Analgesic effects and arthritic changes following tramadol administration in a rat hip osteoarthritis model.

Abstract

We investigated the analgesic effects of tramadol and the arthritic changes following tramadol administration in the rat hip osteoarthritis (OA) model using mono-iodoacetate (MIA). The right hip joints of male Sprague-Dawley rats (n = 5 rats/group) in the Sham group were injected with 25 μl of sterile saline and 1% of fluorogold (FG) retrograde neurotracer. In the MIA + Vehicle and MIA + Tramadol groups, FG and 25 μl of sterile saline with 0.5 mg of MIA were injected into the right hip joint. The MIA + Vehicle and MIA + Tramadol groups were administered daily for 4 weeks, either sterile saline (10 mg/kg, intraperitoneal [i.p.]) or tramadol (10 mg/kg, i.p.). We assessed hyperalgesia every week after MIA administration. Histopathological changes and immunoreactive neurons for calcitonin gene-related peptide (CGRP) in dorsal root ganglia (DRG) were evaluated after 4 weeks of treatment. MIA injection into the hip joint led to mechanical hyperalgesia (p < 0.01), which was significantly reduced by tramadol administration (p < 0.01). Furthermore, daily i.p injection of tramadol significantly suppressed CGRP expression in DRG (p < 0.0001). MIA + Vehicle and MIA + Tramadol groups showed significant cartilage reduction and degeneration compared to the Sham group (p < 0.0001). Interestingly, OA changes significantly progressed in the MIA + Tramadol group compared to the MIA + Vehicle group (p < 0.0001).

• Authors: Keijiro Kanno, Miyako Suzuki-Narita, Yuya Kawarai, Shigeo Hagiwara, Satoshi Yoh, Junichi Nakamura, Sumihisa Orita, Kazuhide Inage, Takane Suzuki, Seiji Ohtori
• Journal: Journal of orthopaedic research : official publication of the Orthopaedic Research Society (J Orthop Res) Vol. 40 Issue 8 Pg. 1770-1777 (08 2022) ISSN: 1554-527X [Electronic] United States
• PMID: 34783063 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.

Chemical References

• Analgesics
• Tramadol
• Calcitonin Gene-Related Peptide
• Iodoacetic Acid

Topics

• Analgesics (pharmacology, therapeutic use)
• Animals
• Calcitonin Gene-Related Peptide (metabolism)
• Disease Models, Animal
• Iodoacetic Acid
• Male
• Osteoarthritis, Hip (metabolism)
• Rats
• Rats, Sprague-Dawley
• Tramadol (pharmacology, therapeutic use)