Brain's 'stop eating' switch found in astrocytes
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- Researchers from the University of Concepción in Chile and the University of Maryland published a study in PNAS on April 6, 2026, showing that astrocytes — long considered support cells — play an active role in appetite regulation through a previously unknown signaling pathway in the hypothalamus.
- Astrocytes carry the HCAR1 receptor, which detects lactate released by tanycytes after a meal; once activated, the astrocytes release glutamate that signals fullness neurons, making them an 'unexpected middleman' in the appetite circuit, according to corresponding author Ricardo Araneda.
- The team found that lactate has a dual effect: it activates fullness neurons through astrocytes while potentially also quieting hunger neurons through a more direct route, Araneda said.
- Araneda, a UMD biology professor, called the HCAR1 receptor pathway a 'novel target' that 'may complement existing therapies like Ozempic' for obesity and eating disorders — though no current medication targets it.
- The study was conducted in animal models, but tanycytes and astrocytes exist in all mammals, including humans; the next step is testing whether altering HCAR1 in astrocytes influences eating behavior.
- The findings are the product of a decade-long collaboration between Araneda's UMD lab and María de los Ángeles García-Robles' lab at the University of Concepción; lead author Sergio López is a doctoral student co-mentored by both who spent eight months at UMD.
Why it matters: The study identifies the HCAR1 receptor on astrocytes as a potential new drug target for obesity and eating disorders — a pathway no current medication, including Ozempic, addresses. Araneda described it as a 'novel target' that 'may complement' existing therapies, giving researchers a fresh biological angle on appetite regulation if animal findings hold in humans.
