynucleotidyl transferase dUTP nick end labeling; W/D—wet-to-dry

HYDROGEN GAS IMPROVES SURVIVAL RATE AND ORGAN DAMAGE IN ZYMOSAN-INDUCED GENERALIZED INFLAMMATION MODEL

Sepsis/multiple organ dysfunction syndrome is the leading cause of death in critically ill patients. Recently, it has been suggested that hydrogen gas (H2) exerts a therapeutic antioxidant activity by selectively reducing hydroxyl radical (•OH, the most cytotoxic reactive oxygen species). We have found that H2 inhalation significantly improved the survival rate and organ damage of septic mice with moderate or severe cecal ligation and puncture. In the present study, we investigated the effects of 2% H2 treatment on survival rate and organ damage in zymosan (ZY)-induced generalized inflammation model. Here, we found that 2% H2 inhalation for 60 min starting at 1 and 6 h after ZY injection, respectively, significantly improved the 14-day survival rate of ZY-challenged mice from 10% to 70%. Furthermore, ZY-challenged mice showed significant multiple organ damage characterized by the increase in serum biochemical parameters (aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and creatinine), as well as lung, liver, and kidney histopathological scores at 24 h after ZY injection, which was significantly attenuated by 2% H2 treatment. In addition, we found that the beneficial effects of H2 treatment on ZY-induced organ damage were associated with the decreased levels of oxidative product, increased activities of antioxidant enzyme, and reduced levels of early and late proinflammatory cytokines in serum and tissues. In conclusion, this study provides evidence that H2 treatment protects against multiple organ damages in ZY-induced generalized inflammation model, suggesting the potential use of H2 as a therapeutic agent in the therapy of conditions associated with inflammation-related multiple organ dysfunction syndrome.ABBREVIATIONS-8-iso-PGF2&agr;-8-iso-prostaglandin F2&agr;; ALT-alanine aminotransferase; AST-aspartate aminotransferase; BUN-blood urea nitrogen; CLP-cecal ligation and puncture; Cr-creatinine; H2-hydrogen; H2O2-hydrogen peroxide; HMGB1-high-mobility group box 1; MODS-multiple organ dysfunction syndrome; NS-normal saline; •OH-hydroxyl radical; ROS-reactive oxygen species; SOD-superoxide dismutase; ZY-zymosan

Noninvasive limb remote ischemic preconditioning contributes neuroprotective effects via activation of adenosine A1 receptor and redox status after transient focal cerebral ischemia in rats

PURPOSES To investigate whether activation of adenosine A1 receptor (A1R) through limb remote ischemic preconditioning (RIPC) by a noninvasive tourniquet contribute neuroprotective effects against rat focal cerebral ischemic injury induced by transient middle cerebral artery occlusion (MCAO). METHODS One hundred twenty-eight Sprague-Dawley (SD) rats were randomly assigned into eight groups (n=16 each): MCAO, Control, 8-cyclopentyl-1,3-dipropulxanthine (DPCPX, Adenosine A1 receptor antagonist), RIPC, DPCPX+RIPC, Vehicle+RIPC, 2-chloro-N(6)-cyclopentyladenosine (CCPA, Adenosine A1 receptor agonist) and CCPA+DPCPX groups. All animals underwent right middle cerebral artery occlusion (MCAO) for 2 h. Limb RIPC consisted of three cycles of 5-minute ischemia followed by 5-minute reperfusion in right hind-limb by tourniquet application. Neurological deficit scores were evaluated 24 h after reperfusion, and then the infarct volume was assessed with diffusion weighted imaging (DWI) and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Inflammation was assessed by serum tumor necrosis factor α (TNF(α)) and NO; oxidative stress was estimated by malondialdehyde (MDA) and 4-hydroxyalkenals (4-HAD), superoxide dismutase (SOD) activity and GSH. RESULTS Animals in the RIPC, Vehicle+RIPC and CCPA groups developed lower neurological deficit scores and smaller brain infarct volumes than the Control group (P<0.01). Animals in the DPCPX, DPCPX+RIPC and CCPA+DPCPX groups developed higher neurological deficit scores and larger brain infarct volumes than the RIPC, Vehicle+RIPC and CCPA groups (P<0.01). DPCPX abolished the protective effects of RIPC and CCPA. RIPC or CCPA induced a significant increase in brain MnSOD (manganese SOD) activity and NO generation, and this activity was abolished by DPCPX pretreatment. RIPC or CCPA induced a significant reduction (P<0.05) in the GSH and MDA+4HDA concentration and an accumulation in the GSSG concentration in both compartments (serum and tissue) as compared with the MCAO group. CONCLUSIONS The present study demonstrates that limb RIPC induced by noninvasive tourniquet reduces cerebral ischemic injury in rats, and the effect of neuroprotection may depend on the activation of adenosine A1 receptors. CCPA pretreatment can induce delayed ischemic tolerance against cerebral ischemia/reperfusion injury. These protective effects are associated with a reduction in oxidative stress, inflammation and endogenous antioxidant preservation.

