Determination of sweetener specificity of horse gut-expressed sweet taste receptor T1R2-T1R3 and its significance for energy provision and hydration.
Authors: Smith Liberty, Moran Andrew W, Al-Rammahi Miran, Daly Kristian, Shirazi-Beechey Soraya P
Journal: Frontiers in veterinary science
Summary
# Editorial Summary The intestinal sweet taste receptor T1R2-T1R3 plays a previously underexplored but potentially significant role in equine glucose and water absorption; when activated by certain sweeteners, it upregulates the sodium-glucose cotransporter SGLT1, enhancing the gut's capacity to absorb glucose, electrolytes and water—a mechanism well-documented in other species but never characterised in horses until now. Smith Liberty's team used heterologous expression methodology to test four sweeteners against equine T1R2-T1R3, revealing that sucralose, stevia and neohesperidin dihydrochalcone (NHDC) successfully activate the receptor, whilst cyclamate does not, establishing a sweetener specificity profile unique to horses. These findings have direct practical implications for formulating oral rehydration solutions and energy supplements tailored to equine physiology, particularly valuable during high-demand periods such as strenuous exercise, pregnancy and lactation when glucose requirements surge. Understanding which sweeteners effectively trigger T1R2-T1R3 activation also offers a preventative strategy against large intestinal disease caused by microbial fermentation of unabsorbed carbohydrate—a common concern when dietary energy supplements reach the colon intact. Farriers, veterinarians and nutritionists can now base sweetener selection on evidence-driven receptor specificity rather than assumptions borrowed from human or other animal models, allowing for more targeted and effective supplementation strategies in equine practice.
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Practical Takeaways
- •Sucralose, stevia, or NHDC could be used as feed additives to enhance glucose and water absorption during high-demand periods (exercise, pregnancy, lactation)
- •Cyclamate should not be used as a sweetener additive in equine feed for these purposes, as it does not activate the equine sweet receptor
- •Strategic use of appropriate sweeteners may reduce colic and large intestinal disease risk by improving carbohydrate absorption rather than allowing fermentation in the hindgut
Key Findings
- •Horse sweet taste receptor T1R2-T1R3 is activated by sucralose, stevia, and NHDC but not cyclamate
- •Sweetener activation of equine T1R2-T1R3 upregulates SGLT1, enhancing glucose, sodium, and water absorption
- •This mechanism could improve energy provision during strenuous exercise, pregnancy, and lactation in horses
- •Sweetener specificity differences among species are driven by amino acid substitutions and pseudogenization of taste receptor genes