脊髓NMDA受体对心包内注射缓激肽诱发大鼠心脏-躯体运动反射的调节作用

Modulation of NMDA receptor to rat cardiacsomatic motor reflex induced by intrapericardial bradykinin in spinal cord

目的:观察鞘内注射N-甲基-D-天门冬氨酸(NMDA)受体激动剂NMDA及拮抗剂5-甲基-二氢-丙环庚烯-亚胺马来酸(MK801)对心包内注射缓激肽(BK)诱发大鼠心脏-躯体运动反射(CMR)的影响,探讨脊髓水平的谷氨酸受体亚型-NMDA对心脏伤害性感受的调节作用。方法:26只雄性SD大鼠随机分为BK组(n=8)、BK+NMDA组(n=6)、BK+MK801组(n=6)及BK+MK801+NMDA组(n=6),观察大鼠心包内注射BK诱发的CMR及鞘内注射药物后CMR的变化,CMR以背斜方肌肌电(EMG)反应为观测指标。结果:心包内间隔40min重复4次注射BK诱发的CMR无明显改变(P>0.05);鞘内注射NMDA后EMG由基础对照的100%增加到(149.86±8.54)%,注射前后EMG比较差异有统计学意义(P<0.05);鞘内注射MK801后EMG由基础对照的100%减少到(96.22±2.31)%,但注射前后EMG比较差异无统计学意义(P>0.05);鞘内联合注射MK801和NMDA,EMG由基础对照的100%增加到(103.09±4.13)%,但注射前后EMG比较差异无统计学意义(P>0.05)。结论:心包内注射BK诱发的CMR具有可靠的重复性,脊髓水平的NMDA受体参与了CMR的调节。

Objective To observe the effects of the intrathecal injection of N-methyl-D-aspartate（NMDA） receptor agonist NMDA and antagonist MK801 on the cardiacsomatic motor reflex（CMR） induced by intrapericardial bradykinin（BK）,and explore the role of Glu receptor NMDA subunit in nociceptive information transmission of the heart in the spinal cord.Methods 26 male SD rats were randomly divided into BK group（n=8）,BK ＋ NMDA group（n=6）,BK ＋ MK801 group（n=6）,and BK ＋ MK801 ＋ NMDA group（n=6）.CMR was induced by intrapericardial BK,and the effects of intrathecal injection of drug in various groups on CMR were observed.The changes of CMR were monitored via electromyogram（EMG） responses of dorsal spinotrapezius muscle to intrapericardial BK.Results There were no significant differences among EMG induced by intrapericardial BK,four times at 40 min intervals.Compared with control,the EMG was increased from 100% of control to（149.86±8.54）% by intrathecal injection of NMDA,there was significant difference of EMG between before and after intrathecal injection of NMDA（P0.05）.However,the EMG was decreased from 100% of control to（96.22±2.31）% by intrathecal injection of MK801,there was no statistically significant difference（P0.05）.The EMG was increased from 100% of control to（103.09±4.13）% by intrathecal combinative injection of MK801 and NMDA,there was no significant difference of EMG between before and after intrathecal combined injection of MK801 and NMDA（P0.05）.Conclusion CMR induced by intrapericardial BK has reliable repeatability and the spinal cord level of NMDA receptor involves in the modulation of CMR.