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Obesity affects taste receptor expression in the brain
Taste perception plays a well-known role in receptor genes. However, significant dif- food consumption: a bite of something sweet ferences in expression were observed when or savory often encourages food intake, while comparing obese and lean mice: overall, a bitter sensation often induces the opposite. obese mice displayed lower expression of Although taste perception is typically associ- sweet and bitter taste receptor genes than ated with peripheral receptors in the mouth lean mice, in both the hypothalamus and and tongue, taste receptor genes are also brainstem. This suggests that short-term expressed in various extra-oral tissues like changes in nutritional status, like fasting, do
the brain and gut. Researchers are consider- Garry Delong, Getty not exert major effects on GPCTR expres- ing whether these receptor genes may play a taste receptor genes (G protein-coupled sion; meanwhile, chronic changes like obesity broader role in food intake, gastric functions, taste receptors, GPCTRs) along with their do appear to affect taste receptor expression and energy homeostasis. If true, this system associated downstream signaling subunits. in brain regions involved with metabolism. may be critical to understanding normal Multiple areas expressed GPCTRs, including The authors propose that the observed appetitive behaviors and controlling weight- the brainstem and hypothalamus, which are downregulation of sweet taste receptor genes related disorders. collectively involved in energy homeostasis. in the brains of obese mice may promote obe- In a recent study, Herrera Moro Chao et The researchers used lean, obese, and sity by causing the animals to desire a larger- al. (Sci. Rep. 6, 29094; 2016) examined how fasted mice to examine how these nutri- than-normal amount of taste sensation to obesity and fasting affect gene expression of tional statuses affect the expression of extra- achieve sufficient taste perception. Further taste receptors and associated signaling com- oral GPCTRs. Lean mice that were fasted research into this hypothesized mechanism plexes, focusing on several brain regions in for 16 hours displayed lower levels of bitter could yield new treatments for obesity, as well mice. Using in situ hybridization and quan- GPCTRs and associated signaling molecules as a better understanding of how nutrition titative PCR, the authors first verified the in the brainstem but not the hypothalamus, interacts with metabolism. extra-oral expression of sweet and bitter and displayed no differences in sweet-tasting James E. Niemeyer Nature America, Inc. All rights reserved. America, Inc. © 201 6 Nature npg
LAB ANIMAL Volume 45, No. 10 | OCTOBER 2016 351