The versatility of the vagus

Area of Science:

• Neuroscience
• Gastroenterology
• Endocrinology

Background:

• The gut communicates with the brain via the vagus nerve to regulate food intake.
• Vagal afferent neurons are key mediators of gastrointestinal satiety signals.
• Mechanisms within vagal afferent neurons modulate these satiety signals.

Purpose of the Study:

• To investigate how the satiety hormone cholecystokinin (CCK) modulates vagal afferent neuron activity.
• To understand CCK's role in regulating the expression of receptors and neurotransmitters involved in food intake.
• To explore the interaction between CCK, ghrelin, and neuronal signaling in appetite control.

Main Methods:

• Analysis of receptor and peptide neurotransmitter expression in vagal afferent neurons under varying CCK concentrations.
• Investigation of the effects of CCK and ghrelin on neuronal signaling pathways, including phosphoCREB.
• Assessment of changes in cannabinoid (CB)-1, melanin concentrating hormone (MCH)-1, Y2 receptors, MCH, and CART expression.

Main Results:

• CCK stimulates vagal afferent neurons and regulates their expression of G-protein coupled receptors and peptide neurotransmitters.
• Fasting increases expression of CB-1 and MCH-1 receptors and appetite-stimulating MCH, while decreasing satiety peptide CART.
• CCK reduces MCH expression and increases CART expression; ghrelin interferes with CCK's actions.

Conclusions:

• CCK acts as a gatekeeper, modulating the capacity of other signals to influence food intake via vagal afferent neurons.
• CCK dynamically regulates the expression of key receptors and peptides in response to feeding and fasting states.
• Understanding these CCK-mediated mechanisms provides insight into appetite regulation and potential therapeutic targets.