Chiu Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 100-116). / Abstract also in Chinese. / TABLE OF CONTENTS --- p.I / ACKNOWLEDGEMENTS --- p.V / LIST OF FIGURES --- p.VI / LIST OF ABBREVIATIONS --- p.VIII / ABSTRACT --- p.1 / Chapter 1. --- INTRODUCTION --- p.5 / Chapter 2. --- LITERATURE REVIEW --- p.7 / Chapter 2.1 --- RETINAL ISCHEMIA --- p.7 / Chapter 2.1.1 --- INDUCTION OF RETINAL ISCHEMIA --- p.7 / Chapter 2.1.2 --- MECHANISMS OF RETINAL ISCHEMIA/REPERFUSION DAMAGE --- p.8 / Chapter 2.1.2.1. --- Free radical --- p.8 / Chapter 2.1.2.2 --- Excitotoxicity --- p.9 / Chapter 2.1.3 --- APOPTOSIS IN RETINAL ISCHEMIA/REPERFUSION INJURY --- p.10 / Chapter 2.2 --- RETINAL DYSTROPHIC ROYAL COLLEGE OF SURGEONS (RCS) RAT --- p.15 / Chapter 2.3 --- BCL-2 FAMILY MEMBERS --- p.16 / Chapter 2.3.1 --- FAMILY MEMBERS AND THEIR INTERACTIONS --- p.16 / Chapter 2.3.2 --- SUBCELLULAR LOCALIZATION --- p.18 / Chapter 2.3.3 --- PHYSICAL STRUCTURE AND PORE FORMATION --- p.19 / Chapter 2.3.4 --- BIOLOGICAL EFFECTS OF BCL-2 --- p.20 / Chapter 3. --- OBJECTIVES --- p.24 / Chapter 4. --- MATERIALS AND METHODS --- p.27 / Chapter 4.1. --- RETINAL ISCHEMIA AND REPERFUSION INDUCED LOSS OF INNER RETINAL ELEMENTS --- p.27 / Chapter 4.1.1. --- TISSUE RESPONSES IN THE RAT RETINAS AFTER TRANSIENT ELEVATED INTRAOCULAR PRESSURE INDUCED RETINAL ISCHEMIA/REPERFUSION INSULT --- p.27 / Chapter 4.1.1.1. --- Induction of retinal ischemia/reperfusion insult with transient elevated intraocular pressure (IOP) --- p.27 / Chapter 4.1.1.2. --- Animal experiments --- p.28 / Chapter 4.1.1.3. --- Histopathology and measurement of inner retinal thickness (IRT) --- p.28 / Chapter 4.1.1.4. --- Flat preparation of the retinas and retinal ganglion cell counts (RGCCs) --- p.29 / Chapter 4.1.2. --- INTERNUCLEOSOMAL DNA FRAGMENTATION AND IN SITU NICKED DNA DETECTIONS AT DIFFERENT TIME AFTER REPERFUSION IN THE RAT RETINAS --- p.30 / Chapter 4.1.2.1. --- Enzyme-linked immunosorbent assay (ELISA) of mono- and oligonucleosomes --- p.30 / Chapter 4.1.2.2. --- In-situ terminal deoxynucleotidyl transferase (TdT)-mediated biotin- dUTP nicked end labelling (TUNEL) --- p.31 / Chapter 4.1.3. --- "IMMUNOHISTOCHEMISTRY OF BCL-2, BAX AND P53" --- p.32 / Chapter 4.1.4. --- "DOUBLE LABELLING OF BCL-2, BAX AND TUNEL" --- p.33 / Chapter 4.1.5. --- IN-SITU REVERSE TRANSCRIPTASE - POLYMERASE CHAIN REACTION OF BCL-2 AND BAX --- p.34 / Chapter 4.1.5.1. --- Primers design and specificity test --- p.34 / Chapter 4.1.5.2. --- In-situ RT-PCR --- p.36 / Chapter 4.2. --- LOSS OF INNER RETINAL ELEMENTS IN THE RETINAL DYSTROPHIC ROYAL COLLEGE OF SURGEONS (RCS) RATS --- p.38 / Chapter 4.2.1. --- HISTOPATHOLOGY --- p.38 / Chapter 4.2.2 --- MORPHOMETRY OF CELLS IN THE RETINAL GANGLION CELL LAYER (RGCL) AND THE INNER NUCLEAR LAYER (INL) --- p.39 / Chapter 4.2.3. --- IMMUNOHISTOCHEMISTRY OF BCL-2 AND BAX --- p.39 / Chapter 5. --- RESULTS --- p.40 / Chapter 5.1. --- RETINAL ISCHEMIA AND REPERFUSION INDUCED LOSS OF INNER RETINAL ELEMENTS --- p.40 / Chapter 5.1.1. --- TISSUE RESPONSES IN THE RAT RETINAS AFTER TRANSIENT ELEVATED INTRAOCULAR PRESSURE INDUCED ISCHEMIA/ REPERFUSION INSULT --- p.40 / Chapter 5.1.1.1. --- Histopathology --- p.40 / Chapter 5.1.1.2. --- Morphometry of inner retinal thickness --- p.40 / Chapter 5.1.1.3. --- Retinal ganglion cell counts (RGCCs) --- p.41 / Chapter 5.1.2. --- INTERNUCLEOSOMAL DNA FRAGMENTATION AND IN SITU NICKED DNA DETECTION AT DIFFERENT TIME AFTER REPERFUSION IN THE RAT RETINAS --- p.41 / Chapter 5.1.2.1. --- Enzyme-linked immunosorbent assay (ELISA) of mono- and oligonucleosomes --- p.42 / Chapter 5.1.2.2. --- In situ TUNEL --- p.42 / Chapter 5.1.3. --- BCL-2 AND RETINAL ISCHEMIA/REPERFUSION INJURY --- p.42 / Chapter 5.1.3.1. --- Immunohistochemistry of Bcl-2 --- p.42 / Chapter 5.1.3.2. --- Double labelling of Bcl-2 and TUNEL --- p.43 / Chapter 5.1.3.3. --- In situ RT-PCR for bcl-2 mRNA --- p.43 / Chapter 5.1.4. --- BAX AND RETINAL ISCHEMIA/REPERFUSION INJURY --- p.44 / Chapter 5.1.4.1. --- Immunohistochemistry of Bax --- p.44 / Chapter 5.1.4.2. --- Double labelling of Bax and TUNEL --- p.45 / Chapter 5.1.4.3. --- In situ RT-PCR for bax mRNA --- p.45 / Chapter 5.1.5. --- P53 IMMUNOREACTIVITY AT VARIOUS TIME AFTER REPERFUSION --- p.46 / Chapter 5.2. --- LOSS OF INNER RETINAL ELEMENTS IN THE RETINAL DYSTROPHIC ROYAL COLLEGE OF SURGEON (RCS) RATS --- p.47 / Chapter 5.2.1. --- HISTOPATHOLOGY --- p.47 / Chapter 5.2.2. --- MORPHOMETRY OF CELLS IN THE RGCL AND INL --- p.47 / Chapter 5.2.3. --- IMMUNOHISTOCHEMISTRY OF BCL-2 AND BAX --- p.47 / Chapter 5.2.3.1. --- Bcl-2 --- p.47 / Chapter 5.2.3.2. --- Bax --- p.48 / Chapter 6. --- DISCUSSION --- p.49 / Chapter 6.1. --- RETINA ISCHEMIA AND REPERFUSION INDUCED LOSS OF RETINAL ELEMENTS --- p.51 / Chapter 6.1.1 --- REPERFUSION TIME DEPENDENT TISSUE RESPONSES IN RAT RETINAS --- p.51 / Chapter 6.1.2 --- ISCHEMIA/REPERFUSION INDUCED APOPTOSIS IN RAT RETINAS --- p.52 / Chapter 6.1.3 --- BCL-2 AND RETINAL ISCHEMIA/REPERFUSION INSULT --- p.53 / Chapter 6.1.4 --- BAX AND RETINAL ISCHEMIA/REPERFUSION INSULT --- p.58 / Chapter 6.1.5 --- P53 AND RETINAL ISCHEMIA/REPERFUSION INJURY --- p.60 / Chapter 6.2. --- LOSS OF INNER RETINAL ELEMENTS IN THE RETINAL DYSTROPHIC ROYAL COLLEGE OF SURGEON (RCS) RAT --- p.61 / Chapter 6.2.1. --- HISTOPATHOLOGY AND MORPHOMETRY --- p.62 / Chapter 6.2.2. --- BCL-2 --- p.63 / Chapter 6.2.3. --- BAX --- p.64 / Chapter 7. --- CONCLUSION --- p.65 / APPENDIX A FIGURES --- p.66 / APPENDIX B REFERENCES --- p.100

Timely reperfusion after a myocardial infarction is necessary to salvage the ischemic region; however, reperfusion itself is a major contributor to the final tissue damage. Currently, there is no clinically relevant therapy available to reduce ischemia-reperfusion injury. While many drugs have shown promise in reducing ischemia-reperfusion injury in preclinical studies, none of these drugs have demonstrated benefit in large clinical trials. Part of the failure to translate therapies can be attributed to the reliance on small animal models for preclinical studies. While animal models encapsulate the complexity of the systemic in vivo environment, they do not fully recapitulate human cardiac physiology. In this thesis, we utilized cardiac tissue engineering methods in conjunction with cardiomyocytes