Submitted on February 21, 2008
Accepted on April 15, 2008
Targeted enhancement of oleoylethanolamide production in proximal small intestine induces across-meal satiety in rats
Jin Fu1, Janet Kim1, Fariba Oveisi1, Giuseppe Astarita2, and Daniele Piomelli3*
1 Pharmacology, University of California, Irvine, Irvine, California, United States
2 Pharmacology, University of California, Irvine, 92697, California, United States
3 Pharmacology, University of California, Irvine, Irvine, California, United States; Italian Institute of Technology, Genova, Italy
* To whom correspondence should be addressed. E-mail: piomelli{at}uci.edu.
Pharmacological administration of the natural lipid amide, oleoylethanolamide (OEA), inhibits food intake in free-feeding rodents by prolonging latency to feed and post-meal interval. This anorexic effect is mediated by activation of type-
peroxisome proliferator-activated receptors (PPAR-). Food intake stimulates mucosal cells in duodenum and jejunum to generate OEA, suggesting that this lipid-derived messenger may act as a local satiety hormone. As a test of this hypothesis, here we examined whether targeted enhancement of small-intestinal OEA production affects feeding behavior in rats. We constructed an adenoviral vector (Ad-NPLD) that directs overexpression of the enzyme N-acylphosphatidylethanolamine (NAPE)-phospholipase D (PLD), which catalyses the hydrolysis of NAPE to generate OEA. Intraduodenal injection of the Ad-NPLD vector resulted in a time-dependent increase in NAPE-PLD expression and OEA production, which was restricted to the proximal small intestine. No such effect was observed after administration of a control adenoviral vector. Enhanced OEA production in Ad-NPLD-injected animals was temporally associated with increased expression of two PPAR- target genes (PPAR- and CD36) and with decreased food intake. The hypophagic phenotype of Ad-NPLD-injected rats was attributable to increase feeding latency and post-meal interval, rather than decreased meal size. The results suggest that localized changes in small-intestinal OEA production, such as those produced by food intake, are sufficient to induce in rats a state of across-meal satiety similar to that elicited by systemic administration of exogenous OEA.
