Expression of the five somatostatin receptor (SSTR1-5) subtypes in rat pituitary somatotrophes: quantitative analysis by double-layer immunofluorescence confocal microscopy.
Using quantitative double-label fluorescence immunocytochemistry and confocal microscopy, we have analysed the pattern of expression of SSTR1-5 in normal rat pituitary somatotrophes. Antipeptide rabbit polyclonal antibodies were produced against the extracellular domains of SSTR1-5. SSTR antigens were colocalized in GH positive cells using rhodamine conjugated secondary antibody for SSTRs and FITC-conjugated secondary antibody for GH. SSTR5 was the predominant subtype which was expressed in 86 +/- 9.7% of GH cells followed by SSTR2 in 42 +/- 6.4% of GH positive cells. SSTR4 and SSTR3 were modestly expressed in 23 +/- 4.7% and 18 +/- 3.2% of somatotrophes respectively whereas SSTR1 was the least expressed subtype occurring in only 5 +/- 1.2% of somatotrophes. These results demonstrate variable expression of the 5 SSTRs in somatotrophes. The preponderance of the SST-28 preferring SSTR5 subtype correlates with the reported higher potency of SST-28 than SST-14 for inhibiting GH secretion.
Kumar
U
U
Department of Medicine, McGill University, Royal Victoria Hospital and Montreal Neurological Institute, Quebec, Canada.
Laird
D
D
Srikant
C B
CB
Escher
E
E
Patel
Y C
YC
D000818:Animals; D000906:Antibodies / Q000032:analysis / Q000276:immunology; D000941:Antigens / Q000032:analysis / Q000276:immunology; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D013006:Growth Hormone / Q000032:analysis; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods*; D010902:Pituitary Gland / Q000737:chemistry* / Q000166:cytology*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D017481:Receptors, Somatostatin / Q000032:analysis* / Q000145:classification / Q000276:immunology; D014162:Transfection
D000906:Antibodies; D000941:Antigens; D017481:Receptors, Somatostatin; D013006:Growth Hormone