derived from human induced pluripotent stem cells, to establish a biomimetic human tissue-engineered model of ischemia-reperfusion injury. The resulting cardiac constructs were subjected to simulated ischemia or ischemia-reperfusion injury in vitro. We demonstrated that the presence of reperfusion injury can be detected and distinguished from ischemic injury. Furthermore, we demonstrated that we were able to detect changes in reperfusion injury in our model following ischemic preconditioning, modification of reperfusion conditions, and addition of cardioprotective therapeutics. This work establishes the utility of the human tissue model in studying ischemia-reperfusion injury and the potential of the human tissue platform to help translate therapeutic strategies into the clinical setting.

Reperfusion injury may mediate renal dysfunction following ischaemia. A murine model was developed to investigate the role of the tissue factor-thrombin-protease activated receptor pathway in renal ischaemia reperfusion injury (IRI). In this model, mice received 25 minutes of ischaemia and subsequent periods of reperfusion. C57BL6, protease activated receptor-1 (PAR-1) knockout mice, and tissue factor (TF) deficient mice were used. Following 24 hours IRI, PAR-1 deficiency resulted in protection against severe renal failure compared to the C57BL6 mice (creatinine, 118.2 ?? 6.3 vs 203 ?? 12 ??mol/l, p&lt0.001). This was confirmed by lesser tubular injury. By 48 hours IRI, this resulted in a survival benefit (survival, 87.5% vs 0%, p&lt0.001). Treatment of C57BL6 mice with hirudin, a specific thrombin inhibitor, offered renoprotection at 24 hours IRI (creatinine, 107 ?? 10 ??mol/l, p&lt0.001), leading to a 60% survival rate at 48 hours IRI (p&lt0.001). TF deficient mice expressing less than 1% of C57BL6 mouse TF were also protected (creatinine, 113.6 ?? 7 ??mol/l, p&lt0.001), with a survival benefit of 75% (p&lt0.001). The PAR-1 knockout, hirudin treated C57BL6 and TF deficient mice had reduced myeloperoxidase activity and tissue neutrophil counts compared to the C57BL6 mice, along with reduced KC and MIP-2 chemokine mRNA and protein expression. Hirudin treatment of PAR-1 knockout mice had no additional benefit over PAR-1 absence alone, suggesting no further contribution by activation of other protease activated receptors (creatinine at 24 hours IRI, 106.5 ?? 10.5 ??mol/l, p&gt0.05). Furthermore, immunofluoresence staining for fibrin(ogen) showed no difference between C57BL6 and PAR-1 knockout mice, suggesting no major contribution by fibrin in this model. Renal IRI resulted in increased levels of TF mRNA expression in the C57BL6, PAR-1 knockout, and hirudin treated C57BL6 mice compared to normal controls, suggesting that TF mRNA expression was upregulated in this model. This resulted in increased TF functional activity in the C57BL6 and PAR-1 knockout mice, but TF activity was negligible in hirudin treated C57BL6 and TF deficient mice. The data therefore suggests that the TF-thrombin cascade contributes to renal IRI by signalling via PAR-1 that then regulates chemokine gene expression and subsequent neutrophil recruitment.

