Astragaloside ? Repair Radiation-induced Brain Injury In Vivo Via NLRP3 Inflammatory Corpuscles And TLR4 Signaling Pathways

Central nervous system(CNS)damage caused by low dose Ionizing radiation(IR)is mainly due to oxidative stress caused by excessive ROS,and a large amount of evidence shows that ROS can activate inflammatory pathways.The inflammatory response of CNS is named neuroinflammation,which has been shown to be a cause of neurological diseases in both experimental and clinical studies.NOD like receptor3(NLRP3)is the most characteristic inflammatory corpuscule,mainly expressed by myeloid cells.NLRP3 is induced by stimulation of TLR activation,cytokines,and other signals.TLR4 is a unique pattern recognition receptor,widely existing in a variety of nerve cells,including Microglia,Astrocyte,Oligodendrocyte and hippocampal neurons.Activation of NLRP3 inflammatory body can affect the occurrence of inflammatory response.It can induce inflammation through the perception and combination of pathogen-associated molecular patterns(PMAPs).Astragaloside IV(AS-IV)is one of the main active substances of Astragaloside.More and more evidences have shown that AS-IV has a prominent effect in treating inflammatory response and oxidative stress.the synapse effect of AS-IV in the treatment of inflammation and oxidative stress.However,whether AS-IV can inhibit the activation of NLRP3 in the brain caused by Ionizing radiation(IR)has not been reported.To explore this issue,in this study,we use paraffin section immunohistochemistry to detect the effect of Astragaloside IV on the expression of microglias,astrocytes,TLR4 and NLRP3 in brain tissue of radiation-injured mice;and we use western blotting to detect the effect of Astragaloside IV on NLRP3 inflammatory corpuscles and TLR4 signaling pathway expressionin in brain tissues of radiation-injured mice.Main results were as follows.Immunohistochemical detection showed that after radiation treatment,the MG cell body became larger,the branches became coarser and shorter;The positive cells in the intervention group of Astragaloside IV were less than those in the radiation group,and the cell morphology tended to be normal.In the radiation group,thenumber of GFAP-labeled positive cells was significantly increased and concentrated around the hippocampus.The labeled astrocytes were hypertrophy with obvious process overlap.The group of astragaloside IV could significantly down-regulate the expression of GFAP.TLR4 positive cells of neurons in the hippocampal dentate gyrus area were significantly increased in the radiation group,and the expression of TLR4 positive cells was decreased in the astragalus intervention group.NLRP3 positive cells were significantly increased in the cortex of the radiation group,Astragalus intervention group can reduce its expression.Compared with Control group,the protein expression of TLR4 in the radiation group extremely significantly increased(P<0.001),the amount of protein expression IKB-? significantly reduced(P<0.001),NF-kB p65,p-p65,TNF-? and the expression IL-6 protein significantly increased(P<0.001,P<0.01,P<0.01,P<0.01),the astragalus group significantly changed this trend,it indicats that Astragaloside IV can significantly inhibit the activation pathway of TLR4 in the body of radiation-induced.Western blotting also showed that the protein expressions of NLRP3 and caspase-1 and the protein expression of IL-1? were significantly increased after radiation treatment compared with the Control group,having significant differences(P<0.05 or P<0.01),and The group of Astragaloside IV can evidently restrain the expression of inflammasome proteins.The expression of NLRP3 and caspase-1 in the IR+AS-L group decreased significantly compared with the IR group(P<0.05 or P<0.01),and it exhibits dose dependence.This indicates that Astragaloside IV can inhibit the physiological effects of NLRP3-caspase-1-IL-1pathway.Overview,This experiment showed that radiation can cause activation of microglia and astrocytes,activate the NLRP3 and TLR4 signaling pathways,and Astragaloside IV can inhibit the activation of microglia and astrocytes,and by inhibiting the activation of NLRP3 inflammasome and the signaling pathway of TLR4 to play a neuroprotective effect on radiation-induced brain injury,this test provides new train of thought and basic data for Astragaloside IV treatment of neurologicaldisease cased by radiation damage.