The Effect of Verbascoside in Neuropathic Pain Induced by Chronic Constriction Injury in Rats.

We examined the effects of verbascoside in rats subjected to chronic constriction injury (CCI). Verbascoside (50, 100, and 200 mg/kg, i.p.), was administered from the day of surgery for 14 days. Spinal cord levels of apoptotic factors and glia markers were quantified on days 3, 7, and 14 post-CCI. Oxidative stress markers were assessed on days 7 and 14. CCI rats exhibited a marked mechanical allodynia, cold allodynia, and thermal hyperalgesia on days 3, 5, 7, 10, and 14 post-CCI. A significant increase in the levels of Iba (a marker of microglia activation) and Bax (a proapoptotic factor) was observed on day 3. Iba remained high on day 7. In contrast, there were no differences in glial fibrillary acidic protein contents between sham and CCI animals. Malondialdehyde increased and reduced glutathione decreased on day 14. Verbascoside significantly attenuated behavioral changes associated with neuropathy. Bax decreased, while Bcl-2 was increased by verbascoside on day 3. Verbascoside also reduced Iba protein on days 3 and 7. The results support evidence that microglial activation, apoptotic factors, and oxidative stress may have a pivotal role in the neuropathic pain pathogenesis. It is suggested that antinociceptive effects elicited by verbascoside might be through the inhibition of microglia activation, apoptotic pathways, and antioxidant properties.