Objective: Ischemic spinal cord injury is a serious complication of aortic surgery. The mechanism underlying ischemic preconditioning (IPC) protection against spinal cord ischemia/reperfusion (I/R) injury is unclear. We investigated the role of spinal cord autoregulation in tolerance to spinal cord I/R injury induced by IPC. Although the extracellular signal-regulated kinases 1 and 2 (ERK1/2) are generally regarded as related to cell survival and proliferation, increasing evidence suggests that the role of the ERK1/2 pathway in I/R injury is contributory to inflammation. We investigated the effect of blocking ERK1/2 pathway to inhibit inflammation reaction in tolerance to spinal cord I/R injury. Methods: In the part 1 study, Sprague-Dawley rats were randomly assigned to 4 groups. IPC (P) group animals received IPC by temporary thoracic aortic occlusion (AO) with a 2-F Fogarty arterial embolectomy catheter for 3 min. I/R injury (I/R) group animals were treated with blood withdrawal and temporary AO for 12 min, and shed blood reinfusion at the end of the procedures. (P+I/R) group animals received IPC, followed by 5 min reperfusion, and then I/R procedures for 12 min. Sham (S) group animals received anesthesia and underwent surgical preparation only. Neurological functions were evaluated, and lumbar segments were harvested for histopathological examination. To evaluate the role of autoregulation in IPC, spinal cord blood flow and tissue oxygenation were continuously monitored throughout the procedure duration. In the part 2 study, spinal cord ischemia rats was induced by occluding the thoracic descending aorta with a balloon catheter introduced through a femoral artery, accompanied by concomitant exsanguinations. Rats in the control group were given dimethyl sulfoxide (vehicle) before undergoing spinal cord ischemia/reperfusion injury. In the U0126-treated group, rats were pretreated with an inhibitor of ERK1/2, U0126, to inhibit ERK1/2 phosphorylation. The sham rats underwent aortic catheterization without occlusion. Parameters, including neurologic status, neuronal survival, inflammatory cell infiltration, and interleukin-1£] production in the spinal cords, were compared between groups. Results: The Tarlov scores in the (I/R) group were significantly lower than those in the (S), (P), and (P+I/R) groups on days 1, 3, 5, and 7. The numbers of surviving motor neurons in the (S), (P), and (P+I/R) groups were significantly higher than those in the (I/R) group. The (P) group exhibited higher spinal cord blood flow and tissue oxygenation after reperfusion than the (S) group. The (P+I/R) group exhibited higher spinal cord blood flow and tissue oxygenation within the first 60 min after reperfusion than the (I/R) groups. In the part 2 study, early ERK1/2 phosphorylation was observed after injury in the control group, followed by abundant microglial accumulation in the infarct area and increased interleukin-1£] expression. In the U0126 group, U0126 treatment completely blocked ERK1/2 phosphorylation. Microglial activation and spinal cord interleukin-1£] levels were significantly reduced. Neuronal survival and functional performance were improved. Conclusions: IPC ameliorates spinal cord I/R injury in rats, probably mediated by triggering spinal cord autoregulation and improving local spinal cord blood flow and tissue oxygenation. The ERK1/2 pathway may play a noxious role in spinal cord ischemia/reperfusion injury by participating in inflammatory reactions and cytokine production. According to our findings, these concepts may be the new therapeutic targets in patients requiring aortic surgery.

