Targeting vulnerable microcircuits in the ventral hippocampus of male transgenic mice to rescue Alzheimer-like social memory loss.

BACKGROUND: Episodic memory loss is a prominent clinical manifestation of Alzheimer's disease (AD), which is closely related to tau pathology and hippocampal impairment. Due to the heterogeneity of brain neurons, the specific roles of different brain neurons in terms of their sensitivity to tau accumulation and their contribution to AD-like social memory loss remain unclear. Therefore, further investigation is necessary. METHODS: We investigated the effects of AD-like tau pathology by Tandem mass tag proteomic and phosphoproteomic analysis, social behavioural tests, hippocampal electrophysiology, immunofluorescence staining and in vivo optical fibre recording of GCaMP6f and iGABASnFR. Additionally, we utilized optogenetics and administered ursolic acid (UA) via oral gavage to examine the effects of these agents on social memory in mice. RESULTS: The results of proteomic and phosphoproteomic analyses revealed the characteristics of ventral hippocampal CA1 (vCA1) under both physiological conditions and AD-like tau pathology. As tau progressively accumulated, vCA1, especially its excitatory and parvalbumin (PV) neurons, were fully filled with mislocated and phosphorylated tau (p-Tau). This finding was not observed for dorsal hippocampal CA1 (dCA1). The overexpression of human tau (hTau) in excitatory and PV neurons mimicked AD-like tau accumulation, significantly inhibited neuronal excitability and suppressed distinct discrimination-associated firings of these neurons within vCA1. Photoactivating excitatory and PV neurons in vCA1 at specific rhythms and time windows efficiently ameliorated tau-impaired social memory. Notably, 1 month of UA administration efficiently decreased tau accumulation via autophagy in a transcription factor EB (TFEB)-dependent manner and restored the vCA1 microcircuit to ameliorate tau-impaired social memory. CONCLUSION: This study elucidated distinct protein and phosphoprotein networks between dCA1 and vCA1 and highlighted the susceptibility of the vCA1 microcircuit to AD-like tau accumulation. Notably, our novel findings regarding the efficacy of UA in reducing tau load and targeting the vCA1 microcircuit may provide a promising strategy for treating AD in the future.

Effect of screen time on sleep in preschool children in Haikou City / 中国学校卫生

Objective@#To understand the impact of screen time on duration and quality of sleep, so as to provide scientific basis for the development of interventions.@*Methods@#A total of 3 584 preschool children in Haikou City were selected by stratified sampling method from March to June in 2022, and the Children s Sleep Habits Questionnaire (CSHQ) and self designed questionnaire were used.@*Results@#The average sleep duration of preschool children was (10.41±0.98)h/d, the rate of sleep deprivation was 28.71 %, and the report rate of sleep problems was 50.47%. The average sleep duration in general as well as on weekdays and weekends decreased by age ( F=21.00, 29.53, 3.26, P ＜0.05), and insufficient sleep duration rate significantly varied by age groups ( χ 2=29.85, P ＜ 0.01 ). The average screen time was (1.15±0.37)h/d, and the screen exposure rate was 55.39%. The total sleep problems ( 52.14 %), poor bedtime habits (43.02%), daytime sleepiness (67.10%), irregular sleep duration (53.05%), and abnormal sleep latency ( 24.99 %) were all higher than those in the non exposed group (48.41%, 39.59%, 63.29%, 48.91%, 19.57 %) ( χ 2= 4.94 , 4.31, 5.69 , 6.08, 14.85, P <0.05). Multiple linear regression analysis showed that age and weekend average screen time were negatively associated with sleep duration ( β =-0.01, -0.06), weekday and weekend average outdoor activity duration were positively correlated with sleep duration ( β =0.08, 0.08) ( P <0.05).@*Conclusion@#Screen exposure to preschool children s sleep time,sleep quality was closely related. Parents should cultivate good sleep habits of preschool children, and limit children s screen time to maximize outdoor activities, so as to ensure healthy development of children.