Fig. 3

S-Equol enhances insulin secretion and inhibits apoptosis from INS-1 cells cultured with high glucose. INS-1 cells were treated for 48 h with or without S-Equol (0.1, 1 and 10 μM) in the continuous presence of high glucose (26.2 mM), and cells cultured with 5 mM of glucose denote the control. (a) GSIS assay. After the treatment of INS-1 cells for 48 h, the basic insulin secretion (BIS) and GSIS were detected respectively in INS-1 cells exposed to 5 or 25 mM glucose medium for 90 min in the continuous presence or absence of S-Equol after a quiescent period of 90 min; (b) PPI mRNA detection by real time-PCR; (c) The expression of Glut2 and UCP-2 was measured by Western blotting analysis and quantified based on the changed folds normalized to their control groups; (d-e) Apoptosis cell assay of INS-1 cells by TUNEL method, Annexin V method and apoptotic rate calculation in INS-1 cells. Lane “1 – 5” represents Control, H, 0.1 μM S-Eq + H, 1 μM S-Eq + H and 10 μM S-Eq + H group respectively. S-Eq, S-Equol; H, High glucose; GSIS, Glucose stimulated insulin secretion; BIS, basic insulin secretion. PPI, Preproinsulin; Glut2, Glucose transporter 2; UCP-2, Uncoupling protein-2. Five to eight independent experiments were run in each experiments and results were presented as means ± SD. *P < 0.05 vs. the Control group, ^# P < 0.05 vs. the H group