We could be a crucial step closer to our understanding of the basics of obesity with discovery of a molecule that makes mice lazier, and reduces all spontaneous physical activity, even looking for food. It’s a molecule called Bsx, which has been isolated from the hypothalamus of mice, and is found across all species including humans.

Scientists from the European Molecular Biology Laboratory and Institute of Human Nutrition, both in Germany, as well as the Obesity Research Center, University of Cincinnati have reported in the June issue of Cell Metabolism, that a brain protein called the Brain-Specific Homeobox Factor, Bsx in short, controls our subconscious physical activity. For instance while we are sitting on the couch watching television, our spontaneous fidgeting or shifting from one side to another are unconscious activities which lead to calorie loss, crucial for controlling body weight. Bsx is also linked to food seeking behavior i.e. going out and looking for food when we are hungry, and increasing food intake. Without Bsx, we are less likely to respond to hunger. These two processes are linked together in our hypothalamus, and Bsx plays a crucial role in regulating these two opposing behaviors as well by regulate the expression of two hypothalamic hormones involved in feeding and body weight, Npy and AgRP.

The researchers believe that individual differences in Bsx levels could explain why some of us are innately more physically active that others, and less prone to putting on body weight as a result of eating. It provides a possible explanation for the first time, why the same diet makes one person fat and the other one thin.

Bsx is yet another potentially valuable piece of the jigsaw puzzle that behavioral scientists researching obesity are looking for – the precise molecular mechanisms why we are so different in the way we approach and react to lifestyles and diets. Maybe one day soon, a drug will be developed that will target Bsx to increase our spontaneous physical activity as an antidote to diet-induced obesity.

Reference

Sakkou, M., Wiedmer, P., Anlag, K., Hamm, A, Seuntjens, E., Ettwiller, L., Tschöp, M.H. and Treier, M., A role for brain-specific homeobox factor Bsx in the control of hyperphagia and locomotory behavior, Cell Metabolism, Vol 5, 450-463, 06 June 2007.