Characteristics of adrenocortical function, gastrin release and gastric secretion in duodenal ulcer etiology

Measurements of serum cortisol and gastrin along with gastric acid-pepsin secretion in the resting state were carried out in gastric and duodenal ulcer patients. Increased basal corticosteroid concentrations were observed in patients with duodenal ulcer and gastric ulcer. Higher concentrations of the hormone were observed in the former group (P less than 0.05 for the latter). Fasting gastrin levels were significantly higher in gastric ulcer patients where gastric secretion is low than those in duodenal ulcer patients (P less than 0.001). These results suggest that the effect of adrenal cortical hormone on lowering the threshold of oxyntic gland cell reactivity against gastrin is an important factor in duodenal ulcer etiology. Extra-antral control mechanism(s) of gastric acid-pepsin secretion should not be overlooked.

Biological activity of neurotensin and its C-terminal partial sequences

A hypothalamic tridecapeptide, neurotensin, and its C-terminal partial sequences down to the dipeptide were synthesized. These peptides were assayed for smooth muscle contracting and blood pressure lowering properties using preparations of isolated stomach fundus, uterus and duodenum of the rat, isolated guinea pig ileum and rabbit carotid artery. Sequences of 6 or more terminal amino acids produced a strong stomach fundus contracting effect, the potencies of the fragments being approximately equivalent to or slightly more than that of the parent tridecapeptide. These fragments also elicited the ileum contracting activity, but the potencies were only one fifth to one tenth that of neurotensin. The tetra- or dipeptide hardly stimulated either the fundus or the ileum. The stimulating effect on the uterus or relaxing effect on the duodenum of neurotensin was not consistent. Rabbit blood pressure was lowered markedly by neurotensin and weakly by its dodecapeptide. From these results, the arginine or arginine-arginine residue down to the C-terminal leucine appears to be essential for the smooth muscle contracting activity of neurotensin. The full length sequence may be needed for the hypotensive effect.