GLP-1 neurons in the nucleus of the solitary tract project directly to the ventral tegmental area and nucleus accumbens to control for food intake

Endocrinology. 2012 Feb;153(2):647-58. doi: 10.1210/en.2011-1443. Epub 2011 Nov 29.

Abstract

Central glucagon-like-peptide-1 (GLP-1) receptor activation reduces food intake; however, brain nuclei and mechanism(s) mediating this effect remain poorly understood. Although central nervous system GLP-1 is produced almost exclusively in the nucleus of the solitary tract in the hindbrain, GLP-1 receptors (GLP-1R) are expressed throughout the brain, including nuclei in the mesolimbic reward system (MRS), e.g. the ventral tegmental area (VTA) and the nucleus accumbens (NAc). Here, we examine the MRS as a potential site of action for GLP-1-mediated control of food intake and body weight. Double immunohistochemistry for Fluorogold (monosynaptic retrograde tracer) and GLP-1 neuron immunoreactivity indicated that GLP-1-producing nucleus tractus solitarius neurons project directly to the VTA, the NAc core, and the NAc shell. Pharmacological data showed that GLP-1R activation in the VTA, NAc core, and NAc shell decreased food intake, especially of highly-palatable foods, and body weight. Moreover, blockade of endogenous GLP-1R signaling in the VTA and NAc core resulted in a significant increase in food intake, establishing a physiological relevance for GLP-1 signaling in the MRS. Current data highlight these nuclei within the MRS as novel sites for GLP-1R-mediated control of food intake and body weight.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dose-Response Relationship, Drug
  • Eating / physiology*
  • Exenatide
  • Gene Expression Regulation
  • Glucagon-Like Peptide 1 / metabolism
  • Glucagon-Like Peptide-1 Receptor
  • Hypoglycemic Agents / administration & dosage
  • Hypoglycemic Agents / pharmacology
  • Male
  • Neurons / cytology*
  • Neurons / physiology
  • Nucleus Accumbens / cytology*
  • Peptides / administration & dosage
  • Peptides / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Glucagon / genetics
  • Receptors, Glucagon / metabolism*
  • Signal Transduction
  • Solitary Nucleus / cytology*
  • Venoms / administration & dosage
  • Venoms / pharmacology
  • Ventral Tegmental Area / cytology*

Substances

  • Glp1r protein, rat
  • Glucagon-Like Peptide-1 Receptor
  • Hypoglycemic Agents
  • Peptides
  • Receptors, Glucagon
  • Venoms
  • Glucagon-Like Peptide 1
  • Exenatide