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

Abstract

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-HT_1B. 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.

References

[1] Scheltens P, De Strooper B, Kivipelto M, et al.. Alzheimer’s disease. Lancet, 2021, 397(10284): 1577-1590

[2] Tiwari S, Atluri V, Kaushik A, et al.. Alzheimer’s disease: pathogenesis, diagnostics, and therapeutics. Int J Nanomedicine, 2019, 14: 5541-5554

[3] 2023 Alzheimer’s disease facts and figures. Alzheimers Dement, 2023,19(4):1598–1695

[4] Grieco SF, Holmes TC, Xu X. Probing neural circuit mechanisms in Alzheimer’s disease using novel technologies. Mol Psychiatry, 2023, 28(10): 4407-4420

[5] Ying Y, Wang JZ. Illuminating Neural Circuits in Alzheimer’s Disease. Neurosci Bull, 2021, 37(8): 1203-1217

[6] Li L, Li J, Dai Y, et al.. Electro-Acupuncture Improve the Early Pattern Separation in Alzheimer’s Disease Mice via Basal Forebrain-Hippocampus Cholinergic Neural Circuit. Front Aging Neurosci, 2021, 13: 770948

[7] Slater C, Wang Q. Alzheimer’s disease: An evolving understanding of noradrenergic involvement and the promising future of electroceutical therapies. Clin Transl Med, 2021, 11(4): e397

[8] Ramirez MJ, Lai MK, Tordera RM, et al.. Serotonergic therapies for cognitive symptoms in Alzheimer’s disease: rationale and current status. Drugs, 2014, 74(7): 729-736

[9] Canter RG, Penney J, Tsai LH. The road to restoring neural circuits for the treatment of Alzheimer’s disease. Nature, 2016, 539(7628): 187-196

[10] Mdawar B, Ghossoub E, Khoury R. Selective serotonin reuptake inhibitors and Alzheimer’s disease. Neural Regen Res, 2020, 15(1): 41-46

[11] Paquelet GE, Carrion K, Lacefield CO, et al.. Single-cell activity and network properties of dorsal raphe nucleus serotonin neurons during emotionally salient behaviors. Neuron, 2022, 110(16): 2664-2679.e2668

[12] Ehrenberg AJ, Nguy AK, Theofilas P, et al.. Quantifying the accretion of hyperphosphorylated tau in the locus coeruleus and dorsal raphe nucleus: the pathological building blocks of early Alzheimer’s disease. Neuropathol Appl Neurobiol, 2017, 43(5): 393-408

[13] Grinberg LT, Rüb U, Ferretti RE, et al.. The dorsal raphe nucleus shows phospho-tau neurofibrillary changes before the transentorhinal region in Alzheimer’s disease. A precocious onset? Neuropathol Appl Neurobiol, 2009, 35(4): 406-416

[14] Hendricksen M, Thomas AJ, Ferrier IN, et al.. Neuropathological study of the dorsal raphe nuclei in late-life depression and Alzheimer’s disease with and without depression. Am J Psychiatry, 2004, 161(6): 1096-1102

[15] Yamamoto T, Hirano A. Nucleus raphe dorsalis in Alzheimer’s disease: neurofibrillary tangles and loss of large neurons. Ann Neurol, 1985, 17(6): 573-577

[16] Chen CP, Eastwood SL, Hope T, et al.. Immunocytochemical study of the dorsal and median raphe nuclei in patients with Alzheimer’s disease prospectively assessed for behavioral changes. Neuropathol Appl Neurobiol, 2000, 26(4): 347-355

[17] Khan KM, Balasubramanian N, Gaudencio G, et al.. Human tau-overexpressing mice recapitulate brainstem involvement and neuropsychiatric features of early Alzheimer’s disease. Acta Neuropathol Commun, 2023, 11(1): 57

[18] Lai MK, Tsang SW, Esiri MM, et al.. Differential involvement of hippocampal serotonin1A receptors and reuptake sites in noncognitive behaviors of Alzheimer’s disease. Psychopharmacology (Berl), 2011, 213(2–3): 431-439

[19] Bartels C, Wagner M, Wolfsgruber S, et al.. Impact of SSRI Therapy on Risk of Conversion From Mild Cognitive Impairment to Alzheimer’s Dementia in Individuals With Previous Depression. Am J Psychiatry, 2018, 175(3): 232-241

