A functional role for central glucagon-like peptide-1 receptors in lithium chloride-induced anorexia

The present study sought to determine whether central glucagon-like peptide-1 (GLP-1)receptor signalling contributes to the anorexigenic effects of systemically administered lithium chloride (LiCl). Male Sprague-Dawley rats with chronic intracerebroventricular (ICV) cannulas were acclimated to a feeding schedule that included daily 30-min access to palatable mash. In the first experiment, ICV infusion of a GLP-1-receptor antagonist [exendin-4-(3-39)] significantly attenuated (10 mu g dose) or completely blocked (20 pg dose) the inhibition of food intake produced by subsequent ICV infusion of GLP-1-(7-36) amide (5 mu g). In the second experiment, rats were infused with 0, 10, or 20 mu g of the GLP-1-receptor antagonist ICV, followed by injection of 0.15 M LiCl (50 mg/kg ip) or the same volume of 0.15 M NaCl. The ability of LiCl treatment to suppress food intake was significantly attenuated in rats that were pretreated with the GLP-1-receptor antagonist. These results support the view that central mechanisms underlying LiCl-induced anorexia include a prominent role for endogenous GLP-1 neural pathways.