Effect of electroacupuncture preconditioning at “Nèiguān” ( PC 6) on gene expression of myocardial opioid receptors in rats with ischemia-reperfusion

Abstract Objective To explore protective effects of electroacupuncture at “Neiguān” ( PC 6) for preconditioning on myocardial ischemia-reperfusion injury (MIRI) and the mechanisms involved. Methods Forty-eight male Wistar rats were randomly divided into a sham operation group (Group N), a MIRI group (Group M) and an electroacupuncture (EA) group (Group E). The MIRI model was established by ligating the left anterior descending artery (LAD) for 30 min followed by reperfusion for 120 min. Partition sutures were passed under LAD without ligation for rats in Group N. Rats in Group E were pretreated with electroacupuncture (EA) applied at bilateral “Neiguān” ( PC 6) for 20 min once a day for 3 consecutive days before ischemia. The infarct size plus the area at risk was evaluated by 2,3,5-triphenyltetrazolium chloride staining, and serum isoenzyme of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) levels were measured by biochemical methods. Myocardium morphological changes were observed under light microscopy. The mRNA expressions of myocardial δ and κ opioid receptors (DOR and KOR) were tested by real-time RT-PCR measurements. Results The myocardial infarct size in Group E was more significantly decreased than that in Group M ( P P P P >0.05), but DOR expression in Group E was significantly higher than that either in Group M or in Group N (both P P >0.05). Conclusion Up-regulation of expression of δ opioid receptors may be involved in protective effects of EA at Neiguān ( PC 6) for preconditioning on MIRI.