4.6. Glucagon-Like Peptide 1 (GLP-1) Secretion

GLUTag cells were seeded on 24-well plates in the amount of 2 × 10⁵ per well 48 h. Confluent cells were pre-incubated for 60 min at fasting conditions (5.6 mM glucose DMEM). Subsequently, cells were incubated in the new portions of the serum-free medium supplemented with tested compounds at either 10 μM working concentrations and/or GPCR antagonists (2 μM of DC, CID, C8, and AH) for 120 min. The buffer supernatants were collected, and cells were lysed with lysis buffer were subjected for competitive ELISA, using the Mouse GLP-1 ELISA Kit according to the supplier’s protocol. Quantities of secreted GLP-1 were normalized to protein contents in respective cell lysates measured according to Bradford Protein Assay.