[20] Sawant N, Kshirsagar S, Reddy PH, et al.. Protective effects of SSRI, Citalopram in mutant APP and mutant Tau expressed dorsal raphe neurons in Alzheimer’s disease. Biochim Biophys Acta Mol Basis Dis, 2024, 1870(2): 166942

[21] Wang XS, Li JJ, Wang YS, et al.. Acupuncture and Related Therapies for the Cognitive Function of Alzheimer’s Disease: A Network Meta-Analysis. Iran J Public Health, 2021, 50(12): 2411-2426

[22] Wei YT, Su ML, Zhu TT, et al.. Effect of acupuncture at the acupoints for Yizhi Tiaoshen on the functional connectivity between the hippocampus and the brain in the patients with Alzheimer’s disease. Zhongguo Zhen Jiu (Chinese), 2023, 43(12): 1351-1357

[23] Jia Y, Zhang X, Yu J, et al.. Acupuncture for patients with mild to moderate Alzheimer’s disease: a randomized controlled trial. BMC Complement Altern Med, 2017, 17(1): 556

[24] Wang X, Ni X, Ouyang X, et al.. Modulatory effects of acupuncture on raphe nucleus-related brain circuits in patients with chronic neck pain: A randomized neuroimaging trial. CNS Neurosci Ther, 2024, 30(3): e14335

[25] Gao N, Shi H, Hu S, et al.. Acupuncture Enhances Dorsal Raphe Functional Connectivity in Knee Osteoarthritis With Chronic Pain. Front Neurol, 2021, 12: 813723

[26] Yu CC, He C, Du YJ, et al.. Preventive electroacupuncture reduces cognitive deficits in a rat model of D-galactose-induced aging. Neural Regen Res, 2021, 16(5): 916-923

[27] China Association of Acupuncture-Moxibustion. Name and location of commonly used acupoints in laboratory animals - Part 3: Mice. Zhen Ci Yan Jiu (Chinese), 2021, 46(5): 445-446

[28] Lueptow LM. Novel Object Recognition Test for the Investigation of Learning and Memory in Mice. J Vis Exp, 2017, 126: 55718

[29] Wu X, Morishita W, Beier KT, et al.. 5-HT modulation of a medial septal circuit tunes social memory stability. Nature, 2021, 599(7883): 96-101

[30] Meneses A. 5-HT systems: emergent targets for memory formation and memory alterations. Rev Neurosci, 2013, 24(6): 629-664

[31] Lesch KP, Waider J. Serotonin in the modulation of neural plasticity and networks: implications for neurodevelopmental disorders. Neuron, 2012, 76(1): 175-191

[32] Nishijo T, Suzuki E, Momiyama T. Serotonin 5-HT(1A) and 5-HT(1B) receptor-mediated inhibition of glutamatergic transmission onto rat basal forebrain cholinergic neurones. J Physiol, 2022, 600(13): 3149-3167

[33] Pinky PD, Pfitzer JC, Senfeld J, et al.. Recent insights on glutamatergic dysfunction in Alzheimer’s disease and therapeutic implications. Neuroscientist, 2023, 29(4): 461-471

[34] Zhou Z, Liu A, Xia S, et al.. The C-terminal tails of endogenous GluA1 and GluA2 differentially contribute to hippocampal synaptic plasticity and learning. Nat Neurosci, 2018, 21(1): 50-62

[35] Benarroch EE. Glutamatergic synaptic plasticity and dysfunction in Alzheimer disease: Emerging mechanisms. Neurology, 2018, 91(3): 125-132

[36] Payet JM, Stevens L, Russo AM, et al.. The role of dorsal raphe nucleus serotonergic systems in emotional learning and memory in male BALB/c mice. Neuroscience, 2023, 534: 1-15

[37] Khodabande F, Akbari E, Ardeshiri MR. The modulation of the spatial reference memory by the orexinergic system of the dorsal raphe nucleus. Life Sci, 2021, 265: 118777

[38] Yu C, Wang L, Kong L, et al.. Acupoint combinations used for treatment of Alzheimer’s disease: A data mining analysis. J Tradit Chin Med, 2018, 38(6): 943-952

[39] Yu CC, Ma CY, Wang H, et al.. Effects of acupuncture on Alzheimer’s disease: evidence from neuroimaging studies. Chin J Integr Med, 2019, 25(8): 631-640

[40] Cai M, Lee JH, Yang EJ. Electroacupuncture attenuates cognition impairment via anti-neuroinflammation in an Alzheimer’s disease animal model. J Neuroinflammation, 2019, 16(1): 264

