Effects of cholecystokinin-receptor antagonists on Fos-like immunoreactivity stimulated by sulfated cholecystokinin-8 in neurons of the myenteric plexus and hindbrain of rats.
OBJECTIVE
To evaluate the role of cholecystokinin (CCK)-receptor antagonists in the activation of enteric and hindbrain neurons by sulfated CCK-8.


METHODS
81 male Sprague-Dawley rats.


METHODS
Rats were allocated to 10 groups (5 to 22 rats/group). Each rat received 2 IP injections (15 minutes between injections). The first injection consisted of a specific CCK2-receptor (CCK2R) antagonist (L365,260; 150, 500, or 1,000 microg/kg), a specific CCK1-receptor (CCK1R) antagonist (devazepide; 150 microg/kg), or 1% dimethyl sulfoxide (DMSO [ie, vehicle]), and the second injection consisted of sulfated CCK-8 (10 microg/kg) or saline (0.9% NaCl) solution. Rats were anesthetized and perfused with 500 mL of Krebs saline solution, and the myenteric plexuses of the duodenum and jejunum were collected. Rats were then perfused with 500 mL of phosphate-buffered 4% formaldehyde solution; rats were then euthanatized, and the hindbrain of each was harvested. Tissues were stained by use of a diaminobenzidine reaction enhanced with nickel to reveal Fos-like immunoreactivity (Fos-LI), a marker of neuronal activation, in the aforementioned neurons.


RESULTS
Sulfated CCK-8 significantly increased Fos-LI in the myenteric and hindbrain neurons, compared with values for the DMSO injections. All dosages of L365,260 failed to attenuate this increase; however, injection of devazepide attenuated the increase in Fos-LI.


CONCLUSIONS
Analysis of the results of this study reveals that sulfated CCK-8 activates myenteric and hindbrain neurons of rats primarily through CCK1 R. It provides evidence that CCK2R are lacking or not functional in the gastrointestinal tract of rats.
Webb
Tennille
T
Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL 36088, USA.
Gulley
Stephen
S
Esdaile
Alton R
AR
Pruitt
Fleurette
F
Sharma
Sanjay K
SK
Williams
Carol S
CS
Sayegh
Ayman I
AI
D000818:Animals; D015870:Gene Expression / Q000187:drug effects; D008297:Male; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors / Q000502:physiology*; D012249:Rhombencephalon / Q000187:drug effects / Q000378:metabolism*; D012844:Sincalide / Q000031:analogs & derivatives* / Q000494:pharmacology
C090019:8-sulfocholecystokinin octapeptide; D016760:Proto-Oncogene Proteins c-fos; D011949:Receptors, Cholecystokinin; D012844:Sincalide