[Effects of polyporus polysaccharide on activity and mRNA expression of inducible nitric oxide synthase in peritoneal macrophages of mice].

OBJECTIVE To study the mechanisms of the antitumor and immunoregulation functions of polyporus polysaccharide (PPS). METHODS The production of nitric oxide (NO), the activity and mRNA expression of inducible nitric oxide synthase (iNOS) in peritoneal macrophages of mice administered with different dose of PPS were observed by Griess reaction, fluorimetry assay and RT-PCR, respectively. RESULTS PPS could elevate the iNOS activity with dose-dependence and stimulate the iNOS mRNA expression of peritoneal macrophages in mice. CONCLUSION The regulation of PPS on the production of NO in peritoneal macrophages of mice may occur at transcriptional level of iNOS. This indicates that the mechanism of PPS's antitumor and immunoregulation functions may be related to increasing NO output of macrophages through stimulating iNOS's denovo synthesis.