Immunohistochemical Detection and Localization of Somatostatin Receptor Subtypes in Prostate Tissue from Patients with Bladder Outlet Obstruction

Background and Aim of the Study: Scant information on the cellular distribution of the five somatostatin receptor (SSTR) subtypes in the normal prostate and in neoplasms of the prostate has been reported in very few studies in which techniques, such as in situ hybridization histochemistry, autoradiography, and more recently immunohistochemistry, have been applied. The aim of the study was to examine immunohistochemically the distribution and localization of these 5 subtypes in the various tissue components in normal prostate. Materials: The study was conducted in 14 surgical specimens of normal prostate tissue from adenomectomy specimens from patients with bladder outlet obstruction. The distribution and localization of the 5 somatostatin receptor (SSTR) subtypes was investigated with an immunohistochemical technique. Specificity of the antibodies against the 5 receptor subtypes was preliminarily investigated. Results: Close to 90% of secretory cells showed a weak positivity in the cytoplasm, the proportion ranging from 86.3% (SSTR4) to 89.9% (SSTR5). Strong immunoreactivity was seen in a small proportion of cells, ranging from 0.8% (SSTR3) to 3.2% (SSTR1). For the subtypes 1 and 3 the greatest proportion of basal cells showed a moderate intensity (42.5 and 41.4%, respectively), strong immunoreactivity being observed only in 18.1 and 15.8% of cells, respectively. For the subtypes 2, 4 and 5, the majority of cells showed a weak intensity (72.3, 65.7 and 65.1%, respectively). Subtype 1 showed a strong immunoreactivity in the cytoplasm in 60% of the smooth muscle cells. With subtypes 2, 3 and 4 the greatest proportion of cells showed a weak intensity (63.4, 89.8 and 81.7%, respectively). With the subtype 5 the majority of cells (59.8%) were negative. Subtype 1 showed a strong immunoreactivity in the cytoplasm in 98.6% of the endothelial cells. With subtypes 3 and 4 the greatest proportion of cells showed a weak intensity (73.5 and 56.4%, respectively). With the subtype 2 and 5 the majority of cells were negative (59.1 and 50.7%, respectively). Conclusions: Our immunohistochemical study on the SSTRs expands our knowledge in the distribution of these subtypes in the various tissue components in the prostate. Such an information may prove useful in developing further non-surgical strategies for the prevention and treatment of benign prostatic hyperplasia and, in particular, of preneoplastic and neoplastic lesions of the prostate.