Evidence that Oral Glucose Detection in Humans Involves Sweetening and Glucose Transporter Pathways
Publication date: October 6, 2021
https://doi.org/10.1371/journal.pone.0256989
Explanation
Since taste-stimulating glucose, whether in the form of disaccharide sucrose or high fructose corn syrup (HFCS), constitutes about half of the commercial sugar sweeteners in use today, it is presumed that oral glucose contributes to the sweetness of foods when combined with fructose.
In light of recent rodent data on the role of oral metabolic glucose signaling, this study will be a psychopharmacological investigation of whether oral glucose detection also involves an additional pathway in humans to conventional sweetness transmission via the class 1 taste receptors T1R2 / T1R3.
In a series of experiments, oral glucose detection thresholds with and without the T1R receptor inhibitor Na-lactizol were compared to sucralose thresholds.
Next, oral glucose detection thresholds were compared between sucralose, the non-metabolizable glucose analogue α-methyl-D-glucopyranoside (MDG), and the glucose co-transporting component sodium (NaCl) with and without Na-lactisol.
Finally, we compared the oral detection thresholds of glucose, MDG, fructose, and sucralose with and without the sodium-glucose cotransporter (SGLT) inhibitor phlorizin.
In each of these experiments, psychopharmacological data were shown to be consistent with glucose being involved in an additional signaling pathway to the sweet taste receptor T1R2 / T1R3 pathway.
The addition of Na-lactizol impaired the detection of the non-caloric sweetener sucralose much more than glucose, consistent with glucose using an additional signaling pathway.
The addition of NaCl had a beneficial effect on the detection of glucose and its analog MDG and on the impairment of sucralose detection. Consistent with glucose utilizing sodium-glucose cotransporters, the addition of the SGLT inhibitor phlorizin impaired the detection of glucose and MDG more than sucralose, but not fructose.
This phenomenon provides further evidence consistent with glucose utilizing sodium-glucose cotransporters.
Taken together, the results support the idea that oral detection of glucose involves two signaling pathways.
