Effect of Glycyrrhiza Polysaccharide on Expression of iNOS mRNA and Generation of NO and iNOS in Mouse Peritoneal Macrophages

This study was designed for understanding how Glycyrrhiza polysaccharide (GP) affects the expression of iNOS mRNA and the generation of NO and iNOS in mouse peritoneal macrophages. iNOS mRNA was isolated by RT-PCR and NO production was assessed by spectrophotometric method based on Griess reaction. Results showed that GP could induce the increases of NO content and iNOS activity in mouse peritoneal macrophages in a dose-dependent manner. A maximum NO and iNOS production and iNOS mRNA expression were observed when the concentration of added GP in culture solution was 400 μg/ml, or when the incubation time was 48 h at a fixed GP concentration of 100 μg/ml. This indicated that the regulation of GP on the production of NO in mouse peritoneal macrophages might occur at the transcriptional level of iNOS, thereby stimulating its large-quantity production and release. Furthermore, antitumor and immuno-regulation functions of GP might be associated with the increased NO production resulting from the ab initio synthesis of iNOS in stimulate macrophages.