Ethyl Pyruvate Attenuates Spinal Cord Ischemic Injury with a Wide Therapeutic Window through Inhibiting High-mobility Group Box 1 Release in Rabbits

Background:Ethyl pyruvate (EP) has been reported to offer a protective effect against ischemic injury through its antiinflammatory action. The nuclear protein high-mobility group box 1 (HMGB1) can activate inflammatory pathways when released from ischemic cells. This study was designed to investigate the neuroprotective effect of EP against spinal cord ischemic injury and the potential role of HMGB1 in this process. Methods:EP was administered at various time points before or after 20 min of spinal cord ischemia in male New Zealand rabbits. All animals were sacrificed at 72 h after reperfusion with modified Tarlov criteria, and the spinal cord segment (L4) was harvested for histopathological examination and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling staining. The HMGB1 levels in serum and spinal cord tissue were analyzed by enzyme-linked immunosorbent assay. Results:The treatment of EP at 30 min before ischemia or at 6 h after reperfusion significantly improved the hind-limb motor function scores and increased the numbers of normal motor neurons, which was accompanied with reduction of the number of apoptotic neurons and levels of HMGB1 in serum and spinal cord tissue. The HMGB1 contents of spinal cord tissue correlated well with the numbers of apoptotic motor neurons in the anterior spinal cord at 72 h after reperfusion. Conclusion:These results suggest that EP affords a strong protection against the transient spinal cord ischemic injury with a wide therapeutic window through inhibition of HMGB1 release.

The effectiveness of repetitive paravertebral injections with local anesthetics and steroids for the prevention of postherpetic neuralgia in patients with acute herpes zoster.

BACKGROUND: The treatment of postherpetic neuralgia (PHN) continues to be a challenge in clinical pain management. In this randomized, controlled study, we assessed the effectiveness of repetitive paravertebral injections with local anesthetics and steroids for the prevention of PHN in patients with acute herpes zoster. METHODS: One hundred thirty-two patients with acute herpes zoster diagnosed 1–7 days after the onset of the rash were randomly assigned to receive either standard therapy (oral antivirals and analgesics) or standard therapy with additional repetitive paravertebral injections of a mixture of 10 mL 0.25% bupivacaine and 40 mg methylprednisolone acetate every 48 h for a week. Efficacy was evaluated at 1, 3, 6, and 12 mo after the end of the treatments. The primary end point was the proportion of patients with zoster-associated pain and/or allodynia 1 mo after inclusion. Statistical analysis was performed based on the intent-to-treat population. RESULTS: One hundred thirteen patients completed the 1-yr follow-up. At 1 mo posttherapy, 13% of patients in the paravertebral group reported zoster-related pain, compared with 45% in the standard group (P < 0.001). At 3, 6, and 12 mo posttherapy, the incidence of PHN was still significantly lower in the paravertebral group than in the standard group. The quality of life improved in both groups at each follow-up time point with no significant difference between groups. CONCLUSION: Repetitive paravertebral anesthetic block in combination with steroids plus standard treatment with acyclovir and analgesics significantly reduced the incidence of PHN than the standard treatment alone.

