• Junad Khan, Qian Wang, Olga A Korczeniewska, Rotem McNeil, Yanfang Ren, Rafael Benoliel, and Eli Eliav.
• Eastman Institute for Oral Health, University of Rochester Medical Center, Rochester, New York, USA.
• Eur J Pain. 2023 Jan 1; 27 (1): 129147129-147.

BackgroundExercise is a known trigger of the inhibitory pain modulation system and its analgesic effect is termed exercise-induced hypoalgesia (EIH). Previous studies have demonstrated that rats with deficient analgesic response following exercise develop more significant hypersensitivity following nerve injury compared to rats with substantial analgesic response following exercise.ObjectivesA rat model of EIH as an indicator of the pain inhibitory system's efficiency was used to explore the association between EIH profiles and the effect of pharmacotherapy on rat's neuropathic pain.MethodsEIH profiles were assessed by evaluating paw responses to mechanical stimuli before and after exercise on a rotating rod. Rats with a reduction of ≤33% in responses were classified as low EIH and those with ≥67% as high EIH. Low and high EIH rats underwent sciatic nerve chronic constriction injury (CCI). Paw responses to mechanical stimuli were measured at baseline, following CCI, and after treatment with diclofenac, duloxetine or pregabalin. In a different group of low and high EIH rats, EIH was measured before and following treatment with the same medications.ResultsLow EIH rats developed more significant hypersensitivity following CCI. Duloxetine and pregabalin successfully reduced hypersensitivity, although significantly more so in low EIH rats. Diclofenac had limited effects, and only on low EIH rats. Four days of duloxetine administration transformed low EIH rats' profiles to high EIH.ConclusionsThe findings of this study suggest that EIH profiles in rats can not only predict the development of hypersensitivity following injury but may also support targeted pharmacological treatment.SignificanceExercise is a known trigger of the inhibitory pain modulation. Rats with deficient analgesic response following exercise develop more significant hypersensitivity following nerve injury. Pain modulation profiles in rats can also support targeted pharmacological treatment; rats with deficient analgesic response following exercise benefit more from treatment with duloxetine and gabapentin. Treatment with duloxetine can improve pain modulation profile.© 2022 European Pain Federation - EFIC ®.

35 keywords...

hide…