Effects of fluorine exposure on miR-204 and BDNF-TrkB pathways in HT22 hippocampal neurons / 中华地方病学杂志

ABSTRACT

Objective:To explore the changes of microRNA (miRNA, miR)-204, brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB) expression levels in HT22 hippocampal neurons exposed to fluorine.Methods:The HT22 cells were exposed to NaF at 0, 2, 4, 6, 8, 10 mg/L. After 24 h, the cell viability was detected by CCK-8. According to the cell survival rate, the NaF concentrations [0.0 (control), 2.5, 5.0 and 10.0 mg/L] were selected for subsequent experiments. The infected (without transfection) and transfected (with the addition of miR-204 agonist) HT22 cells were both exposed to NaF for 24 h. The miR-204, BDNF and TrkB mRNA expression levels in cells were detected by Real time fluorescence quantitative PCR(qRT-PCR); the BDNF and TrkB protein expression levels in cells were detected by Western blotting.Results:Compared with the control group, the cell viabilities in fluorine exposure groups were decreased ( P < 0.01). In the infected groups, compared with the control group, and the miR-204 expression levels were increased ( P < 0.05 or < 0.01). The expressions of BDNF mRNA were decreased in fluorine exposure groups at 5.0 and 10.0 mg/L ( P < 0.01) and the BDNF protein expressions were decreased in all fluorine exposure groups ( P < 0.05 or < 0.01). In the exposure groups, TrkB mRNA expressions were decreased ( P < 0.05 or < 0.01). The TrkB protein expressions were decreased in fluorine exposure groups at 5.0 and 10.0 mg/L ( P < 0.01). In the transfected groups, compared with the control group, the expressions of miR-204 were increased ( P < 0.01) and the mRNA and protein expressions of BDNF and TrkB were decreased ( P < 0.01). The negative correlation was found between NaF concentration and cell survival rate ( r = - 0.989, P < 0.01). Moreover, the mRNA and protein expressions of BDNF and TrkB were negative correlated with NaF concentration ( r = - 0.746, - 0.853, - 0.889, - 0.827, P < 0.01). A positive correlation was found between NaF concentration and miR-204 expression ( r = 0.889, P < 0.01). However, the mRNA and protein expressions of BDNF and TrkB were negative correlated with miR-204 expression ( r = - 0.766, - 0.770, - 0.594, - 0.523, P < 0.01). The positive correlations were found between BDNF mRNA and protein expressions and those of TrkB ( r = 0.657, 0.869, P < 0.01). Conclusion:Fluorine has inhibited the cell activity of HT22, and the mechanism of action may be related to the inhibition of BDNF-TrkB pathway after up-regulation of miR-204 expression.