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目的探讨M型钾离子通道开放剂—瑞替加滨(RTG)对缺血性脑卒中模型大鼠的保护作用及可能机制,为临床治疗脑卒中提供新的思路及科学参考。方法选取SD大鼠75只,随机分为假手术组(15只,Sham组),大脑中动脉闭塞(MCAO)模型组(15只,MCAO组),RTG干预组(45只)。RTG干预组大鼠均经尾静脉给予RTG10 mg/kg,按给药不同时间点再分为RTG 0 h亚组;RTG 1 h亚组;RTG 3 h亚组,每组15只。Sham组和MCAO组不做特殊处理,仅给予等量生理盐水。采用Longa 5分制评分法比较神经功能缺损评分,2,3,5-氯化三苯四唑(TTC)染色测量脑梗死体积,免疫组化检测星形胶质纤维酸性蛋白(GFAP)阳性表达细胞(即星形胶质细胞)数和细胞凋亡蛋白酶-3(Caspase-3)阳性表达细胞数。结果 Sham组无神经功能缺损症状,MCAO组大鼠均表现出一定程度的神经功能缺损症状,如:蜷缩、不能站稳、旋转和倾倒、不能行走等。与MCAO组相比,RTG干预组神经功能缺损症状评分明显降低(P均<0.05),但RTG不同作用时间各亚组间差异无统计学意义(P>0.05)。TTC染色图像显示:Sham组未见梗死灶,MCAO组脑组织可见不同程度的梗死灶,RTG 0 h、1 h、3 h干预组梗死灶体积[(14.06±1.68)%、(14.08±1.60)%、(14.10±2.14)%]较MCAO组明显降低[(28.50±1.02)%,P均<0.05],但RTG不同作用时间各亚组间差异无统计学意义(P>0.05)。免疫组化检测Sham组可见少量星形胶质细胞及Caspase-3阳性细胞;RTG干预组的星形胶质细胞数及Caspase-3阳性细胞数均较MCAO组明显减少(P均<0.05),但RTG不同作用时间各亚组间差异无统计学意义(P>0.05)。结论 RTG对大鼠缺血性脑卒中具有保护作用,其作用机制可能与RTG促进钾离子外流抑制神经元的兴奋性、减轻脑梗死灶周围区炎症,抑制Caspase-3的表达而减少神经元的凋亡有关,但其是否具时间依赖性,有待进一步研究。
Objective To investigate the protective effect and possible mechanism of M-type potassium channel opener, retigabine (RTG) on ischemic stroke rats and provide new ideas and scientific references for the clinical treatment of stroke. Methods Seventy five Sprague Dawley rats were randomly divided into sham operation group (Sham group), middle cerebral artery occlusion group (MCAO group) and RTG intervention group (45). The rats in the RTG intervention group were given RTG 10 mg / kg through the tail vein, and then divided into RTG 0 h subgroup, RTG 1 h subgroup and RTG 3 h subgroup 15 in each group at different time points. Sham group and MCAO group without special treatment, only given the same amount of saline. The Longa 5-point score was used to compare the neurological deficit score, the volume of cerebral infarction was measured by TTC staining and the positive expression of glial fibrillary acidic protein (GFAP) was detected by immunohistochemistry The number of cells (astrocytes) and the number of positive cells expressing Caspase-3. Results There was no neurological deficit in Sham group. Rats in MCAO group showed some symptoms of neurological deficits, such as curled up, unable to stand, rotate and dump, could not walk and so on. Compared with MCAO group, the score of neurological deficit symptom in RTG intervention group was significantly lower than that of MCAO group (all P <0.05), but there was no significant difference between different subgroups of RTG intervention time (P> 0.05). TTC staining showed that there was no infarction in Sham group and different degree of infarction in MCAO group. The volume of infarction in [(14.06 ± 1.68)% and (14.08 ± 1.60) %, (14.10 ± 2.14)%] were significantly lower than those in MCAO group [(28.50 ± 1.02)%, P <0.05, respectively]. However, there was no significant difference between different subgroups of RTG (P> 0.05). A small number of astrocytes and Caspase-3 positive cells were observed in the Sham group by immunohistochemistry. The number of astrocytes and the number of Caspase-3 positive cells in the RTG intervention group were significantly lower than those in the MCAO group (all P <0.05) However, there was no significant difference between different subgroups of RTG in different time (P> 0.05). CONCLUSION: RTG has a protective effect on ischemic stroke in rats. Its mechanism may be related to the inhibition of neuronal excitability induced by RTG stimulation of potassium ion, alleviation of inflammation in the surrounding area of cerebral infarction, inhibition of Caspase-3 expression and reduction of neuronal Apoptosis, but whether it is time-dependent, pending further study.