PM_(2.5)亚急性暴露对糖尿病小鼠主动脉收缩功能的影响

Subacute effects of fine particulate matter on vasoconstriction function of aorta in a diabetic mouse model

目的探讨PM_(2.5)亚急性暴露对糖尿病小鼠血管收缩功能的影响及可能机制。方法 24只8周龄SPF级C57BL/6小鼠腹腔注射链脲佐菌素连续5 d,建立糖尿病小鼠模型。以异氟醚吸入麻醉,采用口咽误吸法分别给予对照组50μl dd H_2O,暴露组50μl 1mg/ml PM_(2.5)悬液,两组均为12只,每周2次,连续3周。用支气管肺泡灌洗分析灌洗液细胞成分及总蛋白浓度;用压力肌动图系统观察胸主动脉对血管收缩剂去氧肾上腺素(PE)的收缩反应;用Taq Man探针法进行q RTPCR分析,比较两组小鼠主动脉肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)及超氧化物歧化酶2(SOD2)m RNA表达。结果 PM_(2.5)暴露组小鼠肺部出现明显的中性粒细胞浸润和蛋白渗漏,表现出明显的炎症反应。压力肌动图结果显示,PM_(2.5)暴露组小鼠主动脉对不同浓度PE的收缩率高于对照组,EC_(120)低于对照组,差异均有统计学意义(P<0.01)。q RTPCR结果显示,PM_(2.5)暴露组小鼠主动脉TNF-α、IL-6和SOD2 m RNA表达明显高于对照组,差异有统计学意义(P<0.05或P<0.01)。结论 PM_(2.5)亚急性暴露可增强糖尿病小鼠主动脉的收缩功能,促进主动脉炎症因子的表达,这可能是PM_(2.5)促进糖尿病人群心血管疾病发生的机制之一。

Objective To explore the subacute effects of fine particulate matter （PM2.5） on vasoconstriction function of aorta in a diabetic mouse model. Methods A total of 24 eight-week old C57BL/6 mice were injected intraperitoneally （i.p.） with 60 mg/（kg .d） of STZ to induce diabetes mellitus in mice, which was confirmed by fasting glucose levels above 2 500 mg/L. Mice were anesthetized with isoflurane and given 50μl aqueous suspension of PMzs extract （lmg/ml） for exposure or 50μl ddH20 for control v/a oropharyngeal aspiration twice a week for three weeks. Broncho-alveolar lavage fluid （BALF） was analyzed for cell differential and total protein levels. 2-mm long segments of aorta were cut and mounted on a 4-channel pressure myograph system. Phenylephrine （PE） was added in graded doses to evaluate vascular contractile function. The relative mRNA levels of TNF-ot, IL-6 and SOD2 were quantified using real-time PCR instrument with TaqMan~ Gene Expression Assay primer/probe sets. Results BALF from exposure group showed significant protein leakage and neutrophil infiltration, which revealed pulmonary inflammation. Myograph results showed that the percentage of PE-induced contraction was significantly higher in exposure group than the control group. Quantitative real time RT-PCR results indicated a significantly higher mRNA expression of TNF-ct, IL-6 and SOD2 in mice exposed to PM2.5 as compared to control mice. Conclusion Subacute exposure to PM2.5 can augment the vasoconstriction function of aorta in a diabetic mouse model and induce the mRNA expression of inflammatory factors, which may be an important mechanism explaining susceptibility to cardiovascular effects associated with PM2.5 exposure among people with diabetes.