Stimulation of apolipoprotein a-iv synthesis in proximal jejunum by
ileal lipid infusion is independent of the presence of jejunal
lipid.
Kalogeris, Theodore J., Takashi Tsuchiya, Koji Fukagawa, Robert Wolf,
and Patrick Tso.
Departments of Physiology and Biophysics and Medicine, Louisiana
State University Medical Center, Shreveport, LA
APStracts 2:0182G, 1995.
Biosynthesis of apolipoprotein (apo) A-IV is stimulated by dietary
lipid, but the precise mechanisms involved are not clearly
understood. Using an intestinally-infused rat model, we compared the
effect of delivery of lipid into different intestinal sites on
mucosal synthesis of apo A-IV in the jejunum and ileum in order to
determine 1) the effect of lipid delivered to one region of the
intestine on A-IV synthesis in the another region of gut, and 2)
whether any such effect is dependent on the presence of lipid in the
latter region. Duodenal infusion of triolein emulsion (40 [mu]mol/h)
increased jejunal A-IV synthesis and mRNA levels by 2-3-fold, but had
no effect on ileal A-IV synthesis or mRNA abundance. Ileal infusion
of lipid emulsion containing monoolein (20 [mu]mol/h) + oleic acid
(40 [mu]mol/h) stimulated A-IV synthesis in both ileum and proximal
jejunum. Retrograde (orad) transport of ileally-infused lipid was not
a likely explanation for the ileal effect on jejunal A-IV synthesis,
since there was negligible luminal and mucosal recovery of 14C-oleic
acid in the jejunum after ileal infusion. Total bile diversion did
not block the effect of ileal lipid on jejunal A-IV synthesis. Ileal,
but not duodenal lipid infusion stimulated A-IV synthesis in a
jejunal Thiry-Vella fistula, and perfusion of an ileal Thiry-Vella
fistula marginally stimulated proximal jejunal A-IV synthesis. Thus,
administration of lipid to the distal gut produces an increase in
mucosal synthesis of apo A-IV in both proximal and distal gut. This
effect appears to be independent of direct jejunal presence of lipid,
suggesting that lipid in the distal intestine may elicit a signal
capable of stimulating jejunal synthesis of apo A-IV.
Received 27 December 1994; accepted in final form 31 August 1995.
APS Manuscript Number G500-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.