Peripheral and central substance P expression in rat CFA-induced TMJ synovitis pain

Abstract

Synovitis contributes to temporomandibular joint (TMJ) pain, nevertheless, the detailed nociceptive mechanism remains unclear. In this study, a rat model of TMJ synovitis was induced by intra-articular injection with complete Freund's adjuvant (CFA). After CFA-induced synovitis, pain behaviors were observed. Then, TMJ, trigeminal ganglion, and trigeminal nucleus caudalis (TNC) tissues were collected, and immunohistochemistry was used to detect the expression of substance P (SP) and protein gene product 9.5 (PGP9.5) in the synovium tissue. Furthermore, the gene expression level of SP and PGP9.5 in synovium was detected by reverse transcription-polymerase chain reaction (RT-PCR). Afterwards, the expression of SP in the trigeminal ganglion and TNC and c-fos in the TNC was detected by immunohistochemistry. Compared with the control group, the expression of SP and PGP9.5 nerve fibers density and gene levels of them in the synovium tissue were significantly increased in CFA-induced TMJ synovitis rats. Similarly, SP expression in the trigeminal ganglion and TNC, and c-fos expression in the TNC were also obviously increased in CFA-induced TMJ synovitis rats. Collectively, CFA-induced rat TMJ synovitis resulted in obvious pain. This nociceptive reaction could be attributed to the augmented quantity of SP and PGP9.5 positive-stained nerve fibers distributed in the inflammatory synovium as well as enhanced SP expression in the trigeminal ganglion and TNC tissue. c-fos expression in the rat TNC illustrates CFA-induced TMJ synovitis can evoke the acute pain.

Melatonin Abates TMJOA Chronic Pain by MT2R in Trigeminal Ganglion Neurons

“…Pain behavior was assessed by the von Frey test and Rat Grimace Scale (RGS), and experimental procedures were performed as previously described (Langford et al 2010; Sperry et al 2018; Xu et al 2019). Detailed information is presented in the Appendix.…”

CircGCN1L1 promotes synoviocyte proliferation and chondrocyte apoptosis by targeting miR-330-3p and TNF-α in TMJ osteoarthritis

“…Transfect miR-330-3p mimics or inhibitor with different concentrations separately into human synoviocytes from the control patients. Collect the cell supernatant at different time points (1,2,4,8,16,32, and 48 h). The secretion of the TNF-α protein was subsequently detected as described in the TNF-α ELISA Kit (Multiscience, Hangzhou, China) with the sensitivity of 0.16 pg/ml.…”

“…3e). Besides, we collected the cell supernatant of synoviocytes, which transfected with miR-330-3p mimics/ inhibitor (50 nM) described above at various time points (1,2,4,8,16,32, and 48 h), and TNF-α protein levels were then detected using ELISA. The level of TNF-α secreted by synoviocytes did not change significantly with miR-330-3p overexpression during the first 8 h, but decreased rapidly from 70 to 55 pg/ml thereafter.…”

“…Temporomandibular joint (TMJ) osteoarthritis (OA) is one of the most common temporomandibular joint diseases and is characterized by joint clicking/noise, pain, and restricted mouth opening and mandible movements, which may affect sufferers physically or mentally and their daily activities 1 . As a motivating factor of TMJOA, TMJ synovitis could activate inflammation throughout the joint, resulting in cartilage degradation and subchondral bone resorption 2,3 . The molecular mechanisms inducing the joint inflammation that leads to TMJOA remain unclear, and clinical treatment effects for TMJOA were limited.…”

The peripheral and central expression of CGRP and IB4 in chronic pain from MIA-induced TMJOA rats

“…To con rm the appropriate concentration of MIA for TMJOA related chronic pain research, different doses of MIA (0.3, 0.5, 1.0, and 2.0 mg/50 µl; n = 4 rats) dissolved in the saline were bilaterally injected into the TMJ cavity, while the identical 50 µl of saline in the control group (n = 4 rats). Pain behavior was assessed by measuring head withdrawal threshold (HWT) with an automated electronic von frey (IITC, CA, U.S.A.) as previously described (22). Brie y, rats were acclimatized to the test environment a week before the measurement.…”