名古屋大学博士学位論文 学位の種類 : 博士(医学)(課程) 学位授与年月日:平成24年2月29日 石黒久昌氏の博士論文として提出された

Abstract The first part of this research was focused on the relationship between injury severity and cell death mechanisms after spinal cord ischemia-reperfusion injury. The major blood supply to the thoracolumbar spinal cord comes from the segmental arteries originating from the thoracoabdominal aorta. Paraplegia cause by spinal cord ischemia is a devastating complication of thoracoabdominal aortic surgery. Previous studies indicated that ischemia-reperfusion injury of the central nervous system causes two distinct types of cell death, necrosis and apoptosis. It was also implicated that the intensity of injury can somehow affect the cell death mechanisms. In the first series of our experiments, by occluding the descending thoracic aorta with or without simultaneously inducing hypovolemic hypotension in rats, we established a model of experimental spinal cord ischemia-reperfusion (SCIR) in which the injury severity can be controlled. Recordings of carotid blood pressure (CBP) and spinal cord blood flow (SCBF) showed that aortic occlusion induced dramatic CBP elevation but SCBF drop in both the normotensive (NT) and hypotensive (HT) groups. However, the HT group demonstrated significantly lower SCBF during aortic occlusion, and much slower elevation of SCBF after reperfusion, and extremely poor neurological performance. Spinal cord lesions were characterized by infarction associated with extensive necrotic cell death, but little apoptosis and caspase-3 activity. In contrast, in the NT group, SCIR resulted in minor tissue destruction associated with persistently abundant apoptosis, augmented caspase-3 activity, and favorable functional outcome. The relative sparing of motoneurons in the ventral horns from apoptosis might have accounted for the minor functional impairment in the NT group. The severity of ischemia-reperfusion (I/R) injury was found to have substantial impact on the histopathological changes and cell death mechanisms, which correlated with neurological performance. These findings implicate that injury severity and duration after injury are two critical factors to be considered in therapeutic intervention. Based on the knowledge that bPrevious studies have implicated both excitotoxicity and apoptosis are involved in the pathogenesis of SCIR injury, we proposedtested the possibility that the N-methyl-D-aspartate (NMDA) receptor antagonist (dizocilpine maleate: (MK801) and the protein synthesis inhibitor (cycloheximide) would produce a synergic effect in the treatment of SCIR injury. In the second series of experiments, I/R iSpinal cord ischemia-reperfusion injury was induced by a thoracic aortic occlusion and blood volume reduction, followed by reperfusion and volume restoration. ischemia-reperfusion Rats were treated with vehicle, MK801, cycloheximide, or combination of MK801 and cycloheximide in combination. The MK801 and combined therapy group got a better recovery of hHind limb motor function recovery was better in the MK801 and combined-therapy groups than in the control and cycloheximide groups. On the 7th day after ischemia-reperfusion injury, all three treated groups showed significantly higher neuronal survival rates (NSR) than that of the control group. Among the three treated groups, the combined-treatment group showed the highest NSR. In addition, the Ttherapeutic effect of the combined-treatment group (27.4% increase of NSR) iwas better than the anticipated by the addition of MK801 and cycloheximide based on NSR data group. The number of apoptotic cells of was significantly reduced in the cycloheximide group and the combined-treatment group, as compared to that of the control group. It was unchanged in the MK-801 group. These results suggest that combined treatments directed at blocking both NMDA receptor-mediated excitotoxic necrosis and caspase-mediated apoptosis might have synergic therapeutic potential in reducing SCIR injury. Mitogen-activated protein kinases (MAPKs) including c-Jun N-terminal kinases (JNK), p38, and extracellular signal-regulated kinases (ERK), play important roles in the transduction of stressful signals and the integration of cellular responses. Although it has been generally held that the JNK and p38 pathways are related to cell death and degeneration, while the ERK pathway, cell proliferation and survival, controversy still exists. The roles of the ERK pathway in I/R injury of the CNS, in particular, remain to be clarified, because contradictory data have been reported by different investigators. Given this controversy, in the third series of experiments, we examined in injured spinal cords the temporal and spatial profiles of ERK1/2 activation following SCIR, and the effects of inhibiting the kinase that phosphorylates ERK1/2, MEK. The results showed that I/R injury induced an immediate phosphorylation of ERK1/2 in the spinal cord, which was alleviated by a MEK inhibitor, U0126. The control group was characterized by poorer neurological outcome, more severe tissue destruction, pronounced apoptosis, and lower neuronal survival. In contrast, the U0126-treated group demonstrated more apparent improvement of hind limb motor function, less