Comparison Of LPS Induced Autism Spectrum Disorder Rat Model With The Classical Model

Objective: Construct lipopolysaccharide(LPS)induced rat autism model,and compare with the classical autism model induced by valproic acid(VPA)so as to provide an experimental basis for the selection of animal models in autism research.Methods: The rats were injected intraperitoneally with 500 mg/kg VPA or 100?g/kg LPS at the gestational day 12.5 or day 9.5 respectively to construct autism spectum disorder model in offspring rat(n=28),meanwhile,the injecting equal volume of PBS were served as their control groups at the corresponding timepoints during the mid-gestation.The rates of fertility of gestational rats,mortality of pups and tail deformity of pups were monitored,the dynamic change of weight and tail length in the pups at the period of PND2-35 as well as the time points of opening eyes of the pups in the PND14-17 were observed.The behavior function of social interaction,communication ability,stereotype and repetitive patterns were confirmed in the PND21-35 pups.ELISA kits were used to determine the concentrations of serum inflammatory cytokines(IL-6,IL-1?,IFN-? and TNF-?)in the pups with or without VPA/LPS treatment.Levels of PTEN,p-Akt and p-m TOR protein expressions in the prefrontal cortex of the pups in the present or absent of VPA/LPS treatment were conduced by Westernblot.Concentrations of 5-HT in the prefrontal cortex with or without VPA/LPS challenge were detected with High performance liquid chromatography(HPLC).Results:(1)Maternal fertility rate was only 33.3% following VPA treatment,which was decreasing trend compared with that of VPA untreatment(85.7%),but there was no statistical difference in the two groups.The rates of offspring mortality(17.07%,*P < 0.05)and tail bending deformity(87.8%,***P < 0.001)were significantly induced by gestational VPA treatment.However,the rates of maternal fertility(100%),offspring mortality(1.75%)and tail deformity(0%)following LPS treatment were not significant differences compared with those without LPS treatment.(2)The weights of offspring rats with VPA challenge at PND 2-35 were decreased significantly(*P < 0.05),and the tail lengths were more shorter than that of the pups without VPA treatment.While the weights and tail lenghs were both increased significantly in the pups with LPS treatment compared with LPS untreatment(*P<0.05).(3)The pups with VPA treatment opened eyes later than its control group,but there was no statistical difference(P=0.072).But time to eye opening of the LPS treated group pups was delayed significantly compared with that of LPS untreatment(**P<0.01).(4)Compared with their untreated groups,both VPA and LPS treated offspring rats stayed shorterly in the strang rat chamber and longer in the novel object chamber.Furthermore,the time of sniffing the peer urine in the rats treated by VPA or LPS was significantly decreased and sniffing the beer increased.In addition,the results of open-field test showed that the times of line crossing were significantly decreased and the time of grooming was statistically increased in theoffspring rats with VPA or LPS gestational challenge.However,the time staying center zone of VPA treated rats was significantly shortened(*P<0.05),and no significant difference was found in the time staying center zone between the rats with or without LPS treatment.In the Morrior water test,escape latercy time of the rats in both VPA(+)and LPS(+)groups were statistically longer than those on the untreatment groups(*P<0.05;**P<0.01).(5)Levels of serum IL-1?,IFN-? and TNF-? were increased significantly in the rat offspring following VPA or LPS treatment(*P <0.05).Level of serum IL-6 was also increased in the pups with LPS treatment(*P<0.05)but not with VPA treatment.(6)The VPA challenge significantly reduced level of PTEN protein expression(**P < 0.01),and induced the expression levels of p-AKT and p-m TOR in the pups' prefrontal cortex(*P<0.05).However,the changes of PTEN,p-AKT and p-m TOR protein expresions levels were just opposite in the LPS treatment group(***P < 0.001;**P < 0.01).(7)The concentration of 5-HT in the prefrontal cortex was also statistically reduced by VPA treatment,but was significantly enhanced by LPS treatment(*P<0.05).Conclusion: The both rat models with LPS or VPA treatment lead to rat's developmental delay and autism-like behaviors,whereas the autism model treated by VPA accompanies with anxirty-like behavior,and there are different induce molecular mechanisms between the LPS and VPA treatment.Therefore,we should make reasonable choice on the basis of research objectives in the period of scientific study.