Oral glucose sensing in cephalic phase insulin release

Area of Science:

• Endocrinology
• Human Physiology
• Nutritional Science

Background:

• Cephalic phase insulin release (CPIR) is a physiological response to food intake that helps regulate postprandial glucose levels.
• The precise sensory mechanisms, particularly gustatory cues, that trigger CPIR remain incompletely understood.
• Existing research suggests carbohydrates like glucose are key elicitors, but the roles of direct glucose detection versus taste perception are debated.

Purpose of the Study:

• To investigate the specific sensory mechanisms, focusing on oral glucose detection and taste, involved in eliciting CPIR in humans.
• To differentiate the contributions of carbohydrate presence versus taste perception in stimulating CPIR.
• To elucidate the interplay between taste inhibition and carbohydrate digestion in modulating CPIR.

Main Methods:

• A controlled study involving 22 healthy adults.
• Four distinct oral stimulation conditions were employed: glucose alone, glucose with a sweet taste inhibitor (Lactisole), maltodextrin alone, and maltodextrin with Lactisole and an oral digestion inhibitor (acarbose).
• Plasma concentrations of c-peptide, insulin, and glucose were measured before and after stimulation in four separate sessions.

Main Results:

• Glucose administered alone effectively elicited CPIR.
• The presence of Lactisole abolished the CPIR response to glucose.
• Maltodextrin alone stimulated CPIR, but this response was negated when Lactisole and acarbose were co-administered.
• These findings highlight the dual role of glucose detection and taste in CPIR.

Conclusions:

• Glucose is a potent stimulus for CPIR, but its associated taste sensation is also a critical cue for triggering this response.
• Both the direct detection of glucose and the perception of its taste are essential for robust CPIR.
• Understanding these gustatory mechanisms provides insight into metabolic regulation and potential therapeutic targets for glucose control.