Somatostatin mediates inhibitory functions through five G protein–coupled somatostatin receptors (sst1-5). We used immunohistochemistry, immunofluorescence, and RT-PCR to determine the presence of somatostatin receptors sst1, sst2A, sst2B, sst3, sst4, and sst5 in normal and IgA nephropathy human kidney. All somatostatin receptors were detected in the thin tubules (distal convoluted tubules and loops of Henle) and thick tubules (proximal convoluted tubules) in the tissue sections from nephrectomy and biopsy samples. Immunopositive sst1 and sst4 staining was more condensed in the cytoplasm of tubular epithelial cells. In normal kidney tissue sections, podocytes and mesangial cells in the glomeruli stained for sst1, sst2B, sst4 and sst5, and stained weakly for sst3. In IgA kidney tissue, the expression of somatostatin receptors was significantly increased with particular immmunopositive staining for sst1, sst2B, sst4, and sst5 within glomeruli. In the epithelial cells, the staining for sst2B and sst4 in proximal tubules and sst1, sst2B, and sst5 in distal tubules was increased. The mRNA expression of sst1-5 was also detected by RT-PCR. Somatostatin and all five receptor subtypes were ubiquitously distributed in normal kidney and IgA nephropathy. The increased expression of somatostatin receptors in IgA nephropathy kidney might be the potential pathogenesis of inflammatory renal disease.

Summary. Background: 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been widely used in clinical practise and their efficacy in reducing cardiovascular risk has been well described. Objectives:To investigate the effect of low doses of fluvastatin (nanomolar) on H 2 O 2 -induced cell damage and the underlying mechanism. Methods and results: Primary cultures of human umbilical vein endothelial cells were used, and the effects of fluvastatin on H 2 O 2 -induced apoptosis, necrosis, and proliferation were observed. H 2 O 2 at a concentration of 100 lM significantly induced apoptotic cell death after 24-h cell culture. Fluvastatin at low concentrations (10-100 nM) prevented H 2 O 2 -induced apoptosis, as determined by a DNA fragmentation assay and by cell counting with trypan blue and Hoechst 33342 nuclei staining. The protective effect of fluvastatin was mediated by the upregulation of Bcl-2 expression as probed by real-time polymerase chain reaction and Western blotting. Using siRNA to knock down the expression of Bcl-2, the protective effect of fluvastatin was abolished. Fluvastatin had no direct effect on the H 2 O 2 -sensitive TRPM2 calcium channel. Conclusions: These results suggest that fluvastatin has a potent protective effect against H 2 O 2 -induced apoptosis via upregulation of Bcl-2 expression. The findings provide a new insight into the mechanism by which fluvastatin is able to modulate the influence of oxidative stress on vascular endothelial cells.