| [Objective] Fluorosis is a widespread endemic disease.Studies have shown that fluorine can damage the nervous system and function of animals.In this study,the properties of transcriptome sequencing with high sensitivity and high throughput were utilized,and hippocampal transcriptome was used as the entry point to explore the specific mechanism of the effect of exercise on the learning and memory ability of fluorosis mice,and to provide evidence for prevention and treatment of fluorosis.[Methods] One hundred and thirty-six adult female ICR mice were randomly divided into 4 groups: control group(distilled water by gavage);Exercise group(gavage distilled water and treadmill exercise);Fluoride group(gavage 24mg/kg NaF);the treadmill running fluoride group(gavage 24mg/kg NaF and treadmill exercise).After 8 weeks,the learning and memory ability,hippocampal morphological structure and hippocampal RNA transcriptome of mice in each group were tested by eight-arm maze,HE staining,nissl-staining,immunohistochemistry and transcriptome sequencing,so as to explore the influence of exercise on the learning and memory ability of fluorosis mice.[Results](1)On the first day of the test,there was no significant difference between the groups in reference memory errors and working memory errors.On the second day of the test,compared to the control group,the reference memory errors and working memory errors were significantly reduced in the exercise group(p < 0.05,p < 0.01).The reference memory errors and working memory errors in the treadmill running fluoride group were still not statistically significant(p > 0.05)compared to the fluoride group.On the third day of the test,compared to the fluoride group,the reference memory errors and working memory errors were significantly reduced in the treadmill running fluoride group(p < 0.05,p < 0.01).(2)HE results showed that the neurons in the hippocampal regions of the control group were neatly arranged and dense,with normal cell morphology,clear contour and dyeing uniformity.However,the nerve cells in the hippocampal areas of the mice in the fluoride group were irregular in shape and arrangement,with unclear cell structure and uneven staining,and the granular cells in the hippocampal dentate gyrus of the mice in this group were irregularly solidified and atrophic.The cell morphology of the hippocampus was improved in the treadmill running fluoride group(3)Nissl results showed that the neurons in the hippocampal regions of the control group were distributed in a neat and dense manner,abundant nissl was observed in the cytoplasm,and the nuclei were large and round,with more nissl particles around.In the fluoride group,the neurons in the hippocampus were disordered,and the intracytoplasmic nidosomes decreased or disappeared.The structure of the nerve cells was clear in the hippocampal area of the mice in the treadmill running fluoride group.Compared to the control group,the number of surviving neurons in the DG area,CA1 area and CA3 area of the hippocampus in the fluoride group showed a decreasing trend,and the difference was not significant(p > 0.05).The number of surviving neurons in the DG and CA3 areas of the hippocampus of the treadmill running fluoride group was significantly higher than that of the fluoride group(p < 0.05),and the number of surviving neurons in the CA1 area was not significantly higher than that of the fluoride group(p > 0.05).(4)Compared to the control group,the number of M1-type microglia cells in the hippocampal areas of the exercise group decreased,but there was no significant difference(p > 0.05).However,the number of M1-type microglia in the DG area of the hippocampus of mice in the fluoride group showed an increasing trend,and there was no statistical significance(p > 0.05);the number of M1-type microglia in the CA1 and CA3 of the hippocampus of mice in the fluoride group was significantly higher than that in the control group(CA1: p < 0.05;CA3: p < 0.01).Compared to mice in the fluoride group,the number of M1-type microglias in the hippocampal areas of mice in the treadmill running fluoride group was significantly reduced(DG: p < 0.05;CA1,CA3: p < 0.01).(5)According to the analysis of high-throughput sequencing results,576 genes were changed in the total RNA samples from the hippocampus of mice in the fluoride group compared to the control group,among which 283 genes were up-regulated and 293 genes were down-regulated.Compared to the fluoride group,the total RNA expression of 670 genes in the hippocampal of the the treadmill running fluoride group was changed,among which 338 genes were up-regulated and 332 genes were down-regulated.GO function analysis was performed on 543 differentially expressed genes in the hippocampus of the control group and the fluoride group,and 453 differentially expressed genes with functional significance in the GO classification were obtained.Among the components of biological processes,the GO enrichment level analysis of differentially expressed genes showed that these genes were related to biological processes such as transcriptional regulation,negative regulation of cell proliferation and angiogenesis.Among the cell components,the GO enrichment level analysis of the differentially expressed gene showed that it was related to the cell components such as postsynaptic membrane,golgi body membrane and lysosomal membrane.In the molecular functional classification,the GO enrichment level analysis of the differentially expressed genes showed that these genes were related to the molecular functions such as calcium ion binding,magnesium ion binding and calmodulin binding.GO function analysis was performed on 646 differentially expressed genes in the hippocampal tissues of the fluoride group and the treadmill running fluoride group,among which 538 differentially expressed genes had functional significance in the GO classification.Among the components of biological processes,GO enrichment level analysis of differentially expressed genes indicated that these genes were related to endocytosis,angiogenesis,cytosolic calcium concentration and other biological processes.In the cell components,the GO enrichment level analysis of the differentially expressed genes indicated that these genes were related to the cell components such as the postsynaptic membrane,apical plasma membrane and tube-base plasma membrane.In the molecular functional classification,the GO enrichment level analysis of the differentially expressed genes indicated that these genes were associated with the binding of zinc ions,calcium ions and magnesium ions.The KEGG gene functional pathway database showed that Neuroactive ligand-receptor interaction was the most reliable of the significantly enriched pathways between the fluoridated group and the fluoridated group,and this pathway was important for neural function.In this pathway,the genes related to learning and memory and in line with the change trend are Drd1a(dopamine receptor D1)and NMDA2B(glutamate receptor ionotropic,NMDA2B).Compared to the control group,the expression levels of Drd1 a and NMDA2 B in the fluorine group were decreased.Drd1 a and NMDA2 B expression levels were increased in the fluoridation group compared with the fluoridation group.[Conclusion] Fluoride exposure can cause the increase of reference memory error and working memory error in mice,while exercise can reduce the reference memory error and working memory error in fluorosis mice.In general,it can be concluded that exercise can promote the learning and memory ability of mice,and can alleviate the damage of learning and memory ability of fluorosis mice.The possible mechanism is that exercise can promote the survival of neurons,inhibit the over-activation of microglia cells by fluoride,and increase the expression of Drd1 a and NMDA2 B,so as to alleviate the nerve injury of fluorosis mice. |
PDF Full Text Request