Brain glucagon-like peptide 1 signaling controls the onset of high-fat diet-induced insulin resistance and reduces energy expenditure.
Résumé
Glucagon-like peptide-1 (GLP-1) is a peptide released by the intestine and the brain. We previously demonstrated that brain GLP-1 increases glucose-dependent hyperinsulinemia and insulin resistance. These two features are major characteristics of the onset of type 2 diabetes. Therefore, we investigated whether blocking brain GLP-1 signaling would prevent high-fat diet (HFD)-induced diabetes in the mouse. Our data show that a 1-month chronic blockage of brain GLP-1 signaling by exendin-9 (Ex9), totally prevented hyperinsulinemia and insulin resistance in HFD mice. Furthermore, food intake was dramatically increased, but body weight gain was unchanged, showing that brain GLP-1 controlled energy expenditure. Thermogenesis, glucose utilization, oxygen consumption, carbon dioxide production, muscle glycolytic respiratory index, UCP2 expression in muscle, and basal ambulatory activity were all increased by the exendin-9 treatment. Thus, we have demonstrated that in response to a HFD, brain GLP-1 signaling induces hyperinsulinemia and insulin resistance and decreases energy expenditure by reducing metabolic thermogenesis and ambulatory activity.
Mots clés
Animals
Blood Glucose
Body Temperature Regulation
Brain Stem
Carbon Dioxide
Diabetes Mellitus
Type 2
Dietary Fats
Energy Metabolism
Glucagon-Like Peptide 1
Glucose Intolerance
Hyperinsulinism
Insulin Resistance
Mice
Inbred C57BL
Motor Activity
Skeletal
Physical Endurance
Proglucagon
RNA
Signal Transduction