Thymol regulates the functions of immune cells in the rat peritoneal cavity after L-arginine-induced pancreatitis

Aims: The present study aimed to evaluate the protective action of thymol towards L-arginine-induced acute pancreatitis (AP) by studying the function of rat peritoneal immune cells. Main methods: Rat peritoneal exudate cells (PECs), obtained 24 h after the injection of L-arginine (350 mg/100 g of b.w.), were evaluated for mitochondrial activity (MTT assay), adherence capacity (methylene-blue assay), and phagocyte enzyme activity (myeloperoxidase, MPO, assay). The activity of alpha-amylase and free MPO, as well as the concentration of reactive oxygen species (ROS, i.e. O-2(-)center dot), were determined in the peritoneal exudate fluid. Also, serum a-amylase activity determination and pancreatic tissue pathohistological analysis were performed. Key finding: The administered thymol (50 and 100 mg/kg, per os) caused a significant decrease in the PEC mitochondrial activity and adherence capacity when compared with these functions of PECs isolated from rats with AP. A decrease in cellular MPO activity, as well as in the levels of ROS, alpha-amylase, and free MPO in peritoneal exudates was found in animals treated with thymol compared to the control animals with AP. Additionally, thymol administration prevented an increase in serum alpha-amylase activity, accompanied by the decrease in pancreatic tissue damage that follows L-arginine application. Significance: The present results showed that thymol exerts significant immunomodulatory properties and a potential to silence PEC functions in inflammatory conditions such as the AP induced by L-arginine.