Electroacupuncture Alleviates Memory Deficits in APP/PS1 Mice by Targeting Serotonergic Neurons in Dorsal Raphe Nucleus

Objective Alzheimer’s disease(AD)has become a significant global concern,but effective drugs able to slow down AD progression is still lacked.Electroacupuncture(EA)has been demonstrated to ameliorate cognitive impairment in individuals with AD.However,the underlying mechanisms remains poorly understood.This study aimed at examining the neuroprotective properties of EA and its potential mechanism of action against AD.Methods APP/PS1 transgenic mice were employed to evaluate the protective effects of EA on Shenshu(BL 23)and Baihui(GV 20).Chemogenetic manipulation was used to activate or inhibit serotonergic neurons within the dorsal raphe nucleus(DRN).Learning and memory abilities were assessed by the novel object recognition and Morris water maze tests.Golgi staining,western blot,and immunostaining were utilized to determine EA-induced neuroprotection.Results EA at Shenshu(BL 23)and Baihui(GV 20)effectively ameliorated learning and memory impairments in APP/PS1 mice.EA attenuated dendritic spine loss,increased the expression levels of PSD95,synaptophysin,and brain-derived neurotrophic factor in hippocampus.Activation of serotonergic neurons within the DRN can ameliorate cognitive deficits in AD by activating glutamatergic neurons mediated by 5-HT1B.Chemogenetic inhibition of serotonergic neurons in the DRN reversed the effects of EA on synaptic plasticity and memory.Conclusion EA can alleviate cognitive dysfunction in APP/PS1 mice by activating serotonergic neurons in the DRN.Further study is necessary to better understand how the serotonergic neurons-related neural circuits involves in EA-induced memory improvement in AD.

Preventive electroacupuncture reduces cognitive deficits in a rat model of D-galactose-induced aging

Acupuncture can reduce cognitive deficits in Alzheimer’s disease.However,whether electroacupuncture can prevent or alleviate the cognitive deficits in animal models of aging remains poorly understood.Studies have shown that disordered epigenetic modifications play a critical role in age-related cognitive decline.Therefore,we hypothesized that preventive electroacupuncture might improve cognitive functions during aging by regulating epigenetic modifications.A rat model of aging was produced by intraperitoneal injection of 120 mg/kg D-galactose for 8 weeks.Baihui and Shenshu acupoints were stimulated by electroacupuncture for 8 weeks from the first day of D-galactose administration.Preventive electroacupuncture alleviated memory impairment,decreased tau hyperphosphorylation,and reduced glycogen synthase kinase-3βprotein and mRNA expression levels in the brainstem dorsal raphe nucleus,where intracellular neurofibrillary tangle lesions first occur.In addition,the DNA methylation level in the promoter region of the glycogen synthase kinase-3βgene was increased.The effects of preventive electroacupuncture were stronger than those of preventive acupuncture.Intraperitoneal injection of 0.4 mg/kg 5-aza-2ʹ-deoxycytidine,an inhibitor of DNA methyltransferase that blocks epigenetic modifications,antagonized the effects of preventive electroacupuncture.Our results suggest that preventive electroacupuncture treatment alleviates cognitive impairment in aging rats probably by affecting the epigenetic modification of the glycogen synthase kinase-3βgene in the dorsal raphe nucleus.This study was approved by the Animal Ethics Committee of Hubei University of Chinese Medicine,China(approval No.HUCMS201712001)on November 28,2017.