Somatostatin receptors on peripheral primary afferent terminals: Inhibition of sensitized nociceptors

Susan M. Carlton, Junhui Du, Elyad Davidson, Shengtai Zhou, Richard E. Coggeshall

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

Somatostatin (SST) is in primary afferent neurons and reduces vascular and nociceptive components of inflammation. SST receptor (SSTR) agonists provide analgesia following intrathecal or epidural administration in humans, but neurotoxicity in the central nervous system (CNS) has been reported in experimental animals. With the rationale that targeting peripheral SSTRs would provide effective analgesia while avoiding CNS side effects, the goals of the present study are to investigate the presence of SSTRs on peripheral primary afferent fibers and determine the behavioral and physiological effects of the SST agonist octreotide (OCT) on formalin-induced nociception and bradykinin-induced primary afferent excitation and sensitization in the rat. The results demonstrate that: (1) SSTR2as are present on 11% of peripheral primary afferent sensory fibers in rat glabrous skin; (2) intraplantar injection of OCT reduces formalin-induced nociceptive behaviors; (3) OCT reduces, in a dose-dependent fashion, responses to thermal stimulation in C-mechanoheat sensitive fibers; and (4) OCT reduces the responses of C-mechanoheat fibers to bradykinin-induced excitation and sensitization to heat. Each of these actions can be reversed following co-injection of OCT with the SSTR antagonist cyclo-somatostatin (c-SOM). Thus, activation of peripheral SSTRs reduces both inflammatory pain and the activity of sensitized nociceptors, avoids deleterious CNS side effects and may be clinically useful in the treatment of pain of peripheral origin.

Original languageEnglish (US)
Pages (from-to)233-244
Number of pages12
JournalPain
Volume90
Issue number3
DOIs
StatePublished - Feb 15 2001

Keywords

  • Nociception
  • Peptide
  • Primary afferent
  • Thermal hyperalgesia

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine

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