131: CAN OBESITY INCREASES MECHANO-ALLODYNIA IN RATS WITH OSTEOARTHRITIS?

Topic: Basic Science
Subtopic: Pain category (ICD-11), Chronic secondary musculoskeletal pain, , , , , , , , , , Assessment and Measurement of Pain/Nociception, Drug development, Behavioral studies

Background and Aims: Obesity is described as an important risk factor for chronic pain development (1). The systemic and local inflammation, as well as overload in the joints are described as important mechanisms for pain onset and development in this population (2,3). In patients with knee osteoarthritis (OA) the perception of pain seems to correlate directly with body weight (4). To better explore how obesity can lead to pain amplification, this study aims to explore the role of obesity on mechanical allodynia and thermal hypersensitivity in rats submitted to OA-induced surgery

Methods: Male Sprague Dawley rats were fed with High-Fat Diet (HFD) or CHOW Diet (CHOW). After 11 weeks, the animals were randomized in other four groups receiving Groove- induced OA or Sham surgery: HFD- Groove, HFD-Sham, CHOW-Groove and CHOW-Sham (n=10, each). Mechanical allodynia was assessed by the 50% paw withdrawal threshold (PWT) using the Von Frey Filaments every two weeks after surgery to monitor pain development. Paw withdrawal frequency was assessed in the Cold Plate at 5°C at week 6 and 12 after surgery. At termination, adipose tissues were weighed, and contralateral infrapatellar fat pad (IFP) adipocyte area was analyzed (n=5/group).

Results: HFD groups showed increased Body (MD=136.6 ± 23.49kg; p<0.0001) and adipose tissue (MD=7.09g ± 0.6; p<0.0001) weight. Allodynia increased in HFD-Groove group than HFD-Sham (MD=0.313 ± 0.08; p=0.002), CHOW-Groove (MD=0.388 ± 0.08, p=0.0002) and CHOW-Sham (MD=0.473 ± 0.08, p<0.0001). No differences were observed in Cold Plate. Obesity (p<0.0001) and OA-surgery (p=0.029) were significant factors for allodynia development. Negative correlations between the Von Frey test and BW (r= -0.43; p=0.005), AT weight (r= -0.42; p=0.007) and IFP weight (r= -0.57; p=0.008) were observed. Greater IFP adipocyte area was observed in HFD-Groove than CHOW groups.

Conclusions: Obesity was the major factor to increase mechanical allodynia in OA rat models when compared with lean animals or animals with obesity without OA. Thermal hypersensitivity was not affected by obesity in this model. Negative correlations between allodynia and obesity characterization suggest that obesity severity has a role in pain progression.

References: 1- Qian, M., Shi, Y., & Yu, M. (2021). The association between obesity and chronic pain among community-dwelling older adults: a systematic review and meta-analysis. Geriatric Nursing, 42(1), 8–15. https://doi.org/10.1016/j.gerinurse.2020.10.017

2- Pan, J., Yin, J., Gan, L., & Xue, J. (2023). Two-sided roles of adipose tissue: Rethinking the obesity paradox in various human diseases from a new perspective. In Obesity Reviews (Vol. 24, Issue 1). John Wiley and Sons Inc. https://doi.org/10.1111/obr.13521

3- Ozcan, M., & Ayar, A. (2024). Endocrine Aspects of Pain Pathophysiology: Focus on Adipose Tissue. Neuroendocrinology, 1–1. https://doi.org/10.1159/000539531

4- Garcia, M. M., Corrales, P., Huerta, M., Czachorowski, M. J., López-Miranda, V., Medina-Gómez, G., Cobos, E. J., Goicoechea, C., & Molina-Álvarez, M. (2024). Adults with excess weight or obesity, but not with overweight, report greater pain intensities than individuals with normal weight: a systematic review and meta-analysis. In Frontiers in Endocrinology (Vol. 15). Frontiers Media SA. https://doi.org/10.3389/fendo.2024.1340465

Presenting Author: Andrea Bezerra
Submitting Author: Andrea Bezerra

Senior Author: Kim Henriksen

IASP 2026 Global Year theme of Neuropathic Pain: No

• Andrea Bezerra: PhD. candidate - Nordic Bioscience
• Khaled Mohamed: PhD - Nordic Bioscience
• Kim Henriksen: PhD. Director - Nordic Bioscience