Expression of somatostatin receptors in splanchnic blood vessels of normal and cirrhotic rats

Abstract

Somatostatin has been used for over two decades to treat acute variceal bleeding. Although it is assumed that somatostatin lowers portal pressure by constriction of the splanchnic arteries, little is known about the expression of somatostatin receptors (SSTR) in splanchnic blood vessels. In this study we investigated SSTR expression in splanchnic blood vessels from normal and cirrhotic rats. Cirrhosis was induced by intraperitoneal injection of 50 mg thioacetamide twice a week for 14 weeks. In portal vein, mesenteric artery and aorta of normal and cirrhotic rats, mRNA for the five known SSTR was measured by quantitative reverse transcriptase-polymerase chain reaction. SSTR subtypes 1, 2, 3 and 4 were expressed, but subtype 5 was undetectable. In the portal vein of cirrhotic animals, SSTR1 was significantly down-regulated as compared with controls. Otherwise, no major differences in receptor expression between normal and cirrhotic animals were observed. Using immunohistochemistry, we identified all five receptors, although the staining of receptor 5 was very weak. All five SSTR are expressed in splanchnic blood vessels. Our results suggest that cirrhosis reduces expression of SSTR1 in portal vein. In other vessels, no major differences between the normal and cirrhotic state were noted.