Effects of Pain Relief Through Minimal Exercise Intervention in a Rat Model of Neuropathic Pain.

We aimed to minimize the frequency of exercise intervention and test the efficacy of pain relief. We also investigated the mechanism of neuropathic pain to determine the best frequency of pain relief for neuropathic pain. The chronic constriction injury (CCI) rat model was randomly divided into three groups: exercise (Ex), No-Ex, and normal. The treadmill exercise intervention was administered, and the 50% withdrawal threshold was assessed using the Von Frey Test. Ionized calcium-binding adaptor molecule 1 (IBA1), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF), C-C chemokine receptor type 2 (CCR2), and tumor necrosis factor receptor-associated factor 6 (TRAF6) activation was determined through immunohistochemistry. In the brain, we examined the increased expression of ß-endorphin/met-enkephalin in the gray matter of the midbrain aqueduct. Co-expression of CCR2, IBA1, and Neu-N was observed in the spinal cord dorsal horn by immunofluorescence staining. The 50% pain response threshold was significantly lower in the Ex group than in the No-Ex group at five weeks post-CCI, indicating a high analgesic effect. In the dorsal horn of the spinal cord, IBA1 and GFAP were significantly decreased in the Ex group than in the No-Ex group at five weeks post-CCI. However, no significant difference in activation of BDNF, CCR2, and TRAF6 was observed. In the midbrain, the Ex group showed a significant increase compared to the No-Ex group. In summary, our results suggest that in minimal-exercise intervention, neuropathic pain relief is achieved by activation of the descending pain inhibitory system in the midbrain.

Effect of the post-learning period on the accuracy and self-efficacy of measuring the joint range of motion.

[Purpose] To verify the effects of the differences in the post-learning period on the accuracy and self-efficacy of measuring the range of passive flexion of the knee and elbow of students. [Participants and Methods] Thirty-six physical therapy students were classified into three groups (short-term, medium-term, and long-term) based on the interval since learning to measure the range of motion. Participants were asked to self-evaluate their efficacy in appropriately measuring the range of motion for knee and elbow flexion using a 10-point Likert scale. Subsequently, the flexion range of the left knee and elbow was measured using a universal goniometer and compared to the measurements obtained using an electronic accelerometer. [Results] Absolute errors in measuring knee flexion were significantly smaller in the medium- and long-term groups than in the short-term group. No other significant main effects or correlations were observed. [Conclusion] Although the accuracy of measuring the range of motion by students improved while they were in school, it did not improve sufficiently based on the joint being assessed. Furthermore, the post-learning period did not affect a student's self-efficacy for measuring the range of motion and did not reflect its accuracy.

Mechanisms of Neuropathic Pain and Pain-Relieving Effects of Exercise Therapy in a Rat Neuropathic Pain Model.

Purpose: Pain disrupts the daily and social lives of patients with neuropathic pain. Effective treatment of neuropathic pain is difficult. Pharmacological treatments for neuropathic pain are limited, and 40-60% of patients do not achieve even partial relief of their pain. This study created a chronic constriction injury (CCI) model in rats to examine the effects of regular exercise on neuropathic pain relief, elucidate the mechanism, and determine the effects of neuropathic pain in the hippocampus. Methods: CCI model rats were randomly divided into exercise (Ex) and no exercise (No-Ex) groups. Normal rats (Normal group) were used as controls. The Ex group exercised on a treadmill at 20 m/min for 30 min, 5 days per week for 5 weeks post-CCI. The 50% pain response threshold was assessed by mechanical stimulation. Using immunohistochemistry, we examined activation of glial cells (microglia and astrocytes) by CCR2 and TRAF6 expression in the spinal cord dorsal horn and DCX and PROX1 expression in the hippocampal dentate gyrus. Results: The 50% pain response threshold was significantly lower in the Ex than in the No-Ex group at 5 weeks post-CCI, indicating pain relief. In the spinal cord dorsal horn, IBA1, CCR2, and TRAF6 expression was markedly lower in the Ex group than in the No-Ex group at 3 weeks post-CCI. IBA1, GFAP, CCR2, and TRAF6 expression was markedly lower in the Ex group than in the No-Ex group at 5 weeks post-CCI. In the hippocampus, DCX, but not PROX1, expression was significantly higher in the Ex group than in the No-Ex group at 3 weeks post-CCI. At 5 weeks post-CCI, both DCX and PROX1 expression was markedly increased in the Ex group compared to the No-Ex group. Conclusion: Our findings suggest that regular exercise can improve the neuropathic pain-induced neurogenic dysfunction in the hippocampal dentate gyrus.