Persistent lack of somatostatin receptors in gastric mucosa of healing ulcers in rats.

Background/aims: Growth factors and their receptors play a role in healing ulcers of the rat. Somatostatin is a putative growth factor in the gastric mucosa with multiple functions mediated by specific receptors. Therefore, the distribution of somatostatin receptors was evaluated in the gastric mucosa of healing ulcers.

Methods: Somatostatin receptors were measured in the gastric mucosa of healthy rats and of rats with cryoulcers and acetic acid-induced ulcers, using somatostatin receptor autoradiography with 125I-[Tyr3]-octreotide or 125I-[Leu8, D-Trp22, Tyr25]-somatostatin-28 as radioligands. Epidermal growth factor receptors were measured on adjacent sections with 125I-epidermal growth factor.

Results: High-affinity somatostatin receptors are present in the gastric fundic mucosa of healthy rats. In contrast, in healing ulcers, the somatostatin receptors are almost lacking in the ulcer edge or scar at 3, 7, 28, 49, and even 84 days after ulcer induction (83%-91% reduction). Similar results are obtained with cryoulcers and with acetic acid-induced ulcers. For comparison, the number of epidermal growth factor receptors are increased in the same healing ulcers.

Conclusions: The persistent absence of somatostatin receptors for several months after ulcer induction may be of pathophysiological significance in ulcer repair and healing.