Effects of chronic sleep restriction on the neuro‐phenotypes of Ctnnd2 knockout mice

Introduction Sleep abnormalities are highly correlated with neurodevelopmental disorders, such as intellectual disability, attention deficit hyperactivity disorder, and autism spectrum disorders (ASD). The severity of behavioral abnormalities is correlated with the presence of sleep abnormalities. Based on previous research, we investigated that Ctnnd2 gene deletion in mice lead to ASD‐like behaviors and cognitive defects. Given the importance of sleep in individuals with ASD, this study aimed to determine the effects of chronic sleep restriction (SR) on wild‐type (WT) mice and on Ctnnd2 deletion‐induced, neurologically related phenotypes in mice. Method WT and Ctnnd2 knockout (KO) mice were both subjected to manual SR (5 h per day) for 21 consecutively days separately, then we compared neurologically related phenotypes of WT mice, WT mice subjected to SR, KO mice, and KO mice subjected to SR using a three‐chamber assay, direct social interaction test, open‐field test, Morris water maze, Golgi staining, and Western blotting. Results The effects of SR on WT and KO mice were different. After SR, social ability and cognition were impaired in both WT and KO mice. Repetitive behaviors were increased, and exploration abilities were decreased in KO mice but not in WT mice. Moreover, SR reduced the density and area of mushroom‐type dendritic spines in WT rather than KO mice. Finally, the PI3K/Akt‐mTOR pathway was found to be involved in the effects induced by SR‐impaired phenotypes in WT and KO mice. Conclusion Overall, results of the present study may have implications for the role of disrupted sleep in patients with CTNND2 gene‐related autism and the evolution of neurodevelopmental disorders. The main finding of our present study is that the deletion of Ctnnd2 gene in mice could lead social interaction disorders, repetitive behaviors, less exploration behaviors and defects in spatial cognition. Besides, the growth of dendritic spines and synapses in prefrontal cortex(PFC) are significantly impaired in Ctnnd2 KO mice. Next, we find that some of these phenotypes in WT and Ctnnd2 KO mice were also influenced by chronic sleep restriction, which is similarly to that seen in human with autism. Finally, we observe that PI3K/Akt‐mTOR signal pathway was inhibited in Ctnnd2 KO mice, and chronic sleep restriction may regulate the development of dendritic spines and synapses mediated by PI3K/Akt‐mTOR signal pathway.