Differential effects of diet and weight on taste responses in diet-induced obese mice

The ever growing obesity epidemic has created a need to develop a better understanding of the underlying mechanisms responsible for this condition. Appetite and consumption are directly influenced by the taste system which determines if potential food items will be ingested or rejected. While previous studies have reported that obese individuals have reduced taste perception, the relationship between these processes is still poorly understood. Earlier work has demonstrated that diet-induced obesity (DIO) directly impairs taste responses, particularly for sweet stimuli. These deficits occurred in the cells located in the oral cavity as well as in the behavioral responses. However, it is not clear if these changes to the taste system are due to obesity or to the high fat diet exposure. The goal of the current study was to determine if diet or excess weight is responsible for the DIO induced taste deficits. Using a combination of live cell imaging, brief-access licking, immunohistochemistry and real-time PCR, we have found that diet and weight gain can each selectivity affect taste. Follow up experiments determined that two key signaling proteins, gustducin and phospholipase C{beta}2, are significantly reduced in the high fat diet without weight gain and obese mice, identifying a potential mechanism for the reduced taste responsiveness to some stimuli. Our data indicate that the relationship between obesity and taste is complex and reveal that for some stimuli, diet alone can cause taste deficits, even without the onset of obesity.