Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Jul;42(5):1441-1451.
doi: 10.1007/s10571-020-01033-8. Epub 2021 Jan 2.

Chronic Pain Causes Peripheral and Central Responses in MIA-Induced TMJOA Rats

Henghua Jiang #  1 , Liqin Xu #  1 , Wen Liu  1 , Mian Xiao  1 , Jin Ke  2 , Xing Long  3
Affiliations

Chronic Pain Causes Peripheral and Central Responses in MIA-Induced TMJOA Rats

Henghua Jiang et al. Cell Mol Neurobiol. 2022 Jul.

Abstract

Chronic pain is the predominant symptom that drives temporomandibular joint osteoarthritis (TMJOA) patients to seek medical care; however, currently used treatment modalities remain less effective. This study aimed to investigate chronic pain and the peripheral and central responses in monoiodoacetate (MIA)-induced TMJOA rats. First, the appropriate dose of MIA was determined based on pain behavior assessment in rats. Alterations of the condylar structure in TMJOA rats were evaluated by histological staining and micro-computed tomography (micro-CT). Second, the period of TMJOA chronic pain was further explored by assessing the numbers of glial fibrillary acidic protein (GFAP)-positive astrocytes and ionized calcium-binding adaptor molecule 1 (IBA-1)-positive microglia in the trigeminal spinal nucleus (TSN) and performing nonsteroidal anti-inflammatory drug (NSAID) efficacy experiments. Finally, the expression of neurofilament 200 (NF200), calcitonin gene-related peptide (CGRP), and isolectin B4 (IB4) in the trigeminal ganglion (TG) and TSN was assessed by immunofluorescence. MIA at 4 mg/kg was considered an appropriate dose. Gradual MIA-induced alterations of the condylar structure were correlated with temporomandibular joint (TMJ) pain. The numbers of GFAP- and IBA-1-positive cells were increased at 2, 3, and 4 weeks after MIA injection. NSAIDs failed to alleviate pain behavior 10 days after MIA injection. CGRP and IB4 levels in the TG and TSN were upregulated at 2 and 4 weeks. These results suggest that TMJOA-related chronic pain emerged 2 weeks after MIA injection. CGRP- and IB4-positive afferents in both the peripheral and central nervous systems may be involved in MIA-induced TMJOA-related chronic pain in rats.

Keywords: CGRP; Chronic pain; IB4; Monosodium iodoacetate; Temporomandibular joint osteoarthritis.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no conflicts of interest.

