Endocrine Abstracts

Background Somatostatin has many putative biological effects in the kidney such as influencing renal blood flow and urine volume, tubular transport and cell regulation. It exerts these effects via five identified G-protein linked receptors. However, only somatostatin receptor proteins 1 and 2A have been described in human kidney so far. In this study, we examined the distribution of somatostatin receptors (SSTRs) in normal human adult kidney. Methods Formalin fixed paraffin embedded sections where immunostained using Dako Catalyzed Signal Amplification system. Sections were incubated in primary antibody (Somatostatin receptors 1-5 including 2A and 2B rabbit monoclonal antibody) over night at 4 degC, and a link antibody followed by streptavidin/biotin complex, amplification reagent and streptavidin-peroxidase was applied. Staining was visualised with diaminobenzidine. Taqman qRT PCR was used to identify the mRNA expression of somatostatin receptors in a normal kidney sample. Results Consistent staining of all SSTRs was seen in the thin tubules (distal and loop of Henle) (n= 9 nephrectomy/biopsy samples). Tubular staining was both cytoplasmic and nuclear. There was also staining of Bowman's epithelial cells in glomeruli for all the receptor subtypes. SSTR5 showed positive staining of mesangial cells in a variable proportion of glomeruli in several of the normal kidney samples examined. SSTR 2-3 had week positive staining mainly in the thin tubules. Taqman qRT PCR also showed positive expression of those receptors in the kidney sample. Conclusion All 5 Somatostatin receptors are expressed in human adult kidney at both mRNA and protein levels. The distribution is consistent with a tubular function.