Electroacupuncture inhibits the interaction between peripheral TRPV1 and P2X3 in rats with different pathological pain

Physiol Res. 2021 Aug 31;70(4):635-647. doi: 10.33549/physiolres.934649. Epub 2021 Jun 1.

Abstract

Chronic pain is regarded to be one of the common and refractory diseases to cure in the clinic. One hundred Hz electroacupuncture (EA) is commonly used for inflammatory pain and 2 Hz for neuropathic pain possibly by modulating the transient receptor potential vanilloid subtype 1 (TRPV1) or the purinergic P2X3 related pathways. To clarify the mechanism of EA under various conditions of pathological pain, rats received a subcutaneous administration of complete Freund's adjuvant (CFA) for inflammatory pain and spared nerve injury (SNI) for neuropathic pain. The EA was performed at the bilateral ST36 and BL60 1 d after CFA or SNI being successfully established for 3 consecutive days. The mechanical hyperalgesia test was measured at baseline, 1 d after model establishment, 1 d and 3 d after EA. The co-expression changes, co-immunoprecipitation of TRPV1 and P2X3, and spontaneous pain behaviors (SPB) test were performed 3 d after EA stimulation. One hundred Hz EA or 2Hz EA stimulation could effectively down-regulate the hyperalgesia of CFA or SNI rats. The increased co-expression ratio between TRPV1 and P2X3 at the dorsal root ganglion (DRG) in two types of pain could be reduced by 100Hz or 2Hz EA intervention. While 100Hz or 2Hz EA was not able to eliminate the direct physical interaction between TRPV1 and P2X3. Moreover, EA could significantly inhibit the SPB induced by the co-activation of peripheral TRPV1 and P2X3. All results indicated that EA could significantly reduce the hyperalgesia and the SPB, which was partly related to inhibiting the co-expression and indirect interaction between peripheral TRPV1 and P2X3.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Disease Models, Animal
  • Electroacupuncture*
  • Ganglia, Spinal / metabolism*
  • Ganglia, Spinal / physiopathology
  • Hyperalgesia / metabolism
  • Hyperalgesia / physiopathology
  • Hyperalgesia / therapy*
  • Male
  • Neuralgia / metabolism
  • Neuralgia / physiopathology
  • Neuralgia / therapy*
  • Pain Threshold
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Purinergic P2X3 / metabolism*
  • Signal Transduction
  • TRPV Cation Channels / metabolism*

Substances

  • P2rx3 protein, rat
  • Receptors, Purinergic P2X3
  • TRPV Cation Channels
  • Trpv1 protein, rat