Figures

Fig. 1
Fig. 1
Experimental design and pain behavior assessment of rats injected with MIA at different doses. A Outline of the experimental design showing that 4.0 mg/kg MIA was identified as the appropriate dose based on pain behavior assessment and was used in the following experiment. B Intra-articular injection of MIA induced dose- and time-dependent pain behavior and head withdrawal thresholds in rats over 35 days (n = 4 rats per group), indicating that 4.0 mg/kg was the minimum and appropriate dose of MIA to induce pain behavior over a longer period. **** (red) indicates p < 0.0001 for the 1.2 mg/kg MIA group VS control group, **** (blue) indicates p < 0.0001 for the 2.0 mg/kg MIA group VS control group, **** (green) indicates p < 0.0001 for the 4.0 mg/kg MIA group VS control group, and **** (yellow) indicates p < 0.0001 for the 8.0 mg/kg MIA group VS control group; NS, no significance. Values are the means ± SDs and were analyzed by two-way ANOVA with Tukey’s test
Fig. 2
Fig. 2
Histopathological analysis of rats with 4.0 mg/kg MIA-induced TMJOA and control rats. A Typical S. O- and HE-stained sections of the TMJ. The condyle was divided into anterior, middle and posterior sections indicated by three dotted squares (a–e), and the square images of the condyle were magnified for statistical analysis (f–o). B, D After analysis of the percentage of the proteoglycan area and chondrocyte number, MIA-injected rats had a significantly lower percentage of proteoglycan area and chondrocyte number than the control group at 2, 3, and 4 weeks (n = 5). C After analysis of the condylar cartilage thickness, MIA-injected rats had a significantly lower condylar cartilage thickness than the control group at 1, 2, 3, and 4 weeks (n = 5). These data suggested that pain-related condylar degeneration was induced by 4.0 mg/kg MIA and mainly started 2 weeks after injection. Double-headed arrow: condylar cartilage thickness. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 VS control, NS: no significance. Values are the means ± SDs and were analyzed by two-way ANOVA with Tukey’s test
Fig. 3
Fig. 3
Micro-CT examination of condylar morphological characteristics. A Superior (a–e) and lateral (f–j) views showing condylar morphological characteristics and subchondral bone changes (k–o) at 1, 2, 3, and 4 weeks after MIA injection. These micro-CT results demonstrate consistent condylar degeneration associated with the histopathological changes, suggesting that pain-related condylar degeneration was induced by 4.0 mg/kg MIA and started 2 weeks after injection. White arrow: condylar bone destruction; white pentagram: osteophyte; P: posterior, A: anterior
Fig. 4
Fig. 4
Gliosis of the TSN and the loss of celecoxib treatment efficacy over time in the MIA-induced TMJOA model. A Representative image of GFAP-positive astrocytes under low magnification (a–e) and high magnification (g–k) in the TSN; representative image of IBA-1-positive microglia in low magnification images (m–q) and high magnification images (s–w) of the TSN and image of control sections (PBS) to demonstrate the specificity of GFAP (f, i) and IBA-1 (r, x) antibodies. B, C Histogram indicating that the number of GFAP-positive astrocytes and IBA-1-positive microglia in the TSN was significantly increased in the MIA group at 2, 3, and 4 weeks compared with that in the saline control group (n = 5). D The analgesic effect of celecoxib (10 mg/kg po) in MIA-treated rats was assessed by measuring the HWT on days 0, 1, 3, 5, 7, 10, 14, 17, 21, 24, 28, 31, and 35 after MIA induction (n = 4), and celecoxib lost treatment efficacy for MIA-induced TMJOA pain from 10 days after MIA injection. These data suggested that chronic pain from MIA-induced TMJOA started 2 weeks after MIA injection. (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 VS control, NS: no significance). Values are the means ± SDs and were analyzed by two-way ANOVA with Tukey’s test
Fig. 5
Fig. 5
Alteration of NF200-, CGRP-, and IB4-positive TG neurons innervating the TMJ. A Representative images of NF200- (a–c), CGRP- (e–g), and IB4-positive (i–k) TG neurons in MIA-injected rats at 2 and 4 weeks after MIA injection; image of control sections (PBS) demonstrating the specificity of NF200 (d), CGRP (h) and IB4 (l) antibodies. B–D Histogram indicating that the positive expression of CGRP and IB4 in the TG at 2 and 4 weeks was significantly higher in the MIA group than in the saline control group; positive NF200 expression in the TG was similar between the MIA and control groups (n = 5). **p < 0.01, ***p < 0.001, ****p < 0.0001 VS control, NS: no significance. Values are the means ± SDs and were analyzed by two-way ANOVA with Tukey’s test
Fig. 6
Fig. 6
Mean immunofluorescence intensity of NF200, CGRP, and IB4 in the trigeminal spinal nucleus. A Typical images of NF200 (a–c), CGRP (e–g), and IB4 (i–k) expressed in the trigeminal spinal nucleus 2 and 4 weeks postinjection; images of control sections (PBS) demonstrating the specificity of NF200 (d), CGRP (h), and IB4 (l) antibodies. B–D Histogram indicating that the mean immunofluorescence intensity of CGRP and IB4 in the TSN at 2 and 4 weeks was significantly higher in the MIA group than in the saline control group; the mean immunofluorescence intensity of NF200 in the TSN was similar between the MIA and control groups (n = 5). **p < 0.01, ****p < 0.0001 VS control, NS: no significance. Values are the means ± SDs and were analyzed by two-way ANOVA with Tukey’s test
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Alvarez P, Chen X, Bogen O, Green PG, Levine JD (2012) IB4(+) nociceptors mediate persistent muscle pain induced by GDNF. J Neurophysiol 108:2545–2553. 10.1152/jn.00576.2012 - PMC - PubMed
    1. Basbaum AI, Bautista DM, Scherrer G, Julius D (2009) Cellular and molecular mechanisms of pain. Cell 139:267–284. 10.1016/j.cell.2009.09.028 - PMC - PubMed
    1. Calvo M, Bennett DL (2012) The mechanisms of microgliosis and pain following peripheral nerve injury. Exp Neurol 234:271–282. 10.1016/j.expneurol.2011.08.018 - PubMed
    1. Cirillo G et al (2010) Intrathecal NGF administration reduces reactive astrocytosis and changes neurotrophin receptors expression pattern in a rat model of neuropathic pain. Cell Mol Neurobiol 30:51–62. 10.1007/s10571-009-9430-2 - PMC - PubMed
    1. Clements KM, Ball AD, Jones HB, Brinckmann S, Read SJ, Murray F (2009) Cellular and histopathological changes in the infrapatellar fat pad in the monoiodoacetate model of osteoarthritis pain. Osteoarthr Cartil 17:805–812. 10.1016/j.joca.2008.11.002 - PubMed

Substances

LinkOut - more resources