| Objective:The present study was designed to investigate the effect of trilobatin?TLB?on?-amyloid 25-35(A?25-35)-induced neuroinflammation in rats and further to explore its possible mechanism.Methods:SD rats were subjected to adaptive feeding for two weeks,and bilateral intracerebroventricular?ICV?injections of A?25-355-35 was applied to induce AD model.The sham group were injected with an equal volume of normal saline.Rats were randomLy divided into 7 groups:sham group?n=15?,sham+TLB 10 mg/kg group?n=15?,A?25-35group?n=15?,A?25-35+TLB 2.5 mg/kg group?n=15?,A?25-35+TLB 5 mg/kg group?n=15?,A?25-35+TLB 10 mg/kg group?n=15?,A?25-35+donepezil group?n=15?.Rats in the sham group and sham+TLB?10 mg/kg?group were injected with the volume–matched normal saline?NS?.After 14 consecutive days of gastric administration,by new object recognition experiment and Y-maze experiment were applied to evaluate the learning and memory ability.Morphological changes and neuronal damage of hippocampal neurons in rats were observed with Nissl staining.The contents of inflammatory factors IL-1?,IL-6and TNF-?were detected using ELISA assay.Immunohistochemical staining was employed to determine the rat hippocampal microglial marker IBA-1 expression and astrocyte marker GFAP expression.The HMGB-1,TLR4,MyD88 and TRAF6 protein expression in the hippocampus of rats and the phosphorylation level of p65-NF-?B were detected by Western blot analysis.Furthermore,the molecular docking technology was used to evaluate the binding energy of TLB with HMGB1.Results:There was no difference in learning and memory abilities between the sham group and the sham+TLB?10 mg/kg?group.The learning and cognitive memory ability of the rats in the model group was significantly impaired than those of sham group,and the new object recognition index and space exploration the free alternation rate were significantly reduced than those of sham group;the neurons of the hippocampal CA1,CA3and DG regions were disturbance,the nuclei were deeply stained and the phenomenon of contraction occurred,and the Nissl bodies number was markedly reduced than those of sham group;the number of positive IBA-1 and GFAP in the hippocampus of rats increased significantly than those of sham group;the inflammatory factors IL-1?,IL-6 and TNF-?levels significantly elevated;HMGB1,TLR4,MyD88,TRAF6 protein expression and phosphorylation of p65-NF-?B level significantly increased than those of sham group.However,TLB?2.5,5,10 mg/kg?markedly dose-dependently increased the new object discrimination index and the free alternating rate of spatial memory exploration;the hippocampal neurons were arranged neatly,and the cell structure was relatively complete and clear,and the neuron survivals number significantly enhanced in TLB?10 mg/kg?group than those of A?25-355-35 group;the positive numbers of IBA-1 and GFAP in the hippocampus of rats decreased significantly in TLB group than those of A?25-355-35 group;the inflammatory factor of IL-1?,IL-6 and TNF-?markedly reduced,and HMGB1,TLR4,MyD88,TRAF6 protein expression and the phosphorylation of p65-NF-?B level were significantly reduced in TLB?2.5,5,10 mg/kg?group than those of A?25-355-35 group.It is worth noting that TLB could directly bind to HMGB1,and its binding energy is-5.06 kcal.The hydrogen bonding interaction sites between TLB and HMGB1 mainly included SerA14,SerA13,SerB46,MetA12 and MetB44.Conclusion:Under this experimental conditions,TLB effectively inhibits A?25-35-induced learning and memory impairment in rats,the mechanism is,at least partially,due ti the regulation of HMGB1/TLR4 signaling pathway. |
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