alleviated capsaicin-induced mechanical allodynia in a rat model through transient receptor potential vanilloid 1 modulation.

BACKGROUND

Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel implicated in pain sensation in response to heat, protons, and capsaicin (CAPS). It is well established that TRPV1 is involved in mechanical allodynia. This study investigates the effect of (Fabaceae) in CAPS-induced mechanical allodynia and its mechanism of action.

METHODS

Mechanical allodynia was induced by the intraplantar (ipl) injection of 40 μg CAPS into the left hind paw of male Wistar rats. Animals received an ipl injection of 100 μg methanolic leaf extract or 2.5% diclofenac sodium 20 minutes before CAPS injection. Paw withdrawal threshold (PWT) was measured using von Frey filament 30, 90, and 150 minutes after CAPS injection. A molecular docking tool, AutoDock 4.2, was used to study the binding energies and intermolecular interactions between constituents and TRPV1 receptor.

RESULTS

The ipsilateral ipl injection of before CAPS injection increased PWT in rats at all time points. decreased mechanical allodynia by 5.35-fold compared to a 3.59-fold decrease produced by diclofenac sodium. The ipsilateral pretreatment with TRPV1 antagonist (300 μg 4-[3-Chloro-2-pyridinyl]- N-[4-[1,1-dimethylethyl] phenyl]-1-piperazinecarboxamide [BCTC]) as well as the β2-adrenoreceptor antagonist (150 μg butoxamine) attenuated the action of . Depending on molecular docking results, the activity of the extract could be attributed to the bindings of campesterol, stigmasterol, and ononin compounds to TRPV1.

CONCLUSIONS

alleviated CAPS-induced mechanical allodynia through 2 mechanisms: the direct modulation of TRPV1 and the involvement of β2 adrenoreceptor signaling.