Trans-activator of Transcription-mediated Delivery of NEP1-40 Protein into Brain Has a Neuroprotective Effect against Focal Cerebral Ischemic Injury via Inhibition of Neuronal Apoptosis

Background:The Nogo-66 antagonistic peptide (NEP1-40) is a potential candidate for therapeutic intervention of neuronal injury. However, delivery of the proteins across the blood–brain barrier is severely limited by its size and biochemical properties. The current study was designed to evaluate the transducible effects of the trans-activator of transcription (TAT) transduction system for NEP1-40 to cross the blood–brain barrier and to clarify whether intraperitoneal administration of TAT-NEP1-40 could protect cerebral neurons from ischemic injury. Methods:Adult male Sprague-Dawley rats were submitted to a 120-min focal ischemia and received an intraperitoneal injection of No-TAT-NEP1-40, TAT-NEP1-40, TAT-&bgr;-galactosidase, or vehicle. The existence of the proteins in the brain was analyzed with immunofluorescence and Western blot techniques at 6 h after injection. Brain ischemic injury was evaluated by neurologic deficit scores, infarction volumes, terminal deoxynucleotidyl transferase-mediated dUDP-biotin nick end labeling staining, and assay of caspase-3 activity. Results:Western blot analysis and immunofluorescence staining confirmed the presence of TAT-NEP1-40 protein in the brains 6 h after injection. Intraperitoneal injection of TAT-NEP1-40 could attenuate the numbers of terminal deoxynucleotidyl transferase-mediated dUDP-biotin nick end labeling–positive cells and activated caspase-3 positive cells, and increase the viability of the cells in the ischemic bounder zone, compared with that treated with No-TAT-NEP1-40, TAT-&bgr;-Gal, or vehicle. Furthermore, treatment with TAT-NEP1-40 significantly improved the neurologic outcomes and reduced the size of the infarction in rats. Conclusions:The results demonstrate that the TAT-NEP1-40 could be efficiently delivered into the rat brains and improve ischemia-induced neurologic outcomes through attenuating cell apoptosis in ischemic brains.

Activation of canonical notch signaling pathway is involved in the ischemic tolerance induced by sevoflurane preconditioning in mice.

Background:A wealth of evidence has demonstrated that sevoflurane preconditioning induces brain ischemic tolerance, but the mechanism remains poorly understood. This study was designed to investigate the role of canonical Notch signaling in the neuroprotection induced by sevoflurane preconditioning in a mouse model. Methods:C57BL/6 mice were pretreated with 1-h sevoflurane exposure at a dose of 2.5% for 5 consecutive days. Twenty-four hours after the last exposure, all mice were subjected to focal cerebral ischemia by right middle cerebral artery occlusion for 60 min. Neurobehavioral scores, brain infarct volumes, and cellular apoptosis were determined at 72 h after reperfusion (n = 10 per group). The activation of Notch signaling was evaluated (n = 5 per group), and its role in ischemic tolerance was assessed by intraperitoneal administration of &ggr;-secretase inhibitor DAPT (100 mg/kg, n = 10 per group) and conditional Notch-RBP-J knockout technique (n = 8 per group). Results:Sevoflurane preconditioning reduced brain infarct volumes (42.5%), improved neurologic outcomes (P < 0.01 vs. control), and attenuated neuronal cell apoptosis (cells positive for terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick-end labeling reduced to 21.2%). The expression of Notch1 intracellular domain (1.35 folds) and the transcriptions of Hes1 (1.95 times) and Hes5 (1.48 times) were up-regulated. DAPT augmented the brain infarcts (1.64-fold) and decreased neurologic scores (P = 0.43 vs. sevoflurane) in sevoflurane-preconditioned mice. Brain infarct volumes, neurobehavioral scores, and apoptotic cell numbers showed no significance between Notch knockout mice with sevoflurane preconditioning and wild-type mice without preconditioning. Conclusions:Sevoflurane preconditioning-induced protective effects against transient cerebral ischemic injuries are mediated by the activation of canonical Notch signaling pathway in mice.