Hunger is, first and foremost, a natural feeling. It’s our body’s way of telling us that we need to consume food for energy. It’s also an unpleasant feeling that derails many people from diets.
It seems that science has now found a way to control a person’s feelings of hunger, which could have significant repercussions for people trying to live a healthier way of life.
A recent study, published in the journal Nature Neuroscience, describes how researchers have located a component of the brain that inhibits and controls eating in mice. More specifically, a group of cells in the hypothalamus, called “AgRP neurons,” are those that monitor our energy levels and cause sensations of hunger. Until now, scientists were unclear about which ‘satiety’ neurons the AgRP neurons target in order to achieve sensations of hunger. Eventually it was discovered that a tiny group of MC4R-expressing neurons within the hypothalamus is the key to all of these activities.
Lab mice involved in the study were genetically engineered so that their MC4R-expressing neurons could be manually controlled. The researchers found that when they manually “shut off” the cells in questions, mice who had eaten all day were still ready to consume food. The opposite was also true. When these cells were “switched on,” unfed mice did not have a desire to eat. This signaled to the researchers that this specific group of cells acts as an on/off switch for the sensation of hunger. Furthermore, it was found that cells located at the back of the brain, known as the lateral parabrachial nucleus (LPBN), were also involved in the process.
Theories abound about the scientific aspects of what we know as hunger: do we eat in order to banish feelings of hunger or because of the positive associations that come along with eating?
Researchers tried to tackle these issues by testing whether the previously identified brain cells would instigate feelings of reward when activated artificially in a unfed mouse. Tests showed that indeed, mice who had the “hunger” cells activated manually displayed signs of pleasure, i.e. spending more time in a situation that activated the cells.
All of these finding could hold great potential in terms of controlling appetite in humans, perhaps in a fight to combat the obesity epidemic.