ABSTRACT
@# Multiple causes of neuropathic pain have been identified and its incidence is likely to increase owing to the ageing global population. Glycyrrhiza glabra (licorice) is a medicinal plant known to be a highly efficacious medicinal herb with several pharmacological effects. Few researchers have demonstrated anti-nociceptive activity of licorice acute pain. The aim of this study was to investigate the anti-nociceptive effect of prepared aqueous extract of Glycyrrhiza glabra root administration on chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain and some selected inflammatory biomarkers in adult male wistar rats. Seven groups of 5 rats per group were used. Groups 1 and 2 were controls. Administration started in groups 3, 4, and 5 three days after surgery and continued for 18 days. Group 3 received 10mg/kg of Imipramine. Groups 4 and 5 received 75mg/kg and 150mg/kg of licorice respectively. Groups 6 and 7 received 75mg/kg and 150mg/kg respectively for 10 days before surgery. Paw withdrawal thresholds were assessed using hot plate method on days 3, 7, 14, and 21. On day 21, plasma level of tumor necrotic factor (TNF-α) and C-reactive protein (CRP) were determined using appropriate ELISA kits. There was significant change in pain threshold in the extract treated ameliorative groups when compared with the control and the ameliorative reference drug. TNF- alpha and CRP concentrations were significantly reduced in groups 6 and 7, compared with groups 1, 2 and 3. In conclusion, anti-nociceptive activity of licorice and its effect on TNF-α, and CRP are dose dependent and administration before surgery was more effective.