Endothelin-A Receptor Antagonism Attenuates Carcinoma-Induced Pain Through Opioids in Mice

Phuong N. Quang, Brian L. Schmidt

Research output: Contribution to journalArticlepeer-review


We previously reported that endothelin A (ET-A) receptor antagonism attenuates carcinoma-induced pain in a cancer pain mouse model. In this study, we investigated the mechanism of ET-A receptor-mediated antinociception and evaluated the role of endogenous opioid analgesia. Squamous cell carcinoma (SCC) cell culture treated with the ET-A receptor antagonist (BQ-123) at 10-6 M and 10-5 M significantly increased production and secretion of β-endorphin and leu-enkephalin, respectively. Behavioral studies were performed by inducing tumors in the hind paw of female nude mice with local injection of cells derived from a human oral SCC. Significant pain, as indicated by reduction in withdrawal thresholds in response to mechanical stimulation, began at 4 days after SCC inoculation and lasted to 18 days, the last day of measurement. Local administration of either naloxone methiodide (500 μg/kg), selective antagonists for μ-opioid receptor (CTOP, 500 μg/kg), or δ-opioid receptor (naltrindole, 11 mg/kg) but not κ-opioid receptor (nor-BNI, 2.5 mg/kg) significantly reversed antinociception observed from ET-A receptor antagonism (BQ-123, 92 mg/kg) in cancer animals. These results demonstrate that antagonism of peripheral ET-A receptor attenuates carcinoma pain by modulating release of endogenous opioids to act on opioid receptors in the cancer microenvironment. Perspective: This article proposes a novel mechanism for ET-A receptor antagonist drugs in managing cancer-induced pain. An improved understanding of the role of innate opioid analgesia in ET-A receptor-mediated antinociception might provide novel alternatives to morphine therapy for the treatment of cancer pain.

Original languageEnglish (US)
Pages (from-to)663-671
Number of pages9
JournalJournal of Pain
Issue number7
StatePublished - Jul 2010


  • Endothelin
  • cancer
  • cancer mouse model
  • oral cancer
  • pain

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine


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