Synthesis and secretion of somatostatin-28 and -14 by fetal rat intestinal cells in culture.
A fetal rat intestinal cell (FRIC) culture model was established to investigate the factors controlling synthesis and secretion of somatostatin-28 (S-28) by the intestine. Immunohistochemical analysis demonstrated the presence of cells containing somatostatin-like immunoreactivity (SLI), many of which emitted long processes toward neighboring cells. Gel chromatography of SLI stored and secreted by nonstimulated FRIC cultures demonstrated a predominance of S-28 (59%), lesser amounts of S-14 (31%), and a minor peak of large molecular weight SLI (10%). Secretion of SLI was stimulated by treatment of cells for 2 h with 5 mM dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP; P less than 0.01) or 2 microM phorbol ester (P less than 0.05), but was unaffected by the calcium ionophore A23187 (2 micrograms/ml). Concomitant treatment with all three agents increased SLI secretion in an additive fashion to 254 +/- 25% of controls (P less than 0.0001). DBcAMP treatment did not alter the distribution of stored or secreted S-28 (59%) and S-14 (33%). After 24 h of exposure to DBcAMP, but not after treatment with phorbol ester, a threefold increment in prosomatostatin mRNA transcript levels was observed. FRIC cultures therefore synthesize and secrete a predominance of S-28 in a regulated manner, making them a promising model for future studies on the biosynthesis and secretion of intestinal somatostatin.
Department of Physiology, University of Toronto, Ontario, Canada.
P L
PL
Brubaker
D J
DJ
Drucker
G R
GR
Greenberg
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D003994:Bucladesine / Q000494:pharmacology; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002478:Cells, Cultured; D002850:Chromatography, Gel; D005576:Colforsin / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005333:Fetus; D005455:Fluorescent Antibody Technique; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects; D011498:Protein Precursors / Q000096:biosynthesis; D012313:RNA / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D053561:Somatostatin-28; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D002087:Butyrates; D011498:Protein Precursors; D012333:RNA, Messenger; D020148:Butyric Acid; D005576:Colforsin; D000431:Ethanol; D013004:Somatostatin; D012313:RNA; D003994:Bucladesine; D053561:Somatostatin-28; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine