title: Pretreatment with intrathecal or intravenous morphine attenuates hepatic ischaemia-reperfusion injury in normal and cirrhotic rat liver.
abstract: BACKGROUND
  Opioids have been shown to attenuate ischaemia-reperfusion injury (IRI) in a number of organs. We evaluated the effect of morphine pretreatment on IRI in both normal and cirrhotic rat liver.
  
  
  METHODS
  Morphine was administered either i.v. or intrathecally (i.t.) 10 min before initiating 1 h of ischaemia followed by 6 h reperfusion in normal rat liver. Hepatic injury was assessed histologically using Suzuki's criteria. These manoeuvres were repeated using the optimal dose of morphine after administration of naloxone methiodide and wortmannin. Serum levels of transaminases were measured, and expression of phosphorylated Akt, Jak2, and STAT3 were assessed by immunoblotting. Similar procedures were repeated on rats with carbon tetrachloride-induced liver cirrhosis, and the levels of phosphorylated protein kinase C (PKC), haem oxygenase-1 (HO-1), and inducible nitric oxide synthase (iNOS) were also evaluated, as these proteins have beneficial effects during IRI.
  
  
  RESULTS
  Morphine pretreatment at 100 µg kg(-1) (i.v.) or 10 µg (i.t.) reduced necrosis, apoptosis, and serum transaminase levels, and increased phosphorylated Akt and STAT3 but not JAK2 expression in normal liver. These changes were reversed by prior administration of naloxone methiodide and wortmannin. Although morphine preconditioning was also protective in cirrhotic liver, STAT3 and JAK2 phosphorylation status was unchanged. There was, however, increased expression of phosphorylated PKC and HO-1, and a reduction in iNOS.
  
  
  CONCLUSIONS
  Morphine preconditioning protects against IRI in both normal and cirrhotic rat liver. This involves opioid receptors, phosphatidylinositol-3-kinase, and Akt. The downstream pathways involved are different for cirrhotic liver, with preliminary evidence suggesting involvement of HO-1.
authors: Department of Anaesthesiology, University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong.
authors: Y
authors: Y
authors: Wang
authors: G T C
authors: GT
authors: Wong
authors: K
authors: K
authors: Man
authors: M G
authors: MG
authors: Irwin
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001219:Aspartate Aminotransferases / Q000097:blood; D015153:Blotting, Western; D002252:Carbon Tetrachloride Poisoning / Q000628:therapy; D002404:Catheterization; D051547:Heme Oxygenase-1 / Q000096:biosynthesis; D020287:In Situ Nick-End Labeling; D007275:Injections, Intravenous; D007278:Injections, Spinal; D019194:Ischemic Preconditioning; D008099:Liver / Q000293:injuries* / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000150:complications* / Q000473:pathology; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine; D051547:Heme Oxygenase-1; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase