Up-regulation of peripheral and central CGRP expression combined with subchondral bone remodeling in rat MIA-induced TMJOA model

Background: Temporomandibular joint osteoarthritis (TMJOA) is a pathological condition marked by subchondral bone remodeling. Osteoarthritis can lead to TMJ pain, nevertheless, the relationship between nociceptive mechanisms and subchondral bone in TMJOA still unclear. Methods: In the present investigation, a rat TMJOA model was established via intra-articular administration of monosodium iodoacetate (MIA). Following the induction of MIA-triggered TMJOA, tissue samples were collected from the TMJ condyle, trigeminal system components including ganglion (TG) and nucleus caudalis (TNC), and hippocampal formation. Micro-computed tomography (Micro-CT) was employed to evaluate subchondral bone degeneration in the TMJ, while tartrate-resistant acid phosphatase (TRAP) staining was conducted to measure the activity of osteoclasts in the subchondral bone. Furthermore, immunofluorescence (IF) staining was performed to detect the expression of calcitonin gene related peptide (CGRP) in the TMJ subchondral bone. Afterwards, immunohistochemistry (IHC) was used to detect the expression of CGRP in the TG, TNC and hippocampus tissues. The experimental results were expressed as mean ± Standard Error of the Mean (SEM) values and two-way Analysis of Variance (ANOVA) with Student-Newman-Keuls post hoc testing was employed for statistical comparisons, adopting a significance threshold of p < 0.05. Results: Compared with the control group, Micro-CT results revealed progressive condylar degeneration over time. Consistently, MIA-induced TMJOA rats demonstrated a pronounced accumulation of TRAP-positive osteoclasts in the subchondral bone. The expression of CGRP in the TMJ subchondral bone, TG, TNC and hippocampus tissues was also obviously increased in MIA-induced TMJOA rats. Conclusions: MIA-induced rat TMJOA pain could be attributed to the augmented exprssion of CGRP in the TMJ subchondral bone, TG, TNC and hippocampus tissues. An elevated level of CGRP stimulated nociception which was implicated in the development of peripheral and central sensitization in TMJOA pain.

Osteoarthritis; Subchondral bone; Pain; Calcitonin gene related peptide; Monosodium iodoacetate; Temporomandibular joint

[1] Yuan W, Wu Y, Huang M, Zhou X, Liu J, Yi Y, et al. A new frontier in temporomandibular joint osteoarthritis treatment: exosome-based therapeutic strategy. Frontiers in Bioengineering and Biotechnology. 2022; 10: 1074536.

[2] Wang D, Qi Y, Wang Z, Guo A, Xu Y, Zhang Y. Recent advances in animal models, diagnosis, and treatment of temporomandibular joint osteoarthritis. Tissue Engineering, Part B: Reviews. 2023; 29: 62–77.

[3] Zhao H, Luo D, Yang JJ, Yuan MJ, Liu L, Yu WH. Clinical effect and analysis of exercise treatment for temporomandibular joint osteoarthritis. Chinese Journal of Stomatology. 2022; 57: 701–707. (In Chinese)

[4] Jiang H, Xu L, Liu W, Xiao M, Ke J, Long X. Chronic pain causes peripheral and central responses in MIA-induced TMJOA rats. Cellular and Molecular Neurobiology. 2022; 42: 1441–1451.

[5] Jiang H, Fang W, Feng Y, Liu X, Zhao J, Xu L, et al. Bafilomycin A1 mitigates subchondral bone degeneration and pain in TMJOA rats. International Immunopharmacology. 2025; 147: 113947.

[6] Chen W, Wang Q, Tao H, Lu L, Zhou J, Wang Q, et al. Subchondral osteoclasts and osteoarthritis: new insights and potential therapeutic avenues. Acta Biochimica et Biophysica Sinica. 2024; 56: 499–512.

[7] Wang H, Yuan T, Wang Y, Liu C, Li D, Li Z, et al. Osteoclasts and osteoarthritis: novel intervention targets and therapeutic potentials during aging. Aging Cell. 2024; 23: e14092.

