Dietary experience with glucose and fructose fosters heightened avidity for glucose-containing sugars independent of TRPM5 taste transduction in mice

ABSTRACT

Objective

Experience with metabolically distinct sugars, glucose and fructose, enhances attraction to the orosensory properties of glucose over fructose. To gain insight into which sensory signals are affected, we investigated how this nutritive learning reshapes behavioral responding to various sugars in brief access taste tests in C57BL6/J (B6) mice and assessed whether sugar-exposed mice lacking the TRPM5 channel involved in G-protein coupled taste transduction could acquire these types of preferences for glucose-containing sugars.

Methods

B6, TRPM5 knockout (KO), and TRPM5 heterozygous (Het) mice were given extensive access to water (sugar naïve) or 0.316, 0.56, and 1.1 M glucose and fructose (sugar-exposed) and then tested, whilst food deprived, for their relative avidities for glucose, fructose, sucrose, maltose, and/or a non-metabolizable glucose analog in a series of taste tests.

Results

Sugar-exposed B6 mice licked relatively more for glucose than fructose, driven by an increased avidity for glucose, not an avoidance of fructose, and licked more for maltose, compared to their sugar-naïve counterparts. Sugar-exposed B6 mice did not lick with such avidity for a non-metabolizable glucose analog. TRPM5 KO mice took longer to acquire the sugar discrimination than the Het controls, but both groups ultimately licked significantly more for glucose than fructose. Het mice displayed clear preferential licking for sucrose over fructose, while licking comparably high for glucose, sucrose, and maltose. KO mice licked significantly more for maltose than sucrose.

Conclusions

Collectively, the findings suggest that ingestive experience with glucose and fructose primarily reprograms behavioral responding to a TRPM5-independent orosensory signal generated by glucose-containing sugars.

KEYWORDS:

• Taste
• nutrient learning
• sugar reward
• chemosensory processing
• glucoregulation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by NIH [R01DC018562] and University of Southern California Dornsife College Institutional Start up (to LAS).

Notes on contributors

Verenice Ascencio Gutierrez

Verenice Ascencio Gutierrez is now a PhD student in the Department of Psychology at the University of Buffalo.

Aracely Simental Ramos

Aracely Simental Ramos is currently a PhD student in the Neuroscience Graduate Program at the University of Southern California.

Shushanna Khayoyan

Shushanna Khayoyan has a BS in Neuroscience from UCLA and is a former laboratory technician at the University of Southern California.

Lindsey A. Schier

Lindsey A. Schier is a Gabilan Assistant Professor of Biological Sciences at the University of Southern California.