Ferulic Acid Produces Neuroprotection Against Radiation-induced Neuroinflammation By Affecting NLRP3 Inflammasome Activation

Objective:Radiation cognitive impairment that characterized by hippocampal-dependent learning and memory deficits is a serious complication after brain radiotherapy.Neuroinflammation mediated by microglia is a critical event that accelerates the cognitive or functional decline.Ferulic acid（FA）,a phenolic plant component,is a main pharmacodynamic material basis of Siwutang.Our previous studies showed that FA could effectively improve bone marrow suppression in irradiated mice and alleviate radiation-induced intestinal injury.The purpose of the current study was to observe the protective effect and relevant mechanisms of FA on radiation-induced neuroinflammation.Method:The radiation injury models in mice and cells were established by ⁶⁰Co-γray.（1）The learning and memory level in mice was detected by the Morris water maze test.（2）The pathological changes of hippocampal tissue were observed by HE staining.（3）The viability of BV-2 cells was detected by CCK-8 assay and the cell morphology changes were observed using an inverted microscope after detection.（4）The Iba-1 and NLRP3 expression in BV-2 cells was detected by Immunofluorescence assay.（5）The m RNA transcription level of inflammatory factors in the hippocampus and BV-2 cells was detected by Q-PCR assay.（6）The protein expression of inflammatory factors in the hippocampus and BV-2 cells was detected by Western blot assay.（7）After gene NLRP3 was knocked down by si RNA technology,the effect of FA on transcription and expression level of inflammatory factors were detected by Q-PCR and Western blot assay in BV-2 cells after radiation,and the mechanism of inflammation was further verified.Result:（1）The Morris water maze test showed that FA effectively improved the decline of learning and memory in irradiated mice.（2）The results of HE staining test showed that FA effectively alleviated pyramidal cells shrinkage and granulosa cells’nuclear concentration and hyperchromatism in the hippocampus after radiation.（3）Based on the results of CCK-8 test,Western blot and cell morphological changes,BV-2cells were treated at 24 h after 8 Gy radiation to establish the cell radiation damage model and 2.5,5,10μmol/L FA was determined to be used in the subsequent experiments.（4）The results of the Immunofluorescence assay showed that FA could inhibit the activation of BV-2 cells and expression of NLRP3 in BV-2 cells after radiation.（5）The results of Q-PCR assay showed that FA could reduce increasing m RNA transcription of inflammatory factors in hippocampal tissue and BV-2 cells after radiation.（6）The results of Western blot assay showed that FA could reduce increasing protein expression of inflammatory factors in hippocampal tissue and BV-2 cells after radiation.（7）After effectively knocking down the gene NLRP3,the inhibitory effect of FA on inflammatory cytokines expression in BV-2 cells after radiation was significantly weakened.Conclusion:This study demonstrated that FA targeted NLRP3inflammasome to produce neuroprotection against radiation-induced nerve injury.Moreover,these findings suggested that FA might hold promising therapeutic potential for radiation cognitive impairment.