Cephalic phase responses (CPRs) are digestion-related physiological changes that occur prior to nutrient absorption. These changes prepare the animal (both human and non-human) for nutrient absorption and the disruption of homeostasis that results when the body is challenged by the intake of food (see Powley, 1977 for a review). CPRs are triggered by food cues such as the sight and smell of food, thoughts of food, and stimuli that have been conditioned to signal the presentation of food (Feldman & Richardson, 1986). Understanding CPR’s are important because they are thought to influence later phases of digestion (Powley, 1977). Numerous CPRs have been identified, most notably insulin (e.g. Sjöström, Garellick, Krotkiewski, & Luyckx, 1980). Blood glucose (BG) has received comparatively less attention. There is convincing evidence that CPRs are both innate and acquired through experience. Several studies have demonstrated that CPRs can be classically conditioned (Brunstrom, & Mitchell, 2007; Powley & Berthoud, 1985). To test the hypothesis that a cephalic phase BG response is dependent on the food’s glycemic index, we allowed 19 male mice to consume a high GI food (Froot Loops) and a low GI food (cheese) on alternate days over a 4-week period. We predicted they would come to learn the physiological consequence of each (an increase in BG to the former and little to no increase in the latter). Subsequently, when exposed to the sight and smell alone of each food, the mice would respond with similar, albeit weaker, BG responses. To control for the possibility that the mice are responding to the palatability of the food rather than its glycemic index, we will record the time each mouse spends touching/orienting toward the container in which the food is presented. Data collection is on-going but the results will be presented at the conference.
