Effect of Methanol Extract of Polygonum minus on Neuropathic Pain and Cognitive Dysfunction in Rats

Introduction: Polygonum minus is one of the traditional medicinal plants. It contains various bioactive ingredients such as flavonoids and essential oil. It possesses the potential pharmacological actions, cytotoxicity, and antiproliferative actions. The role of Polygonum minus on neuropathic pain and cognitive functions remains to be explored. The present study was designed to evaluate the role of methanolic extract of Polygonum minus (PM) in paclitaxel (PT) and scopolamine (SCO) induced neuropathic pain and cognitive dysfunction in rats respectively. Methods: The PT (2 mg/kg; i.p. for 10 days) and SCO (1 mg/kg; i.p. for 4 days) were used for the induction of neuropathic pain and cognitive dysfunction in rats. The PM (200 and 400 mg/kg; for 10 days) was used for testing neuro-analgesic effect and the PM (150 mg/kg; for 4 days) was used for cognitive function study. The neuropathic pain was assessed by plantar, tail immersion, and pinprick tests. The cognitive function was assessed by the Morris water maze test. The reference drugs, that is, pregabalin (10 mg/kg) and donepezil (1 mg/kg) used for the assessment of neuropathic pain and cognitive function. Besides, the hippocampal tissue samples were used for the estimation of acetylcholinesterase activity, thiobarbituric acid reactive substances, reduced glutathione, and total protein levels. Results: The administration of PM ameliorated the PT- and SCO-induced neuropathic pain and cognitive dysfunctions in a dose-dependent manner. Conclusion: The PM possesses the potential neuroprotective actions due to its potential antioxidant, lipid peroxidation inhibition, and regulation of cholinergic neurotransmitter functions.