MUNICH, Germany, Aug. 12 (UPI) -- A better understanding of how the brain regulates sugar uptake may lead to better treatments for diabetes and obesity, say researchers in Germany.
Sugar uptake in the brain is not passive, researchers at Technical University of Munich found in recent experiments. The organ responds to other hormones when transporting sugar -- which the researchers say changes their approach to sugar- and metabolism-related disease.
The same researchers recently found astrocytes, the most common cells in the brain, which regulate the ability for substances to pass through the blood-brain barrier, react to leptin the same way they react to insulin. Both have been linked to hunger and metabolism, in which astrocytes are now recognized as playing a role.
The new study, published in the journal Cell, suggests receptors on astrocytes, or the lack thereof, play a role in how much sugar arrives in the brain -- which uses more sugar than any other organ in the body -- and affects the regulation of hunger.
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"Our results showed for the first time that essential metabolic and behavioral processes are not regulated via neuronal cells alone and that other cell types in the brain, such as astrocytes, play a crucial role," Matthias Tschöp, a researcher at the German Center for Diabetes Research, said in a press release. "This represents a paradigm shift and could help explain why it has been so difficult to find sufficiently efficient and save medicines for diabetes and obesity until now."
Researchers suspected the supply of sugar to the brain was unlikely to be random, looking at astrocytes for a possible role in the process because they thought the idea they were "less important support cells" was a poor explanation for their existence.
Using positron emission tomography, researchers were able to show that hormones such as insulin and leptin act specifically on such "support" cells to regulate sugar intake into the brain, like a "sugar switch."
The researchers found missing insulin receptors on the surface of astrocytes resulted in less activity in neurons that curb food uptake as part of the brain's regulation of metabolism.
Astrocytes without insulin receptors were less efficient at transporting glucose into the brain -- especially in the area of satiety centers, located in the hypothalamus.
Dr. Cristina García-Cáceres, a neurobiologist at the Helmholtz Diabetes Center and lead author of the study, said new research will be required to adjust the concept of food intake and function of metabolism, which she said may lead to the discovery of ways of modulating sugar addiction, as well as better treatment for obesity and diabetes.
"We have a lot of work ahead of us," García-Cáceres said, "but at least now we have a better idea of where to look."