[8] Yu H, Huang T, Lu WW, Tong L, Chen D. Osteoarthritis pain. International Journal of Molecular Sciences. 2022; 23: 4642.

[9] Liebmann K, Castillo MA, Jergova S, Best TM, Sagen J, Kouroupis D. Modification of mesenchymal stem/stromal cell-derived small extracellular vesicles by calcitonin gene related peptide (CGRP) antagonist: potential implications for inflammation and pain reversal. Cells. 2024; 13: 484.

[10] Nekomoto A, Nakasa T, Ikuta Y, Ding C, Miyaki S, Adachi N. Feasibility of administration of calcitonin gene-related peptide receptor antagonist on attenuation of pain and progression in osteoarthritis. Scientific Reports. 2023; 13: 15354.

[11] Jiang W, Jin Y, Zhang S, Ding Y, Huo K, Yang J, et al. PGE2 activates EP4 in subchondral bone osteoclasts to regulate osteoarthritis. Bone Research. 2022; 10: 27.

[12] Kopruszinski CM, Lee G, Martin LK, Barber KR, Moutal A, Dodick DW, et al. A male-specific mechanism of meningeal nociceptor sensitization promoting migraine headache. Cephalalgia. 2024; 44: 3331024241281493.

[13] Gao J, Wang D, Zhu C, Wang J, Wang T, Xu Y, et al. 1H-MRS reveals abnormal energy metabolism and excitatory-inhibitory imbalance in a chronic migraine-like state induced by nitroglycerin in mice. The Journal of Headache and Pain. 2024; 25: 163.

[14] Greco R, Demartini C, Francavilla M, Zanaboni AM, Tassorelli C. Antagonism of CGRP receptor: central and peripheral mechanisms and mediators in an animal model of chronic migraine. Cells. 2022; 11: 18.

[15] Barroso J, Branco P, Apkarian AV. The causal role of brain circuits in osteoarthritis pain. Nature Reviews Rheumatology. 2025; 21: 261–274.

[16] Karsan N, Edvinsson L, Vecsei L, Goadsby PJ. Pituitary cyclase-activating polypeptide targeted treatments for the treatment of primary headache disorders. Annals of Clinical and Translational Neurology. 2024; 11: 1654–1668.

[17] Chung MK, Wang S, Alshanqiti I, Hu J, Ro JY. The degeneration-pain relationship in the temporomandibular joint: current understandings and rodent models. Frontiers in Pain Research. 2023; 4: 1038808.

[18] Pitcher T, Sousa-Valente J, Malcangio M. The monoiodoacetate model of osteoarthritis pain in the mouse. Journal of Visualized Experiments. 2016; 16: 53746.

[19] Nwosu LN, Mapp PI, Chapman V, Walsh DA. Relationship between structural pathology and pain behaviour in a model of osteoarthritis (OA). Osteoarthritis and Cartilage. 2016; 24: 1910–1917.

[20] Yuan Z, Jiang D, Yang M, Tao J, Hu X, Yang X, et al. Emerging roles of macrophage polarization in osteoarthritis: mechanisms and therapeutic strategies. Orthopaedic Surgery. 2024; 16: 532–550.

[21] Xue P, Zhang W, Shen M, Yang J, Chu J, Wang S, et al. Proton-activated chloride channel increases endplate porosity and pain in a mouse spine degeneration model. Journal of Clinical Investigation. 2024; 134: e168155.

[22] Hanaka M, Iba K, Dohke T, Kanaya K, Okazaki S, Yamashita T. Antagonists to TRPV1, ASICs and P2X have a potential role to prevent the triggering of regional bone metabolic disorder and pain-like behavior in tail-suspended mice. Bone. 2018; 110: 284–294.

[23] Park SH, Eber MR, Widner DB, Shiozawa Y. Role of the bone microenvironment in the development of painful complications of skeletal metastases. Cancers. 2018; 10: 141.

