The Mechanism Of Sodium Butyrate Improving Learning And Memory Impairment In Fluorosis Mice Through Glycolysis Pathway

ObjectiveExcessive fluoride often exists in natural water sources,and long-term excessive intake is easy to induce chronic fluorosis.Fluorosis is a major public health problem in many countries around the world,including China.High concentrations of fluorine can accumulate in the brain through the blood-brain barrier,causing severe neurotoxicity such as neuronal apoptosis,chronic inflammatory reactions,and learning and memory impairment.Sodium butyrate is a histone deacetylase inhibitor,which has important research potential in the correction of glucose metabolism disorders.It has been confirmed that it can correct cognitive disorders,learning and memory disorders,emotional disorders,etc.,in a variety of neurological diseases.However,whether it can improve the learning and memory impairment of fluorosis remains unclear.The purpose of this study was to investigate the effect of sodium butyrate on the neurotoxicity of fluoride,and to explore the specific mechanism of the neuroprotective effect of sodium butyrate based on glycolytic metabolism,so as to provide more theoretical basis for the treatment of nervous system injury caused by fluoride poisoning.Method50 mice were randomly divided into five groups:control group(C),fluorosis group(F),sodium butyrate group(SB),fluorosis+low-dose sodium butyrate group(F+S1),fluorosis+high-dose sodium butyrate group(F+S2),with 10 mice in each group.Mice in groups F,F+S1 and F+S2 were given free drink of 100mg/L fluorine-containing distilled water daily,while mice in groups C and S were given distilled water.After fluoride exposure lasted for 3 months,sodium butyrate was administered intragastric administration.Mice in group SB and F+S2 were intragastric administration of 1000mg/kg sodium butyrate daily,mice in group F+S1 were intragastric administration of 500mg/kg sodium butyrate daily,mice in group C and F were intragastric administration of isodose normal saline for 8 weeks,during which fluoride concentration remained unchanged.Morris water maze test was used to detect the spatial learning and memory ability of mice.Weigh and weigh your brain;The incidence and degree of dental fluorosis were observed.Fluoride ion selective electrode was used to detect the fluorine content in blood and urine.HE staining was used to detect the pathological changes in the DG,CA1 and CA3 regions of the hippocampus.The protein abundance of glycolytic enzymes PKM2,LDH,HK,tricarboxylic acid circulating enzymes PDH,MDH,and glycolytic related pathways PI3K,AKT,P-AKT and HIF-1 α were detected by Western Blot.PK,LDH,HK activities,lactic acid and ATP contents were detected by biochemical kit.Results1.The mice model of sodium butyrate antagonism against fluorosis was established.Compared with mice in group C and group SB,the weight,brain weight,and incidence of dental fluorosis of mice in group F were higher.Compared with mice in group F,the weight and brain weight of mice in the high-dose sodium butyrate treatment group were recovered.Fluoride concentration in serum and urine of mice was detected by fluoride ion selective electrode method.The results showed that there were significant fluoride accumulation in serum and urine of three fluorine-infected groups,group F,F+S1 and F+S2.2.The results of Morris water maze showed that in the positioning navigation experiment,compared with group C,the escape latency of mice in group F was prolonged on the third and fourth days(p<0.05),while the escape latency of mice in group F+S2 was significantly shortened compared with group F(p<0.05).In the space exploration experiment,compared with C,the number of piercing of mice in group F decreased and the proportion of their retention time in the target quadrant decreased(p<0.05);compared with group F,the number of piercing of mice in group F+S2 increased and the proportion of their retention time in the target quadrant increased(p<0.05).In addition,there was no significant difference in swimming speed among the groups,and the exercise ability of the groups was not affected.3.HE staining results showed that nerve cells in the DG region,CA1 region and CA3 region of the hippocampus of mice in group C and group S were closely arranged,with distinct layers,normal cell morphology and distinct structure.Compared with C,the arrangement of nerve cells in the CA3 region of mice in group F was looser,and nucleolysis and deep staining appeared,and the space between nerve cells in the CA1 region was wider and looser.The number of nerve cells in DG region decreased.Compared with mice in F group,the reduction of nuclear consolidation in CA3 region was less in F+S1 and F+S2 groups,the space and arrangement of nerve cells in CA1 region were basically similar to the control group,and the number of nerve cells in DG region was increased.4.Western blotting results showed that compared with group C,the abundations of glycolytic enzymes PKM2,LDH and HK proteins in the hippocampus of group F were decreased,while the abundations of glycolytic negative regulatory proteins MDH and PDH proteins were increased.The protein abundance of PKM2,LDH,HK,MDH and PDH in hippocampus of mice in high-dose sodium butyrate antagonistic group basically recovered to the levels of control group(p<0.05).In addition,we also detected changes in the expression of PI3K/AKT/HIF-1α in the glycolytic pathway,and the results showed that the expressions of PI3K,P-AKT/AKT and HIF-1α in the hippocampus of mice in group F were decreased.The PI3K/AKT/HIF-1α signaling pathway was activated by 500 and 1000mg/kg sodium butyrate(p<0.05).5.The results of biochemical kit showed that compared with group C,the activities of PK,LDH and HK in the hippocampus of group F were decreased,and the contents of lactic acid and ATP were decreased(p<0.05).Compared with F group,the activities of PK,LDH and HK in F+S2 group were increased,and the contents of lactic acid and ATP were increased(p<0.05).Conclusion1.Subchronic fluoride exposure can lead to decreased body weight,brain weight and hippocampal weight,and fluoride accumulation in serum and urine in mice.2.Subchronic fluoride exposure can cause learning and memory dysfunction in mice and induce histopathological changes in hippocampus.3.The PI3K/AKT/HIF-1α signaling pathway and glycolysis were inhibited in the hippocampus of subchronic fluoride exposure rats.4.Sodium butyrate can play a neuroprotective role by promoting the inhibition of hippocampal glycolysis in mice exposed to sub chronic fluoride,and the antagonistic effect is more obvious at 1000mg/kg.