Nitric oxide production in mouse peritoneal macrophages enhanced with glycyrrhizin

The enhancement of nitric oxide (NO) production in glycyrrhizin (GL)-induced macrophages (M phi) in response to lipopolysaccharide (LPS) was investigated. No production in GL-induced macrophage culture supernatants was stimulated in response to LPS (10 micrograms/ml) for 24- or 48- h cultures, and these levels were compared three times with the levels in saline-induced peritoneal exudate cell cultures. Furthermore, M phi induced with proteose peptone (PP) containing GL could generate greater NO production than M phi induced with PP alone. However, no stimulation of NO production was observed by addition of GL in the cultures of M phi induced with thioglycollate or Bacillus Calmette Guerin. Moreover, GL-induced M phi showed cytostasis against such tumor target cells as L 1210 and P 388 lymphoma cell lines. These observations indicate that GL can activate the M phi in vivo system and stimulate NO production in response to LPS.