Circadian misalignment impairs oligodendrocyte myelination via Bmal1 overexpression leading to anxiety and depression-like behaviors

Circadian misalignment (CM) caused by shift work can increase the risk of mood impairment. However, the pathological mechanisms underlying these deficits remain unclear. In the present study, we used long-term variable photoperiod (L-VP) in wild-type mice to better simulate real-life shift patterns and study its effects on the prefrontal cortex (PFC) and hippocampus, which are closely related to mood function. The results showed that exposure to L-VP altered the activity/rest rhythms of mice, by eliciting phase delay and decreased amplitude of the rhythms. Mice with CM developed anxiety and depression-like manifestations and the number of mature oligodendrocytes (OL) was reduced in the medial prefrontal cortex and hippocampal CA1 regions. Mood impairment and OL reduction worsened with increased exposure time to L-VP, while normal photoperiod restoration had no effect. Mechanistically, we identified upregulation of Bmal1 in the PFC and hippocampal regions of CM mice at night, when genes related to mature OL and myelination should be highly expressed. CM mice exhibited significant inhibition of the protein kinase B (AKT)/mTOR signaling pathway, which is directly associated to OL differentiation and maturation. Furthermore, we demonstrated in the OL precursor cell line Oli-Neu that overexpression of Bmal1 inhibits AKT/mTOR pathway and reduces the expression of genes OL differentiation. In conclusion, BMAL1 might play a critical role in CM, providing strong research evidence for BMAL1 as a potential target for CM therapy.

Abnormal gray matter volume and functional connectivity patterns in social cognition-related brain regions of young children with autism spectrum disorder

Autism spectrum disorder (ASD) is associated with abnormal brain imaging findings, but descriptions thereof are inconsistent. The aim of the present study was to investigate brain abnormalities in young children with ASD using a combination of structural and functional brain magnetic resonance imaging (MRI). Structural and resting-state functional MRI was performed in 67 children with ASD (aged 2-7 years) and 39 age-matched typically developing (TD) controls. Voxel-based morphometry was used to evaluate differences in brain structure between groups. Topologic parameters of the functional brain network were compared by graph theoretic analysis and network connectomes were compared with network-based statistics. A support vector machine (SVM) was used to discriminate between ASD and TD groups. Results demonstrated young children with ASD had increased gray matter volumes (GMVs) in the right medial superior frontal gyrus and left fusiform gyrus compared with the TD group. The ASD group had altered subnetwork connectivity in frontal and temporal lobes and other social cognition-related brain regions. Functional connectivity in the left superior temporal gyrus and left temporal pole of the middle temporal gyrus was positively correlated with adaptability and language developmental quotient (DQ) in children with ASD. The combination of the brain structural and functional features had 86.2% accuracy in discriminating between ASD and TD. The present study shows that young children with ASD have altered GMVs and functional networks in social cognition-related brain regions, which are potential neuroimaging biomarkers for ASD.