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目的:观察电刺激延髓外侧网状核(LRN)对大鼠心包内辣椒素(IC)诱发心脏-躯体运动反射(CMR)的下行性抑制作用并探讨其作用机制。方法:22只雄性SD大鼠随机分为电刺激组、电刺激+鞘内注射3g.L-1育亨宾组、电刺激+鞘内注射5g.L-1育亨宾组和电刺激+鞘内注射溶媒组,观察各组处理因素干预后大鼠IC诱发CMR的脊斜方肌肌电(EMG)的变化。结果:与对照组比较,电刺激(10、20和30μA)LRN能够抑制EMG,随着刺激强度的增加,抑制效果也加强,EMG分别下降到对照组的51.41%、21.11%和1.43%,(P<0.001),同时伴有或不伴有血压的改变;与电刺激组比较(10μA),鞘内注射肾上腺素能α2受体拮抗剂育亨宾(3和5g.L-1)部分逆转了电刺激LRN对CMR的抑制作用,EMG从41.34%分别升高到72.40%和78.73%(P<0.01)。结论:电刺激LRN对CMR具有下行性抑制作用,脊髓水平的α2受体参与了其抑制作用。
AIM: To observe the descending inhibitory effect of electrical stimulation of lateral medullary nucleus of medulla oblongata (LRN) on pericardial capsaicin (IC) -induced cardiac-somatic motor reflex (CMR) in rats and its possible mechanism. Methods: Twenty-two male Sprague-Dawley rats were randomly divided into electrical stimulation group, intrathecal injection of 3g.L-1 yohimbine group, electrical stimulation + intrathecal injection of 5g.L-1 yohimbine group and electrical stimulation + Intrathecal injection of vehicle group, to observe the changes of EMG in rats induced by CCl after ICI treatment. Results: Compared with the control group, LRN of 10, 20 and 30μA could inhibit EMG. With the increase of stimulation intensity, the inhibitory effect was also enhanced. EMG decreased to 51.41%, 21.11% and 1.43% of the control group respectively P <0.001), with or without changes in blood pressure. Compared with the electrical stimulation group (10μA), intrathecal injection of adrenergic α2-receptor antagonist yohimbine (3 and 5g.L-1) partially reversed The inhibition of CMR by electrical stimulation of LRN increased from 41.34% to 72.40% and 78.73%, respectively (P <0.01). CONCLUSION: Electrical stimulation of LRN has a descending inhibitory effect on CMR, and spinal cord α2 receptor participates in its inhibition.