[Effects of the ginseng polysaccharides on reducing liver glycogen]

The ginseng polysaccharides GH1 (100, 200 mg.kg-1) iv reduced liver glycogen and increased adenosine-3',5'-cyclic monophosphate (cAMP) level and adenyl cyclase (AC) activity in mice. The action of GH1 was completely antagonized by propranolol, inhibitor of adrenergic beta receptor. The stimulating effect of GH1 on AC activity was significant 2 and 4 h after iv GH1. However, GH1 at concentration of 20-120 mumol.L-1 in vitro showed no manifest effect on AC activity. GH1 stimulated the activities of 3',5'-cyclic-GMP phosphodiesterases (PDE) and calmodulin (CaM) in a dose-dependent manner. It is suggested that the reduction of liver glycogen induced by GH1 resulted from its obvious increase of cAMP which promoted glycogenolysis and decreased glycogenesis.