Objective      To investigate the effect of S-equol (S-Eq)

the active metabolite of daidzein

on the insulin secretion disorder induced by high glucose in rat insulinoma cell line INS-1.      Methods      INS-1 cells were treated with 26.2 mmol/L glucose in the absence or presence of different concentrations (0.1

1

10and 100 μmol/L) of S-Eq for 24 h. In this way

the cells were divided into 6 groups: control group (C)

high glucose group (H)

0.1 μmol/L S-Eq＋high glucose group (0.1 μmol/L S-Eq+H)

1 μmol/L S-Eq＋high glucose group (1 μmol/L S-Eq+H)

10 μmol/L S-Eq＋high glucose group (10 μmol/L S-Eq+H)

and 100 μmol/L S-Eq＋high glucose group (100 μmol/L S-Eq+H). The cell viability was examined by CCK-8 assay

and the glucose-stimulated insulin secretion (GSIS) was tested with ELISA. INS-1 cell apoptosis was detected by TUNEL assay and Annexin V-FITC/PI flow cytometry. The mRNA expression of preproinsulin (PPI)

glucose transporter 2 (Glut2)

and uncoupling protein 2 (UCP2) was tested by real-time PCR while the expression of Glut2 and UCP2 proteins was tested by Western blotting.      Results      S-Eq significantly increased the cell vitality of INS-1 cells stimulated by high glucose

and 1 μmol/LS-Eq had the most obvious effect (P0.05). The insulin secretion of INS-1 cells was significantly reduced by high glucose treatment

but S-Eq could remarkably increase insulin secretion in high glucose-treated INS-1 cells (P0.05). Meanwhile

0.1

1and 10 μmol/L of S-Eq reduced the apoptosis of high glucose-treated INS-1 cells

increased the expressions of PPI mRNA

Glut2 mRNA and protein

and significantly inhibited the expression of UCP2 at mRNA and protein levels (P0.05).      Conclusion      S-Eq can alleviate high glucose-induced insulin secretion disorder in INS-1 cells through inhibiting apoptosis and regulating the expressions of Glut2 and UCP2.