Engineering an endomorphin-2 gene for use in neuropathic pain therapy

Darren Wolfe, Shuanglin Hao, Jian Hu, Rahul Srinivasan, James Goss, Marina Mata, David J. Fink, Joseph C. Glorioso

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Endomorphin-2 (EM-2) is a carboxy-amidated tetrapeptide that binds the μ-opioid receptor with high affinity and is analgesic in several animal models of pain. Endomorphin peptides have been isolated from bovine and human brain, but no DNA sequences corresponding to a potential preproendomorphin gene have been identified in human genome sequence databases. In this study we designed a tripartite synthetic gene to direct production, cleavage, and amidation of EM-2, and placed the endomorphin gene expression cassette in a replication defective Herpes simplex virus (HSV) vector (vEM2). Biosynthesis of amidated endomorphin-2 peptide was quantified by radioimmunoassay and the identity confirmed by mass spectroscopy following vEM2 transduction of cultured primary dorsal root ganglion neurons. Subcutaneous inoculation of vEM2 resulted in vector delivery to dorsal root ganglion where expression of EM-2 peptide from the engineered gene was confirmed by ELISA. vEM2 delivery provided an analgesic effect in the spinal nerve ligation model of neuropathic pain measured by reduction of mechanical allodynia and thermal hyperalgesia. The analgesic effect of vEM2 was blocked by intrathecal delivery of the μ-receptor antagonist CTOP. The gene construct design described represents a broadly useful platform for biosynthesis and delivery of carboxy-amidated peptides for therapeutic and experimental purposes, and the results demonstrate that HSV-gene transfer to sensory neurons provides an effective means to achieve local biosynthesis of endomorphin peptides for the treatment of chronic pain.

Original languageEnglish (US)
Pages (from-to)29-38
Number of pages10
Issue number1-3
StatePublished - Dec 15 2007
Externally publishedYes


  • μ-opioid receptor
  • Endomorphin
  • Gene transfer
  • Neuropathic pain
  • Viral vector

ASJC Scopus subject areas

  • Clinical Neurology
  • Psychiatry and Mental health
  • Neurology
  • Neuroscience(all)
  • Pharmacology
  • Clinical Psychology


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