RT-PCR and immunocytochemistry studies support the presence of somatostatin, cortistatin and somatostatin receptor subtypes in rat Kupffer cells

Abstract

The present study investigated the presence of somatostatin receptor subtypes (ssts) and the endogenous peptides somatostatin and cortistatin in rat Kupffer cells, since modulation of these cells by somatostatin may be important for the beneficial effect of somatostatin analogues in a selected group of hepatocellular carcinoma patients. Kupffer cells were isolated from rat liver in agreement with national and EU guidelines. RT-PCR was employed to assess the expression of somatostatin, cortistatin and ssts in Kupffer cells. Western blot analysis and immunocytochemistry were employed to assess the expression and the localization of the receptors, respectively. Quiescent Kupffer cells were found to express sst 1–4 mRNA, while immunocytochemical studies supported the presence of only the sst 3 and sst 4 receptors, which were found to be internalized. However, sst 1 and sst 2A receptors were detected by western blotting. RT-PCR and RIA measurements support the presence of both somatostatin and cortistatin. Stimulation of the cells with LPS activated the expression of the sst 2, sst 3 and sst 4 receptors. The present data provide evidence to support the presence of ssts and the endogenous neuropeptides somatostatin and CST in rat Kupffer cells. Both peptides may act in an autocrine manner to regulate sst receptor distribution. Studies are in progress in order to further characterize the role of ssts in Kupffer cells and in hepatic therapeutics.