Segmental expression of somatostatin receptor subtypes sst(1) and sst(2) in tubules and glomeruli of human kidney

Somatostatin is known to modulate mesangial and tubular cell function and g rowth, but the somatostatin receptor (sst) subtypes responsible for these e ffects have not been defined. There are at least five different sst recepto r subtypes (sst(1)-sst(5)). We used RT-PCR to demonstrate that normal human kidney consistently expresses mRNA for sst(1) and sst(2) (9 of 9 donors). Some donors expressed sst(4) or sst(5) mRNA, but none expressed sst(3) mRNA . Expression of sst(1) and sst(2) was further assessed by staining serial s ections of normal human kidney with sst1 and sst2 antisera, Arachis hypogae a (AH) lectin (to define distal tubule/collecting duct cells), Phaseolus vu lgaris lectin (proximal tubules), and Tamm-Horsfall protein (THP) antiserum (thick ascending limb of the loop of Henle). Specificity of antisera was d emonstrated by transfection and absorption studies. Sst(2), but not sst(1), was expressed in glomeruli. Intense sst(1) and sst(2) staining localized e xclusively to AH(+) and THP+ tubules. Thus sst(1) and sst(2) subtype-select ive analogs may be useful to beneficially modulate renal cell function in p athological conditions.