Vitex polygama extract and the flavonoid orientin alleviates vincristine-induced neuropathic pain in mice: possible role of muscarinic and opioid receptors and nitric oxide.

Neuropathic pain affects 7-10% of the global population and is often poorly managed by current pharmacological treatments, which can cause significant adverse effects. This study evaluated the hydroalcoholic extract of Vitex polygama (VPE) and its flavonoid orientin in a vincristine-induced neuropathic pain model. Neuropathic pain was induced by vincristine and assessed using the hot plate test (for thermal hyperalgesia) and von Frey test (for mechanical allodynia). Atropine, naloxone, and L-NAME were used to investigate the mechanism of action of VPE. Antinociceptive effects of VPE were observed at a dose of 30 mg/kg, reversed by muscarinic and opioid receptor antagonists and a nitric oxide synthase inhibitor, indicating the involvement of multiple pathways. Orientin (30 mg/kg) also demonstrated novel antinociceptive activity, inhibited by atropine, indicating muscarinic receptor involvement. This study demonstrated the newsworthy antinociceptive activity of V. polygama and its flavonoid orientin in a vincristine-induced neuropathic pain model.