[41] Jiang Y, Lin Y, Tan Y, et al.. Electroacupuncture ameliorates cerebrovascular impairment in Alzheimer’s disease mice via melatonin signaling. CNS Neurosci Ther, 2023, 29(3): 917-931

[42] Yu CC, Du YJ, Wang SQ, et al.. Experimental evidence of the benefits of acupuncture for Alzheimer’s disease: an updated review. Front Neurosci, 2020, 14: 549772

[43] Rodríguez JJ, Noristani HN, Verkhratsky A. The serotonergic system in aging and Alzheimer’s disease. Prog Neurobiol, 2012, 99(1): 15-41

[44] Nazarali AJ, Reynolds GP. Monoamine neurotransmitters and their metabolites in brain regions in Alzheimer’s disease: a postmortem study. Cell Mol Neurobiol, 1992, 12(6): 581-587

[45] Nagai Y, Kisaka Y, Nomura K, et al.. Dorsal raphe serotonergic neurons preferentially reactivate dorsal dentate gyrus cell ensembles associated with positive experience. Cell Rep, 2023, 42(3): 112149

[46] Wu YY, Jiang YL, He XF, et al.. 5-HT in the dorsal raphe nucleus is involved in the effects of 100-Hz electroacupuncture on the pain-depression dyad in rats. Exp Ther Med, 2017, 14(1): 107-114

[47] Xu Y, Zhu X, Chen Y, et al.. Electroacupuncture alleviates mechanical allodynia and anxiety-like behaviors induced by chronic neuropathic pain by regulating rostral anterior cingulate cortex-dorsal raphe nucleus neural circuit. CNS Neurosci Ther, 2023, 29(12): 4043-4058

[48] Zhou L, Liu MZ, Li Q, et al.. Organization of functional long-range circuits controlling the activity of serotonergic neurons in the dorsal raphe nucleus. Cell Rep, 2017, 18(12): 3018-3032

[49] Li YW, Li W, Wang ST, et al.. The autonomic nervous system: a potential link to the efficacy of acupuncture. Front Neurosci, 2022, 16: 1038945

[50] Hachem LD, Wong SM, Ibrahim GM. The vagus afferent network: emerging role in translational connectomics. Neurosurg Focus, 2018, 45(3): E2

[51] Wang L, Zhang J, Guo C, et al.. The efficacy and safety of transcutaneous auricular vagus nerve stimulation in patients with mild cognitive impairment: a double blinded randomized clinical trial. Brain Stimul, 2022, 15(6): 1405-1414

[52] Wang JY, Zhang Y, Chen Y, et al.. Mechanisms underlying antidepressant effect of transcutaneous auricular vagus nerve stimulation on CUMS model rats based on hippocampal α7nAchR/NF-κB signaling pathway. J Neuroinflammation, 2021, 18(1): 291

[53] Liu TT, Chen SP, Wang SJ, et al.. Vagus nerve stimulation inhibits cortical spreading depression via glutamate-dependent TrkB activation mechanism in the nucleus tractus solitarius. Cephalalgia, 2024, 44(2): 3331024241230466

[54] Ren J, Friedmann D, Xiong J, et al.. Anatomically defined and functionally distinct dorsal raphe serotonin subsystems. Cell, 2018, 175(2): 472-487.e20

[55] Sari Y. Role of 5-hydroxytryptamine 1B (5-HT_1B) receptors in the regulation of ethanol intake in rodents. J Psychopharmacol, 2013, 27(1): 3-12

[56] Nishijo T, Momiyama T. Serotonin 5-HT_1B receptor-mediated calcium influx-independent presynaptic inhibition of GABA release onto rat basal forebrain cholinergic neurons. Eur J Neurosci, 2016, 44(1): 1747-1760

[57] Varrone A, Svenningsson P, Forsberg A, et al.. Positron emission tomography imaging of 5-hydroxytryptamine1B receptors in Parkinson’s disease. Neurobiol Aging, 2014, 35(4): 867-875

[58] Garcia-Alloza M, Hirst WD, Chen CP, et al.. Differential involvement of 5-HT(1B/1D) and 5-HT6 receptors in cognitive and noncognitive symptoms in Alzheimer’s disease. Neuropsychopharmacology, 2004, 29(2): 410-416

[59] Golembiowska K, Dziubina A. Inhibition of amino acid release by 5-HT_1B receptor agonist in the rat prefrontal cortex. Pol J Pharmacol, 2002, 54(6): 625-631

