The effect of somatostatin on 5-hydroxytryptamine release from a carcinoid tumor.
One of the major manifestations of the carcinoid syndrome is secretory diarrhea thought to be due to overproduction of 5-hydroxytryptamine (5-HT). Synthetic somatostatin analogues have proved to be clinically effective in controlling this diarrhea. We have established a continuous cell line from a human pancreatic carcinoid tumor that secretes 5-HT. We examined the ability of the somatostatin analogue, SMS 201-995, to inhibit 5-HT release in vitro. Tumor cells were exposed to SMS 201-995 (10(-6) mol/L), pentagastrin (10(-9) mol/L), acetylcholine (10(-5) mol/L), and isoproterenol (10(-5) mol/L) alone and in combination; 5-HT release was assayed with high pressure liquid chromatography. We found that pentagastrin (6.43 +/- 0.64 ng/ml), isoproterenol (20.24 +/- 2.17 ng/ml), and acetylcholine (12.39 +/- 1.10 ng/ml) each stimulated release of 5-HT compared to control values (4.38 +/- 0.42 ng/ml). SMS 201-995 significantly reduced release of 5-HT in response to isoproterenol and acetylcholine but did not inhibit the effect of pentagastin. These data suggest that different agents do not act through the same pathway to stimulate 5-HT release from human pancreatic carcinoid cells.
Lawrence
J P
JP
Department of Surgery, University of Texas Medical Branch, Galveston 77550.
Ishizuka
J
J
Haber
B
B
Townsend
C M
CM
Thompson
J C
JC
D000109:Acetylcholine / Q000494:pharmacology; D002276:Carcinoid Tumor / Q000378:metabolism*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D015282:Octreotide / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D010418:Pentagastrin / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism*; D013004:Somatostatin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D012701:Serotonin; D013004:Somatostatin; D010418:Pentagastrin; D007545:Isoproterenol; D000109:Acetylcholine; D015282:Octreotide