The gastrin/cholecystokinin-B receptor antagonist L-365,260 reduces basal acid secretion and prevents gastrointestinal damage induced by aspirin, ethanol and cysteamine in the rat.
L-365,260, a nonpeptide antagonist of gastrin/CCK-B receptors, was evaluated in receptor binding, antisecretory and gastrointestinal damage assays. L-365,260 binds potently and stereo-selectively to gastrin and CCK-B sites in guinea pig tissue. In contrast, L-365,260 binds to the isolated canine parietal cell gastrin receptor weakly, and without stereoselectivity. In the pylorus-ligated rat, low doses of L-365,260, given i.v., attenuated pentagastrin-stimulated acid secretion, whereas higher doses were required to inhibit both histamine-stimulated and basal acid secretion. In an aspirin-induced gastric damage model, L-365,260 was 2.4-fold less potent than the standard histamine H2 antagonist cimetidine in preventing gastric damage when given i.v., and was 8.3-fold less potent than cimetidine when given p.o. Moreover, the ED50 value for L-365,260, given i.v., in prevention of aspirin-induced gastric damage (11.5 mg/kg) agreed well with its ED50 value for inhibition of basal acid secretion (12.6 mg/kg). At doses as great as 100 mg/kg p.o., neither L-365,260 nor cimetidine had an effect on ethanol-induced gastric damage. L-365,260, although p.o. less bioavailable relative to cimetidine in the aspirin gastric damage model, was as potent as cimetidine in the prevention of cysteamine-induced duodenal ulcers in the rat. We conclude that the gastrin/CCK-B receptor antagonist L-365,260, at doses supramaximal for the inhibition of pentagastrin-stimulated secretory responses in vivo, inhibits gastrointestinal damage in models of peptic ulcer disease by an antisecretory mechanism of action.
Pendley
C E
CE
Department of Pharmacology, Rhône-Poulenc Rorer Central Research, Collegeville, Pennsylvania.
Fitzpatrick
L R
LR
Ewing
R W
RW
Molino
B F
BF
Martin
G E
GE
D000818:Animals; D001241:Aspirin / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D001570:Benzodiazepinones / Q000494:pharmacology*; D003543:Cysteamine / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D004064:Digestive System / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D005744:Gastric Acid / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D010671:Phenylurea Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors*
D001570:Benzodiazepinones; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; C058121:L 365260; D000431:Ethanol; D003543:Cysteamine; D001241:Aspirin