[60] Hu XJ, Wang FH, Stenfors C, et al.. Effects of the 5-HT_1B receptor antagonist NAS-181 on extracellular levels of acetylcholine, glutamate and GABA in the frontal cortex and ventral hippocampus of awake rats: a microdialysis study. Eur Neuropsychopharmacol, 2007, 17(9): 580-586

[61] Wang J, Mei Y, Zhang X, et al.. Aberrant serotonergic signaling contributes to the hyperexcitability of CA1 pyramidal neurons in a mouse model of Alzheimer’s disease. Cell Rep, 2023, 42(3): 112152

[62] Teixeira CM, Rosen ZB, Suri D, et al.. Hippocampal 5-HT input regulates memory formation and schaffer collateral excitation. Neuron, 2018, 98(5): 992-1004.e4

[63] Zhou MH, Sun FF, Xu C, et al.. Modulation of Kalirin-7 expression by hippocampal CA1 5-HT(1B) receptors in spatial memory consolidation. Behav Brain Res, 2019, 356: 148-155

[64] Wang Z, Lin B, Liu W, et al.. Electroacupuncture ameliorates learning and memory deficits via hippocampal 5-HT1A receptors and the PKA signaling pathway in rats with ischemic stroke. Metab Brain Dis, 2020, 35(3): 549-558

[65] Bukke VN, Archana M, Villani R, et al.. The dual role of glutamatergic neurotransmission in Alzheimer’s disease: from pathophysiology to pharmacotherapy. Int J Mol Sci, 2020, 21(20): 7452

[66] Diering GH, Huganir RL. The AMPA receptor code of synaptic plasticity. Neuron, 2018, 100(2): 314-329

[67] Paoletti P, Bellone C, Zhou Q. NMDA receptor subunit diversity: impact on receptor properties, synaptic plasticity and disease. Nat Rev Neurosci, 2013, 14(6): 383-400

[68] Babaei P. NMDA and AMPA receptors dysregulation in Alzheimer’s disease. Eur J Pharmacol, 2021, 908: 174310

[69] Guntupalli S, Park P, Han DH, et al.. Ubiquitination of the GluA1 subunit of AMPA receptors is required for synaptic plasticity, memory, and cognitive flexibility. J Neurosci, 2023, 43(30): 5448-5457

[70] Lu K, Li C, Liu J, et al.. Impairments in endogenous AMPA receptor dynamics correlates with learning deficits in Alzheimer’s disease model mice. Proc Natl Acad Sci USA, 2023, 120(40): e2303878120

[71] Sturgill JF, Steiner P, Czervionke BL, et al.. Distinct domains within PSD-95 mediate synaptic incorporation, stabilization, and activity-dependent trafficking. J Neurosci, 2009, 29(41): 12845-12854

[72] Vickers CA, Stephens B, Bowen J, et al.. Neurone specific regulation of dendritic spines in vivo by post synaptic density 95 protein (PSD-95). Brain Res, 2006, 1090(1): 89-98

[73] De Pins B, Cifuentes-Díaz C, Farah AT, et al.. Conditional BDNF delivery from astrocytes rescues memory deficits, spine density, and synaptic properties in the 5xFAD mouse model of Alzheimer disease. J Neurosci, 2019, 39(13): 2441-2458

[74] Hsiao YH, Hung HC, Chen SH, et al.. Social interaction rescues memory deficit in an animal model of Alzheimer’s disease by increasing BDNF-dependent hippocampal neurogenesis. J Neurosci, 2014, 34(49): 16207-16219

[75] Pei W, Meng F, Deng Q, et al.. Electroacupuncture promotes the survival and synaptic plasticity of hippocampal neurons and improvement of sleep deprivation-induced spatial memory impairment. CNS Neurosci Ther, 2021, 27(12): 1472-1482

[76] Zhang K, Liu R, Zhang J, et al.. Electroacupuncture ameliorates depression-like behavior in rats by enhancing synaptic plasticity via the GluN2B/CaMKII/CREB signaling pathway. Evid Based Complement Alternat Med, 2021, 2021: 2146001

[77] Yu CC, Wang J, Ye SS, et al.. Preventive electroacupuncture ameliorates D-salactose-induced Alzheimer’s disease-like pathology and memory deficits most likely, via Inhibition of GSK3β/mTOR signaling pathway. Evid Based Complement Alternat Med, 2020, 2020: 1428752