胡黄连苷Ⅱ对脑缺血再灌注后大鼠脑组织的保护作用及其机制

PROTECTIVE EFFECT OF PICROSIDE Ⅱ ON RAT BRAIN TISSUE AFTER CEREBRAL ISCHEMIA/REPERFUSION AND RELATED MECHANISM

目的探讨胡黄连苷Ⅱ对脑缺血再灌注(I/R)后大鼠脑组织的保护作用及其机制。方法应用线栓法制作大鼠大脑中动脉缺血再灌注模型,分为假手术组(A组)、模型对照组(B组)、胡黄连苷Ⅱ组(C组),A组除不插线外,其余步骤同B组,B组构建MCAO/R模型,C组在大鼠缺血2h再灌注2h后将胡黄连苷Ⅱ10mg/kg灌胃,于缺血2h再灌注后2、6、12、24、48h分别对B组、C组进行Bederson评分,于缺血后24h应用TUNEL染色方法检测A、B、C组皮质、纹状体和海马区各标本的细胞凋亡情况,于缺血后24h应用免疫组化染色方法检测A、B和C组皮质、纹状体和海马区神经元中Toll样受体4(TLR4)及环氧化酶-2(COX-2)的表达情况。结果脑I/R后24、48h,C组大鼠Bederson评分与B组相比明显减低(F=229.45、297.21,q=7.48、8.52,P<0.05)。B组的大鼠脑I/R后皮质、纹状体和海马区凋亡细胞数显著高于A组(F=19.27～62.58,q=10.39～23.55,P<0.05);C组凋亡神经元数与B组相比明显降低(q=3.11～7.57,P<0.05)。B组大鼠皮质、纹状体和海马区TLR4的表达明显高于A组(F=13.08～15.19,q=7.23～7.77,P<0.05);C组大鼠TLR4的表达明显低于B组(q=3.86～4.47,P<0.05)。B组大鼠皮质、纹状体和海马区COX-2的表达明显高于A组(F=29.90～75.91,q=10.87～11.58,P<0.05);C组大鼠COX-2的表达明显低于B组(q=6.31～7.20,P<0.05)。结论胡黄连苷Ⅱ可能通过选择性抑制皮质、纹状体、海马中TLR4及COX-2的过表达来减轻脑I/R损伤,从而发挥I/R后脑保护作用。

Objective To investigate the protective effect of picroside Ⅱ on rat brain tissue after cerebral ischemia/reperfusion (I/R) and related mechanism. Methods The suture method was used to establish a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). The rats were divided into sham-operation group (group A), model control group (group B), and picroside Ⅱ group (group C). The surgery in group A was the same as that in group B, except that no wire was inserted. The rats in group B were used to establish a model of MCAO/R, and those in group C were picroside Ⅱ 10 mg/kg by gavage after 2 h of occlusion and 2 h of reperfusion. Bederson score was determined for groups B and C after 2 h of occlusion and 2, 6, 12, 24, and 48 h after reperfusion. At 24 h after occlusion, TUNEL staining was used to measure cell apoptosis in the cortex, the striatum, and the hippocampus in groups A, B, and C, and immunohistochemical staining was used to measure the expression of Toll-like receptor 4 (TLR4) and cyclooxygenase-2 (COX-2) in the neurons in the cortex, the striatum, and the hippocampus. Results Compared with group B at 24 and 48 h after cerebral I/R, group C had a significant reduction in Bederson score ( F =229.45, 297.21 , q =7.48,8.52, P <0.05). After cerebral I/R, group B had a significantly higher number of apoptotic cells in the cortex, the striatum, and the hippocampus than group A ( F =19.27-62.58, q =10.39-23.55, P <0.05), and compared with group B, group C had a significant reduction in the number of apoptotic neurons ( q =3.11-7.57, P <0.05). Group B had significantly higher expression of TLR4 in the cortex, the striatum, and the hippocampus than group A ( F =13.08-15.19, q =7.23-7.77, P <0.05), and group C had significantly lower expression of TLR4 than group B ( q =3.86-4.47, P <0.05). Group B had significantly higher expression of COX-2 in the cortex, the striatum, and the hippocampus than group A ( F =29.90-75.91, q =10.87-11.58, P < 0.05 ), and group C had significantly lower expression of COX-2 than group B ( q =6.31-7.20, P <0.05). Conclusion Picroside Ⅱ can alleviate cerebral ischemic injury and exert a cerebral protection effect after I/R, possibly by selectively inhibiting the overexpression of TLR4 and COX-2 in the cortex, the striatum, and the hippocampus.