Circadian changes in the pharmacological effects of red ginseng saponins in mice

Pharmacological effects of the saponins extracted from root of Panax ginseng C. A. Meyer (Chinese red ginseng; GS) were studied with adult male mice standardized to 12h of light (from 07:30 to 19 : 30) alternating with 12 h of darkness. Functional activities were assessed every 4 h within 24 h. The levels of serum corticosterone, 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in the whole brain as well as the contents of glycogen. glucose, DNA, RNA and protein in the liver exhibited circadian variations. After administration of GS at the dose of 70 mg/kg (ip) to mice the serum corticosterone rose dramatically from 73 + 17 to 518 + 71 yg/L at the beginning of light span (peak) but it only increased 88 vg/L at the beginning of dark span (trough). ip administration of GS (100 mg/kg) accelerated the syntheses of DNA, RNA and protein, had no effect to glucose, but depleted the content of glycogen in the liver. Circadian patterns of hepatic DNA, RNA and glycogen almost paralled to that of control mice. The maximal and significant changes from control levels of glycogen DNA, RNA or protein occurred at 12 :00, 16 : 00. 00:00, or 20 :00, respectively. Ip treatment with GS 200 mg/kg to mice increased the level of 5-HT which had a circadian pattern approximatly similar to that of serum corticosterone; it increased the level of 5-HIAA at 08:00 and 16:00 but decreased at 20:00. To conclude, the pharmacological effects of GS showed a circadian stage-dependent changes, and the range of those changes may be related to the control levels in many cases.