Cutaneous endothelin-A receptors elevate post-incisional pain

Area of Science:

• Pain research
• Neuroscience
• Pharmacology

Background:

• Post-incisional pain involves complex mechanisms including peripheral and central sensitization.
• Endothelin-1 (ET-1) is implicated in pain pathways, acting through endothelin-A receptors (ET(A)).

Purpose of the Study:

• To investigate the role of ET-1 acting via ET(A) in developing post-incisional pain and hyperesthesia in a rat model.
• To determine the efficacy of blocking ET(A) receptors in preventing pain sensitization.

Main Methods:

• Rats underwent skin incision, and post-incisional pain was assessed using cutaneous trunci muscle reflexes (CTMR).
• The selective ET(A) antagonist BQ-123 was administered locally at the incision site 15 minutes or 24 hours before surgery.
• Primary (near wound) and secondary (distant, spinal) pain responses were evaluated.

Main Results:

• Incisional pain caused primary tactile allodynia and hyperalgesia, and secondary hyperesthesia.
• Local BQ-123 administration 15 minutes before incision suppressed primary allodynia and significantly inhibited secondary allodynia and hyperalgesia.
• Blockade of ET(A) receptors in the immediate peri-operative period prevented the development of central sensitization.

Conclusions:

• ET-1 released by skin incision activates peripheral nociceptors and sensitizes spinal circuits, contributing to post-incisional pain.
• Peri-operative blockade of ET(A) receptors is effective in preventing the development of central sensitization and subsequent pain hypersensitivity.