Preventive effects of progesterone on the electrophysiological response of sciatic nerve in the chronic constriction injury model of neuropathic pain in the rat

Introduction: Peripheral neuropathy (PN) is resulted from damage to the peripheral nervous system (PNS) and usually causes weakness, numbness, and neuropathic pain, which is a type of chronic pain. Despite the variety of treatment options, treating neuropathic pain faces challenges and the existing treatments are not yet satisfactory. Nervous steroids show important physiological regulators of PNS function. Progesterone is a neurosteroid that has both analgesic and anti-inflammatory properties. Also, GABA-A receptors play an important role in mediating the effect of progesterone. This study was designed to determine whether progesterone can prevent electrophysiological deterioration of the sciatic nerve in the chronic constriction injury (CCI) model of neuropathic pain in rats and that do this effect through GABA-A receptors.
Materials and Methods: In this study, 140 male Wistar rats in 14 groups (n=10) were used. Neuropathic pain was created by the CCI method in the relevant groups. After CCI induction, progesterone and bicuculline or their vehicles were administered daily until day 13 post-CCI. After that, nerve conduction velocity (NCV) tests were performed according to Julu methods on days 14 and 27 after CCI.
Results: According to the findings of this study, daily injections of progesterone for 12 days before complete neuropathic pain evolution in CCI rats could prevent significantly the reduction of sensory and motor nerve conduction velocities compared to the CCI group on days 14 and 27 after CCI. Furthermore, this effect of progesterone was blocked by bicuculline administration
Conclusion: The findings of this study showed that before complete neuropathic pain evolution, chronic progesterone administration may prevent electrophysiological disorders of the sciatic nerve (at least to some extent through GABA-A receptors) in CCI-induced peripheral neuropathy and these effects continue in the accepted range time of the CCI mode.