L-type calcium channel blockade mechanisms of panaxadiol saponins against anoxic damage of cerebral cortical neurons isolated from rats.
AIM: To identify the changes of L-type Ca2+ channel on cerebral cortical neurons of rats during anoxia and the protective mechanisms of panaxadiol saponins (PDS) against anoxic injury. METHODS: Patch-clamp technique of cell-attached configuration and in vitro cerebral anoxic modle built with actuely isolated cortical cells of Wistar rats. RESULTS: The open time of L-type Ca2+ channel of cortical neurons increased significantly from (2.85 +/- 0.21) ms to (9.1 +/- 1.0) ms (P < 0.01) under anoxia. The particular change was a long-lasting open, which was more than 20 ms in some cases. At the same time, the close time decreased from (38 +/- 8) ms to (10 +/- 3) ms (P < 0.01) and the open-state probability raised from (0.047 +/- 0.008) to (0.165 +/- 0.025) (P < 0.01). PDS (1.5 g.L-1) inhibited the activity of L-type Ca2+ channel both in normal and anoxic condition [open time from (2.23 +/- 0.47) ms and (9.1 +/- 1.0) ms to (1.03 +/- 0.25) ms and (2.1 +/- 0.4) ms; close time from (38 +/- 10) ms and (10 +/- 3) ms to (74 +/- 16) ms and (46 +/- 10 ms); open-state probability from (0.043 +/- 0.006) and (0.165 +/- 0.025) to (0.012 +/- 0.004) and (0.021 +/- 0.009), respectively, P all < 0.01]. The results of PDS were similar to those of verapamil, but were weaker compared with verapamil. CONCLUSION: The L-type Ca2+ channels of rat cerebral cortical neurons were obviously opened during anoxia. The channels in normal and anoxic condition were effectively blocked by PDS. It was one of the important mechanisms by which PDS protected brain from the anoxic injury. (+info)
American ginseng extract reduces scopolamine-induced amnesia in a spatial learning task.
OBJECTIVE: To determine if HT-1001, an extract of American ginseng, affects scopolamine-induced memory and performance deficits in a spatial learning task, alters brain concentrations of aminergic neurotransmitters, and alters choline uptake in synaptosome preparations. DESIGN: Animal study. ANIMALS: 48 Sprague Dawley rats. INTERVENTIONS: Long-term oral administration of a test material or control solution. Intraperitoneal administration of scopolamine (2 mg/kg) 30 minutes before testing. OUTCOME MEASURES: Performance on Morris water maze task, choline uptake, aminergic neurotransmitter analysis, in vitro monoamine oxidase analysis (of compounds). RESULTS: HT-1001 protected against scopolamine-induced amnesia and increased choline uptake in synaptosomal preparations. HT-1001 did not alter brain concentrations of norepinephrine, dopamine, 5-HT (serotonin), 3,4-dihydroxyphenylacetic acid or 5-hydroxyindoleactic acid. HT-1001 had a very weak ability to inhibit monoamine oxidase activity in vitro. CONCLUSIONS: HT-1001 demonstrates a capacity to protect against scopolamine-induced memory deficits. (+info)
Glucocorticoid receptor-induced down-regulation of MMP-9 by ginseng components, PD and PT contributes to inhibition of the invasive capacity of HT1080 human fibrosarcoma cells.
