SIRT3 Mediates The Study Of Sepsis-associated Encephalopathy By Regulating CypD Acetylation

Objective:To investigate the expression of CypD and acetylated CypD on the sepsis-associated encephalopathy in mice and their effects on the sepsis-associated encephalopathy.Methods:Male C57BL/6 mice,at the age of 3～4 months,were randomly assigned to two groups:sham group and cecal ligation puncture(CLP)group(n=21).Animals in CLP group underwent CLP surgery.The cognitive function was assessed using the learning version of the Morris water maze test in 4th～6th days after surgery.HE stained sections were used to observe the hippocampus in mice.Elisa method was used to detect the levels of interleukin 6(IL-6)and tumor necrosis factor-α(TNF-α).Then,the level of CypD and acetylated CypD in the hippocampus were determined.Results:1.Compared with the Sham group,the mice suffering CLP spent more time to find the platform(P<0.05).The mice in the sham group spent more time in the third quadrant where the platform was located compared with those undergoing CLP surgery(P<0.05).Swimming speeds were also analyzed,and no significant differences were observed in these two groups(P>0.05).2.Compared with the Sham Group,the damage to hippocampus tissue in the CLP group was more aggravated(P<0.05).However,the damage to hippocampus was most hard in the 4th day after CLP operation.3.Compared with the Sham Group,the expression of IL-6 and TNF-a were increased in the CLP group(P<0.05).However,the levels of IL-6 and TNF-a were increased most in the 4th day after surgery.4.Compared with the Sham Group,the expression of CypD and acetylated CypD were increased in the CLP group(P<0.05).However,the levels of CypD and acetylated CypD were increased most in the 4th day after surgery.Conclusion:The damage to hippocampus was more aggravates in SAE mice and the expression of IL-6、TNF-α、CypD and acetylated CypD were increased after CLP,and these level were increased most in the 4th day.Objective:The present study aimed to investigate cognitive dysfunction in the hippocampus induced by sepsis-associated encephalopathy(SAE)via acetylation of cyclophilin D(CypD)and opening of mitochondrial permeability transition pore(mPTP).It also explored whether activating sirtuin 3(SIRT3)can mediate deacetylation of CypD and prevent the development of SAE.Methods:Male mice were randomly assigned to six groups:sham group,cecal ligation puncture(CLP)group,CypD siRNA transfection(CypD-si)group,CypD control siRNA transfection(CypD-c)group,SIRT3 overexpression vector pcDNA3.1(SIRT3-p)group,and SIRT3 empty vector pcDNA3.1(SIRT3-v)group(n = 18).The CypD-si and CypD-c groups were transfected with CypD siRNA and CypD control siRNA,respectively.The SIRT3-p and SIRT3-v groups were injected with SIRT3 pcDNA3.1 and vector pcDNA3.1,respectively.The cognitive function was assessed using the learning version of the Morris water maze test.Then,cell apoptosis and the levels of CypD,acetylated CypD,SIRT-3,interleukin 6(IL-6),tumor necrosis factor-α(TNF-α),and caspase-3 in the hippocampus were determined.Results:1.Compared to the Sham group,the latency of the mice underwent CLP surgery was longer and they spent less time to find the platform(P<0.05).Compared to the CLP group the latency of the CypD-si group and SIRT3-p group was shorter,and they spent more time to find the platform(P<0.05).There are no significant differences in swimming speeds among these groups(P>0.05).2.Compared to the Sham group,the cell apoptosis in the hippocampus of the mice underwent CLP increased(P<0.05).Compared to the CLP group,the cell apoptosis of CypD-si group and SIRT3-β group decreased significantly(P<0.05).3.Compared to the Sham group,the mPTP opening in the hippocampus of the mice underwent CLP operation increased significantly(P<0.05).Compared to the CLP group,the mPTP opening of CypD-si group and SIRT3-p group decreased(P<0.05).4.Compared to the Sham group,the expression of IL-6、TNF-α、CypD and acetylated CypD increased,the level of SIRT3 decreased(P<0.05).Compared to the CLP group,the expression of IL-6、TNF-α、caspase-3、CypD and acetylated CypD decreased,and the level of SIRT3 increased significantly(P<0.05).Conclusions:Activating SIRT3-mediated deacetylation of CypD attenuated learning and memory dysfunction induced by SAE.