Effect of PPAR-γ Activation and Inhibition onGlucose-Stimulated Insulin Release in INS-1e Cells.

Santini, Eleonora; Fallahi, Poupak; Ferrari, Silvia Martina; Masoni, Antonio; Antonelli, Alessandro; Ferrannini, Ele

Peroxisome proliferator-activated receptor (PPAR)-γ is expressed in human β-cells and in the rat β-cell line INS-I. Previous studies have suggested that PPAR-γ agonism (e.g., thiazolidinediones) enhances glucose-stimulated insulin secretion (GSIS) from islets or INS-1 cells. We tested the direct effect on insulin release by INS-le of a PPAR-γ agonist (Ro4389679-000-001 at 0.2 and 0.4 µmol/l) and a PPAR-γ antagonist (SR202 at 0.2 and 0.4 mmol/l). Cells were incubated in 11 mmol/l glucose for 96 h and then challenged with 3.3, 7.5, 11.0, and 20.0 mmol/l glucose for 1 h. Under these control conditions, insulin concentrations in the medium rose from 19 plusmn; 4 ng/ml (mean plusmn; SE) to 82 plusmn; 5, 107 plusmn; 11, and 103 plusmn; 10 ng/ml (P < 0.0001 by ANOVA). Preincubation for 48 h with the PPAR-γ agonist potentiated GSIS (to 154 plusmn; 14 and 156 plusmn; 12 ng/ml at 20 mmol/l glucose, P < 0.01). Cell insulin content was not altered by either acute glucose challenge or PPAR-γ agonist coincubation. Preincubation for 48 h with SR202 at the higher dose caused a 30% inhibition of GSIS, with no change in cell insulin contents. When cells were preincubated with 11 mmol/l glucose plus 1 mmol/l oleate, GSIS was significantly potentiated (by 30%, P < 0.0001); adding Ro4389679-000-001 or SR202 to these preincubations reduced GSIS to the respective levels seen in the absence of oleate (P < 0.0001 for both effects). In conclusion, INS-le cells display a PPAR-γ tone that is symmetrically modulated and competitively stimulated by oleate. Diabetes 53 (Suppl. 3):S79-S83, 2004

PEROXISOMES; PANCREATIC beta cells; CELL lines; INSULIN; ISLANDS of Langerhans; BLOOD sugar

Diabetes, 2004, Vol 53, pS79

0012-1797

Academic Journal

10.2337/diabetes.53.suppl_3.S79