tissue destruction, lack of apoptosis, and higher neuronal survival. In addition, administration of U0126 also significantly increased the activation of nuclear factor-£eB (NF-£eB) and the expression of cellular inhibitor of apoptosis protein 2 (c-IAP2). These findings implicate that the mechanisms underlying the neuroprotection afforded by ERK1/2 inhibition may be through the NF-£eB-c-IAP2 axis. The activation of the MEK-ERK signaling pathway appeared to be harmful in SCIR injury. Strategies aimed at blocking this pathway may bear potential therapeutic benefits in the treatment of SCIR injury. The second part of the research was focused on the pathophysiology of surgery-associated paraspinal muscle injury and measures to protect surgically violated paraspinal muscles. The wide dissection and forceful retraction of paraspinal muscles which are often required for posterior spinal sugery may severely jeopardize the muscles structurally and functionally. Immediate posteoperative pathological changes in the surgically violated paraspinal muscles may cause severe pain and a delay of patient ambulation. Long-term sequelae of surgical injury of paraspinal muscles include chronic back pain and impaired back muscle strength. Ironically, being a common complication of posterior spinal surgery, paraspinal muscle injury is so often neglected. Limited previous data indicate that the underlying pathophysiology of muscle damage involve both mechanical and ischemic mechanisms. We hypothesized that surgical dissection and retraction may produce oxidative stress within the paraspinal muscles. Meanwhile, we also proposed that the oxidative stress may trigger certain protective mechanisms within the insulted muscles. The first part of our study was a human study conducted to assess the significance of oxidative stress, and the relationship between it and the stress response mediated by heat shock protein 70 (HSP70) induction within paraspinal muscles under intraoperative retraction. A group of patients with lumbar spondylolisthesis treated with posterolateral lumbar spinal fusion, pedicle fixation and laminectomy were enrolled. Multifidus muscle specimens were harvested intraoperatively before, at designated time points during, and after surgical retraction. Muscle samples were analyzed for HSP70 and malondialdehyde (MDA) levels. Both HSP70 expression and MDA production within multifidus muscle cells were increased significantly by retraction. HSP70 expression then dropped after a peak at 1.5 hr of retraction, whereas MDA levels remained elevated even after release of retractors for reperfusion of the muscles. Histopathological and immunohistochemical evidence indicated that the decline of HSP70 synthesis within muscle cells after prolonged retraction was the result of severe muscle damage. These results highlighted the noxious impact of intraoperative retraction on human paraspinal muscles, and the significance of oxidative stress at the cellular and molecular levels. It is also implicated that intraoperative maneuvers aimed at reducing the oxidative stress within the paraspinal muscles may help attenuating surgery-associated paraspinal muscle damage. Given the findings of the first part of our study, and the knowledge that inflammation is a major postoperative pathological finding in surgically injured paraspinal muscles, we proceeded to examine the roles of two important inflammatory mediators, cyclooxygenase (COX)-2 and nuclear factor (NF)-£eB, in the pathogenesis of retraction-associated paraspinal muscle injury. A rat model of paraspinal muscle dissection and retraction that mimicks the conditions in human posterior spinal surgery was established. In the control group, paraspinal muscles were dissected from the spine through a dorsal incision, and then laterally retracted. Paraspinal muscle specimens were harvested before, and at designated time points during and after persistent retraction. The time course of NF-£eB activation as well as the expression of COX-2 were examined. Severity of inflammation was evaluated based on histopathology and myeloperoxidase (MPO) activity. NF-£eB activation was inhibited by the administration of pyrrolidine dithiolcarbamate (PDTC) in the PDTC-treated group. In the control group, retraction induced an early increase of NF-£eB/DNA binding activity in paraspinal muscle cells, which persited throughout the whole course of retraction. COX-2 expression was not detectable until 1 day after surgery, and reached a peak at 3 days. The time course of COX-2 expression correlated with that of inflammatory pathology and MPO activity. Extensive muscle fiber loss and collagen fiber replacement were observed at 7 days after surgery. Pretreatment with PDTC inhibited intraoperative NF-£eB activation and greatly downregulated postoperative COX-2 expression and inflammation in the muscles. Fibrosis following inflammation was also significantly abolished by PDTC administration. These findings indicate that NF-£eB-regulated COX-2 expression and inflammation play an important role in the pathogenesis of surgery-associated paraspinal muscle injury. Therapeutic strategies involving NF-£eB inhibition may be applicable to the prevention of such injury.

