Postprandial Glucagon Action in the Human Brain

Area of Science:

• Metabolic Research
• Neuroendocrinology
• Human Physiology

Background:

• Elevated fasting glucagon is linked to hyperglycemia, but postprandial glucagon's role is less understood.
• Emerging evidence suggests metabolic benefits from rising postprandial glucagon, potentially via brain pathways.
• Understanding glucagon's effects on the human brain is crucial for its translational relevance.

Purpose of the Study:

• To investigate the postprandial effects of glucagon on the human brain.
• To determine if experimentally elevated glucagon influences brain activity related to metabolism and food intake.

Main Methods:

• Oral glucose tolerance tests (OGTT) combined with functional magnetic resonance imaging (fMRI) in 30 volunteers.
• Measurement of brain activity and connectivity at fasting, 30, and 120 minutes post-glucose.
• Comparison between participants with suppressed glucagon (receiving low-dose glucagon infusion) and those with endogenous glucagon rise.

Main Results:

• Experimentally increasing glucagon during OGTT significantly enhanced postprandial brain responsivity in the hippocampus, hypothalamus, and ventral striatum.
• These brain regions are critical for regulating appetite, systemic metabolism, and food intake.
• The observed brain responses correlated with the rise in glucagon, irrespective of its source (endogenous or exogenous).

Conclusions:

• Postprandial glucagon exerts significant effects on key human brain areas involved in metabolic regulation.
• These findings may explain the body weight management benefits observed with multi-agonists targeting the glucagon receptor.