Expression of cholecystokinin A receptors in neurons innervating the rat stomach and intestine.
OBJECTIVE
Two distinct receptors, cholecystokinin (CCK)-A and CCK-B, mediate CCK effects in the digestive system. The aim of this study was to elucidate the cellular sites of expression of CCK-A receptor in the rat stomach and small intestine.


METHODS
We developed and characterized an antibody to the N-terminal region (LDQPQPSKEWQSA) of rat CCK-A receptor and used it for localization studies with immunohistochemistry.


RESULTS
Specificity of the antiserum was demonstrated by (1) detection of a broad band at 85-95 kilodaltons in Western blots of membranes from CCK-A receptor CHO-transfected cells; (2) cell surface staining of CCK-A receptor-transfected cells, (3) translocation of CCK-A receptor immunostaining in CCK-A receptor-transfected cells after exposure to CCK; and (4) abolition of tissue immunostaining by preadsorbtion of the antibody with the peptide used for immunization. CCK-A receptor immunoreactivity was localized to myenteric neurons and to fibers in the muscle and mucosa. In the stomach, myenteric neurons and mucosal fibers were abundant. Many CCK-A receptor myenteric neurons contained the inhibitory transmitter vasoactive intestinal polypeptide, and some were immunoreactive for the excitatory transmitter substance P. Subdiaphragmatic vagotomy reduced the density of CCK-A receptor fibers in the gastric mucosa by approximately 50%, whereas celiac/superior mesenteric ganglionectomy had no detectable effect on fiber density.


CONCLUSIONS
CCK-A receptor is expressed in functionally distinct neurons of the gastrointestinal tract. CCK-A receptor may mediate reflexes stimulated by CCK through the release of other transmitters from neurons bearing the receptor.
Sternini
C
C
CURE Digestive Diseases Research Center, Division of Digestive Diseases, University of California, Los Angeles, California, USA. csternin@ucla.edu
Wong
H
H
Pham
T
T
De Giorgio
R
R
Miller
L J
LJ
Kuntz
S M
SM
Reeve
J R
JR
Walsh
J H
JH
Raybould
H E
HE
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D006224:Cricetinae; D005260:Female; D007150:Immunohistochemistry; D007422:Intestines / Q000294:innervation*; D008969:Molecular Sequence Data; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000235:genetics / Q000378:metabolism*; D013270:Stomach / Q000294:innervation*; D014018:Tissue Distribution; D014162:Transfection; D014628:Vagotomy
D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin