Mechanism of valproic acid-induced dendritic spine and synaptic impairment in the prefrontal cortex for causing core autistic symptoms in mice / 南方医科大学学报

OBJECTIVE@#To investigate the mechanism of valproic acid (VPA) -induced impairment of the dendritic spines and synapses in the prefrontal cortex (PFC) for causing core symptoms of autism spectrum disorder (ASD) in mice.@*METHODS@#Female C57 mice were subjected to injections of saline or VPA on gestational days 10 and 12, and the male offspring mice in the two groups were used as the normal control group and ASD model group (n=10), respectively. Another 20 male mice with fetal exposure to VPA were randomized into two groups for stereotactic injection of DMSO or Wortmannin into the PFC (n=10). Open field test, juvenile play test and 3-chamber test were used to evaluate autistic behaviors of the mice. The density of dendrite spines in the PFC was observed with Golgi staining. Western blotting and immunofluorescence staining were used to detect the expressions of p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR and the synaptic proteins PSD95, p-Syn, and Syn in the PFC of the mice.@*RESULTS@#Compared with the normal control mice, the mice with fetal exposure to VPA exhibited obvious autism-like behaviors with significantly decreased density of total, mushroom and stubby dendritic spines (P < 0.05) and increased filopodia dendritic spines (P < 0.05) in the PFC. The VPA-exposed mice also showed significantly increased expressions of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR (P < 0.01) and lowered expressions of PSD95 and p-Syn/Syn in the PFC (P < 0.05 or 0.001). Wortmannin injection into the PFC obviously improved the ASD-like phenotype and dendritic spine development, down-regulated PI3K/Akt/mTOR signaling pathway and up-regulated the synaptic proteins in VPA-exposed mice.@*CONCLUSION@#In male mice with fetal exposure to VPA, excessive activation of PI3K/Akt/mTOR signaling pathway and decreased expressions of the synaptic proteins PSD95 and p-Syn cause dendritic spine damage and synaptic development disturbance in the PFC, which eventually leads to ASD-like phenotype.

Effects of CTNND2 knockout on cerebellar development and motor function in mice / 解剖学报

Objective To investigate the effects of CTNND2 knockout on cerebellar neuronal development and motor function in mice, as well as its possible mechanisms. Methods The mice were divided into two groups (n = 10 in each group), all of them were 7 weeks old : wild-type (WT) C57BL/6J mice were treated as control group, and homozygous of CTNND2 knockout (CTNND2 7) mice were treated as experimental group, the genotype of CTNND2 7 mice were detected with PCR. The motor function of two groups were detected by beam walking test, hanging wire test and gait analysis test. The changes of cerebellar Purkinje cells were detected by immunofluorescence staining and Golgi staining. Western blotting was performed to detect the expression levels of synapse-associated proteins phosphorylated synapsin 1 (p-Synl), synapsin 1 (Synl), ELKS and postsynaptic density protein 95(PSD95), as well as phosphoinositide 3-kinase (PI3K), phosphorylated protein kinase B (p-Akt), protein kinase B (Akt), phosphorylated mammalian target of rapamycin (p-mTOR) and mammalian target of rapamycin (mTOR). Results Compared with the WT mice, except the increase in time to traverse the beam, there was a decrease in the proportion of pass on the beam, or latency to fall from the hanging wire, or score of hanging wire, or fore-stride length and hind-stride length of CTNND2 7 mice. There was also a decrease in numbers of Purkinje cells and its dendritic arborization in cerebellum of CTNND2 7 mice. The ratio of p-Synl/ Synl, p-Akt/Akt and p-mTOR/mTOR, as well as the expression levels of ELKS, PSD95 and PI3K were lower than those of WT mice. Conclusion CTNND2 knockout can affect the number and dendritic architecture of Purkinje cells, as well as synthesis of synapse-associated proteins in cerebellum by down-regulating PI3K/Akt/mT0R signaling pathway, resulting in cerebellar developmental disorder, thereby affecting motor function of mice.