| Part I Effects of berberine on postoperative cognitive function and neuroinflammation in aged miceObjective:To investigate the effects of berberine(BBR)on cognitive function after operation,neuroinflammation and the activation of microglia in aged mice,and the effects of BBR on lipopolysaccharide(LPS)-induced cytokine expressions in BV2 cells.Methods:1.One hundred and eighteen C57BL/6 mice,aged 20 months,were equally randomized into four groups: group control+vehicle,group control + BBR,group isoflurane anesthesia + surgery + vehicle(group surgery + vehicle),group isoflurane anesthesia + surgery + berberine(group surgery + BBR).Postoperative cognitive dysfunction(POCD)animal model was established by isoflurance anesthesia and exploratory laparotomy.In the groups of control + BBR and surgery + BBR,berberine at 10 mg/kg was intraperitoneally administered immediately post-surgery once a day for 3 consecutive days.The mice in the other two groups were administered with the same volume of vehicle.Open field test and the training of fear conditioning test were carried out at 6 d post-surgery,while the contextual and cued fear conditioning tests were performed at 7 d post-surgery to observe cognitive changes.The expressions of tumor nectosis factor-?(TNF-?),interleukin-1?(TNF-?)and interleukin-6(IL-6)in the prefrontal cortex and hippocampus were evaluated at24 h and 7 d post-surgery by enzyme-linked immunosorbent assay(ELISA).The activation of microglial cells in the prefrontal cortex and hippocampus was assessed by immunofluorescence assay at 24 h post-surgery.2.In vitro study,we examined the effects of various concentrations of berberine(0,2.5,5,10 ?mol/ml)on LPS-induced inflammatory mediators released from culturedBV2 cells.The expressions of TNF-? and IL-1? in BV2 cells were measured by ELISA.Results:1.In the contextual fear conditioning tests,the freezing time to context in the group surgery + vehicle was significantly decreased compared with the group control +vehicle(P < 0.05),whereas the freezing time to context in the group surgery + BBR was significantly increased compared with the group surgery + vehicle(P < 0.05).However,there was no difference in the cued fear conditioning test among the four groups(P > 0.05).2.Compared with group control + vehicle,the expression of TNF-?,IL-1? and IL-6in the prefrontal cortex and IL-1? and IL-6 in the hippocampus at 24 h after surgery in the group surgery + vehicle was up-regulated,the number of ionized calcium binding adaptor molecule1(IBA1)-positive microglial cells in the prefrontal cortex and DG,CA1 and CA3 regions of the hippocampus was significantly increased at 24 h after surgery in the group surgery + vehicle.Compared with group surgery +vehicle,the expressions of TNF-?,IL-1? and IL-6 in the prefrontal cortex and IL-1?and IL-6 in the hippocampus at 24 h after surgery was down-regulated in the group surgery + BBR,the number of IBA1-positive microglial cells in the prefrontal cortex and DG,CA1 and CA3 regions of the hippocampus at 24 h after surgery in the group surgery + BBR was significantly decreased(all P < 0.05).3.LPS stimulation induced significantly increased expressions of TNF-? and IL-1? in BV2 cells.Pretreatment with berberine(2.5,5,10 ?mol/ml)significantly inhibited LPS-induced TNF-? and IL-1? expressions in a concentration-dependent manner.Conclusion:1.Berberine could significantly alleviate POCD in aged mice.2.Berberine could significantly alleviate surgery-induced neuroinflammation in theprefrontal cortex and hippocampus in aged mice.3.Pretreatment with berberine significantly inhibited LPS-induced inflammatory mediators released from cultured BV2 cells.Part II Effects of endotoxin tolerance induced by lipopolysaccharide preconditioning on postoperative cognitive function and neuroinflammation in aged miceObjective: To investigate the effects of endotoxin tolerance induced by lipopolysaccharide(LPS)preconditioning on the cognitive function after operation,neuroinflammation and the activation of microglia in aged mice.Methods: One hundred and seventy-two male C57BL/6 mice,aged 12-14 months,weighing 24-36 g,were randomly assigned to the 6 groups: group control(group Con,n = 22),group surgery(group Sur,n = 30),surgery + repeated LPS 72 h before surgery(group Sur + LPS-72 h,n = 30),surgery + LPS 24 h before surgery(group Sur + LPS-24 h,n = 30),surgery + LPS 6 h before surgery(group Sur + LPS-6 h,n =30),surgery + LPS 0 h before surgery(group Sur + LPS-0 h,n = 30).In group Sur +LPS-72 h,LPS was administered intraperitoneally at dose of 0.2 mg/kg three times within 3 days at interval of 24 hours.In group Sur + LPS-24 h,group Sur + LPS-6 h or group Sur + LPS-0 h,LPS was respectively administered intraperitoneally at a dose of 0.2 mg/kg at 24 h,6 h or 0 h before surgery.Mice in groups Con and Sur received the equal volume of vehicle.Postoperative cognitive dysfunction(POCD)animal model was established by isoflurance anesthesia and exploratory laparotomy.Open field test and the training of fear conditioning test were carried out at 6 d after surgery,while the contextual and cued fear conditioning tests were performed at 7 d after surgery to observe the cognitive changes of old mice.The expressions of TNF-?,IL-1?,IL-6 and interleukin-10(IL-10)in hippocampus at 24,72 and 168 h after surgery were evaluated by ELISA.The activation of microglial cells in hippocampus at 7 d after surgery was assessed by the expression of IBA1 by immunofluorescence assay.Results:1.In the contextual fear conditioning tests,the freezing time to context in the groupSur was significantly decreased compared with the group Con,whereas the freezing time to context in the group Sur + LPS-24 h was significantly increased compared with the group Sur(P < 0.05).However,there was no difference in the cued fear conditioning test among the six groups(P > 0.05).2.The expressions of TNF-?,IL-1? and IL-6 at 24 h after surgery in group Sur were significantly increased compared with the group Con(P < 0.05),However,there was no difference in the expressions of IL-10 among six groups(P > 0.05).The expressions of TNF-?,IL-1? and IL-6 at 24 h after surgery in groups Sur + LPS-72 h and Sur + LPS-24 h were significantly decreased compared with the group Sur(P <0.05),However,there was no difference in the expressions of IL-10 among six groups(P > 0.05).3.The number of IBA1-positive activated microglial cells in DG,CA1 and CA3 regions of the hippocampus at 7 d after surgery were significantly increased in group Sur compared with the group Con(P < 0.05),but decreased in groups Sur + LPS-72 h and Sur + LPS-24 h compared with the group Sur(P < 0.05).Conclusion:1.Low-dose LPS preconditioning may significantly alleviate surgery-induced cognitive impairment in aging mice.2.Low-dose LPS preconditioning may significantly alleviate surgery-induced neuroinflammation and activation of microglial cells in hippocampus in aging mice. |
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