Central and peripheral GLP-1 systems independently suppress eating

Area of Science:

• Neuroscience
• Endocrinology
• Gastroenterology

Background:

• Glucagon-like peptide-1 (GLP-1) is an anorexigenic peptide involved in appetite regulation.
• The peripheral and central GLP-1 systems are thought to be linked by preproglucagon (PPG) neurons in the nucleus tractus solitarii (NTS).
• Direct evidence for this proposed gut-brain satiation circuit is lacking.

Purpose of the Study:

• To investigate the role of NTS PPG neurons in the GLP-1 satiation circuit.
• To determine the inputs and necessity of NTS PPG neurons for GLP-1 mediated eating suppression.
• To explore potential therapeutic strategies for obesity by targeting these pathways.

Main Methods:

• Utilized mouse models to study NTS PPG neuron activity and their role in satiation.
• Investigated vagal inputs to NTS PPG neurons, focusing on GLP-1 and oxytocin receptors.
• Assessed the effects of GLP-1 receptor agonists and NTS PPG neuron activation on eating behavior.

Main Results:

• NTS PPG neurons encode satiation signals, consistent with vagal input from gastrointestinal distension.
• NTS PPG neurons primarily receive vagal input from oxytocin-receptor-expressing neurons, not GLP-1 receptor neurons.
• NTS PPG neurons are not essential for eating suppression by GLP-1 receptor agonists.
• Concurrent activation of NTS PPG neurons and GLP-1 receptor agonists resulted in more potent appetite suppression than semaglutide alone.

Conclusions:

• Central and peripheral GLP-1 systems suppress eating via independent gut-brain circuits.
• NTS PPG neurons represent a distinct pathway for appetite regulation.
• Pharmacological activation of NTS PPG neurons combined with GLP-1 receptor agonists presents a potential strategy for obesity treatment.