Is This Brain Cell the Key to Controlling Appetite?
What is the brain made of? Our gray matter is not just a network of thinking neurons: there are an equal number of star-shaped cells called astrocytes. These cells have long been known to play a supportive role, ensuring structural integrity and acting as a sort of energy reserve for surrounding neurons. Now, according to new research published in the Proceedings of the National Academy of Sciencesthey could also be key players in regulating our appetites.
“People tend to immediately think of neurons when they think about how the brain works,” study author Ricardo Araneda, of the University of Maryland, said in a statement. “But we’re discovering that astrocytes, which we once thought of as just secondary support cells, are also involved in how our brains regulate how much we eat. This research changes the way we think about these communication circuits.”
Astrocytes, the researchers discovered, may be the intermediaries in a neuronal process of appetite regulation that begins with another specialized brain cell: the tancyte. These cells line brain cavities filled with cerebrospinal fluid and have connections that extend deep into the hypothalamus, a region of the brain that regulates appetite. After a meal, glucose concentrations increase in the cerebrospinal fluid and tancytes split the molecule into lactate.
Read more: “These cells generate electricity in the brain. They are not neurons”
Lactate is typically used as another energy source, but in astrocytes, the researchers found, it acts as a signal. When astrocytes detect lactate, they release another chemical signal to neurons which in turn triggers a feeling of fullness.
“Researchers believed that lactate produced from tanycytes ‘talked’ directly to neurons involved in appetite control,” Araneda said. “But we discovered that there was an unexpected middleman in this conversation, astrocytes.”
To monitor the process, they administered glucose to a single mouse tancyte while monitoring the activity of surrounding astrocytes and found that several star-shaped cells responded.
“We also noticed a kind of double effect,” Araneda said. “The hypothalamus contains two opposing populations of neurons: those that promote hunger and those that suppress it. We found that it might be possible that lactate could act on both simultaneously: activating satiety neurons through astrocytes, while potentially calming hunger neurons through a more direct pathway.
Although this study was conducted using mice as model organisms, the researchers point out that tancytes and astrocytes are present in all mammals, even humans. This means that this newly discovered mechanism could pave the way for appetite suppression therapies. “This would be a new target that could complement existing therapies like Ozempic, for example, and improve the lives of many people suffering from obesity and other appetite-related problems,” Araneda said.
If there’s one thing we have an insatiable appetite for, it’s appetite suppression.
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Main image: Andrei Zastrozhnov / Adobe Stock
