“Lost” meat, how to “pick it up”

American researchers found that the signals that triggered hunger in the brains of fasted mice were stronger, which caused them to eat more until they regained weight. This may explain why people tend to regain weight after losing weight. The study was published March 24 in Cell-Metabolism.

Hunger may increase after weight loss. Image credit: Shutterstock/Okrasiuk

Nearly half of the obese patients who participated in the weight-loss program regained the weight they lost within 5 years. The mechanism that drives this weight regain is unknown, but it may be related to neuronal cells in the hypothalamus called AgRP. These cells have previously been shown to play an important role in regulating hunger.

Brad Lowell of Beth Israel Deaconess Medical Center said, “When the body is low on energy, they are activated; And when they are active, they cause intense hunger pangs. ”

Many different areas of the brain send signals to AgRP neurons through synapses. These synapses can change the intensity of the signals that travel along them – the stronger the connection of the synapses, the stronger the signal.

To understand how weight loss affects these synapses, Lowell’s team measured postmortem brain activity in nine mice, five of whom fasted for 16 hours before being tested. The researchers used a light-activated cell technique to stimulate brain regions that signal AgRP neurons. In response, fasted mice had more activity in the paraventricular nucleus (PVH) than in non-fasting mice. Previous studies have shown that this brain region is involved in metabolism and growth.

The researchers silenced PVH neurons from another group of fasting mice and then tracked how much food the mice ate over a 24-hour period. They found that the mice ate an average of about 33 percent less food than the control mice and regained less weight within 7 days. Further experiments showed that once the mice regained the weight lost due to fasting, the amplified signal from PVH neurons returned to normal.

These findings suggest that weight recovery is driven by a temporary increase in signaling from PVH neurons to AgRP neurons. Lowell says that to solve these problems, you need to understand how hunger works. He also said that future therapies that inhibit neuronal signals from PVH could help people maintain weight loss gains. However, more research is needed to understand the function of PVH neurons and the consequences of silencing them. “Can it be done without side effects? We don’t know that yet. (Source: China Science News Wang Jianzhuo)

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