We examined the effects of the purified ginseng components, panaxadiol (PD) and panaxatriol (PT), on the expression of matrix metalloproteinase-9 (MMP-9) in highly metastatic HT1080 human fibrosarcoma cell line. A significant down-regulation of MMP-9 by PD and PT was detected by Northern blot analysis. However, the expression of MMP-2 was not changed by treatment with PD and PT. Quantitative gelatin based zymography confirmed a markedly reduced expression of MMP-9, but not MMP-2 in the treatment of PD and PT. To investigate whether the reduced level of MMP-9 by PD and PT affects the invasive capacity of HT1080 cells, we conducted an in vitro invasion assay with PD and PT treated cells. The results of the in vitro invasion assay revealed that PD and PT reduced tumor cell invasion through a reconstituted basement membrane in the transwell chamber. Because of the similarity of chemical structure between PD, PT and dexamethasone (Dexa), a synthetic glucocorticoid, we investigated whether the down-regulation of MMP-9 by PD and PT were mediated by the nuclear translocation of glucocorticoid receptor (GR). Increased GR in the nucleus of HT1080 human fibrosarcoma cells treated by PD and PT was detected by immunocytochemistry. Western blot and gel retardation assays confirmed the increase of GR in the nucleus after treatment with PD and PT. These results suggest that GR-induced down-regulation of MMP-9 by PD and PT contributes to reduce the invasive capacity of HT1080 cells. (+info)
Effect of aerobic exercise and ginsenosides on lipid metabolism in diet-induced hyperlipidemia mice.
AIM: To study the effect of aerobic exercise and its combination with Gin (ginsenosides from stems and leaves of ginseng) on lipid metabolism in diet-induced hyperlipidemia mice. METHODS: The mouse hyperlipidemia model was set up by feeding high cholesterol diet. Unloaded swimming was designed to be a manner of aerobic exercise. The effects of aerobic exercise and its combination with Gin on total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-c) in serum, malondialdehyde (MDA), and superoxide dismutase (SOD) in liver tissue were measured; the thymus and liver were weighed. RESULTS: (1) The mouse hyperlipidemia model was set up successfully: TC and MDA increased (P < 0.05) but HDL-c and SOD decreased (P < 0.05); the liver weight increased and the thymus weight reduced; fatty liver was found; (2) aerobic exercise reduced TC but increased MDA and HDL-c in cholesterol-rich diet mice; the liver weight did not reduce, and fatty liver did not clear up; and (3) when aerobic exercise combined with Gin, TC and TG decreased markedly (P < 0.01), and MDA also decreased (P < 0.05); SOD and HDL-c increased markedly (P < 0.01); the thymus weight increased and the liver weight decreased to normal level; fatty liver cleared up. CONCLUSION: Aerobic exercise could lower serum lipid to some extent but could not satisfactorily regulate lipid metabolism. When combined with Gin, aerobic exercise could better lower serum lipid, regulate lipid metabolism, promote antioxidation, and enhance immune activity. (+info)
Caspase 3-mediated cleavage of p21WAF1/CIP1 associated with the cyclin A-cyclin-dependent kinase 2 complex is a prerequisite for apoptosis in SK-HEP-1 cells.
Apoptosis of SK-HEP-1 human hepatoma cells induced by treatment with ginsenoside Rh2 (G-Rh2) is associated with rapid and selective activation of cyclin A-associated cyclin-dependent kinase 2 (Cdk2). Here, we show that in apoptotic cells, the Cdk inhibitory protein p21(WAF1/CIP1), which is associated with the cyclin A-Cdk2 complex, undergoes selective proteolytic cleavage. In contrast, another Cdk inhibitory protein, p27(KIP1), which is associated with cyclin A-Cdk2 and cyclin E-Cdk2 complexes, remained unaltered during apoptosis. Ectopic overexpression of p21(WAF1/CIP1) suppressed apoptosis as well as cyclin A-Cdk2 activity induced by treatment of SK-HEP-1 cells with G-Rh2. The suppressive effects of p21(WAF1/CIP1) were much higher in the cells transfected with p21D112N, an expression vector that encodes a p21(WAF1/CIP1) mutant resistant to caspase 3 cleavage. Overexpression of cyclin A in SK-HEP-1 cells dramatically up-regulated cyclin A-Cdk2 activity and accordingly enhances apoptosis induced by treatment with G-Rh2. These up-regulating effects were blocked by coexpression of a dominant negative allele of cdk2. Furthermore, olomoucine, a specific inhibitor of Cdks, also blocked G-Rh2-induced apoptosis. These data suggest that the induction of apoptosis in human hepatoma cells treated with G-Rh2 occurs by a mechanism that involves the activation of cyclin A-Cdk2 by caspase 3-mediated cleavage of p21(WAF1/CIP1). (+info)
Ginsenoside-induced relaxation of human bronchial smooth muscle via release of nitric oxide.
