Cholecystokinin-33 is more effective than cholecystokinin-8 in inhibiting food intake and in stimulating the myenteric plexus and dorsal vagal complex.
We compared the abilities of cholecystokinin-33 (CCK-33) and CCK-8 to reduce food intake and to activate feeding-related areas of the nervous system. (1) Overnight food-deprived rats were presented with a 10% sucrose solution, and intake was measured at 5-min intervals throughout a 90-min test beginning immediately after intraperitoneal injections of 1, 3, or 5 nMol/kg of CCK-33, CCK-8, or the vehicle control. In the initial 20 min (first meal), both peptides were equally effective, producing large reductions of food intake. Thereafter, however, CCK-33 was more effective than CCK-8, producing much more sustained reductions. Overall, both peptides reduced total food intake, but CCK-33 was more effective than CCK-8. (2) Possible roles for the myenteric plexus of the duodenum and the dorsal vagal complex (DVC) of the brainstem in the differential satiety effects of CCK-33 and CCK-8 were examined by quantifying CCK-33- and CCK-8-stimulated Fos-like immunoreactivity (Fos-LI) in each site. Consistent with the greater ability of CCK-33 to produce sustained inhibitions of food intake, CCK-33 produced more Fos-LI than CCK-8 in nearly every section of the sampled sites. The results demonstrate: (1) Different forms of CCK have different efficacies in reducing food intake; (2) CCK-33 produces a much more prolonged satiety action than CCK-8; and (3) the myenteric plexus and DVC may play roles in these differential satiety actions.
Cooper
Marvis S
MS
Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama, USA.
Reeve
Joseph R
JR
Abdalla
Mohamed O
MO
Moyer
Laura
L
Raboin
Shannon J
SJ
Green
Gary M
GM
Sayegh
Ayman I
AI
D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology*; D002452:Cell Count; D002766:Cholecystokinin / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D007150:Immunohistochemistry; D008297:Male; D009197:Myenteric Plexus / Q000187:drug effects*; D010446:Peptide Fragments / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects; D014630:Vagus Nerve / Q000187:drug effects*
D001067:Appetite Depressants; D010446:Peptide Fragments; D016760:Proto-Oncogene Proteins c-fos; C410885:cholecystokinin 8; D002766:Cholecystokinin