Brain Pathway Behind Sugar Cravings

Even after eating a large meal, many people can still crave (渴望) sweets. New research in mice suggests that the same brain cells that control feelings of fullness are also behind our desire for sugar, providing a possible explanation for why we love desserts.

Earlier studies have shown that certain chemicals in the brain, called opioids (阿片类物质), play a big role in sugar cravings. These opioids are made by brain cells in an area called the arcuate nucleus (弓状核), which controls hunger, metabolism, and hormones. These cells, called POMC neurons, are responsible for making us feel full after eating.

To find out if these cells have a role in sugar cravings, Henning Fenselau and his team at the Max Planck Institute for Metabolism Research studied how these chemicals work in the brain. They used a special solution to track the signals from these cells in brain slices taken from mice. They found that the area with the most opioid receptors was the paraventricular nucleus of the thalamus (PVT), which helps control feeding behavior. This suggests that sugar cravings might be caused by communication between the arcuate nucleus and the PVT.

The researchers then watched how the mice’s brains reacted when they ate regular food and later a sugary treat. After 90 minutes, when the mice were likely full, they were given the sugary food. The brain activity in these areas increased dramatically as the mice ate the dessert, even before they began eating, showing that this brain pathway might be responsible for their sugar cravings.

Using a technique called optogenetics, the team switched off the signals from the POMC neurons to the PVT. When they did this, the mice ate 40% less dessert. Fenselau explained that these brain cells, which usually stop us from feeling hungry, also trigger the desire for sugar when we’re full. This could explain why people often eat sweets even when they’re not hungry.

Fenselau thinks this pathway might have developed because sugar is an easy source of energy for the body. He hopes this research could lead to new ways to treat obesity, although he points out that many factors in the brain influence our hunger and cravings.