At Cambridge University, a Labrador retriever is wagging its tail and trying to break into a transparent box with a sausage inside. It may seem trivial, but it's part of an important study aimed at understanding obesity in dogs, which could also have implications for humans.
Eleanor Raffan, a canine geneticist, is studying the role of the pro-opiomelanocortin (POMC) gene in regulating body weight. Her recent research, published in the journal Science Advances, shows that dogs with a specific mutation of the POMC gene tend to be hungrier, have a 25% lower resting metabolic rate and consequently gain more weight.
This gene produces several peptides in the brain that regulate energy balance. One of these peptides, β-MSH, is difficult to study in humans due to its rarity, which makes dogs an excellent model.
Labradors, in particular, proved to be a valuable object for this research. More than 10% of smooth-haired Labradors have a mutation in the POMC gene that affects the production of β-MSH. This makes them naturally prone to obesity, providing a unique opportunity to study this disease.
In 2016, the discovery of the POMC mutation associated with body weight in Labradors led to further research into how this mutation affects energy intake and expenditure.
According to The Scientist, Raffan's team fed the dogs a can of food every 20 minutes until the dogs refused any more. Surprisingly, all the dogs ate large quantities, regardless of their mutation. However, in the sausage-in-a-box test, the dogs with the mutation were more persistent and hungrier for food than those without it.
To study energy expenditure, Raffan measured the dogs' resting metabolic rates. The dogs with the POMC mutation burned fewer calories at rest, which, combined with increased hunger, contributed to their obesity.
Understanding these mechanisms is crucial for developing treatments for obesity. Carmelo Quarta, from the University of Bordeaux, who was not involved in the study, stressed the potential of this research for the development of new drugs.
Hannah Thomasy, PhD
