大气颗粒物与高脂高糖饮食对雄性大鼠大脑皮质及海马组织中CREB、BDNF、ERK1/2基因表达的影响

Effects of atmospheric particulate matters and high-fat and high-glucose diet on mRNA expressions of CREB, BDNF, and ERK1/2 in cerebral cortex and hippocampus in male rats

[背景]大气颗粒物污染和高脂高糖饮食均与认知功能、神经退行性疾病发病相关,但研究两者的联合作用文献报道较少。[目的]研究大气颗粒物与高脂高糖饮食对雄性大鼠认知功能及大脑皮质和海马组织中环磷腺苷效应元件结合蛋白(CREB)、脑源性神经营养因子(BDNF)和细胞外调节蛋白激酶(ERK)1/2基因表达的影响。[方法] 3周龄SD雄性大鼠48只,随机分为对照组(普通饲料喂养,无大气颗粒物暴露,CC组)、高脂高糖组(高脂高糖饲料喂养,无大气颗粒物暴露,HC组)、大气颗粒物组(普通饲料喂养,暴露大气颗粒物,CP组)和高脂高糖大气颗粒物暴露组(高脂高糖饲料喂养,暴露大气颗粒物,HP组)。通过独立通气笼盒,CP和HP大鼠自然吸入含大气颗粒物的空气,CC和HC组大鼠自然吸入通过高效过滤器过滤大气颗粒物的空气(空气动力学直径>0.1 μm大气颗粒物被过滤掉)。暴露结束采用旷场实验评价大鼠的认知功能,采用RT-qPCR检测海马组织与大脑皮质组织中CREB、BDNF、ERK1和ERK2 mRNA表达。组间比较采用单因素方差分析,交互作用采用析因方差分析。[结果]与CC组相比,CP组大鼠跨格次数减少为(46.60±16.55)次,HP组大鼠活动总路程、跨格次数降低至(163.17±32.54)m和(43.40±8.40)次,中央区活动时间升高至(7.58±1.27)s(均P < 0.05)。HC组大鼠大脑皮质CREB、ERK2,CP组的CREB、ERK2,HP组的CREB、ERK1、ERK2和BDNF mRNA表达水平均低于CC组(P < 0.05);HP组大脑皮质中CREB、BDNF mRNA表达水平均低于HC组(P < 0.05);HP组大脑皮质中CREB、ERK1、BDNF mRNA表达水平均低于CP组(P < 0.05)。HC组大鼠海马组织ERK2,CP组CREB、ERK2,HP组中4种基因的mRNA表达水平均低于CC组(P < 0.05);HP组海马组织中4种基因的mRNA水平均低于HC组(P < 0.05);HP组海马组织中ERK1和BDNF mRNA表达水平均低于CP组(P < 0.05)。析因方差分析结果显示,大气颗粒物与高脂高糖饮食对雄性大鼠总路程、跨格次数、中央区活动时间以及大脑皮质和海马组织中CREB mRNA表达的影响不存在交互作用(均P > 0.05)。[结论]一定浓度的大气颗粒物以及高脂高糖饮食单独暴露可降低大脑皮质和海马组织中CREB、BDNF和ERK1及ERK2基因表达水平,尚未发现二者具有联合作用。

[Background] Both atmospheric particulate matter pollution and combined high-fat and highglucose diet are related to cognitive function and neurodegenerative diseases, but there are few reports on the synergistic effect of the two factors.[Objective] The study is conducted to investigate the effects of atmospheric particulate matters and combined high-fat and high-glucose diet on the mRNA expressions of cAMP-response element binding protein (CREB), brain derived neurotrophic factor (BDNF), extracellular regulated protein kinases 1 (ERK1), and extracellular regulated protein kinases 2 (ERK2) in cerebral cortex and hippocampus in male rats.[Methods] A total of 48 male SD rats aged three weeks were randomly divided into four groups:control group (normal feed, no atmospheric particulate matter exposure, CC group), high-fat and high-glucose diet group (high-fat and high-glucose feed, no atmospheric particulate matter exposure, HC group), atmospheric particulate matter exposure group (normal feed, atmospheric particulate matter exposure, CP group), and atmospheric particulate matter exposure plus high-fat and high-glucose diet group (high-fat and high-glucose feed, atmospheric particulate matter exposure, HP group). In independent ventilation cages, the rats in the CP and HP groups inhaled air containing atmospheric particulate matters, while the rats in the CC and HC groups inhaled air filtered by high efficiency filters (atmospheric particulate matters with aerodynamic diameter >0.1 μm were filtered out). Rats' cognitive function was measured by open field test after the three-month exposure. The mRNA expressions of CREB, BDNF, ERK1, and ERK2 in hippocampus and cerebral cortex were detected by RT-qPCR. One-way ANOVA was used for comparison between groups, and factorial ANOVA was used for interaction effects.[Results] The average number of grid crossings of rats in the CP group was 46.60±16.55, and the total distance and the number of grid crossings of rats in the HP group were (163.17±32.54)m and 43.40±8.40, respectively, all lower than those in the CC group;the time spent in the central grid in the HP group[(7.58±1.27) s] was higher than that in CC group (Ps < 0.05). In cerebral cortex:the mRNA expression levels of CREB and ERK2 in the HC group, CREB and ERK2 in the CP group, as well as CREB, ERK1, ERK2, and BDNF in the HP group were all lower than those in the CC group (P < 0.05);the mRNA expression levels of CREB and BDNF in the HP group were lower than those in the HC group (P < 0.05);the mRNA expression levels of CREB, ERK1, and BDNF in the HP group were lower than those in the CP group (P < 0.05). In hippocampus:the mRNA expression levels of ERK2 in the HC group, CREB and ERK2 in the CP group, as well as the four genes in the HP group were all lower than those in the CC group (P < 0.05);the mRNA expression levels of the four genes in the HP group were lower than those in the HC group (P < 0.05);the mRNA expression levels of ERK1 and BDNF in the HP group were lower than those in the CP group (P < 0.05). The results of factorial ANOVA showed that there was no interaction between atmospheric particulate matter and combined highfat and high-glucose diet on the total distance, the number of grid crossings, the time spent in the central grid, and the mRNA expression levels of CREB in cerebral cortex and hippocampus in male rats (Ps> 0.05).[Conclusion] Particulate matters at certain levels and combined high-fat and high-glucose diet may separately reduce the mRNA expressions of CREB, BDNF, ERK1, and ERK2 in cerebral cortex and hippocampus in male rats, but the synergistic effects of the two factor have not been observed.