Attenuation of TRPV1 and TRPV4 Expression and Function in Mouse Inflammatory Pain Models Using Electroacupuncture

Area of Science:

• Neuroscience
• Pain Research
• Acupuncture Studies

Background:

• Inflammatory pain mechanisms are not fully understood.
• Transient receptor potential vanilloid subtype 1 (TRPV1) and TRPV4 receptors are implicated in inflammatory pain.
• The role of these receptors in electroacupuncture (EA)-mediated analgesia remains unclear.

Purpose of the Study:

• To investigate the analgesic effects of EA in mouse models of inflammatory pain.
• To determine the involvement of TRPV1 and TRPV4 receptors in EA's pain-relieving mechanisms.
• To explore EA's impact on dorsal root ganglion (DRG) neuronal excitability.

Main Methods:

• Induction of inflammatory pain in mice using carrageenan or complete Freund's adjuvant (CFA).
• Administration of EA at the ST36 acupoint.
• Assessment of pain behaviors using mechanical and thermal hyperalgesia tests.
• Analysis of TRPV1 and TRPV4 protein expression in DRG neurons via immunostaining and Western blotting.
• Evaluation of DRG neuronal electrophysiological properties using whole-cell recording.

Main Results:

• EA treatment significantly reversed mechanical and thermal hyperalgesia in inflammatory pain models.
• EA attenuated the elevated protein levels of TRPV1 and TRPV4 in DRG neurons.
• EA modulated the action potential (AP) threshold, rise time, fall time, and the percentage and amplitude of TRPV1 and TRPV4.
• EA ameliorated peripheral nerve hyperexcitation in the affected DRG neurons.

Conclusions:

• Electroacupuncture (EA) demonstrates a significant analgesic effect on inflammatory pain in mice.
• EA exerts its pain-relieving effects by downregulating TRPV1 and TRPV4 protein expression in DRG neurons.
• EA normalizes DRG neuronal excitability, contributing to its antinociceptive properties.
• This study elucidates a novel mechanism for EA-mediated analgesia involving TRPV1 and TRPV4 regulation.