Prefrontal Nectin3 Reduction Mediates Adolescent Stress-Induced Deficits of Social Memory,Spatial Working Memory,and Dendritic Structure in Mice

Chronic stress may disrupt the normal neurodevelopmental trajectory of the adolescent brain(especially the prefrontal cortex) and contribute to the pathophysiology of stress-related mental illnesses,but the underlying molecular mechanisms remain unclear.Here,we investigated how synaptic cell adhesion molecules(e.g.,nectin3)are involved in the effects of adolescent chronic stress on mouse medial prefrontal cortex(mPFC).Male C57BL/6N mice were subjected to chronic social instability stress from postnatal days 29 to 77.One week later,the mice exposed to chronic stress exhibited impaired social recognition and spatial working memory,simplified dendritic structure,and reduced spine density in the mPFC.Membrane localization of nectin3 was also altered,and was significantly correlated with behavioral performance.Furthermore,knocking down mPFC nectin3 expression by adeno-associated virus in adolescent mice reproduced the stress-induced changes in behavior and mPFC morphology.These results support the hypothesis that nectin3 is a potential mediator of the effects of adolescent chronic stress on prefrontal structural and functional abnormalities.

DNA hypomethylation promotes learning and memory recovery in a rat model of cerebral ischemia/reperfusion injury

Cerebral ischemia/reperfusion injury impairs learning and memory in patients.Studies have shown that synaptic function is involved in the formation and development of memory,and that DNA methylation plays a key role in the regulation of learning and memory.To investigate the role of DNA hypomethylation in cerebral ischemia/reperfusion injury,in this study,we established a rat model of cerebral ischemia/reperfusion injury by occlusion of the middle cerebral artery and then treated the rats with intraperitoneal 5-aza-2′-deoxycytidine,an inhibitor of DNA methylation.Our results showed that 5-aza-2′-deoxycytidine markedly improved the neurological function,and cognitive,social and spatial memory abilities,and dose-dependently increased the synaptic density and the expression of SYP and SHANK2 proteins in the hippocampus in a dose-dependent manner in rats with cerebral ischemia/reperfusion injury.The effects of 5-aza-2′-deoxycytidine were closely related to its reduction of genomic DNA methylation and DNA methylation at specific sites of the Syp and Shank2 genes in rats with cerebral ischemia/reperfusion injury.These findings suggest that inhibition of DNA methylation by 5-aza-2′-deoxycytidine promotes the recovery of learning and memory impairment in a rat model of cerebral ischemia/reperfusion injury.These results provide theoretical evidence for stroke treatment using epigenetic methods.