| BackgroundToxoplasma gondii is a protozoan that can parasitize in all nucleated cells of warmblooded animals including humans.Its intermediate host consists of humans and multiple kinds of animals,as well as cats and other mammals of the felidae family being its final host.Human’s postnatal infections are caused by ingestion of meats with toxoplasma cysts or by drinking of water contaminated with oocyst.The infection of Toxoplasma gondii with humans and animals has been globally widespread.For a long time,the latent infection of Toxoplasma gondii with immunocompetent individuals has been attributed to lacking clinical manifestations.Moreover,only the infection with the immunosuppressed individuals can cause deadly damage.However,in recent years,increasing evidence has revealed that the harm of Toxoplasma gondii infection to humans may not be limited to the lack of clinical manifestations.Sometimes,this infection to human beings can cause brain dysfunction such as schizophrenia and depression.More recently,studies have shown that when women are infected with Toxoplasma gondii,their personality become more cheerful and outgoing and for men,this infection increases their impulse to adventure and more traffic accidents.These above studies indicate that the mental disorders caused by Toxoplasma gondii infection are related to human gender.Some studies have also shown that Toxoplasma gondii infection can alter sex hormone levels of animals.Therefore,in order to investigate the mechanism of gender-related abnormal brain function of hosts infected with Toxoplasma gondii,we set up to establish the gonadal deficiency animal model in which the mice’s ovaries or testis were surgically removed.After the peripheral blood sex hormone levels were significantly decreased,animals were then infected with toxoplasma gondii and the expression status of brain function-related molecules,such as brain-derived neurotrophic factor(BDNF)、Reelin and glutamate decarboxylase(GAD67),were examined.ObjectiveTo investigate the expression profile of BDNF,Reelin and GAD67 in brain tissues of Sex hormone deficiency mice after infection with Toxoplasma gondii.Method80 10-years-old NIH mice(40 male and 40 female)were randomly divided into 8 subgroups,i.e.,for female mice,control group(F1,n=10),castration group(F2,n=10).Toxoplasma gondii infection group(F3,n=10)and castration plus Toxoplasma gondii infection group(F4,n=10);for male mice,control group(M1,n=10),castration group(M2,n=10)),Toxoplasma infection group(M3,n=10),castration plus Toxoplasma gondii infection group(M4,n=10).The mice’s ovaries or testis were surgically removed for female and male mice,separately.Two methods including keratinocyte smears and E2 detection in peripheral blood were used to verify the castration of female mice.Naked-eye observation and peripheral blood testosterone level were used to verify the castration effect of male mice.After the one week of castration,each mouse in the F3,M3,F4,and M4 groups was orally infected with 4-5 PRU strain cysts of toxoplasma gondii.Detection of specific IgG antibody against toxoplasma gondii in serum was performed using an ELISA kit 60 days postinfection.The Morris water maze positioning cruise and space exploration experiments were used to detect changes in learning and memory in mice.The protein levels of BDNF,Reelin and GAD67 in brain tissues,as well as estradiol(E2)and testosterone(T)in peripheral blood were quantitatively detected by ELISA.The mRNA levels of BDNF,Reelin and GAD67 in mice brain tissues were assessed by Real-time quantitative RT-PCR.Result1.The positive rate of the infected group was 100 % using an anti-Toxoplasma IgG ELISA kit 60 days post-infection.2.Morris water maze and E2 and T level: for female mice,The escape latency of castration mice was longer than the normal control group(P<0.05),and escape latency of infected group was shorter than that of control group(P<0.05),and castration + infection group was shorter than the castration group(P<0.05).The level of E2 in peripheral blood of castration group was lower than that of normal control group(P<0.05),and infected group was higher than that of normal control group(P<0.05),and castration + infection group was higher than the castration group(P<0.05).For male mice,The escape latency of castration mice was longer than the normal control group(P<0.05),and escape latency of infected group was shorter than that of control group(P<0.05),and castration + infection group was longer than the castration group(P<0.05)and the testosterone level in infection and castration + infection group were increased(P <0.05).3.Protein and mRNA levels of BDNF,Reelin and GAD67 in female mice: The protein level of BDNF in castration group was not statistically different than in castration group(P>0.05),and castration + infection group was higher than in castration group(P<0.05),and infected group was higher than normal control group(P<0.05).BDNF IV mRNA expression in castration group was higher than normal control group(P<0.05),and castration + infection group was lower than castration group(P<0.05),infection group was lower than normal control group(P<0.05);BDNF IX mRNA expression in castration group was lower than normal control group(P<0.05),castration + infection group and castration group were not statistically different.There was no significant difference between the infected group and the control group.For BDNF mRNA expression,the castrated group was lower than the castration group(P<0.05),the castrated + infected group was lower than the castration group(P<0.05),and the infected group was lower than the normal control group(P<0.05);Reelin protein level: castration + infection group and castration group were not statistically different.There was no significant difference between the castration group and the control group,the infection group was higher than the normal control group(P<0.05).For Reelin mRNA expression,castrated + the infection group was lower than the castration group(P<0.05),and the infection group was lower than the control group(P<0.05).For the GAD67 protein expression,castration + infection group and castration group were not statistically different,and there was no significant difference between the infection group and the normal control group.For GAD67 mRNA expression: castration + infection group was lower than the castration group(P< 0.05),the infected group was higher than the normal control group(P<0.05).4.Protein and mRNA levels of BDNF,Reelin and GAD67 in male mice: The protein level of BDNF in castration group was not statistically different than in castration group(P>0.05),and castration + infection group was higher than in castration group(P<0.05),and infected group was higher than normal control group(P<0.05);The BDNF IV mRNA expression in castration group was higher than normal control group(P<0.05)and castration + infection group was lower than in castration group(P<0.05).Its expression in the infection group was not statistically different(P>0.05).The BDNF IX mRNA expression in castration group was higher than normal control group(P<0.05),castrated + infection group was lower than in the castration group(P<0.05),and its expression in the infection group was lower than in normal control group(P<0.05).BDNF mRNA expression in castration group was lower than normal control group(P<0.05),castrated + infected group was higher than in castration group(P<0.05),infection group was lower than normal control group(P<0.05);Reelin protein level in castration + infection group was higher than in castration group(P<0.05),and its expression in the infection group was higher than in normal control group(P<0.05),castration group and normal control group were not statistically different,the Reelin mRNA expression in castrated + the infection group was higher than in castration group(P<0.05),and its expression in the infected group was lower than the normal control group(P<0.05),and castration group was lower than the normal control group(P<0.05).GAD67 protein level in castration group was lower than in normal control group(P<0.05),the castration + infection group was higher than in castration group(P<0.05),and its expression in the infection group was higher than in normal control group(P<0.05);GAD67 mRNA expression in castration group was higher than in normal control group(P<0.05),the castration + infection group was lower than in castration group(P<0.05)),and its expression in the infected group was lower than in the normal control group(P<0.05).ConclusionToxoplasma gondii infection under sex hormone-deficient status increased the estradiol level in peripheral blood of female mice,as well as the spatial memory ability.It also increased the the testosterone level in peripheral blood of male mice,but decreased the spatial memory ability.Moreover,the expreesion profile of BDNF,Reelin and GAD67 at protein and mRNA levels was changed.These alterations were different between male and female mice. |
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