Novel liver hormone cuts cravings for sweets, alcohol

In a good news for those who cannot shun their drink and also have "sweet tooth", scientists have discovered for the first time a liver hormone that works via brain to reduce cravings for sweets and alcohol in mammals.

The team found that a hormone produced by the liver -- fibroblast growth factor 21 (FGF21) -- suppresses the consumption of simple sugars.

"This is the first time a hormone made in the liver has been shown to affect sugar and alcohol preference in mammals," said Steven Kliewer, professor of molecular biology and pharmacology at UT Southwestern medical centre and co-senior author of the study.

The hormone is associated with environmental stress such as extreme dietary changes or cold temperature exposure. It is also produced when mammals consume carbohydrates.

Because of FGF21's unique effects, forms of the protein are being evaluated as drugs for the treatment of obesity, Type 2 diabetes and alcohol dependence.

"Our findings raise the possibility that FGF21 administration could affect nutrient preference and other reward behaviours in humans, and that the hormone could potentially be used to treat alcoholism," Kliewer added.

The researchers found that mice with elevated levels of FGF21 showed reduced preference for sweetener and alcohol-laced water as well as a marked decrease in levels of dopamine -- a neuro-transmitter that plays a central role in reward behaviour.

"We found that FGF21 administration markedly reduces sweet and alcohol preference in mice and sweet preference in larger animal models," said co-senior author David Mangelsdorf.

"We have known for a while that FGF21 can enhance insulin sensitivity," noted Lucas BonDurant, doctoral student at University of Iowa.

Now, there is this dimension where FGF21 can help people who might not be able to sense when they have had enough sugar, which may contribute to diabetes, he pointed out.

"However, FGF21 does not reduce intake of all sugars (sucrose, fructose, and glucose) equally. FGF21 also does not impact the intake of complex carbohydrates," noted researchers from the University of Iowa.

The findings, published in the journal Cell Metabolism, suggest that additional studies are warranted to assess the effects of FGF21 on sweet and alcohol preference and other reward behaviour in humans.