Cephalic phase response in systemic glucose metabolism: How taste triggers glucose homeostasis

Cephalic phase responses (CPRs) are anticipatory and conditioned responses elicited by the stimulation of food-related cues in the oral and nasal cavities. By initiating autonomic and endocrine reactions before absorption of nutrients, CPRs can blunt acute-postprandial hyperglycemia. Taste-related information is critical for triggering CPRs, but the neural mechanisms underlying taste-driven CPRs remain incompletely elucidated.

Current evidence supports a model in which taste-driven CPRs arise from coordinated processing across peripheral taste receptors, the rostral component of the nucleus of the solitary tract, dorsal vagal complex, vagal parasympathetic outputs, and modulatory forebrain circuits, with neuroimmune inputs representing a newly emerging layer of regulation.

While considerable progress has been made in refining understanding of the neural mechanisms behind taste-driven CPRs in rodents and humans, further studies are required to clarify the complex central mechanisms underlying the integration of internal states and external information during CPRs. Elucidating these pathways will not only deepen understanding of the role of the central nervous system in systemic glucose regulation, but it will also provide critical insights into how these anticipatory responses are altered by aging and metabolic disorders such as diabetes.