{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T01:49:20Z","timestamp":1790732960031,"version":"4.1.0"},"reference-count":39,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2025,9,17]],"date-time":"2025-09-17T00:00:00Z","timestamp":1758067200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Education","award":["2020R1I1A3058246"],"award-info":[{"award-number":["2020R1I1A3058246"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Electroacupuncture (EA) has shown analgesic potential for neuropathic pain, yet its underlying molecular mechanisms remain incompletely understood. This study aimed to investigate whether EA relieves neuropathic pain by modulating CCL2\/CCR2 signaling and microglial activation in the spinal cord. Neuropathic pain was induced in rats by L5 spinal nerve ligation. EA was administered at acupoints ST36 and GB34 (1 mA, 2 Hz, 30 min) daily from postoperative days 3 to 7. Rats were assigned to anesthetized control (ANE), non-acupoint stimulation (NAP), and acupoint stimulation (ACU) groups. Pain behavior was evaluated using paw withdrawal threshold and latency. Western blot and immunofluorescence were used to assess CCL2, CCR2, Iba1, IL-1\u03b2, and TNF-\u03b1 expression in the L4\u2013L6 spinal cord. EA significantly attenuated mechanical allodynia and thermal hyperalgesia in the ACU group, accompanied by reductions in CCL2, CCR2, microglial marker Iba1, and pro-inflammatory cytokines. Most importantly, intrathecal administration of recombinant CCL2 completely abolished EA\u2019s analgesic effects, establishing the causal necessity of CCL2\/CCR2 signaling in EA-mediated analgesia. These findings suggest that EA exerts its analgesic effects through downregulation of the CCL2\/CCR2 pathway and inhibition of microglial activation. The reversal of EA\u2019s effects by exogenous CCL2 supports the critical role of spinal chemokine signaling in EA-mediated analgesia.<\/jats:p>","DOI":"10.3390\/ijms26189049","type":"journal-article","created":{"date-parts":[[2025,9,17]],"date-time":"2025-09-17T13:03:02Z","timestamp":1758114182000},"page":"9049","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Electroacupuncture Alleviates Neuropathic Pain by Inhibiting Spinal CCL2-Driven Microglial Activation"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5441-9972","authenticated-orcid":false,"given":"Vishnumolakala","family":"Sindhuri","sequence":"first","affiliation":[{"name":"Research Institute for Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5287-1671","authenticated-orcid":false,"given":"Min-Jae","family":"Koo","sequence":"additional","affiliation":[{"name":"Research Institute for Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-1934-7652","authenticated-orcid":false,"given":"Seung Heon","family":"Jeon","sequence":"additional","affiliation":[{"name":"Department of Korean Medical Science, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6283-0171","authenticated-orcid":false,"given":"Ki-Tae","family":"Ha","sequence":"additional","affiliation":[{"name":"Department of Korean Medical Science, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"},{"name":"Department of Korean Medicine, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6033-5847","authenticated-orcid":false,"given":"Seungtae","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Korean Medical Science, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"},{"name":"Department of Korean Medicine, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7773-3905","authenticated-orcid":false,"given":"Sungtae","family":"Koo","sequence":"additional","affiliation":[{"name":"Department of Korean Medicine, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1016\/j.pain.2013.11.013","article-title":"Neuropathic pain in the general population: A systematic review of epidemiological studies","volume":"155","author":"Austin","year":"2014","journal-title":"Pain"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17002","DOI":"10.1038\/nrdp.2017.2","article-title":"Neuropathic pain","volume":"3","author":"Colloca","year":"2017","journal-title":"Nat. Rev. Dis. Primers"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2204","DOI":"10.1016\/j.pain.2011.06.017","article-title":"A new definition of neuropathic pain","volume":"152","author":"Jensen","year":"2011","journal-title":"Pain"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"778","DOI":"10.1038\/nature01786","article-title":"P2X4 receptors induced in spinal microglia gate tactile allodynia after nerve injury","volume":"424","author":"Tsuda","year":"2003","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1292","DOI":"10.1016\/j.neuron.2018.11.009","article-title":"Microglia in pain: Detrimental and protective roles in pathogenesis and resolution of pain","volume":"100","author":"Chen","year":"2018","journal-title":"Neuron"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"846","DOI":"10.1007\/s13311-020-00905-7","article-title":"Central nervous system targets: Glial cell mechanisms in chronic pain","volume":"17","author":"Grace","year":"2020","journal-title":"Neurotherapeutics"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1038\/nri3621","article-title":"Pathological pain and the neuroimmune interface","volume":"14","author":"Grace","year":"2014","journal-title":"Nat. Rev. Immunol."