Month: September 2022

SWEET PREFERENCE. “By contrast, mice exhibit a strong preference for sucrose solution over H2O. Indeed, the consumed volume was significantly increased in line with the predilection of mice for sucrose solutions (Fig. 3b).” https://lnkd.in/dzPDm5w View in LinkedIn

THE DATA. “The amount of H2O consumed by the control group from either of the two bottles, both containing H2O, is depicted in Fig. 3c. Overall, the data shows that in all three experiments mice consumed comparable amounts of H2O and D2O, with significant increase of consumption of the sucrose solution.” https://lnkd.in/dzPDm5w View in LinkedIn

THE HYPOTHESIS. “The chemical dissimilarity of D2O from sugars and other sweeteners raises the question whether the effect we observed in human subjects is mediated by TAS1R2/TAS1R3, which is the major receptor for sweet taste.” https://lnkd.in/dzPDm5w View in LinkedIn

TESTING THE HYPOTHESIS. “This was first explored by combining water samples with lactisole as an established TAS1R2/TAS1R3 inhibitor. Using the two-alternative forced-choice (2AFC) method, in which the participant must choose between two samples, 18 out of 25 panelists chose pure D2O as sweeter than D2O + 0.9 mM lactisole solution (p 

CONCLUSION. “In an additional experiment, the sweetness of pure D2O was scored significantly higher than that of D2O + 0.9 mM lactisole solution (p = 0.0003), while the same amount of lactisole had no effect on the perception of sweetness of H2O that served as control (Fig. 4b). These results suggest that D2O elicits sweetness via the TAS1R2/TAS1R3 sweet taste receptor.” https://lnkd.in/dzPDm5w View in LinkedIn

ALTERNATIVE CONFIRMATION. “To confirm the involvement of the sweet taste receptor TAS1R2/TAS1R3 in D2O signaling we performed functional calcium mobilization assays using HEK 293 FlpIn T-Rex cells heterologously expressing both required TAS1R subunits as well as the chimeric G protein Gα15Gi343.” https://lnkd.in/dzPDm5w View in LinkedIn

AFFIRMATION. “As seen in Fig. 5a, D2O at 1.85 M and 5.84 M concentrations in H2O (3.3% and 10.4%, respectively) elicited robust responses in TAS1R2/TAS1R3 expressing cells. The strong reduction or absence of D2O-elicited fluorescence response in the presence of lactisole confirmed the dependence on TAS1R2/TAS1R3.” https://lnkd.in/dzPDm5w View in LinkedIn

TITRATION. “The inhibitory effect of lactisole on D2O-activation of the human sweet taste receptor was confirmed using an IP1 assay, while lactisole exposure had no effect on cells treated with pure H2O water, as expected (Fig. 5c). As a control, 960 mM D-glucose elicited increase in IP1 levels in TAS1R2/TAS1R3 expressing cell, which was inhibited in the presence of lactisole.” https://lnkd.in/dzPDm5w View in LinkedIn

CELLULAR DOSE RESPONSE. “We further used an IP1 assay on non-transfected HEK 293T cells, where we observed that dose-dependent curves of carbachol—an agonist of the endogenous muscarinic receptor 3 (M3)47—did not show any difference between H2O and D2O-based media (Fig. 6a) and that cell medium that had either 10% or 100% D2O, did not activate basal IP1 accumulation (Fig. 6b).” https://lnkd.in/dzPDm5w View in LinkedIn

MOLECULAR DOSE RESPONSE. “Next, TAS1R2/TAS1R3 receptor along with the chimeric Gα16gust44 subunit were transiently expressed, and the functionality was illustrated by dose-dependent response to D-glucose (Fig. 6c). Finally, and in agreement with calcium imaging, we found that 10% D2O activated these cells. Activation by 100% D2O was even more pronounced (Fig. 6d).” https://lnkd.in/dzPDm5w View in LinkedIn