Effect On Oxidative Stress Of Developmental Exposure To Lead In Alzheimer’s Disease-like Lesion And Resveratrol Intervention In Mice

Lead (Pb) is a ubiquitous environmental heavy metal pollutant which has thestrong neurotoxicity and damages cognitive function. Lead exposure at puberty cancause Alzheimer’s disease(AD)-like lesion formation. Resveratrol (Res) whichbelongs to polyphenol compounds could prevent neurodegenerative diseases andacute injury. The antioxidant effect of silent information regulator factor1(SIRT1)activated by resveratrol has always been a research hotspot, and oxidative stress isone of the important mechanisms of AD. The oxidative stress regulation byresveratrol may play a role in AD-like lesion in mice.ObjectiveBased on AD-like amyloidosis caused by lead exposure, regarding the formationof Aβ and cognitive effect as end points of observation, intervening with resveratrol,exploring the potential relationship of lead exposure and SIRTl related antioxidativestress effect in nerve damage by studying the expression of SIRTl and its relatedeffector molecules phosphorylated FOXO3a and PGC-lα, all above provide clues forthe etiology and pathogenesis of AD research and looking for potential drug targets.Methods1. Animal model establishment: choosing35clean level healthy weaningC57BL/6mice which were21days old after birth as the research object,the experimental group was responsible for feeding the mice. According to bodyweight the rats were randomly divided into5groups: Res gavage group; controlgroup;9M lead exposed group;9M lead exposure coupled with Res gavage group;3M lead exposure coupled with Res gavage group. The method that a free drink of2g/L lead acetate solution was applied to implement lead exposure; And after threemonths of lead exposure resveratrol gavage was started at the dose of50mg/kgBw d,continuous gavage six days a week, the gavage process lasted six months.2. Behavioral tests: After the lead exposure, Morris water maze experiment wasbegun for the determination of spatial learning and memory ability in mice.3.Tissue extract: eyeball blood, whole blood and brain tissue was collected in two days after the water maze experiment after anesthesia in mice, the cortex wasisolated and weighed after saline rinse, then put in frozen storage tube-80℃.4. Molecular index measurement: the mice blood lead was determined withZ-5000polarization zeeman atomic absorption spectrometer; cerebral cortex GSH-Pxactivity was determined by Glutathione peroxidase(GSH-Px) test kit; GSH content inthe cerebral cortex in mice was determined by reduced glutathione checkerboard;mice Aβ(1-40) content in cerebral cortex was determined by Aβ(1-40) ELISA kit;mouse cerebral cortex SIRT1, phosphorylated FOXO3a (Ser253), PGC-lα expressionlevels were analyzed with Western blot.Results1. Morris water maze results: the average escape latencies in mice decreasedwith the date changing in first five days (F=2.799, P<0.05); the average escapelatency of9M lead exposed group and9M lead exposure coupled with Res gavagegroup was greater than the control group,3M lead exposure coupled with Res gavagegroup(P<0.05) respectively, the average escape latency of9M lead exposed groupwas greater than the Res gavage group (P<0.05). When the platform was removed inthe sixth day of the experiment, the average escape latencies of9M lead exposedgroup and9M lead exposure coupled with Res gavage group is greater than thecontrol group and3M lead exposure coupled with Res gavage group respectively(P<0.05).2. Mice blood lead levels: blood lead levels in mice differ between theexperimental groups(F=92.21, P<92.21), blood lead level of Res gavage group andthe control group were less than9M lead exposed group,9M lead exposure coupledwith Res gavage group and3M lead exposure coupled with Res gavage grouprespectively（P<0.001）；blood lead level of9M lead exposed group and9M leadexposure coupled with Res gavage group were greater than3M lead exposure coupledwith Res gavage group respectively (P<0.001).3. GSH-Px activity and GSH content: GSH content in the cerebral cortexdiffered between these groups of mice (F=6.177, P<0.05), GSH content of the Resgavage group and control group was higher than that of9M lead exposed group,9M lead exposure coupled with Res gavage group and3M lead exposure coupled withRes gavage group(P <0.05), GSH content of3M lead exposure coupled with Resgavage group was higher than that of9M lead exposed group (P<0.05).GSH-Px activity in cerebral cortex differed between these groups ofmice(F=10.195, P<0.001), GSH-Px activity of the Res gavage group was greater thanthe control group (P<0.05), GSH-Px activity of9M lead exposed group,9M leadexposure coupled with Res gavage group and3M lead exposure coupled with Resgavage group were less than the control group (P<0.05), GSH-Px activity of3M leadexposure coupled with Res gavage group was greater than9M lead exposedgroup(P<0.05).4. Aβ(1-40) content: Aβ(1-40) content in the cerebral cortex in mice of eachgroup was different(F=3.285, P<0.05), Aβ(1-40) content of9M lead exposed groupwas greater than the Res gavage group, control group,3M lead exposure coupled withRes gavage group respectively(P<0.05).5. Western blot analysis results: SIRT1protein expression levels of the cerebralcortex nuclei differed between the experimental groups of mice(F=216.779, P<0.001),SIRT1level of the control group was higher than other groups (P<0.05), SIRT1levelsof the Res gavage group,9M lead exposure coupled with Res gavage group and3Mlead exposure coupled with Res gavage group were lower than9M lead exposedgroup(P<0.05), SIRT1level of the Res gavage group was higher than9M leadexposure coupled with Res gavage group and3M lead exposure coupled with Resgavage group(P<0.05).Phosphorylated FOXO3a expression levels in brain cortex differed between theexperimental groups of mice(F=18.17, P<0.001), phosphorylated FOXO3a level ofthe Res gavage group was lower than other groups(P<0.05), phosphorylated FOXO3alevel of the control group was higher than other groups (P<0.05), phosphorylatedFOXO3a level of9M lead exposed group was higher than3M lead exposure coupledwith Res gavage group(P<0.05).PGC-lα expression levels in the total protein of cerebral cortex differedbetween the experimental groups of mice(F=58.632, P<0.001), the Res gavage group was higher than the control group(P<0.05), PGC-lα expression levels of9M leadexposed group,9M lead exposure coupled with Res gavage group and3M leadexposure coupled with Res gavage group were lower than control group(P<0.05), ofwhich PGC-lα expression level of3M lead exposure coupled with Res gavage groupwas higher than9M lead exposed group; PGC-lα expression level in corticalcytoplasm protein differed between the experimental groups ofmice(F=67.327,P<0.001), PGC-lα expression level of Res gavage group was lowerthan the control group(P<0.05), PGC-lα expression level of9M lead exposed groupwas higher than the control group(P<0.05), that of9M lead exposure coupled withRes gavage group and3M lead exposure coupled with Res gavage group was lessthan9M lead exposed group(P<0.05).Conclusions1. Developmental lead exposure can reduce the Phosphorylated FOXO3a,PGC-lα and SIRT1expression level in mouse cerebral cortex, cause PGC-lα strandingin the cytoplasm, impair the ability to antioxidant, eventually damage the spatiallearning and memory ability in mice.2. Resveratrol could prevent oxidative stress and protect nerve system byreducing phosphorylated FOXO3a protein level and enhancing the content and thetransfer into the nuclear of PGC-lα in mice, potentially through adjusting the transferof SIRTI from nuclear to cytoplasm.