Ginsenoside, an extract of Panax ginseng, is an essential constituent of anti-asthmatic Chinese herbal medicine. To elucidate whether ginsenoside affects airway smooth muscle tone and, if so, what the mechanism of action is, we studied relaxant responses of human bronchial strips under isometric condition in vitro, and directly measured the release of nitric oxide (NO) by an amperometric sensor for this molecule. Addition of ginsenoside relaxed the tissues precontracted with acetylcholine in a dose-dependent manner, the maximal relaxation and the ginsenoside concentration required to produce 50% relaxation being 67+/-8% and 210+/-29 microg ml(-1), respectively. The relaxant responses to ginsenoside were inhibited by N(G)-nitro-L-arginine methylester (L-NAME) and removal of the epithelium, but not by N(G)-nitro-D-arginine methylester (D-NAME) or tetrodotoxin. This inhibitory effect of L-NAME was reversed by L-arginine but not by D-arginine. Addition of ginsenoside to the medium containing bronchial tissues dose-dependently increased NO-selective electrical current, and this effect was greatly attenuated by the epithelial removal or Ca(2+)-free medium. Ginsenoside also increased tissue cyclic GMP contents, an effect that was abolished in the presence of L-NAME. It is concluded that ginsenoside induces relaxation of human bronchial smooth muscle via stimulation of NO generation predominantly from airway epithelium and cyclic GMP synthesis. This action might account for the anti-asthmatic effect of Panax ginseng. (+info)
A novel activation of Ca(2+)-activated Cl(-) channel in Xenopus oocytes by Ginseng saponins: evidence for the involvement of phospholipase C and intracellular Ca(2+) mobilization.
1. The signal transduction mechanism of ginsenosides, the active ingredients of ginseng, was studied in Xenopus oocytes using two-electrode voltage-clamp technique. Ginseng total saponin (GTS), i.e., an unfractionated mixture of ginsenosides produced a large outward current at membrane potentials more positive than -20 mV when it was applied to the exterior of oocytes, but not when injected intracellularly. The effect of GTS was concentration-dependent (EC(50): 4.4 microg ml(-1)) and reversible. 2. Certain fractionated ginsenosides (Rb(1), Rb(2), Rc, Rf, Rg(2) and Ro) also produced an outward current in a concentration-dependent manner with the order of potency of Rf>Ro>Rb(1)=Rb(2)>Rg(2)>Rc. Other ginsenosides (Rd, Re and Rg(1)) had little or no effect. 3. The GTS effect was completely blocked by bath application of the Ca(2+)-activated Cl(-) channel blocker niflumic acid and by intracellular injection of the calcium chelator BAPTA or the IP(3) receptor antagonist heparin. Also, the effect was partially blocked by bath-applied U-73122, a phospholipase C (PLC) inhibitor and by intracellularly injected GTP gamma S, a non-hydrolyzable GTP analogue. Whereas, it was not altered by pertussin toxin (PTX) pretreatment. 4. These results indicate that: (1) interaction of ginsenosides with membrane component(s) at the extracellular side leads to Ca(2+)-activated Cl(-) channel opening in Xenopus oocyte membrane; and (2) this process involves PLC activation, the release of Ca(2+) from the IP(3)-sensitive intracellular store and PTX-insensitive G protein activation. (+info)
Enzymatic preparation of genuine prosapogenin, 20(S)-ginsenoside Rh1, from ginsenosides Re and Rg1.
It was found that a lactase preparation from Penicillium sp. nearly quantitatively hydrolyzed ginsenosides Re and Rg1, which are major saponins in roots of Panax ginseng, to a minor saponin, 20(S)-ginsenoside Rh1 [6-O-beta-D-glucopyranosyl-20(S)-protopanaxatriol]. This is the first report on the enzymatic preparation of ginsenoside Rh1 with a high efficiency. This enzyme also readily hydrolyzed ginsenoside Rg2 to ginsenoside Rh1. (+info)