In the gut, mu-, delta-, and
kappa-opioid receptors are present in the submucous and myenteric plexi and in enterocytes. Using pharmacological methods, our group has shown that intestinal
inflammation enhances the antitransit and antisecretory effects of systemic
opioids. The aim of the present study was to evaluate whether the enhanced antisecretory effects of delta and kappa-agonists were associated with an increased transcription and/or expression of these receptors at central (brain and spinal cord) and/or peripheral sites (gut); we also evaluated the expression of delta- and
kappa-opioid receptors in dissected sections of the gut containing the myenteric (MP/LM) or submucous (SP/M) plexi. The
mRNA and
protein levels of both
opioid receptors were determined using a
reverse-transcriptase polymerase chain reaction and immunoprecipitation/Western blot, respectively. Intestinal
inflammation significantly augmented the transcription of
delta-opioid receptors in the spinal cord (34%) and in the whole gut (102%). Also increased
mRNA and
protein levels of
delta-opioid receptors in the MP/LM and SP/M preparations. The
kappa-opioid receptors gene transcription was not altered by
inflammation, whereas
kappa-opioid receptors protein levels were significantly enhanced in the SP/M preparation. No changes in gene transcription or
protein levels for delta- and
kappa-opioid receptors could be demonstrated in the brain. These results suggest that local transcriptional and post-transcriptional changes of the delta- and
kappa-opioid receptors genes could be responsible for the enhanced antisecretory effects of delta- and kappa-
opioid agonists during intestinal
inflammation.