基于NLRP3炎症小体探究氟暴露诱导小鼠抑郁样行为的分子机制OA

This study aimed to investigate the molecular mechanisms underlying fluoride exposure induced depression-like behavior in mice based on the NOD-like receptor thermal protein domain associated protein 3(NLRP3)inflammasome.Sixty C57BL/6J mice were randomly divided into four groups:Control group,25 mg/L fluoride group,50 mg/L fluoride group,and 100 mg/L fluoride group.Control group was given distilled water,while the fluoride groups received sodium fluoride in drinking water at the respective concentrations for 90 days.Behavioral tests,including the forced swim test and tail suspension test,were conducted on six mice per group to assess depression-like behavior.Blood-brain barrier permeability was evaluated using Evans blue staining,hippocampal histopathological changes were observed with hematoxylin-eosin(H.E.)staining,and alterations in the tryptophan-kynurenine pathway were measured using enzyme-linked immunosorbent assay(ELISA).Real-time fluorescent quantitative polymerase chain reaction(qPCR)was used to determine mRNA expression levels of depression-related genes,inflammatory cytokines,and NLRP3 inflammasome-related genes in brain tissue,followed by Pearson correlation analysis among all parameters.The results showed that,compared with the Control group,exposure to 100 mg/L fluoride significantly induced depression-like behavior in mice(P<0.05),the Evans blue content in the brain tissues of mice exposed to 50 and 100 mg/L fluoride increased significantly(P<0.01 or P<0.001),indicating disruption of the blood-brain barrier.In the hippocampal regions—CA1,CA2,CA3,and dentate gyrus(DG)—of all three fluoride-exposed groups,neurons exhibited varying degrees of disordered arrangement,widened intercellular spaces,nuclear condensation and shrinkage,hyperchromasia,and blurred nuclear membranes.Compared with the Control group,exposure to 50 and 100 mg/L fluoride significantly increased indoleamine 2,3-dioxygenase(IDO)activity and kynurenine(KYN)content,while decreasing tryptophan(TRP)and 5-hydroxytryptamine(5-HT)levels(P<0.05,P<0.01,or P<0.001),leading to dysregulation of the tryptophan-kynurenine metabolic pathway.The mRNA expression of depression-related genes—brain-derived neurotrophic factor(BDNF),glutamate decarboxylase 67(GAD67),and vesicular GABA transporter(VGAT)—was extremely significantly downregulated(P<0.01 or P<0.001),while the mRNA expression of inflammatory cytokines interleukin-18(IL-18)and interferon-γ(IFN-γ)was significantly upregulated(P<0.05 or P<0.01).In addition,exposure to 100 mg/L fluoride markedly upregulated the mRNA expression of NLRP3 inflammasome-related factors,including NLRP3,cysteine-dependent aspartate-directed protease-1(Caspase-1),and apoptosis-associated speck-like protein containing a CARD(ASC)(P<0.01 or P<0.001).Correlation analysis revealed that the NLRP3 inflammasome showed significant correlations with all other measured indicators(P<0.05,P<0.01,or P<0.001).In summary,fluoride exposure can induce depression-like behavior in mice,which may be associated with NLRP3-mediated neuroinflammation and dysregulation of the tryptophan-kynurenine metabolic pathway.