南方医科大学学报

南方医科大学学报 ›› 2018, Vol. 38 ›› Issue (09): 1066-.doi: 10.12122/j.issn.1673-4254.2018.09.07

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中脑导水管周围灰质腹外侧区微注射内吗啡肽1诱导大鼠心脏伤害性感受的下行性抑制

韩曼，刘晓华，杜剑青   

  • 出版日期:2018-09-20 发布日期:2018-09-20

Microinjection of endomorphin-1 in the ventrolateral periaqueductal gray induces descending inhibition of cardiac nociception by activating μ-opioid receptor in rats

  • Online:2018-09-20 Published:2018-09-20

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摘要： 目的观察中脑导水管周围灰质腹外侧区（VLPAG）微注射内吗啡肽1（EM1）对大鼠心包内缓激肽（BK）诱发的心脏伤害 性感受的调控作用及其μ阿片受体机制。方法雄性SD大鼠随机分为两组：肌电组和c-Fos 组。两组均各分为5 小组：0.9% NaCl组、BK组、BK+EM1组、BK+CTOP组、BK+CTOP+EM1组。通过心包内注射BK建立大鼠心脏伤害性感受模型，观察心 脏-躯体运动反射的变化，该反射以背斜方肌肌电（EMG）为观测指标；同时观察T3~T5脊髓背角c-Fos的表达。结果（1）与0.9% NaCl组相比，心包内BK诱发了大鼠背斜方肌EMG活动，T3~T5脊髓背角c-Fos阳性表达显著增加（P<0.05）；（2）与BK组相比， VLPAG微注射EM1剂量依赖性地抑制了背斜方肌EMG活动，c-Fos阳性表达显著减少（P<0.05）；VLPAG微注射CTOP，EMG 活动与c-Fos阳性表达无显著性差异（P>0.05）；（3）与BK+EM1组相比，VLPAG微注射CTOP翻转了EM1对EMG活动与c-Fos 阳性表达的抑制作用（P<0.05）。结论EM1通过激活μ阿片受体参与了VLPAG对大鼠心脏伤害性感受的下行性抑制调控作用。

Abstract: Objective To observe descending inhibition of cardiac nociception induced by microinjection of endomorphin-1 (EM1) in the ventrolateral periaqueductal gray (VLPAG) in rats effect and explore the role of μ-opioid receptor in mediating this effect. Methods Male SD rats were randomized into electromyography (EMG) group and c-Fos group, both of which were further divided into 5 subgroups, namely 0.9% NaCl group, bradykinin (BK) group, BK+EM1 group, BK+CTOP group, and BK+CTOP+EM1 group. Rat models of cardiac nociception were established by intrapericardial injection of BK. The changes of cardiaosomatic motor reflex induced by BK were observed by assessing EMG responses of the dorsal spinotrapezius muscle; c-Fos expression in the spinal dorsal horn at levels T3-T5 was tested. Results Compared with 0.9% NaCl, intrapericardial BK injection induced obvious EMG activities and significantly increased c-Fos expression in the spinal dorsal horn at T3-T5 (P< 0.05). Compared with BK injection, microinjection of EM1 in the VLPAG dose-dependently inhibited EMG activities and significantly decreased c-Fos expression (P<0.05); microinjection of CTOP in the VLPAG produced no significant effect on EMG or c-Fos expression (P>0.05). Microinjection of CTOP obviously reversed EM1-induced inhibition of EMG activities and c-Fos expression (P<0.05). Conclusion Microinjection of EM1 in the VLPAG produces descending inhibition of cardiac nociception in rats by activating μ-opioid receptor.