[24] Abe Y, Iba K, Sasaki K, Chiba H, Kanaya K, Kawamata T, et al. Inhibitory effect of bisphosphonate on osteoclast function contributes to improved skeletal pain in ovariectomized mice. Journal of Bone and Mineral Metabolism. 2015; 33: 125–134.

[25] Ni S, Ling Z, Wang X, Cao Y, Wu T, Deng R, et al. Sensory innervation in porous endplates by Netrin-1 from osteoclasts mediates PGE2-induced spinal hypersensitivity in mice. Nature Communications. 2019; 10: 5643.

[26] Russo AF, Hay DL. CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond. Physiological Reviews. 2023; 103: 1565–1644.

[27] Kanno K, Suzuki-Narita M, Kawarai Y, Hagiwara S, Yoh S, Nakamura J, et al. Analgesic effects and arthritic changes following tramadol administration in a rat hip osteoarthritis model. Journal of Orthopaedic Research. 2022; 40: 1770–1777.

[28] Sample SJ, Hao Z, Wilson AP, Muir P. Role of calcitonin gene-related peptide in bone repair after cyclic fatigue loading. PLOS ONE. 2011; 6: e20386.

[29] Heffner MA, Genetos DC, Christiansen BA. Bone adaptation to mechanical loading in a mouse model of reduced peripheral sensory nerve function. PLOS ONE. 2017; 12: e187354.

[30] He H, Chai J, Zhang S, Ding L, Yan P, Du W, et al. CGRP may regulate bone metabolism through stimulating osteoblast differentiation and inhibiting osteoclast formation. Molecular Medicine Reports. 2016; 13: 3977–3984.

[31] Wu H, Lin XQ, Long Y, Wang J. Calcitonin gene-related peptide is potential therapeutic target of osteoporosis. Heliyon. 2022; 8: e12288.

[32] Wang L, Shi X, Zhao R, Halloran BP, Clark DJ, Jacobs CR, et al. Calcitonin-gene-related peptide stimulates stromal cell osteogenic differentiation and inhibits RANKL induced NF-κB activation, osteoclastogenesis and bone resorption. Bone. 2010; 46: 1369–1379.

[33] Orita S, Ishikawa T, Miyagi M, Ochiai N, Inoue G, Eguchi Y, et al. Pain-related sensory innervation in monoiodoacetate-induced osteoarthritis in rat knees that gradually develops neuronal injury in addition to inflammatory pain. BMC Musculoskeletal Disorders. 2011; 12: 134.

[34] Durham PL. Diverse physiological roles of calcitonin gene-related peptide in migraine pathology: modulation of neuronal-glial-immune cells to promote peripheral and central sensitization. Current Pain and Headache Reports. 2016; 20: 48.

[35] Wang H, Zhang X, He JY, Zheng XF, Li D, Li Z, et al. Increasing expression of substance P and calcitonin gene-related peptide in synovial tissue and fluid contribute to the progress of arthritis in developmental dysplasia of the hip. Arthritis Research & Therapy. 2015; 17: 4.

[36] Koop LK, Hawkins JL, Cornelison LE, Durham PL. Central role of protein kinase A in promoting trigeminal nociception in an in vivo model of temporomandibular disorders. Journal of Oral & Facial Pain and Headache. 2017; 31: 264–274.

[37] Kramer PR, Kerins CA, Schneiderman E, Bellinger LL. Measuring persistent temporomandibular joint nociception in rats and two mice strains. Physiology & Behavior. 2010; 99: 669–678.

[38] Ernberg M. The role of molecular pain biomarkers in temporomandibular joint internal derangement. Journal of Oral Rehabilitation. 2017; 44: 481–491.

[39] Zhi X, Wu F, Qian J, Ochiai Y, Lian G, Malagola E, et al. Nociceptive neurons promote gastric tumour progression via a CGRP-RAMP1 axis. Nature. 2025; 640: 802–810.

[40] Cheng JK, Ji RR. Intracellular signaling in primary sensory neurons and persistent pain. Neurochemical Research. 2008; 33: 1970–1978.