慢性弓形虫感染对大鼠海马神经细胞凋亡周期及caspase-3与细胞色素C蛋白表达的影响

目的观察弓形虫慢性感染对大鼠海马神经细胞周期、细胞凋亡及半胱氨酸蛋白酶-3(caspase-3)和细胞色素C(Cytc)表达的影响。方法将20只成年雄性SD大鼠随机分成2组:弓形虫感染组和正常对照组。弓形虫感染组每只大鼠腹腔注射纯化弓形虫速殖子2×107/ml悬液2ml;正常对照组大鼠每只腹腔注射2ml灭菌生理盐水。感染10周后应用流式细胞术检测大鼠海马神经细胞周期和细胞凋亡,罗丹明123染色检测其线粒体膜电位;应用免疫组化法检测海马caspase-3和Cytc蛋白表达。结果弓形虫感染10周后,大鼠海马神经细胞凋亡率为(49.3±13.6)%,与正常对照组(40.1±11.2)%相比较,差异有统计学意义(P0.05),G0/G1期细胞百分率增高(P0.05),出现G0/G1期阻滞,S期细胞减少(P0.05);感染组线粒体膜电位为(22.1±6.8)%,比对照组的(25.4±9.4)%低(P0.05);caspase-3和Cytc蛋白表达则均显著增高(P0.05)。结论弓形虫慢性感染可能导致大鼠海马神经细胞凋亡,进而引起一定的认知功能障碍。

Changes of apoptosis and its related protein expressions of hippocampal neurons in rats with Toxoplasma gondii chronic infection

Objective To explore the changes of hippocampal neuron apoptosis,cell cycle progression and its related protein expressions in rats with Toxoplasma gondii infection.Methods Twenty male rats were randomly divided into 2 groups：a Toxoplasma intected group and normal control group.The rats in the Toxoplasma infected group were injected intraperitoneally with Toxoplasma gondii tachyzoites 107/ml× 2 ml to establish Toxoplasma infected models.At the end of 10th week,the percentage of the hippocampal neuron apoptosis in the rats suffered from Toxoplasma gondii was measured with flow cytometry（FCM）,and their cell cycle progression was measured with propidium iodide（PI）dying,and their mitochondrial membrane potential was measured with FCM under the Rhodamine 123 dying.The protein expressions of Cyt c and caspase-3 were detected with immunohistochemical methods.Results Compared with the normal controls,the cell percentage of the hippocampal neuron apoptosis in the Toxoplasma infected rats at the end of the 10th week increased significantly（P0.05）;the cell percentage of G0/G1 phase increased significantly （40.1±11.2）% vs（49.3±13.6）%,P0.05],while the cell percentage of S phase decreased significantly（P0.05）;the mitochondrial membrane potential decreased significantly （25.4±9.4）% vs（22.1±6.8）%,P0.05）,and the expressions of caspase-3 and Cyt c proteins also increased significantly（P0.05）.Conclusion The Toxoplasma gondii chronic infection maybe results in the hippocampal neuron apoptosis,which might be the reason for the change of cognitive function disorder in the rats with Toxoplasma gondii chronic infection.