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
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174542 |
| Date | January 2012 |
| Creators | Wang, Yuan, 王苑 |
| Contributors | Wong, GTC, Man, K, Irwin, MG |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47849848 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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