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Updated: May 9, 2026

Real-time Analysis of Gut-brain Neural Communication: Cortex wide Calcium Dynamics in Response to Intestinal Glucose Stimulation
Published on: December 29, 2023
Hindbrain GLP-1 receptor-mediated suppression of food intake requires a PI3K-dependent decrease in phosphorylation of
Laura E Rupprecht1, Elizabeth G Mietlicki-Baase, Derek J Zimmer
1Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
Glucagon-like peptide-1 receptors in the brainstem control feeding by activating PI3K and Akt pathways. This research reveals how these pathways suppress appetite, offering new insights into metabolic regulation.
Area of Science:
- Neuroscience
- Endocrinology
- Molecular Biology
Background:
- Glucagon-like peptide-1 receptors (GLP-1R) in the nucleus tractus solitarius (NTS) regulate feeding behavior.
- Previous studies identified rapid PKA-mediated signaling pathways (suppression of AMPK, activation of MAPK) involved in GLP-1R's feeding suppression.
Purpose of the Study:
- To investigate the intracellular signaling pathways responsible for the long-term hypophagic (appetite-suppressing) effects of GLP-1R activation in the hindbrain.
- To test the hypothesis that a phosphoinositide 3-kinase (PI3K)/Akt-dependent pathway is involved in GLP-1R-mediated feeding control.
Main Methods:
- Behavioral studies in rats involving intracerebroventricular (icv) administration of PI3K inhibitor (LY-294002) and an Akt translocation inhibitor (triciribine) alongside GLP-1R agonist (exendin-4).
- Immunoblot analyses of ex vivo NTS tissue and in vitro GLP-1R-expressing neurons (GT1-7) to assess Akt phosphorylation.
- Time-dependent analysis of GLP-1R activation effects on signaling pathways.
Main Results:
- Inhibition of hindbrain PI3K activity attenuated the food intake and body weight suppressive effects of exendin-4.
- Pharmacological inhibition of PIP3-dependent Akt translocation also reduced exendin-4's appetite-suppressing effects.
- GLP-1R activation led to decreased phosphorylation of Akt in NTS tissue and GT1-7 neurons, challenging the notion of obligatory Akt activation by PI3K.
Conclusions:
- Hindbrain GLP-1R activation requires PI3K activation and PIP3-dependent translocation of Akt to the plasma membrane.
- Contrary to some views, GLP-1R activation suppresses, rather than activates, Akt phosphorylation at the plasma membrane, mediating appetite suppression.
- These findings elucidate novel intracellular mechanisms underlying GLP-1R's role in feeding regulation.
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