Enhanced Expression Of Nischarin In Aging Brain Modulates Plasticity Of Dendritic Spine

Objectives:We aim to determine the change of nischarin expression in aging brain,clarify the impact of nischarin expression alteration on dendritic spine density and discuss the possible mechanism of nischarin expression.Methods:Using western blot assay to analyze the expression of nischarin in the cerebral cortex and hippocampus of rats and mice between different ages and the expression of nischarin in the hippocampal neurons of rat and mouse between different days in vitro,respectively.Using immunofluorescence assay to analyze the expression and localization of nischarin in rat brain slice of different ages and the expression and localization of nischarin in rat hippocampal neurons of different days in vitro.Constructing an shRNA to effectively knockdown nischarin expression;transfecting it to primary cultured hippocampal neurons to knockdown the nischarin expression and observing the quantitative and morphological alteration in dendritic spine.Incubating the primary cultured hippocampal neurons with LPS,IL-1? and IL-6,using western blot assay to analyze the expression of nischarin.Results:The expression of nischarin increases with age and reaches the maximum in 2 years old rats,among which the expression in hippocampus is significantly increased compared to the 16 weeks old counterparts.The expression of nischarin in primary cultured hippocampal neurons increases with the days in vitro and the expression in 20 days in vitro is significantly increased compared to 13 days in vitro.The fluorescence of nischarin in the brain slice and primary hippocampal neurons increase with age or days in vitro.The constructed Nischarin-shRNA can effectively inhibit the expression of nischarin.The spine density in hippocampal pyramidal neuron transfected with shRNA is significantly increased compared to neurons transfected with shRNA as control.The thin dendritic spine density is altered most obviously,while there's no obvious change in the mushroom spine and stubby spine.Western blot analysis shows that the expression of nischarin of neurons incubated with LPS,IL-1? and IL-6 is significantly increased compared to the control group which was incubated with PBS solution.Conclusion:Nischarin expression increases in the hippocampus of aged rats;the inhibition of nischarin promotes the growth of thin spine in hippocampal pyramidal neurons;LPS and cytokines increase the expression of nischarin in neurons.The findings above lead us to hypothesize that nischarin may be associated with cognitive decline in brain aging.