Pioglitazone ameliorates palmitate induced impairment of mitochondrial morphology and function and restores insulin...

This study aimed to investigate the effect of pioglitazone (PIO) on insulin secretion and mitochondrial ultrastructure and function in 3 cells. HIT-T15 cells were treated with control or palmitate (free fat acids, FFA) or/and PIO and divided into 7 groups: Control group; 0.5 mmol/l FFA (LF); 0.5 mmol/l FFA plus 10-7 mol/I PIO (LFLP); 0.5 mmol/l FFA plus 10-5mol/I PIO (LFHP); 1.0 mmol/l FFA (HF); 1.0 mmol/l FFA plus 10-7mol/I PIO (HFLP); 1.0 mmol/l FFA plus 10-5 mol/I PIO (HFHP). Apoptotic peaks, mitochondrial ultrastructure, ATP/ADP, mRNA levels of peroxisome proliferater activated receptor gamma coactivator-1 (PGC-1) and nucleus respiratory factor-1 (NRF-1) as well as insulin secretion were measured. The results showed that palmitate impaired mitochondrion structure, which could be alleviated by PIO. Palmitate could increase apoptotic peaks, decrease ATP/ADP ratio, enhance the expression of PGC-1 mRNA and NRF-1 mRNA, and decrease glucose stimulated insulin secretion (GSIS). In contrast, PIO could decrease apoptotic peaks, restore partly ATP/ADP ratio, decrease the expression of PGC-1 mRNA and NRF-1 mRNA, and increase GSIS level. These results demonstrate that PIO could ameliorate palmitate induced damage to mitochondrion ultrastructure and function and restore GSIS, accompanied by the modulation of PGC-1 and NRF-1 expression. These findings provide new insight into the hypoglycemic effects of PIO and help develop new agents for diabetes therapy.