Picroside II Inhibits Neuronal Apoptosis and Improves the Morphology and Structure of Brain Tissue following Cerebral Ischemic Injury in Rats

This paper aimed to explore the protective effects of picroside II against the neuronal apoptosis and changes in morphology and structure that follow cerebral ischemic injury in rats. A focal cerebral ischemic model was established by inserting a monofilament thread to achieve middle cerebral artery occlusion (MCAO) in 60 Wistar rats, and intraperitoneal injections of picroside II (20 mg/kg) were administered. The neurobehavioral functions were evaluated with the modified neurological severity score (mNSS) test. The cerebral infarct volumes were measured with tetrazolium chloride (TTC) staining. The morphology and ultrastructure of the cortical brain tissues were observed with hematoxylin-eosin staining and transmission electron microscopy, respectively. The apoptotic cells were counted with terminal deoxynucleotidyl transferase dUTP nick-end labeling and flow cytometry, and pERK1/2 expression was determined by immunohistochemical assay and Western blot. The results indicated that neurological behavioral malfunctions and cerebral infarcts were present in the MCAO rats. In the model group, the damage to the structures of the neurons and the blood brain barrier (BBB) in the cortex was more severe, and the numbers of apoptotic cells, the early apoptotic ratio (EAR) and pERK1/2 expression were significantly increased in this group compared to the control group (P<0.05). In the treatment group, the neurological behavioral function and the morphology and ultrastructure of the neurons and the BBB were improved including the number of Mi increased and relative area of condensed chromosome and basement (BM) thickness descreased, and the cerebral infarct volume, the number of apoptotic cells, the EAR and pERK1/2 expression were significantly decreased compared to the model group (P<0.05). These results suggest that picroside II reduced apoptosis and improved the morphology and ultrastructure of the neurons and the BBB and that these effects resulted in the recovery of the neurobehavioral function of rats with cerebral ischemia.

本研究旨在探讨胡黄连苷II对大鼠脑缺血损伤后神经元凋亡及形态结构变化的保护作用。实验通过线栓法构建60只Wistar大鼠大脑中动脉闭塞（middle cerebral artery occlusion, MCAO）局灶性脑缺血模型，并对干预组大鼠腹腔注射胡黄连苷II（20 mg/kg）。采用改良神经功能缺损评分（modified neurological severity score, mNSS）评估大鼠神经行为功能；通过氯化三苯基四氮唑（tetrazolium chloride, TTC）染色法检测脑梗死体积；分别采用苏木精-伊红染色与透射电子显微镜观察大脑皮层组织的形态学与超微结构；采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（terminal deoxynucleotidyl transferase dUTP nick-end labeling, TUNEL）与流式细胞术计数凋亡细胞；通过免疫组织化学法与蛋白质印迹（Western blot）检测pERK1/2的表达水平。结果显示，MCAO模型大鼠出现神经行为功能障碍与脑梗死灶。与对照组相比，模型组大鼠皮层神经元及血脑屏障（blood brain barrier, BBB）结构损伤更为严重，凋亡细胞数量、早期凋亡率（early apoptotic ratio, EAR）及pERK1/2表达水平均显著升高（P<0.05）。干预组大鼠神经行为功能得以改善，神经元及血脑屏障的形态与超微结构得到修复，具体表现为线粒体数量增加、染色质固缩相对面积及基底膜（basement membrane, BM）厚度均降低；与模型组相比，干预组脑梗死体积、凋亡细胞数量、早期凋亡率及pERK1/2表达水平均显著降低（P<0.05）。上述结果表明，胡黄连苷II可通过抑制细胞凋亡、改善神经元及血脑屏障的形态与超微结构，促进脑缺血大鼠神经行为功能的恢复。