Objective To investigate the effects and mechanisms of olfactory three-needle(OTN)electroacupuncture(EA)stimulation of the olfactory system on cognitive dysfunction,synaptic plasticity,and the gut microbiota in senesc...Objective To investigate the effects and mechanisms of olfactory three-needle(OTN)electroacupuncture(EA)stimulation of the olfactory system on cognitive dysfunction,synaptic plasticity,and the gut microbiota in senescence-accelerated mouse prone 8(SAMP8)mice.Methods Thirty-six SAMP8 mice were randomly divided into the SAMP8(P8),SAMP8+OTN(P8-OT),and SAMP8+nerve transection+OTN(P8-N-OT)groups according to a random number table(n=12 per group),and 12 accelerated senescence-resistant(SAMR1)mice were used as the control(R1)group.EA was performed at the Yintang(GV 29)and bilateral Yingxiang(LI 20)acupoints of SAMP8 mice for 4 weeks.The Morris water maze test,transmission electron microscopy,terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL)staining,Nissl staining,Golgi staining,Western blot,and 16S rRNA sequencing were performed,respectively.Results Compared with the P8 group,OTN improved the cognitive behavior of SAMP8 mice,inhibited neuronal apoptosis,increased neuronal activity,and attenuated hippocampal synaptic dysfunction(P<0.05 or P<0.01).Moreover,the expression levels of synaptic plasticity-related proteins N-methyl-D-aspartate receptor 1(NMDAR1),NMDAR2B,synaptophysin(SYN),and postsynaptic density protein-95(PSD95)in hippocampus were increased by OTN treatment(P<0.05 or P<0.01).Furthermore,OTN greatly enhanced the brain-derived neurotrophic factor(BDNF)/cAMP-response element binding(CREB)signaling and phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin(PI3K/AKT/mTOR)signaling compared with the P8 group(P<0.05 or P<0.01).However,the neuroprotective effect of OTN was attenuated by olfactory nerve truncation.Compared with the P8 group,OTN had a very limited effect on the fecal microbial structure and composition of SAMP8 mice,while specifically increased the genera Oscillospira and Sutterella(P<0.05).Interestingly,the P8-N-OT group showed an abnormal fecal microbiota with higher microbialα-diversity,Firmicutes/Bacteroidetes ratio and pathogenic bacteria(P<0.05 or P<0.01).Conclusions OTN improved cognitive deficits and hippocampal synaptic plasticity by stimulating the olfactory nerve and activating the BDNF/CREB and PI3K/AKT/mTOR signaling pathways.Although the gut microbiota was not the main therapeutic target of OTN for Alzheimer’s disease,the olfactory nerve was essential to maintain the homeostasis of gut microbiota.展开更多
基金Supported by the National Natural Science Foundation of China(No.82074552)the Shaanxi Science and Technology Department Project(No.2018JM7041)Shaanxi Province TCM"Double Chain Integration"Young and Middle-Aged Scientific Research Innovation Team Construction Project(No.2022-SLRH-LJ-012)。
文摘Objective To investigate the effects and mechanisms of olfactory three-needle(OTN)electroacupuncture(EA)stimulation of the olfactory system on cognitive dysfunction,synaptic plasticity,and the gut microbiota in senescence-accelerated mouse prone 8(SAMP8)mice.Methods Thirty-six SAMP8 mice were randomly divided into the SAMP8(P8),SAMP8+OTN(P8-OT),and SAMP8+nerve transection+OTN(P8-N-OT)groups according to a random number table(n=12 per group),and 12 accelerated senescence-resistant(SAMR1)mice were used as the control(R1)group.EA was performed at the Yintang(GV 29)and bilateral Yingxiang(LI 20)acupoints of SAMP8 mice for 4 weeks.The Morris water maze test,transmission electron microscopy,terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL)staining,Nissl staining,Golgi staining,Western blot,and 16S rRNA sequencing were performed,respectively.Results Compared with the P8 group,OTN improved the cognitive behavior of SAMP8 mice,inhibited neuronal apoptosis,increased neuronal activity,and attenuated hippocampal synaptic dysfunction(P<0.05 or P<0.01).Moreover,the expression levels of synaptic plasticity-related proteins N-methyl-D-aspartate receptor 1(NMDAR1),NMDAR2B,synaptophysin(SYN),and postsynaptic density protein-95(PSD95)in hippocampus were increased by OTN treatment(P<0.05 or P<0.01).Furthermore,OTN greatly enhanced the brain-derived neurotrophic factor(BDNF)/cAMP-response element binding(CREB)signaling and phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin(PI3K/AKT/mTOR)signaling compared with the P8 group(P<0.05 or P<0.01).However,the neuroprotective effect of OTN was attenuated by olfactory nerve truncation.Compared with the P8 group,OTN had a very limited effect on the fecal microbial structure and composition of SAMP8 mice,while specifically increased the genera Oscillospira and Sutterella(P<0.05).Interestingly,the P8-N-OT group showed an abnormal fecal microbiota with higher microbialα-diversity,Firmicutes/Bacteroidetes ratio and pathogenic bacteria(P<0.05 or P<0.01).Conclusions OTN improved cognitive deficits and hippocampal synaptic plasticity by stimulating the olfactory nerve and activating the BDNF/CREB and PI3K/AKT/mTOR signaling pathways.Although the gut microbiota was not the main therapeutic target of OTN for Alzheimer’s disease,the olfactory nerve was essential to maintain the homeostasis of gut microbiota.