},{"key":"ref_8","first-page":"2349","article-title":"Pathophysiology of peripheral neuropathic pain: Immune cells and molecules","volume":"27","author":"Thacker","year":"2007","journal-title":"J. Neurosci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"12396","DOI":"10.1523\/JNEUROSCI.3016-07.2007","article-title":"Expression of CCR2 in both resident and bone marrow-derived microglia plays a critical role in neuropathic pain","volume":"27","author":"Zhang","year":"2007","journal-title":"J. Neurosci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4096","DOI":"10.1523\/JNEUROSCI.3623-08.2009","article-title":"JNK-induced MCP-1 production in spinal cord astrocytes contributes to central sensitization and neuropathic pain","volume":"29","author":"Gao","year":"2009","journal-title":"J. Neurosci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"7947","DOI":"10.1073\/pnas.1331358100","article-title":"Impaired neuropathic pain responses in mice lacking the chemokine receptor CCR2","volume":"100","author":"Abbadie","year":"2003","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1016\/j.immuni.2009.09.010","article-title":"Chemokines and chemokine receptors: Standing at the crossroads of immunobiology and neurobiology","volume":"31","author":"Ransohoff","year":"2009","journal-title":"Immunity"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"e13693","DOI":"10.1371\/journal.pone.0013693","article-title":"Selective chemokine receptor usage by central nervous system myeloid cells in CCR2-red fluorescent protein knock-in mice","volume":"5","author":"Saederup","year":"2010","journal-title":"PLoS ONE"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1038\/s41586-021-04001-4","article-title":"A neuroanatomical basis for electroacupuncture to drive the vagal\u2013adrenal axis","volume":"598","author":"Liu","year":"2021","journal-title":"Nature"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e23713","DOI":"10.1097\/MD.0000000000023725","article-title":"Evaluation of the effectiveness and safety of the press-needle technique combined with electroacupuncture for neuropathic pain: A randomized pilot clinical trial","volume":"99","author":"Moon","year":"2020","journal-title":"Medicine"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1654","DOI":"10.1213\/ANE.0000000000001212","article-title":"Electroacupuncture Enhances the Antiallodynic and Antihyperalgesic Effects of Milnacipran in Neuropathic Rats","volume":"122","author":"Li","year":"2016","journal-title":"Anesth. Analg."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1016\/j.jpain.2017.11.005","article-title":"Acupuncture for chronic pain: Update of an individual patient data meta-analysis","volume":"19","author":"Vickers","year":"2018","journal-title":"J. Pain"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"482","DOI":"10.1097\/ALN.0000000000000101","article-title":"Mechanisms of acupuncture\u2013electroacupuncture on persistent pain","volume":"120","author":"Zhang","year":"2014","journal-title":"Anesthesiology"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"38","DOI":"10.3389\/fnint.2019.00038","article-title":"The involvement of descending pain inhibitory system in electroacupuncture-induced analgesia","volume":"13","author":"Lv","year":"2019","journal-title":"Front. Integr. Neurosci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1136\/acupmed-2015-010773","article-title":"Inhibition of spinal microglia and astrocytes contributes to the anti-allodynic effect of electroacupuncture in neuropathic pain induced by spinal nerve ligation","volume":"34","author":"Liang","year":"2016","journal-title":"Acupunct. Med."},{"key":"ref_21","first-page":"447","article-title":"Electroacupuncture inhibits NLRP3-mediated microglial pyroptosis to ameliorate chronic neuropathic pain in rats","volume":"18","author":"Zhang","year":"2025","journal-title":"J. Pain Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1016\/j.jpain.2014.01.498","article-title":"From peripheral to central: The role of ERK signaling pathway in acupuncture analgesia","volume":"15","author":"Park","year":"2014","journal-title":"J. Pain"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1038\/s41583-025-00914-5","article-title":"How microglia contribute to the induction and maintenance of neuropathic pain","volume":"26","author":"Malcangio","year":"2025","journal-title":"Nat. Rev. Neurosci."