| Objective: The aim of the current study was to seek out scientific evidence to determine whether icariside(40)(40)(ICS(40)(40))contributes to the recovery from neuroinflammation induced by intracerebroventricular administration of lipopolysaccharide(LPS)in rats,and its underlying mechanism.Methods: Sixty healthy male Sprague-Dawley(SD)rats weighing 250-280 g were randomly divided into five groups as follows: sham group(n=9),sham+ICS(40)(40)-H(n=9),LPS(n=14),LPS+ICS(40)(40)-L(n=14),LPS+ICS(40)(40)-H(n=14)groups,respectively.After the rats were adaptive fed for one week,rats in LPS+ICS(40)(40)-L and LPS+ICS(40)(40)-H groups were both intragastrically administered with ICS(40)(40)at dosages of 3 mg/kg and 10 mg/kg once a day.Rats in sham+ICS(40)(40)-H group were intragastrically administered with ICS(40)(40)at a dosage of 10 mg/kg per day,while the sham and LPS groups were administered with volume-matched NS,instead.After 7 days,all animals were given anesthesia with 2%sodium pentobarbital and fastened to a stereotaxic apparatus positioned according to the coordinates: 1.0 mm posterior to bregma,1.5 mm lateral to sagittal suture,3.5 mm beneath the surface of brain slowly injected LPS(10 μg/μL)bilaterally into each lateral ventricle(5μL/ventricle)and then leaving the needle for 5 min.Meanwhile,the sham group and the sham+ICS(40)(40)-H group were done with volume-matched NS,instead.After 24 h,the brains of rats were taken out.The morphological changes of hippocampal neurons and neuronal damage were observed by Hematoxylin-Eosin(HE)staining and Nissl staining.At the same time,the activation of the glia cell markers IBA-1 and GFAP were detected by Immunohistochemistry.The expression of inflammatory factors COX-2,IL-1β,TNF-α and TLR4,My D88,TRAF6,as well as the degradation of IκB-α and phosphorylation of NF-κB p65 levels in hippocampus of rats were detected by Western blot.Results: Neurons in CA1,CA3 and DG regions of hippocampus in model group were disorderly arranged and a large number of it appeared to be lost,contracted and deeply stained compared with the sham group.Moreover,the activation of IBA-1 and GFAP in hippocampus of rats in model group were significantly increased than those in the sham group.The expression of proinflammatory factors including COX-2,IL-1β and TNF-α as well as the TLR4,My D88 and TRAF6 were significantly increased by LPS injection.Besides,LPS decreased the protein content of IκB-α and significantly increased the phosphorylation of NF-κB p65.After pre-treatment with ICS(40)(40),the boundary of cells became clear and the hippocampal neurons arranged more neatly than that of LPS alone,as well as the number of hippocampal neurons surviving in ICS(40)(40)administration group were significantly increased and few cells appeared to degenerated(CA1: P<0.01;CA3: P<0.01;DG: P<0.01).ICS(40)(40)10 mg/kg significantly inhibited the activation of IBA-1(CA1:P<0.01;CA3: P<0.01;DG: P<0.01)and GFAP(CA1: P<0.01;CA3: P<0.01).However,pre-treatment with ICS II 10 mg/kg not only significantly reduced the expressions of inflammatory factors including COX-2,IL-1β and TNF-α in hippocampus of model rats(P<0.01;P<0.01;P<0.01),but also down-regulated the expressions of TLR4,My D88 and TRAF6(P<0.05;P<0.05;P<0.01).Notably,ICS II 10 mg/kg significantly increased the protein content of IκB-α(P<0.01)and simultaneously decreased the phosphorylation of NF-κB p65 level(P<0.05).Conclusion: Pre-treatment with ICS(40)(40)alleviates the LPS-induced neuroinflammation and neuronal damage in hippocampus,as well as significantly inhibits the over-activation of microglia and astrocytes.And its mechanism is closely related to the regulation of TLR4/My D88/NF-κB signaling pathway.ICS(40)(40)has a potential value as a new therapeutic agent to treat neuroinflammation-related diseases,such as Alzheimer. |
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