Effects of combined chronic progesterone administration and forced exercise on behavioral pain responses in the neuropathic pain model of chronic constriction injury in rats

Introduction: Neuropathic pain is a chronic pain that results from damage to the central and peripheral nerves. According to the previous studies, physical activity or progesterone can be an effective treatment for alleviating sensory neuropathic pain individually. In this way, the combined effect of chronic progesterone and forced exercise on behavioral pain responses in the neuropathic pain model of chronic constriction injury in rats was considered. Materials and Methods: Eighty male Wistar rats were used in 8 groups (n=10). First, neuropathic pain was induced by CCI in the respective groups. For the treatment of neuropathic pain, animals in the groups received progesterone (6 mg/kg) started 12 days after the operation until day 26. In exercise groups, the exercise started 12 days after surgery until day 33. Behavioral tests were performed on days 12 and 33. Results: Interestingly, we found that CCI-induced neuropathy could produce thermal hyperalgesia and mechanical allodynia in experimental groups on day 12 before exercise and progesterone therapy. After the stabilization of neuropathic pain, co-administration of progesterone (6 mg/kg) for 14 days and moderate intensity exercise for 3 weeks in the respective group could alleviate neuropathic pain compared with the CCI and each of treated groups individually. Conclusion: The findings of this study showed that co-administration of chronic progesterone and forced exercise after the stabilization of neuropathic pain may alleviate neuropathic pain