细胞周期抑制剂对大鼠局灶性脑缺血后胶质细胞增殖和瘢痕形成的影响及对神经元的保护作用

Effects of cell cycle inhibitor on astroglial proliferation and scar formation and neuroprotection after focal cerebral ischemia in rats

目的观察选择性细胞周期抑制剂 olomoucine 对胶质细胞增殖和瘢痕形成及神经元凋亡的影响。方法建立光化学法诱导大鼠局灶性脑缺血模型,随机分为假手术组、对照组和干预组,采用 MRI 显示梗死灶并计算其梗死灶体积;应用免疫荧光化学法检测胶质纤维酸性蛋白(GFAP)的表达及通过 TUNEL 方法检测神经元凋亡;免疫印迹法观察光照侧皮质 GFAP、增殖细胞核抗原(proliferation cell nuclear antigen,PCNA)、周期索蛋白 A 和周期素蛋白 B1蛋白的表达。结果缺血后3、7、30 d 对照组(5.10%±0.35%,4.60%±0.26%,3.96%±0.28%)梗死灶体积占全脑体积百分比值的平均值明显大于干预组(2.27%±0.28%,1.87%±0.19%,1.08%±0.18%,P<0.05);缺血后各时间点组 GFAP 表达明显增强,对照组明显强于干预组,并且7、30 d 对照组梗死灶周边可见明显的胶质瘢痕形成,以30 d 最为显著;缺血后3 d 梗死灶周围可见大量 TUNEL 阳性染色细胞,对照组[(41±11)个/高倍视野]数量明显多于干预组[(26±8)爪/高倍视野,P<0.05];干预组大鼠(22.44%±2.17%)NeuN+TUNEL 双标阳性表达明显弱于对照组大鼠(34.41%±3.10%,P<0.05);3、7、30 d 的 GFAP、PCNA、周期素蛋白 A 和周期素蛋白 B1蛋白量表达,对照组明显高于干预组。结论通过对细胞周期的调控,可部分抑制胶质细胞的活化增殖及瘢痕形成,同时减小脑梗死体积及减少神经元凋亡。

Objective To observe the effects of cell cycle inhibitor on astrocytic proliferation and scar formation and to study neuronal apoptosis after focal cerebral ischemia in rats. Methods Ischemic model was established by photochemistry method. T2-weighted MRI was performed on the 3rd, 7th, and 30th day after focal cerebral ischemia. The expression of glial fibrillary acidic protein （GFAP） and apoptosis was observed by immunofluorescence. The protein levels of GFAP and proliferation cell nuclear antigen （PCNA）, CyclinA and CyclinB1 were measured by Western blotting from the ischemic and sham animals finished on the 3rd, 7th, and 30th day. Results A marked and significant reduction of brain infarction volume was found in Olomoucine-treated ischemic animals （2. 27%±0. 28% , 1.87% ±0. 19% , 1.08% ± 0. 18% ） as compared with controls（5. 10% ±0. 35%, 4. 60% ±0. 26%, 3. 96%±0. 28%, P 〈0. 05）. Olomoucine significantly reduced the expression of GFAP, and Olomoucine could reduce scar formation on the 7th and 30th day in rats. On the 3rd day after focal cerebral ischemia, the TUNEL-positive staining number of control group （41 ± 11 ） was higher than that of the treatment group （ 26 ± 8, P 〈 0. 05 ）, and the apoptosis ratio of the treatment group （22. 44% ± 2. 17 % ） was lower than that of control group （34. 41% ± 3. 10% ）. Western blotting indicated that there were increased protein levels of control group for GFAP,PCNA, CyclinA and CyclinB1 compared to those of the treatment group on the 3rd, 7th and 30th day after cerebral ischemia. Conclusion Cell cycle inhibitor could partially inhibit activation and proliferation of astrocyte and neuronal apoptosis, decrease infarction volume after ischemia, and thereby further help create an environment that benefits neuronal survival and nervous function reconstruction.