Distinct Neural Sites of GLP-1R Expression Mediate Physiological versus Pharmacological Control of Incretin Action

Abstract

Summary: Glucagon-like peptide 1 (GLP-1) receptors are widely distributed throughout the nervous system, enabling physiological and pharmacological control of glucose and energy homeostasis. Here we elucidated the importance of Glp1r expression within cellular domains targeted by expression of Wnt1-Cre2 or Phox2b-Cre. Widespread loss of neural Glp1r in Glp1rΔWnt1−/− mice had no effect on basal food intake, gastric emptying, and glucose homeostasis. However, the glucoregulatory actions of GLP-1R agonists, but not gut-selective DPP-4 inhibition, were preserved in Glp1rΔWnt1−/− mice. Unexpectedly, selective reduction of Glp1r expression within neurons targeted by Phox2b-Cre impaired glucose homeostasis and gastric emptying and attenuated the extent of weight loss achieved with sustained GLP-1R agonism. Collectively, these studies identify discrete neural domains of Glp1r expression mediating GLP-1-regulated control of metabolism and the gut-brain axis and reveal the unexpected importance of neuronal Phox2b+ cells expressing GLP-1R for physiological regulation of gastric emptying, islet hormone responses, and glucose homeostasis. : Varin et al. use Wnt1-Cre2 and Phox2b-Cre to target distinct GLP-1R+ neuronal populations with different roles in physiological versus pharmacological control of food intake, glucose homeostasis, gastric emptying, and the gut-brain glucoregulatory axis. Keywords: glucagon-like peptide 1, brain, metabolism, gut hormones, obesity, enteric nervous system, type 2 diabetes