Behavioral and Histological Aspects of Osteoarthritis Pain

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Behavioral and Histological Aspects of Osteoarthritis Pain

Journal Title: The 2nd Annual Meeting of International Center for Neuroscience Research - Year 2021, Vol 2, Issue 1

Abstract

Background and aims: Osteoarthritis (OA) is a degenerative joint disease, which is identified by cartilage degradation, subchondral bone remodeling, and inflammation of joint capsule. Each of these changes can impact on the function of sensory neurons innervating the joint and surrounding bones, so can be an important source of pain. There is growing evidence that pathological changes in bone surrounding osteoarthritic joints play an important role in the pathogenesis of OA pain. The aim of this study was to compare histological changes in the joint and subchondral bone at early vs late stage OA, and determine how the histological changes relate to pain behavior, in a rodent model of monosodium iodoacetate (MIA)-induced OA pain. Methods: OA was induced by intra-articular injection of MIA into the rat knee joint. Control rats had saline injected into the knee joint. Pain behavior was assessed using the dynamic weight bearing apparatus (Bioseb, France) on day 0, 3 and 28 of the study. Histological changes in the knee joint and surrounding bones were assessed using Haematoxylin and Eosin at days 3 (early OA) and 28 (late OA) after MIA or saline injection, and compared to pain behavior at the same timepoints. Histology was scored using a modified OARSI scale (Gerwin et al., 2010). Results: There was a rapid decrease (by day 3) in weight bearing of MIA injected animals (n=6), relative to saline injected animals (n=6) (Two-way ANOVA with repeated measures; Bonferroni’s multiple comparisons; P<0.0001). Weight bearing remained significantly reduced in MIA injected animals to at least day 28 (Two-way ANOVA with repeated measures; Bonferroni’s multiple comparisons; P<0.01). At day 3, there were significant histological changes in particular tissues of the joint (Welch’s unpaired t-test; P<0.001), but not the surrounding bone (MannWhitney test; P>0.05), in MIA (n=6) relative to saline (n=6) injected animals. Articular tissue changes included synovitis and meniscus inflammation. At day 28, there were still significant changes in particular tissues of MIA (n=6) vs saline (n=6) injected animals (Welch’s unpaired t-test; P<0.01), but the mean score was lower than for day 3. At day 28, there were also significant histological changes in the subchondral bone in MIA (n=6) vs. saline (n=6) injected animals (Welch’s unpaired t-test; P<0.001). Bone changes included chondrocyte hypertrophy, full thickness damage to the cartilage, subchondral bone lesions and fragmentation, and osteophyte formation. There were no histological changes, at either timepoint, in the joint or surrounding bone of saline injected control animals (n=12). Conclusions: The results of this study suggest that altered pain behaviors in early MIA-induced OA are attributable to changes in the articular tissues of the joint but not surrounding bones, while altered pain behavior in late MIAinduced OA are attributable predominantly to changes in the surrounding bones.

Authors and Affiliations

Vida Nazemian*, Michael Morgan, Jason Ivanusic

Keywords

Osteoarthritis Pain

Behavioral and Histological Aspects of Osteoarthritis Pain

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EP ID EP701732
DOI -
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