Appetites are modulated by tanycytes

Debating whether or not to eat that warm and soft chocolate chip cookie can be tough: succumb to desire or avoid the extra calories? Despite the time wasted over the decision, cravings usually trump other considerations. However, there may finally be a way to suppress such cravings. Led by Mohammad K. Hajihosseini from the University of East Anglia’s School of Biological Sciences, researchers have identified stem cells that have the potential to control appetite.

Initially, scientists believed that nerve cells in the brain controlling appetite were formed in the womb and could not be altered during a person’s lifetime. Investigating this previous theory, researchers looked at the hypothalamus of the brain, which is known to regulate biological functions like sleep cycles and hormone release.

After tracking the development of stem cells, Hajihosseini and his team discovered that brain cells known as tanycytes add neurons to the appetite controlling part of the brain all throughout one’s lifetime, not just while the embryo is in the womb. Hajihosseini’s work disproves original notions about appetite regulating neurons.

“We have found that tanycytes seem to generate neurons that are destined to become incorporated into the nearby appetite regulating areas of the hypothalamus,” Hajihosseini wrote in an email to The News-Letter.

“From these findings we infer that neurons or circuits that regulate appetite are not fixed in number. Moreover, that by modulating the behaviour of tanycytes, it may be possible to modulate the number of appetite-regulating neurons and hence modulate appetite. These findings could therefore be used to devise a sustained solution to eating disorders such as obesity and age-related anorexia.”

In the constant search to find a way to reduce the risks associated with obesity, appetite controlling stem cells may prove to be the long-awaited solution. According to the Centers for Disease Control and Prevention, over one-third of the adult population in the U.S. is obese. Associated health problems include arthritis, cancer, heart disease and diabetes, which can create a large financial burden as well.

The important discovery of this population of cells came by chance.

“This was serendipitous,” Hajihosseini wrote. “For several years we had been working with a gene called Fibroblast growth factor 10 (FGF10), studying its role in bone development and pathologies associated with a rare congenital disease called Apert syndrome. Our mouse model of Apert syndrome showed brain defects and we knew FGF10 plays a causative role in Apert syndrome. So we wanted to know whether FGF10 is present in the embryonic mouse brain. For the sake of curiosity, we also wanted to know whether FGF10 is present in the adult brain. The latter revealed that FGF10 is present at high levels in tanycytes.”

While the presence and importance of tanycytes as an appetite controlling population of cells has only been studied experimentally in animal subjects, there is promise that humans also have these cells.

“We need to learn more about genes and cellular mechanisms that regulate the biology and behavior of tanycytes,” Hajihosseini wrote. “We believe this information will help us devise ways of instructing tanycytes to generate the desired cell types and rewire appetite-regulating circuitry to treat eating disorders.

“It is highly likely the events we have described in mice also occur in humans. Hence development of molecules or drugs that can modulate the behaviour and activity of tanycytes in mice is likely to be as effective in humans, but obviously this awaits the development of such reagents and drugs.”