3-Deoxyglucosone Induces Glucagon-Like Peptide-1 Secretion from STC-1 Cells via Upregulating Sweet Taste Receptor Expression under Basal Conditions.

3-Deoxyglucosone (3DG) is derived from D-glucose during food processing and storage and under physiological conditions. We reported that glucagon-like peptide-1 (GLP-1) secretion in response to an oral glucose load and high-glucose stimulation was decreased by acute 3DG administration. In this study, we determined the acute effect of 3DG on GLP-1 secretion under basal conditions and investigated the possible mechanisms. Normal fasting rats were given a single acute intragastric administration of 50 mg/kg 3DG. Plasma basal GLP-1 levels and duodenum 3DG content and sweet taste receptor expression were measured. STC-1 cells were acutely exposed to 3DG (80, 300, and 1000 ng/ml) for 1 h under basal conditions (5.6 mM glucose), and GLP-1 secretion, intracellular concentrations of cyclic adenosine monophosphate (cAMP) and Ca, and molecular expression of STR signaling pathway were measured. Under the fasted state, plasma GLP-1 levels, duodenum 3DG content, and duodenum STR expression were elevated in 3DG-treated rats. GLP-1 secretion was increased in 3DG-treated cells under either 5.6 mM glucose or glucose-free conditions. 3DG-induced acute GLP-1 secretion from STC-1 cells under 5.6 mM glucose was inhibited in the presence of the STR inhibitor lactisole, which was consistent with the observation under glucose-free conditions. Moreover, acute exposure to 3DG increased the protein expression of TAS1R2 and TAS1R3 under either 5.6 mM glucose or glucose-free conditions, with affecting other components of STR signaling pathway, including the upregulation of transient receptor potential channel type M5 TRPM5 and the increment of intracellular Ca concentration. In summary, the glucose-free condition was used to first demonstrate the involvement of STR in 3DG-induced acute GLP-1 secretion. These results first showed that acute 3DG administration induces basal GLP-1 secretion in part through upregulation of STR expression.