Effects of Peroxisome Proliferator-Activated Receptor-γ Activation on Apoptosis in Rats with Acute Pancreatitis

To investigate the effects and mechanisms of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activation on the induction of apoptosis in rats with acute pancreatitis. Severe acute pancreatitis (SAP) and mild acute pancreatitis (MAP) were induced and pre-treated with pioglitazone, which is a ligand of PPAR-gamma. The expression of inflammatory factors (TNF-alpha and IL6) of the pancreas was detected by ELISA. The apoptosis in pancreas were detected by TUNEL assay and the activity of caspase 3 was determined. Phosphorylation of p65 in pancreas of SAP or MAP was determined by western-blot. Expression levels of PPAR-gamma proteins were elevated in the pancreases of SAP or MAP rats pre-injected with pioglitazone intraperitoneally. Downregulation of the expression TNF-alpha and IL6 and relief of pathological changes in the pancreas suggested that pioglitazone had protective effects on acute panceatitis. In pioglitazone pre-treated groups, a TUNEL assay indicated a high level of apoptosis in SAP but little apoptosis in MAP, showing pioglitazone could promote taurocholate-induced apoptosis but inhibit ceruleininduced apoptosis in pancraeatic aniniar cells. Furthermore, caspase 3 activity was high in SAP but low in MAP, implying that the apoptotic mechanism in pancreatic acinar cells of AP rats was correlated with caspase 3 activity. Phosphorylation of p65 was reduced in SAP or MAP group pretreated with pioglitazone, indicating that pioglitazone reduced the inflammation reaction by inhibiting the activation of the NF-kappa B. These results indicated that activation of PPAR-gamma induced apoptosis in pancreatic acinar cells of SAP rats but inhibited apoptosis in pancraeatic acinar cells of MAP rats, which demonstrated that PPAR-gamma may be an efficiently therapeutic target in pancreatic inflammation.