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.

Melatonin ameliorates sleep-wake disturbances and autism-like behaviors in the Ctnnd2 knock out mouse model of autism spectrum disorders.

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder characterized by atypical patterns of social interaction and communication, as well as restrictive and repetitive behaviors. In addition, patients with ASD often presents with sleep disturbances. Delta (δ) catenin protein 2 (CTNND2) encodes δ-catenin protein, a neuron-specific catenin implicated in many complex neuropsychiatric diseases. Our previous study demonstrated that the deletion of Ctnnd2 in mice led to autism-like behaviors. However, to our knowledge, no study has investigated the effects of Ctnnd2 deletion on sleep in mice. In this study, we investigated whether the knockout (KO) of exon 2 of the Ctnnd2 gene could induce sleep-wake disorders in mice and identified the effects of oral melatonin (MT) supplementation on Ctnnd2 KO mice. Our results demonstrated that the Ctnnd2 KO mice exhibited ASD-like behaviors and sleep-wake disorders that were partially attenuated by MT supplementation. Overall, our current study is the first to identify that knockdown of Ctnnd2 gene could induce sleep-wake disorders in mice and suggests that treatment of sleep-wake disturbances by MT may benefit to autism-like behaviors causing by Ctnnd2 gene deletion.