The Effect Of PM_2.5 Combined With High Fat Diet On TNF-α Mediated Neuroinflammatory Response In Cerebral Cortex Of Rats Offspring

Objective To observe the neuroinflammatory response of rats exposed to PM_2.5and high-fat diet（HFD）during pregnancy and lactation,and to explore the molecular mechanism of neuroinflammatory response of rats exposed to PM_2.5and HFD through TNF-α pathway,so as to reveal the interaction between PM_2.5and HFD.Methods Adult SD rats were mated according to the ratio of male and female 2:1.Pregnant rats were randomly divided into control group,high fat diet group,PM_2.5low exposure group,PM_2.5high exposure group,HFD+PM_2.5low exposure group and HFD+PM_2.5high exposure group.Control group,low exposure group and high exposure group were fed with common feed,the rest were fed with HFD.PM_2.5was exposed to PM_2.5by on-line concentration of fine particles and animal exposure system.The low and high exposure doses of PM_2.5were set as twice and four times of the outdoor atmospheric PM_2.5concentration respectively.The mother rats were exposed to PM_2.5for 5 hours a day and 5 days a week from the 0 day of pregnancy.After being born,the pups and their mother were fed together until the 21 st day（postnatal day,PND21）.Then the young rats were fed with common feed and exposed to PND60.The food intake of pregnant rats was recorded.The changes of body length and tail length of offspring were recorded.The contents of metal elements in PM_2.5and the cerebral cortex in different developmental stages（PND21,PND42,PND60）were analyzed by inductively coupled plasma mass spectrometry（ICP-MS）during the experiment.The contents of IL-6 and TNF-α in the serum of the offspring were detected by enzyme-linked immunosorbent assay（ELISA）.The protein expression levels of TNF-α,TNFR1,TNFR2,t-NF-κB p65 and phosphorylated NF-κB p65 in the cerebral cortex were determined by Western blot.Results 1 The concentrations of PM_2.5in clean room,outdoor air,low and high dose exposure in cabinet during the period were（3.52±1.73）,（60.59±21.37）,（127.38±43.16）and（256.45±81.34）μg/m³,respectively.2 Compared with the control group,the food intake of HFD group,HFD+low exposure group and HFD+high exposure group during pregnancy and lactation period decreased.3 Compared with the control group,the body length of PND21 pups HFD group,HFD+low exposure group,HFD+high exposure group increased（P<0.05）.Compared with the low exposure group,the tail length of the PND21 HFD+low exposure group female pups increased（P<0.05）.4 The order of metal elements in atmospheric PM_2.5during exposure: aluminum>lead>manganese>chromium>arsenic>nickel>selenium>antimony>cadmium>thallium.5 Compared with control and HFD group,the aluminum and lead content in the cerebral cortex of PND0 other groups increased（P<0.05）.The content of aluminum,manganese and chromium in offsprings of PND21 high-dose group and HFD+high-dose group was higher than that of control group（P<0.05）.The content of aluminum and nickel in offsprings of PND42,PND60 high-dose group and HFD+high-dose group was higher than that of control group（P<0.05）.The content of chromium in offsprings of PND21 HFD+high-dose group was higher than that of control group（P<0.05）.The content of manganese and arsenic in the high-dose,HFD+high-dose groups of male offsprings of PND60 was higher than that in the control group（P<0.05）.The content of selenium in the high-dose,HFD+high-dose groups of PND42 and PND60 was higher than that in the control group（P<0.05）.The content of lead in other groups of offsprings in each stage was higher than that in the control group（P<0.05）.6 PM_2.5and HFD increased the levels of TNF-α in serum of PND21 pups and PND42 male rats（P<0.05）.PM_2.5and HFD increased the levels of IL-6 in serum of rats in PND21 and PND42（P<0.05）.PM_2.5and HFD had synergistic effect on IL-6 content of PND21 male pups（P<0.05）.PM_2.5increased the level of TNF-α in serum of PND60 male rats（P<0.05）.PM_2.5increased the level of IL-6 in serum of PND60 pups（P<0.05）.7 PM_2.5and HFD increased the expression levels of TNFR1,TNFR2 protein of PND21 male offspring and the NF-κB p65 protein of PND21 pups in the cerebral cortex（P<0.05）.Low-dose PM_2.5and HFD have antagonistic effects on the expression level of TNFR1 protein and a synergistic effect on the expression level of TNFR2 protein in the cerebral cortex of PND21 male offspring（P<0.05）.High-dose PM_2.5and HFD have a synergistic effect on the expression level of TNFR1 protein and an antagonistic effect on the expression level of TNFR2 protein in the cerebral cortex of PND21 male pups（P<0.05）.PM_2.5increased the expression levels of TNFR1 of PND42 male pups and TNFR2,p-NF-κB p65 of PND42 female pups in the cerebral cortex（P<0.05）.HFD increased the expression levels of TNF-α,TNFR1,TNFR2 of PND42 male pups and TNFR2,p-NF-κB p65 protein of PND42 female pups in the cerebral cortex（P<0.05）.Low doses of PM_2.5and HFD have antagonistic effects on the expression levels of TNF-α and TNFR1 protein in the cerebral cortex of PND42 male pups（P<0.05）.High doses of PM_2.5and HFD have a synergistic effect on the expression levels of TNF-α and TNFR1 protein in the cerebral cortex of PND42 male pups（P<0.05）.PM_2.5and HFD have a synergistic effect on the expression levels of TNFR2 and t-NF-κB p65 protein in the cerebral cortex of PND42 male pups（P<0.05）.PM_2.5increased the expression levels of TNF-α,t-NF-κBp65 of PND60 pups and increased the expression levels of TNFR2,p-NF-κB p65 protein of PND60 female pups in the cerebral cortex（P<0.05）.HFD increased the expression levels of TNF-α of PND60 pups and TNFR1,p-NF-κB p65 of PND60 male pups in the cerebral cortex（P<0.05）.Conclusions 1 Combined exposure of PM_2.5and high-fat diet can cause systemic inflammation and neuroinflammation in rat pups,especially in male offspring.2 PM_2.5and high-fat diet increased the expression of TNF-α and its receptors in the cerebral cortex of the offspring.The combined effects of different doses of PM_2.5and high-fat diet on the expression of TNF-α,TNFR1 and TNFR2 in the cerebral cortex of the offspring varied.3 PM_2.5combined with high-fat diet can activate NF-κB signal pathway in cerebral cortex of offspring rats through TNF-α,and cause inflammatory damage.There is a synergistic effect between PM_2.5and high-fat diet.Figure 5;Table 24;Reference 122...