| Objective To observe the influence of probiotics on postoperative cognitive function and kp pathway related molecules in rats induced by cardiopulmonary bypass,then to explore the protective effects and possible mechanism of probiotics on brain and cognitive function.Methods A total of 48 adult male Sprague-Dawley rats(SPF grade),weighting400-450 g,were provide by the Animal Experimental Department of the General Hospital of Northern Theater Command.The rats were randomly divided into four groups(n=6):Sham operation(S group),Probiotics+Sham operation(P group),CPB surgery(C group),Probiotics+CPB(H group).Each group was divided into two subgroups:7 days and 28 days.The rats in each group were trained in water maze 4 times a day for 5 days before operation.Using the water maze to conduct the place navigation test,remove the low intelligence or unable to swim,and ensure that there is no statistically significant difference in the cognitive function of rats in each group before the experiment.In the P and H group,the rats were administered with 2ml suspension of gold bifidobacteria(a trifecta of bifidobacterium,streptococcus pyreophilus and lactobacillus,containing 1x10^8/g of viable bacteria)one week before surgery.In the S and C group,the rats were administered with 2ml normal saline one week before surgery.All the rats were performed mechanical ventilation and arteriovenous punctured after anesthesia.CPB was not allowed in the S and P group.In the C and H group underwent CPB for 1 h.After 7 days and 28 days of the surgery,the water maze test was performed in rats.After the track images and data were automatically collected by the small animal behavior recording and analysis system of SUPER MAZE,the rats were immediately anesthetized and sacrificed.Then venous blood was sterlie extracted and the bilateral hippocampus was isolated and removed.The right side was fixed with 4% paraformaldehyde solution to make sections for optical mirror detection use;the other side was placed in a cryopreserved tube stored at-80℃ refrigerator.Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of inflammatory factors including TNF-α and IFN-γ;high performance liquid chromatography(HPLC)was used to detect the concentrations of KYN and TRP in plasma.Western-blot was used to detect the changes of PND associated proteins Aβand tau proteins in brain tissue.All the statistical analyses were performed using SPSS 19.0 software.Normally distributed measurement data are expressed as mean ± standard deviation((?)±s).Two subgroups comparisons were analyzed with independent sample T test,multiple comparisons were one-way ANOVA,followed by using LSD to comparison between groups.P<0.05 was statistically significant difference.Results1.Morris water maze results of rats in each group(1)the results of water maze test before the surgery In hidden platform tests,there were no significant differences in all groups in the average latency and swim speed(P>0.05).In space exploration experiments,the distance and time of swimming in the target quadrant,the number of crossing platform had no significant differences in all groups(P>0.05).(2)the results of water maze test after the surgery In hidden platform tests,compared with S group,the average latency were shorted in P group 7 days and 28 days after the surgery(P>0.05);the average latency were extended in C and H groups 7 days and 28 days after the surgery(P<0.05);Compared with C group,the average latency were shorted in H group7 days and 28 days after the surgery(P<0.05);Compared with 7 days after surgery the average latency were slight shortened 28 days after surgery had no significant differences in all groups(P>0.05).Compared with 7 days after surgery the swim speed were slight slower 28 days after surgery had no significant differences in all groups(P>0.05).In space exploration tests,compared with S group,the distance and time of swimming in the target quadrant,the number of crossing platform were significantly increased in P group 7 days and 28 days after the surgery(P<0.05),the distance and time of swimming in the target quadrant,the number of crossing platform were significantly reduced in H and C groups 7 days and 28 days after the surgery(P<0.05);Compared with C group,the distance and time of swimming in the target quadrant,the number of crossing platform were significantly increased in H group 7 days and 28 days after the surgery(P<0.05);Compared with 7 days,the distance and time of swimming in the target quadrant,the number of crossing platform were slightly increased in 28 days after surgery had no significant differences in all groups(P>0.05).2.Pathomorphology changes in hippocampal of rats in all groups HE dyeing method observed that the pyramidal cells in the CA1 area of hippocampus were arranged closely and orderly,the staining is shallow,the nucleolus is obvious,there is no obvious that other damage signs of neuronal degeneration were observed in S and P groups 7 days and 28 days after the surgery.The pyramidal cells in the CA1 area of hippocampus were arranged loosely,the staining was non uniform,and appeared more karyopyknosis and nuclear concentration in C group 7 days and 28 days after the surgery.The pyramidal cells in the CA1 area of hippocampus were arranged mild disorders,the staining was sightly uniform,there is a slight increase in denatured neurons,in H group 7 days and 28 days after the surgery.3.Comparison of the expressions of Aβ and p-Tau protein in hippocampus among rats in all groups Compared with S group,the expressions of Aβ and p-tau protein were significantly decreased in P group 7 days and 28 days after the surgery(P<0.05),the expressions of Aβ and p-tau protein were significantly increased in H and C groups 7 days and 28 days after the surgery(P<0.05);Compared with C group,the expressions of Aβ and p-tau protein were significantly decreased in H group 7 days and 28 days after the surgery(P<0.05).Compared with 7 days after surgery,the expressions of Aβ and p-tau protein were slightly reduced in28 days after surgery had no significant differences among all groups(P>0.05).4.Comparison of the plasma concentrations of TNF-α and IFN-γ among rats in all groups Compared with S group,the plasma concentrations of TNF-α and IFN-γwere decreased in P group 7 days after the surgery(P<0.05),the plasma concentrations of TNF-α and IFN-γ were increased in H and C group 7 days after the surgery(P<0.05);Compared with C group,the plasma concentrations of TNF-α and IFN-γ were significantly decreased in H group(P<0.05);compared with 7 days,the concentration of TNF-α and IFN-γ were decreased to recovered the normal level before surgery in 28 days after surgery among all groups.5.Comparison of the plasma ratio of Kyn/Trp among rats in all groups Compared with S group,the ratio of Kyn/Trp and Kyn were decreased,Trp was increased in P group 7 days after the surgery(P<0.05);the ratio of Kyn/Trp and Kyn were increased,Trp was decreased in H and C group 7 days after the surgery(P<0.05).Compared with C group,the ratio of Kyn/Trp and Kyn were decreased,Trp was increased in the H group 7 days after the surgery(P<0.05);Compared with 7 days after surgery,the ratio of Kyn/Trp and Kyn were slightly decreased,Trp was slightly increased in 28 days after surgery had no significant differences among all groups(P>0.05).Conclusions1.The abnormal metabolism of KP pathway caused by inflammatory reaction after CPB may be one of the causes of PND.2.Probiotics can regulate the anti/inflammatory cytokine balance,thereby reducing the inflammatory response and the expression of Aβ and phosphorylated Tau proteins,thus improving postoperative cognitive function in rats.3.Probiotics can reduce the Kyn/Trp ratio and reduce the IDO enzyme activity to regulate the kynurenine pathway to play a role in brain protection. |
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