苯并[a]芘致小鼠认知功能障碍中突触相关蛋白和EphA/EphrinA5的变化

Variations of synaptic associated proteins and EphA/EphrinA5 in mice with cognition deficits following benzo[a]pyrene treatment

[背景]苯并[a]芘(BaP)是一类广泛存在于环境中的污染物,可引起认知障碍,而认知功能与突触可塑性密切相关。[目的]探讨突触相关蛋白和促红细胞生成素产生肝细胞受体(EphA4、EphA5)及其配体(EphrinA5)在BaP致小鼠认知功能障碍中的变化,为研究BaP致认知障碍的作用机制提供新的思路。[方法]将40只SPF级8周龄雄性ICR小鼠随机分成4组,分别为溶剂对照组(植物油)以及0.5、2和10 mg·kg^(-1)BaP染毒组,每组10只,腹腔注射染毒,隔天染毒1次,共30次,持续60 d。溶剂对照组注射等体积的植物油。染毒结束用旷场实验检测小鼠在新环境中的中心停留时间和站立次数。用Western blotting检测小鼠大脑皮质中突触素(SYP)、突触后致密物质95(PSD95)、EphA4、EphA5和EphrinA5的蛋白表达。[结果]染毒结束后,各染毒组小鼠体重增重呈剂量依赖性降低。与溶剂对照组相比,10 mg·kg^(-1)BaP组小鼠平均体重增重减少5.78g(P<0.05)。旷场实验结果显示,与溶剂对照组比较,10 mg·kg^(-1)BaP组的小鼠在中心区停留的平均时间延长了34.42 s,而后肢站立次数减少了21.57次(P<0.05)。Western blotting结果显示,与溶剂对照组比较,10 mg·kg^(-1)BaP染毒组小鼠大脑皮质中SYP、PSD95和EphrinA5的蛋白表达量分别下降32.2%、34.8%和14.9%(P<0.05),EphA4、EphA5蛋白表达量分别升高41.3%和40.0%(P<0.05)。[结论]突触相关蛋白和EphA/EphrinA5可能与BaP致小鼠认知功能障碍有关。

[Background]Benzo[a]pyrene(BaP)is a kind of widespread pollutants in the environment,and can cause cognitive impairment.Cognitive function is closely related to synaptic plasticity.[Objective]This experiment investigates the changes of synaptic related proteins and erythropoietin-producing hepatocellular receptors(EphA4 and EphA5)and their ligand(EphrinA5)in mice with cognitive impairment induced by BaP,and to provide new ideas for the mechanism study on cognitive impairment induced by BaP.[Methods]Forty SPF 8-week-old male ICR mice were randomly categorized into four groups,including one solvent control group(vegetable oil)and three BaP-treated groups(0.5,2,and 10 mg·kg^(-1)BaP),10 mice per group.The treated groups were administered BaP at designed concentrations by intraperitoneal injection,once every other day,30 times in total for 60 d.The solvent control group was injected with the same amount of vegetable oil.After 60d,open field test was used to detect the average time spent in the central area and the number of rear up of mice in a new environment,and the protein expressions of synaptophysin(SYP),postsynaptic density 95(PSD95),EphA4,EphA5,and EphrinA5 in cerebral cortex were detected by Western blotting.[Results]After the designed BaP treatment,the weight gain of mice decreased in a dose-dependent manner.Compared with the solvent control group,the average weight gain of mice in the 10 mg·kg^(-1)BaP group decreased by 5.78 g(P<0.05).The results of open field experiment showed that compared with the solvent control group,the average time spent in the central area of mice in the 10 mg·kg^(-1)BaP group increased by 34.42 s,while the number of standing on hind limbs decreased by 21.57(P<0.05).The Western blotting results showed that the protein expressions of SYP,PSD95,and EphrinA5 in the 10 mg·kg^(-1)BaP group decreased by 32.2%,34.8%,and 14.9%respectively(P<0.05)compared with the solvent control group,while the protein expressions of EphA4 and EphA5 in the 10mg·kg^(-1)BaP group increased by 41.3%and 40.0%respectively(P<0.05).[Conclusion]Synaptic associated proteins and EphA/EphrinA5 proteins are probably correlated with the cognitive impairment in mice induced by BaP.