Delta-opioid receptor mRNA expression and immunohistochemical localization in porcine ileum.
Opiates have potent antidiarrheal actions that are mediated in part by delta-opioid receptors (DOR). We examined DOR localization within subregions of porcine ileum, a tissue analogous to human small bowel. A partial cDNA sequence for porcine DOR was obtained after reverse transcription-polymerase chain reaction cloning of forebrain RNA; it encoded the end of transmembrane domain 1 through the beginning of transmembrane domain 7 and exhibited 93% nucleotide identity with human DOR. Positive signals for DOR mRNA were found in all subregions of the porcine ileal wall. With an antiserum recognizing an N-terminal epitope in murine DOR, DOR-like immunoreactivity was localized in neurons within myenteric and submucous ganglia, longitudinal and circular smooth muscle, and villous lamina propria. The DOR agonist [D-Ser2, Leu5, Thr6]enkephalin (DSLET) attenuated circular smooth muscle contractions in porcine ileum that were evoked by electrical stimulation of myenteric cholinergic neurons. These results are consistent with previous reports of the DOR-mediated neuromodulation that underlies the antipropulsive and antisecretory effects of opioids in the intestinal tract.
Department of Veterinary PathoBiology, University of Minnesota Academic Health Center, Minneapolis, USA.
D R
DR
Brown
S
S
Poonyachoti
M A
MA
Osinski
T R
TR
Kowalski
M S
MS
Pampusch
R P
RP
Elde
M P
MP
Murtaugh
D000818:Animals; D004558:Electric Stimulation; D017615:Enteric Nervous System / Q000187:drug effects / Q000502:physiology; D005260:Female; D015870:Gene Expression; D007082:Ileum / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008297:Male; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000187:drug effects / Q000378:metabolism*; D013552:Swine
D012333:RNA, Messenger; D017465:Receptors, Opioid, delta