},{"key":"ref_24","first-page":"295","article-title":"The environment and disease: Association or causation?","volume":"58","year":"1965","journal-title":"Proc. R. Soc. Med."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1038\/nrn2533","article-title":"Pathological and protective roles of glia in chronic pain","volume":"10","author":"Milligan","year":"2009","journal-title":"Nat. Rev. Neurosci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1111\/j.1471-4159.2007.04969.x","article-title":"Monocyte chemoattractant protein-1 functions as a neuromodulator in dorsal root ganglia neurons","volume":"104","author":"Jung","year":"2008","journal-title":"J. Neurochem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"883","DOI":"10.1038\/nn.2562","article-title":"Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture","volume":"13","author":"Goldman","year":"2010","journal-title":"Nat. Neurosci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1016\/j.molmed.2010.12.006","article-title":"Pain-relieving prospects for adenosine receptors and ectonucleotidases","volume":"17","author":"Zylka","year":"2011","journal-title":"Trends Mol. Med."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"882","DOI":"10.1213\/ANE.0000000000001097","article-title":"Electroacupuncture relieves nerve injury-induced pain hypersensitivity via the inhibition of spinal P2X7 receptor-positive microglia","volume":"122","author":"Xu","year":"2016","journal-title":"Anesth. Analg."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"624","DOI":"10.1002\/j.1532-2149.2011.00055.x","article-title":"Electroacupuncture reduces the expression of proinflammatory cytokines in inflamed skin tissues through activation of cannabinoid CB2 receptors","volume":"16","author":"Su","year":"2012","journal-title":"Eur. J. Pain"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1038\/nm.3479","article-title":"Dopamine mediates vagal modulation of the immune system by electroacupuncture","volume":"20","author":"Yehia","year":"2014","journal-title":"Nat. Med."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Hou, S., Chen, C.Y., Zhou, R.Z., He, L.X., Zhao, X.X., Chen, S.S., Yang, S., Yin, H.Y., and Yu, S.G. (2024). Electroacupuncture may alleviate inflammatory pain by downregulating the expression of P2Y14 receptor in the primary somatosensory cortex. Purinergic Signal., 1\u20137.","DOI":"10.1007\/s11302-024-10058-3"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1016\/j.neulet.2003.12.019","article-title":"Acupuncture and endorphins","volume":"361","author":"Han","year":"2004","journal-title":"Neurosci. Lett."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"10655","DOI":"10.1073\/pnas.0610811104","article-title":"Inhibition of spinal microglial cathepsin S for the reversal of neuropathic pain","volume":"104","author":"Clark","year":"2007","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.jneuroim.2008.04.011","article-title":"Glia in pathological pain: A role for fractalkine","volume":"198","author":"Milligan","year":"2008","journal-title":"J. Neuroimmunol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5189","DOI":"10.1523\/JNEUROSCI.3338-07.2008","article-title":"Cytokine mechanisms of central sensitization: Distinct and overlapping role of interleukin-1\u03b2, interleukin-6, and tumor necrosis factor-\u03b1 in regulating synaptic and neuronal activity in the superficial spinal cord","volume":"28","author":"Kawasaki","year":"2008","journal-title":"J. Neurosci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1016\/0304-3959(92)90041-9","article-title":"An experimental model for peripheral neuropathy produced by segmental spinal nerve ligation in the rat","volume":"50","author":"Kim","year":"1992","journal-title":"Pain"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/0304-3959(88)90026-7","article-title":"A new and sensitive method for measuring thermal nociception in cutaneous hyperalgesia","volume":"32","author":"Hargreaves","year":"1988","journal-title":"Pain"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1016\/1056-8719(94)90087-6","article-title":"A method to perform direct transcutaneous intrathecal injection in rats","volume":"32","author":"Mestre","year":"1994","journal-title":"J. Pharmacol. Toxicol. Methods"}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/26\/18\/9049\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:47:03Z","timestamp":1760035623000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/26\/18\/9049"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,17]]},"references-count":39,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["ijms26189049"],"URL":"https:\/\/doi.org\/10.3390\/ijms26189049","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,17]]}}}