Chemical coding of neurons expressing δ- and κ-opioid receptor and type I vanilloid receptor immunoreactivities in the porcine ileum

Sutthasinee Poonyachoti, Anjali Kulkarni-Narla, David R. Brown

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56 Scopus citations


Opioid drugs have profound antidiarrheal and constipating actions in the intestinal tract and are effective in mitigating abdominal pain. Mediators of intestinal inflammation and allergy produce increased mucosal secretion, altered bowel motility and pain due to their ability to evoke enteric secretomotor reflexes through primary afferent neurons. In this study, the distribution of δ- and κ-opioid receptor (DOR and KOR, respectively) immunoreactivities in chemically identified neurons of the porcine ileum was compared with that of the capsaicin-sensitive type 1 vanilloid receptor (VR1). DOR and VR1 immunoreactivities were observed to be highly localized in choline acetyltransferase (ChAT)- and calcitonin gene-related peptide (CGRP)-positive neurons and nerve fibers of the submucosal and myenteric plexuses and both receptors exhibited frequent colocalization. In the inner submucosal plexus, they also were colocalized in substance P (SP)-positive neurons. Neurons in the outer submucosal plexus expressed DOR immunoreactivity alone or in combination with VR1. KOR-immunoreactive neurons were found only in the myenteric plexus; these cells coexpressed immunoreactivity to ChAT, CGRP, vasoactive intestinal peptide (VIP) or nitric oxide synthase (NOS). In addition, some KOR-positive neurons coexpressed immunoreactivities to DOR and VR1. Based on their neurochemical coding, opioid and vanilloid receptor-immunoreactive neurons in the submucosal and myenteric plexuses may include primary afferents and constitute novel therapeutic targets for the palliation of painful intestinal inflammatory, hypersensitivity and dysmotility states.

Original languageEnglish (US)
Pages (from-to)23-33
Number of pages11
JournalCell and Tissue Research
Issue number1
StatePublished - 2002

Bibliographical note

Funding Information:
This investigation was supported by NIH grant R01 DA-10200 to D.R.B. and Thailand Research Fund contract PDF/29/2544 to S.P. S.P. was supported by a Royal Thai Government scholarship and A.K-N. was a postdoctoral trainee supported by NIH Psychoneuroimmunology Training Grant T32 DA-07239


  • Calcitonin gene-related peptide
  • Choline acetyltransferase
  • Epithelial ion transport
  • Intestinal propulsion
  • Pig (Yorkshire)
  • Sensory neurotransmission
  • Substance P


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