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2003. / Vita. Includes bibliographical references (leaves 203-234).

Thesis (Ph. D.)--University of California, San Diego, 2003. / Vita. Includes bibliographical references (leaves 162-178).

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Hepatic ischaemia-reperfusion injury occurs when patients undergoing liver operations such as liver transplantation, tumour resection and shock. Intravenous and intrathecal administration of morphine can be used to provide analgesia prior or after liver surgery. It has been reported that systemically administered morphine conferred protective effect on numerous organs, including heart, brain and kidney. The focus of my research is to investigate the effect of intravenous and intrathecal morphine preconditioning on normal and cirrhotic livers. Further, PI3K/Akt, STAT3 and HO-1/iNOS pathways had been shown to ameliorate hepatic ischemia-reperfusion injury. Hence, we aim to investigate these possible signaling pathways associated with morphine mediated hepato-protection. A partial hepatic ischaemia reperfusion injury model in rats was used. The experiments were divided into two series: one involved in normal livers and the other one involved in cirrhotic livers. For the normal livers, morphine at different doses were administrated intravenously or intrathecally prior the onset of ischaemia, and the experiments were repeated with previous intravenous administration of naloxone methiodide (opioid receptor antagonist), or wortmannin (Akt inhibitor), respectively. For the cirrhotic livers, morphine at optimal doses were injected intravenously or intrathecally prior the onset of ischaemia. Those rats with only induced hepatic ischaemia-reperfusion injury only were marked as control groups. The effect of morphine preconditioning on hepatic architecture, apoptosis and liver function were evaluated respectively by hematoxylin-eosin (H&E) staining, Terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) staining, the expression of cleaved Caspase-3, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Meanwhile, the expression of phosphorylated Akt, phosphorylated JAK2, phosphorylated STAT3, HO-1 and iNOS were detected by Western Blot to determine the signaling pathways involved by intravenous and intrathecal morphine preconditioning. The normal livers series presented intravenous and intrathecal morphine preconditioning at the 100μg/kg, 10μg/kg, respectively, better persevered hepatic architecture when compared with control groups. The degree of liver cell apoptosis and expression of cleaved caspase-3 were also reduced by intravenous and intrathecal morphine preconditioning. In additional, intravenous and intrathecal morphine preconditioning ameliorated hepatocellular damage by reducing ALT&AST release. Moreover, the expressions of phosphorylated Akt and its downstream protein STAT3 were significantly increased by intravenous and intrathecal morphine preconditioning, compared with their respective control groups. The hepato-protective effect of intravenous and intrathecal morphine preconditioning was reversed by naloxone methiodide or wortmannin pretreatment. The similar pattern of protection was observed in cirrhotic livers. Both intravenous and intrathecal morphine preconditioning protected hepatic architecture much better than control groups. They also attenuated hepatic apoptosis degree and hepatocellular enzyme release. Furthermore, the expression of HO-1 was up-regulated, whereas the expression of iNOS was down-regulated by intravenous and intrathecal morphine preconditioning. In summary, this study provided evidence that intravenous and intrathecal morphine preconditioning could attenuate hepatic ischaemia-reperfusion injury in normal and cirrhotic livers. The involvement of opioid receptors, Akt/STAT3 pathway and HO-1 pathway might be the underlying mechanisms of morphine hepato-protection. Finally, the protective effect of morphine preconditioning might provide a potential therapeutic approach for clinical usage. / published_or_final_version / Anaesthesiology / Master / Master of Philosophy