# Miyako Bidens pilosa Extract Ameliorates Allodynia and Suppresses Spinal Microglial Activation in Mice with Partial Sciatic Nerve Ligation

## TL;DR

A plant extract from Miyako Island reduces neuropathic pain in mice by suppressing spinal microglial activation.

## Contribution

MBP is shown to alleviate neuropathic pain and reduce microglial activation in a mouse model.

## Key findings

- MBP significantly reduced mechanical allodynia in mice with neuropathic pain.
- MBP attenuated thermal hyperalgesia and decreased Iba1-positive microglia in the spinal cord.
- MBP may be a novel plant-derived treatment for neuropathic pain.

## Abstract

Neuropathic pain, characterized by chronic allodynia, remains difficult to manage with current pharmacotherapies. Microglial activation plays a pivotal role in the development and maintenance of neuropathic pain and represents a promising therapeutic target. We previously demonstrated that Miyako Bidens pilosa extract powder (MBP), derived from Miyako Island, Okinawa, suppresses glial activation in a mouse model of amyotrophic lateral sclerosis. In this study, we investigated the analgesic potential of MBP in a mouse model of neuropathic pain. Neuropathic pain was induced in male ICR mice by partial sciatic nerve ligation (PSNL). Mice were orally administered MBP (2 g/kg) or vehicle daily. Mechanical allodynia was assessed using von Frey filaments. On postoperative day 7, MBP-treated mice exhibited significantly reduced allodynia compared to vehicle-treated mice. MBP also attenuated thermal hyperalgesia on postoperative day 7. Lumbar spinal cords (L5) were subjected to immunohistochemical analysis for ionized calcium-binding adaptor molecule 1 (Iba1), a microglial marker. MBP significantly decreased the number of Iba1-positive microglia in the ipsilateral dorsal horn. These results suggest that MBP alleviates neuropathic pain, at least in part, by suppressing microglial activation in the spinal cord. MBP may represent a novel plant-derived therapeutic candidate for treating neuropathic pain.