Segmental expression of somatostatin receptor subtypes sst1and sst2in tubules and glomeruli of human kidney

Abstract

Somatostatin is known to modulate mesangial and tubular cell function and growth, but the somatostatin receptor (sst) subtypes responsible for these effects have not been defined. There are at least five different sst receptor subtypes (sst₁-sst₅). We used RT-PCR to demonstrate that normal human kidney consistently expresses mRNA for sst₁and sst₂(9 of 9 donors). Some donors expressed sst₄or sst₅mRNA, but none expressed sst₃mRNA. Expression of sst₁and sst₂was further assessed by staining serial sections of normal human kidney with sst₁and sst₂antisera, Arachis hypogaea (AH) lectin (to define distal tubule/collecting duct cells), Phaseolus vulgaris lectin (proximal tubules), and Tamm-Horsfall protein (THP) antiserum (thick ascending limb of the loop of Henle). Specificity of antisera was demonstrated by transfection and absorption studies. Sst₂, but not sst₁, was expressed in glomeruli. Intense sst₁and sst₂staining localized exclusively to AH⁺and THP⁺tubules. Thus sst₁and sst₂subtype-selective analogs may be useful to beneficially modulate renal cell function in pathological conditions.