Role of δ opioid receptor in brain injury following asphyxial cardiac arrest-resuscitation in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of δ opioid receptor in the brain injury following asphyxial cardiac arrest-resuscitation in rats.Methods Ninety-six pathogen-free male Sprague-Dawley rats,weighing 300-350 g,were randomly divided into 4 groups (n =24 each)sham operation group (group S),asphyxial cardiac arrest-resuscitation group (group M),δ opioid receptor agonist BW373U86 group (group B) and δ opioid receptor antagonist naltrindole group (group N).Cardiac arrest was induced by clamping the tracheal tube for 8 min.Mechanical ventilation with pure oxygen was performed.Epinephrine 0.02 mg/kg and 5％ NaHCO3 1 mg/kg were injected intravenously as soon as chest compression was started.Appearance of spontaneous breathing and MAP ＞ 50 mm Hg (lasting for more than 10 min) were considered to be signs of successful recovery of spontaneous circulation (ROSC).BW373U86 and naltrindole 1 mg/kg were injected via the femoral vein immediately after ROSC in groups B and N,respectively,while the equal volume of normal saline was given instead in groups S and M.Neurological deficit score (NDS) was evaluated at 3,24 and 72 h after ROSC.The rats were then sacrificed,brains were isolated and the hippocampus was obtained for detection of the expression of brain-derived neurotrophic factor (BDNF)and tyrosine receptor kinase B (TrkB)mRNA by RT-PCR.The histological grading (HG) of neurons and number of survival neurons in hippocampal CA1 region were determined at 72 h after ROSC.Results Compared with group S,the expression of BDNF and TrkB mRNA was significantly up-regulated,HG was increased,and NDS and the number of survival neurons were decreased in groups M,B and N (P ＜ 0.05).Compared with group M,the expression of BDNF and TrkB mRNA was significantly up-regulated in group B,the expression of BDNF and TrkB mRNA was down-regulated in group N,and HG was significantly decreased,and NDS and the number of survival neurons were increased in groups B and N (P ＜ 0.05).NDS was significantly lower,the number of survival neurons was smaller,the expression of BDNF and TrkB mRNA was lower,and HG was higher in group N than in group B (P ＜ 0.05).Conclusion Activation of δ opioid receptor can reduce the brain injury following asphyxial cardiac arrest-resuscitation in rats and the mechanism may be related to up-regulation of BDNF and TrkB after activation of δ opioid receptor.