Stimulation of jejunal synthesis of apolipoprotein A-IV by ileal lipid infusion is blocked by vagotomy.
We examined the role of vagal innervation in lipid-stimulated increases in expression and synthesis of intestinal apolipoprotein A-IV (apoA-IV). In rats with duodenal cannulas and superior mesenteric lymph fistulas given duodenal infusions of lipid emulsion, vagotomy had no effect on either intestinal lipid transport, lymphatic apoA-IV output, or jejunal mucosal apoA-IV synthesis. In rats with jejunal Thiry-Vella fistulas, ileal lipid infusion elicited a twofold stimulation of apoA-IV synthesis without affecting apoA-IV mRNA levels; vagotomy blocked this increase in apoA-IV synthesis. Direct perfusion of jejunal Thiry-Vella fistulas produced 2- to 2.5-fold increases in both apoA-IV synthesis and mRNA levels in the Thiry-Vella segment; these effects were not influenced by vagal denervation. These results suggest two mechanisms whereby lipid stimulates intestinal apoA-IV production: 1) a vagal-dependent stimulation of jejunal apoA-IV synthesis by distal gut lipid that is independent of changes in apoA-IV mRNA levels and 2) a direct stimulatory effect of proximal gut lipid on both synthesis and mRNA levels of jejunal apoA-IV that is independent of vagal innervation.
Kalogeris
T J
TJ
Department of Surgery, Louisiana State University Medical Center, Shreveport, Louisiana 71130, USA. tkalog@lsumc.edu
Holden
V R
VR
Tso
P
P
D000818:Animals; D001054:Apolipoproteins A / Q000235:genetics* / Q000378:metabolism; D002914:Chylomicrons / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D007082:Ileum / Q000294:innervation / Q000378:metabolism*; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology; D007412:Intestinal Fistula / Q000378:metabolism / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism; D007583:Jejunum / Q000294:innervation / Q000378:metabolism*; D008208:Lymphatic System / Q000378:metabolism / Q000473:pathology; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000493:pharmacokinetics*; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology / Q000601:surgery
D001054:Apolipoproteins A; D002914:Chylomicrons; D012333:RNA, Messenger; D014280:Triglycerides; C022205:apolipoprotein A-IV