Background/aims: The neuropeptide somatostatin exerts multiple functions in the gastrointestinal tract and may also play a regulatory role in inflammatory bowel disease, as several other neuropeptides do, e.g., substance P or calcitonin gene-related peptide. Therefore, the expression of somatostatin receptors was evaluated in tissue sections of diseased intestines and compared with controls.
Methods: Somatostatin receptors were measured in intestinal samples of 6 patients with Crohn's disease, 3 with ulcerative colitis, and 7 controls using somatostatin receptor autoradiography with 125I-[Tyr3]-octreotide or 125I-[Leu8,D-Trp22,Tyr25]-somatostatin-28 as radioligands. Substance P receptors were measured similarly on adjacent sections.
Results: Somatostatin receptors are present in high density in most intramural veins, but not in arteries, of intestines in florid Crohn's disease or ulcerative colitis. The receptors are specific and of high affinity for somatostatin-14 and -28, as well as for octreotide. Somatostatin receptors remain undetectable in the veins of noninflamed control intestine. Substance P receptors are identified in the somatostatin receptor-positive veins and also in arteries.
Conclusions: The expression of receptors for somatostatin in veins of inflamed intestines suggests an active involvement of this peptide in the pathophysiology of inflammatory bowel disease and perhaps of inflammation in general.