title: Activating mu-opioid receptors in the spinal cord mediates the cardioprotective effect of remote preconditioning of trauma.
abstract: BACKGROUND
  Remote precoditioning of trauma (RPCT) confers cardioprotective effects against myocardial ischemia/reperfusion injury, which are mediated by spinal opioid receptors. The aim of this study was to identify the roles of opioid receptor subtypes in the cardioprotective effect of RPCT and possible mechanisms.
  
  
  METHODS
  In this study, 192 Sprague-Dawley rats were allocated to 12 groups. Except for the sham group, rats in all groups were subjected to myocardial ischemia reperfusion. Rats in the ischemia precondition (IPC) group were treated with IPC. In the RPCT groups, an abdominal incision was made 15 min before inducing ischemia. The selective delta-, kappa-, and mu-opioid receptor antagonists were administered to groups of animals receiving RPCT, respectively. Data were collected for myocardial infarct size, intercellular adhesion molecule 1 (ICAM-1), plasma cardiac troponin I (cTnI) concentrations, activation of protein kinase C epsilon (PKCe) in myocardial cell membranes, and adenosine release in the spinal cord.
  
  
  RESULTS
  Compared with the control groups, infarct size, plasma concentrations of cTnI, and myocardial ICAM-1 expression were significantly lower, while adenosine release and PKCe activation were enhanced in the IPC and RPCT groups. Compared with the RPCT group, infarct size, plasma cTnI concentration, and myocardial ICAM-1 expression were greater and adenosine release and PKCe activation were reduced in the mu-opioid receptor antagonist plus RPCT group.
  
  
  CONCLUSIONS
  The spinal mu-opioid receptor mediated the cardiac protective effect of RPCT. The mechanism may be enhanced by adenosine release in the spinal cord and PKCe activation in the myo-cardium, thereby inhibiting inflammation induced by ischemia/reperfusion injury.
authors: Bin
authors: B
authors: Mei
authors: Wanhong
authors: W
authors: Li
authors: Xinqi
authors: X
authors: Cheng
authors: Xuesheng
authors: X
authors: Liu
authors: Department of Anesthesiology, the First Affiliated Hospital of Anhui Medical University, Hefei City, Anhui Province, China, China. ay_mz_902@163.com.
authors: Erwei
authors: E
authors: Gu
authors: Ye
authors: Y
authors: Zhang
mesh_terms: D000241:Adenosine / Q000096:biosynthesis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004195:Disease Models, Animal; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*; D019210:Troponin I / Q000097:blood
chemical_list: D017450:Receptors, Opioid, mu; D019210:Troponin I; D018799:Intercellular Adhesion Molecule-1; D000241:Adenosine
keywords: adenosine; inflammation; myocardial reperfusion injury; opioid receptor; remote preconditioning of trauma; spinal cord