The Effect of Harmane on Hyperalgesia Induced by Stressed Male Mice in the Presence and Absence of Moderated Exercise

Introduction: Physical exercise has positive effects on stress-induced pain response, while chronic stress persuades a negative effect on cognitive functions. Depending on the nature, duration and intensity of the stressor, it can repress pain (stress-induced analgesia) or exacerbate pain (stress-induced hyperalgesia). Furthermore, beneficial effects of Harmane on stress processes have been reported in rodents. This study aimed to investigate the effects of Harmane and moderate physical activity (associated or not) on pain response in restraint stressed mice. Materials and Methods: Harmane was injected intraperitoneally at doses of 0.1, 0.3 and 0.6 mg/kg, every other day until 28 days, and pain response of the adult NMRI mice was detected using the hot-plate test Results: The results exhibited that Harmane, at all doses used, did not alter pain perception in mice; however, 3- but not 6 and 9-day restraint stress (3 hours per day) induced hyperalgesia per se. In addition, Harmane reduced hyperalgesia in 3-day stressed mice, while moderate treadmill running (10 m/min for 30 min/day, 5 day/week) caused hyperalgesia in 6- and 9-day stressed mice. Furthermore, the hyperalgesia induced by moderate treadmill running in 9-day stressed mice restored by Harmane. Conclusion: The findings indicated that Harmane has a protective effect on hyperalgesia induced by stress per se or potentiated effect of moderate treadmill running in stressed mice.