Expression and coupling of somatostatin receptors in rat adrenal (PC12) and pituitary (GC) cell lines.
Somatostatin (somatotropin release-inhibiting factor, SRIF) interacts with G-protein coupled receptors (sst) designated sst1 through sst5. In PC12 and GC cells, SRIF binding sites were identified and mRNA receptor expression was evaluated. SRIF binding sites were expressed at a much lower density in PC12 (Kd = 21.2 +/- 3.9 nM; Bmax = 31 +/- 8 fmol/mg protein) than in GC cells (Kd = 6.4 +/- 1.6 nM; Bmax = 643 +/- 29 fmol/mg protein). sst3 receptor mRNA (81% of the total) was mainly expressed in PC12 cells, while sst1/2 receptor mRNAs were mostly expressed in GC cells (64 and 29%, respectively). In PC12 cells, adenylyl cyclase (AC) activity was unaffected by SRIF-14 (binding all SRIF receptors), octreotide (specific for sst2/3/5 receptors), BIM 23056 (binding sst3/5 receptors) or CH275 (specific for sst1 receptors), 1 microM each. In GC cells, SRIF-14 or octreotide, but not the two other peptides, significantly inhibited AC activity.
Dipartimento di Fisiologia e Biochimica G. Moruzzi, Universita' degli Studi di Pisa, Italy.
G
G
Traina
C
C
Lanneau
A
A
Arnoux
B
B
Porokhov
P
P
Bagnoli
J
J
Epelbaum
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D015342:DNA Probes; D015870:Gene Expression / Q000502:physiology; D007457:Iodine Radioisotopes; D009474:Neurons / Q000737:chemistry* / Q000201:enzymology; D016716:PC12 Cells; D010902:Pituitary Gland / Q000166:cytology*; D012333:RNA, Messenger / Q000032:analysis; D011869:Radioligand Assay; D051381:Rats; D017481:Receptors, Somatostatin / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015342:DNA Probes; D007457:Iodine Radioisotopes; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; D000262:Adenylyl Cyclases