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Neurons that make us eat too much?
A well fed mouse from the experiment consuming bacon and donuts, despite already having its energy requirements met. This image highlights an important health issue: the growing abundance and easy access of energy-dense foods can facilitate the overeating that leads to obesity.
[Image courtesy of Josh Jennings]
Researchers have found a circuit in the mouse brain that makes the rodents eat even when they aren't hungry. And the same brain circuit prevents the mice from eating when they are hungry, they say. This network of neurons involves a region of the brain called the lateral hypothalamus, or LH, which controls some behaviors, like eating, and the researchers suggest that it might lead to new treatments for eating disorders and obesity in humans.
Joshua Jennings and his colleagues studied a group of neurons located in part of the mouse brain called the bed nucleus of the stria terminalis, or BNST. The neurons have been known to block activity in the LH. So, the researchers used a combination of optics (light) and genetics to activate these BNST neurons in live mice, and then they observed how those BNST neurons affected neurons in the LH.
They discovered that, when BNST neurons were activated, they blocked the action of a group of neurons in the LH known as glutamatergic neurons. This blockage is what caused the rodents to chow down on food even when they were already full, according to the researchers. In particular, it led the mice to seek out high-calorie foods. However, when Jennings and his team prevented the BNST neurons from blocking the glutamatergic neurons in the LH, they say that the mice refused to eat anything.