Identification and Characterization of a Specific Receptor for Cholecystokinin on Isolated Fundic Glands from Guinea Pig Gastric Mucosa Using a Biologically Active¹²⁵I-CCK-8 Probe

Abstract

Specific binding sites for cholecystokinin (CCK) have been identified and characterized in fundic glands isolated by collagenase treatment from guinea pig gastric mucosa using a biologically active 125I-labeled derivative of the C-terminal octapeptide of CCK (125IIE-CCK-8). The time course of binding to these glands was rapid, temperature dependent and saturable. At 24, 30 and 37 degrees C, half-maximal binding was reached at 5 min and full binding at 30 min. The addition of a large excess of CCK-8 after 15 and 30 min of binding at 24 degrees C caused a prompt and rapid decline in radioligand bound showing that the interaction was reversible. There was a progressive decline in the amount of 125IIE-CCK-8 bound to fundic glands with increasing concentrations of CCK-8 and other structurally related peptides. Gastrin II displaced 50% of the radioligand at 1.6nM, CCK-8 at 3.2nM, gastrin I at 16nM, and desulfated-CCK-8 and pentagastrin at 59nM. Secretin did not displace the radioligand from fundic glands at 1.0uM. The binding was also tissue specific as glands isolated from the antral mucosa did not contain specific binding sites for 125IIE-CCK-8. This data provides evidence for specific receptors for CCK on gastric fundic glands that may be involved in the control of acid and pepsinogen secretion.

Seasonality of food intake in ruminants: recent developments in understanding

“…While there is virtually no information concerning the roles of these hormones in the expression of seasonality of intake in ruminants, CCK, which is secreted in response to ingestion of food and interacts with sensors in the gut wall (Praissman et al 1983) and pancreas (Steigerwalt & Williams, 1981), was found to act as a satiety factor in ruminants (Farningham et al 1993), with its effects being potentiated by central administration of insulin (Riedy et al 1995;Woods et al 1996). Thus, CCK may be involved in the determination of meal pattern and therefore level of intake.…”

Tyrosine modification increases the affinity of gastrin for ferric ions

“…The IC 50 values for the binding of gastrin 17 were slightly higher than the values, which range from 0.94 to 6.4 nM, previously reported for the cloned human CCK2 receptor (Ito et al 1993 ; Lee et al 1993 ; Pisegna et al 1992 ). The affinity of gastrin 17 SO 4 for the cloned human CCK2 receptor does not appear to have been reported previously, but data for binding to dispersed gastric glands from the guinea pig fundus also suggest that sulphation increases the affinity for the CCK2 receptor, in that case by a factor of tenfold, from 16 to 1.6 nM (Praissman et al 1983 ). Binding of gastrin 17 , gastrin 17 SO 4 and gastrin 17 PO 4 to the CCK1 receptor was not detected in our experiments (Fig.…”