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Autoradiographic and functional development of gastric cholecystokinin receptors in the rat
G J Schwartz1, T H Moran, P R McHugh
1Department of Psychiatry and Behavioral Sciences Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Abstract:
To determine the functional role for and the pharmacological specificity of developing gastrointestinal CCK receptors, in vitro pyloric contractility and autoradiographic CCK receptor binding were examined in pups aged 1-20 days. CCK contracted the gastroduodenal junction at all ages, while nonsulfated CCK-8 (d-CCK) was less potent. Autoradiographic studies revealed CCK binding localized to the gastroduodenal junction throughout development. MK-329, a specific type A CCK receptor antagonist, completely displaced 125I CCK-8 binding at all ages, while d-CCK displaced binding at ages at which d-CCK elicited gastroduodenal contractility. The results demonstrate a physiological role for and pharmacological specificity of neonatal gastroduodenal CCK receptors.