March 17, 2004 -- An enzyme produced in the brain may play a major role in regulating what people eat and whether they become fat.
A new study shows that the enzyme, known as AMPK (AMP-activated protein kinase), may act in at least two distinct ways to affect food intake and potentially contribute to obesity.
Researchers say the protein is already known to affect energy balance by acting like a fuel gauge to help cells monitor their own energy levels. But their findings indicate that AMPK may also be mediated hormones known to affect appetite, such as leptin.
Researchers say that further study into how this protein affects the mind-body pathway to overeating may pave the way for new approaches in the treatment of obesity.
Enzyme May Yield New Obesity Treatments
Many factors, such as energy needs and behaviors, play a role in determining what, when, and how much people eat and may contribute to obesity.
It's easy to see how consuming more calories that the body burns off through physical activity leads to weight gain, but researchers are now gaining a better understanding of how other biological factors like hormones and other chemicals produced in the body can affect what people eat and why they become overweight.
For example, previous studies have shown that having low levels of the hormone leptin can cause laboratory mice to overeat and become obese.
In this study, published today in the journal Nature, researchers have identified another key player in this process.
The study showed that hormones, such as leptin, involved in appetite control also regulate AMPK activity in the hypothalamus, a part of the brain known to be involved in regulating food intake.
Researchers found that by infusing leptin into mice they could suppress the activity of the enzyme AMPK in brain areas associated with appetite control.
They also found that when AMPK activity was decreased in these areas of the brain, mice ate less and gained weight more slowly than normal mice.
When the levels of the enzyme were boosted, mice ate more and gained more weight than normal mice.
Researchers say the results show that this protein and appetite-suppressing hormones work together to affect food intake, and more studies are needed to understand this complex interaction.