Differential Effects of Intracerebroventricular Glucagon-Like Peptide-1 on Feeding and Energy Expenditure Regulation

Abstract

Intracerebroventricular (ICV) administration of glucagon-like peptide-1-(7–37) amide (GLP-1) has been shown to modulate food and water intake. The present studies further characterize the effects of ICV GLP-1 in the regulation of energy balance in lean and obese animals. In both obese and lean Zucker rats, a single ICV infusion of GLP-1 (1–30 μg) resulted in a dose-dependent reduction of food intake and decrease in respiratory quotient relative to the saline control during the first 2 h of the nocturnal cycle. In obese Zucker rats, the food intake was reduced by 73 ± 11% of the control at the 30 μg dose, whereas a modest 45 ± 18% reduction was observed in lean rats. Despite the large reduction in food intake seen with GLP-1, there was no compensatory decrease in nocturnal oxygen consumption in the obese Zucker rats. Interestingly, low doses of GLP-1 (1 μg) in lean Zucker rats, which had minimal effects on food intake, caused a 19 ± 7% increase in O 2 consumption during the first 2 h of the nocturnal cycle. These data suggest that central GLP-1 may be an important factor controlling negative energy balance in both the lean and obese Zucker rats.