The role of apolipoprotein A-IV in regulating glucagon-like peptide-1 secretion.

Both glucagon-like peptide-1 (GLP-1) and apolipoprotein A-IV (apoA-IV) are produced from the gut and enhance postprandial insulin secretion. This study investigated whether apoA-IV regulates nutrient-induced GLP-1 secretion and whether apoA-IV knockout causes compensatory GLP-1 release. Using lymph-fistula-mice, we first determined lymphatic GLP-1 secretion by administering apoA-IV before an intraduodenal Ensure infusion.

Lipid transport in cholecystokinin knockout mice.

Cholecystokinin (CCK) is released in response to lipid feeding and regulates pancreatic digestive enzymes vital to the absorption of nutrients. Our previous reports demonstrated that cholecystokinin knockout (CCK-KO) mice fed for 10 weeks of HFD had reduced body fat mass, but comparable glucose uptake by white adipose tissues and skeletal muscles. We hypothesized that CCK is involved in energy homeostasis and lipid transport from the small intestine to tissues in response to acute treatment with dietary lipids.

Overexpression of apolipoprotein C-III decreases secretion of dietary triglyceride into lymph.

Abstract Apolipoprotein C-III (apoC-III) is not only predominantly synthesized by the liver but also by the small intestine. Because apoC-III is secreted from the intestine on the chylomicron along with lipid absorption, we questioned whether apoC-III might play a role in intestinal lipid absorption and/or transport. Using both wild-type (WT) and apoC-III transgenic (apoC-III Tg) mice, we showed that apoC-III Tg mice have decreased lymphatic lipid transport compared with WT mice in response to an intraduodenal infusion of radiolabeled lipid.

Is apolipoprotein A-IV rate limiting in the intestinal transport and absorption of triglyceride?

Apolipoprotein A-IV (apoA-IV) is synthesized by the intestine and secreted when dietary fat is absorbed and transported into lymph associated with chylomicrons. We have recently demonstrated that loss of apoA-IV increases chylomicron size and delays its clearance from the blood. There is still uncertainty, however, about the precise role of apoA-IV on the transport of dietary fat from the intestine into the lymph.