Comparison of opioid receptor distributions in the rat ileum

• Published in: Life sciences (1973) Vol. 78; no. 14; pp. 1610 - 1616
• Main Authors: Gray, A.C., Coupar, I.M., White, P.J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 28.02.2006
• Subjects: Animals; Female; Ileum - chemistry; Ileum - innervation; Immunohistochemistry; Interstitial cells; Myenteric plexus; Myenteric Plexus - chemistry; Myenteric Plexus - cytology; Neurons - chemistry; Rats; Rats, Wistar; Receptors, Opioid - analysis; Submucous plexus; Tissue Distribution; δ-opioid receptor; κ-opioid receptor; μ-opioid receptor; PBS; DMSO; ICC; Interstitial cells; ir; Submucous plexus; μ-opioid receptor; interstitial cells of Cajal; FIT; Cluorescein isothiocyanate; dimethyl sulfoxide; δ; κ-opioid receptor; phosphate buffered saline; δ-opioid receptor; κ; Immunoreactive (-ity); Myenteric plexus; μ
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2005.07.048

The cellular expression patterns of μ-, δ- and κ-opioid receptors in the rat ileum were examined using fluorescence immunohistochemistry. Double-labelling was used to examine cellular receptor co-localisation as a pre-requisite for intracellular molecular interactions, such as heterodimerisation. Tissues were stained as whole-mount preparations. Strong, broadly distributed immunoreactivity (ir) was observed for each receptor in the myenteric and submucous plexuses. Although intracellular μ- and δ-ir patterns differed in ganglion neurons, μ/δ co-expression was extensive in these cells. μ/δ co-expression was also observed in interstitial cells, which were diffusely distributed in submucous plexus preparations but generally located adjacent to myenteric plexus structures. Punctate κ-ir was seen broadly in nerve fibres in both plexuses, suggesting localisation in varicosities. Neuronal μ/κ co-localisation was not apparent, although κ-ir fibres were often apposed against μ-ir cells. μ/κ co-localisation was detected in interstitial cells in submucous plexus preparations. Similarities in μ and δ expression patterns might reflect similar functional properties previously detected for these receptors. This study indicates that the rat gastrointestinal tract might provide a useful tool for the future study of molecular interactions between opioid receptor types.