Ginseng Total Saponins Research Articles

Effects of Ginseng Total Saponin on [3H]DAGO Bindings of Opioid μ-Receptors

Crude synaptic membrane fractions from the frontal cortex, striatum, brain stem and whole brain of rat were prepared to assay the effects of ginseng total saponin (GTS) on [³H]DAGO bindings of the opioid μ-receptors. Scatchard plots analysis binding data demonstrated that GTS (0.1 mg/ml) decreased the affinity of specific [³H]DAGO bindings without changes in Bmax in the frontal cortex and striatum. On the other hand, GTS did not affect the [³H]DAGO bindings in the brain stem and whole brain. These results suggest that the regulation of [³H]DAGO bindings by GTS may play roles in the change of the pharmacological responses of μ-opioids.

Inhibitory effect of ginsenosides on NMDA receptor-mediated signals in rat hippocampal neurons

Alternative medicines such as herbal products are increasingly being used for preventive and therapeutic purposes. Ginseng is the best known and most popular herbal medicine used worldwide. In spite of some beneficial effects of ginseng on the CNS, little scientific evidence shows at the cellular level. In the present study, we have examined the direct modulation of ginseng on the activation of glutamate, especially NMDA, receptors in cultured hippocampal neurons. Using fura-2-based digital imaging techniques, we found ginseng total saponins inhibited NMDA-induced but less effectively glutamate-induced increase in [Ca 2+] i . Ginseng total saponins also modulated Ca 2+ transients evoked by depolarization with 50 mM KCl along with its own effects on [Ca 2+] i . Furthermore, we demonstrated that ginsenoside Rg 3 is an active component for ginseng actions on NMDA receptors. The data obtained suggest that the inhibition of NMDA receptors by ginseng, in particular by ginsenoside Rg 3, could be one of the mechanisms for ginseng-mediated neuroprotective actions.

인삼 추출물이 난소를 절제한 백서의 항산화효소 활성에 미치는 영향

노화과정에 산소라디칼이 관여할 가능성을 노화유도된 쥐를 동물모델로 하여 알아보았다. 난소를 절제한 rat와 난소를 절제하지 않은 정상의 rat에서의 생리활성에 미치는 인삼 추출물의 효과를 연구하였다. 난소를 절제한 rat에 각각 GTS (Ovx+GTS 군)와 GW (Ovx+GW 군)를 투여하고, 이것과 비교하기 위해 난소를 절제한 대조군(Ovx군)과 마지막으로 난소를 절제하지 않은 정상군(Sham군)으로 하여 항산화효과에 관한 실험방법으로 진행하였다. 노화유도된 쥐의 각 조직에서 lipid peroxidation이 증가되었고 free radical반응이 더 심하게 일어난 간 조직에서 노화진행이 그만큼 촉진되었음을 알 수 있었다. 간소라디칼반응이 항진된 원인을 규명코자 간 조직에서 미토콘드리아와 세포질분획에서 항산화효소의 활성을 조사한 결과, SOD와 glutathion reductase활성이 감소되었으며 노화나 지질과산화가 심하게 진행되었던 간 조직에서 이들 항산화효소의 활성감소가 심한 경향을 나타내었다. 생체는 free radical을 조절할 수 있는 다양한 항산화계가 존재하여 free radical을 효율적으로 제거함으로써 생체의 항상성을 유지할 수 있다. 이러한 항산화계에는 superoxide dismutase (SOD), glutathion (GSH) peroxidase, GSH reductase, GSH S-transferase, catalase등의 항산화효소가 있다. SOD는 반응성을 가진 산소species인 superoxide anion을 macrophage와 polymorphonuclear leucocyte의 항균작용같은 세포방어기구에서 중요한 역할을 한다. 원칙상 눈, 피부등의 byaus이 공기중의 산소에 노출되면 oxidative stress가 커짐으로서 조직이 훼손되나 SOD같은 효소에 의해 보호되고 손상이 방지되는 것으로 알려지고 있다. 실제로 신체부위에 적용해 보면 쉽게 활성상실이 일어나므로 fatty arid와 공유결합시켜 효과적으로 superoxide radical을 제거할 수 있다. AST의 활성은 Ovx군이 Sham군에 비해 2.11배 높게 나타났으며, ALT 활성은 변화가 나타나지 않았다. AST 활성에서는 각각의 물질을 투여한 군에서는 유의적인 감소 경향을 보였다. 과산화지질함량은 Ovx군이 Sham군에 비해 높게 나타났으며, 각각의 인삼추출물을 투여한 군에서는 62%∼72%의 저해률을 보였다. 항산화 효소들은 Sham군에 비해 Ovx군에서 낮게 나타났는데, 각 물질의 투여 군에서는 유의성있는 증가를 보였다. 이러한 결과에서 보듯이, 난소 절제로 생성된 많은 free radical은 항산화효소에 의해서 감소되었으며, 그리고 인삼 추출물이 항산화 효소 대신에 노화를 저해하는 작용을 하는 것으로 사료되었다. In order to observe the bioactivity of ovariectomized rats, nonovariertoized (sham) group, ovariectomized (Ovx) group, ovariectomized ginseng total saponin (GTS)-treated (Ovx+ GTS) group and ovariectomized ginseng water extract (GW)-treated (Ovx+CW) group were made. We measured AST (L-aspartate aminotransferase) and ALT (L-alanin aminotransferase) in sera, and MDA (malondialdehyde:lipid peroxidation), SOD (superoxide dismutase), catalase, total-glutathione (GSH + GSSG) and GPx (glutathione peroxidase) in liver tissue total homogenates of rat. AST activity of serum in Ovx group was 2.11 times increased, but ALT activity was not changed compared to Sham group. In AST activity, they tend to decrease significantly in each substance such as GTS and GW administered group. Lipidperoxides of each fraction in Ovx group were highly increased compared to Sham group. Extracts of ginseng-treated group markedly inhibited lipid peroxidation by 62% ∼72%. And as the result of the measurements of SOD, catalase, total-glutathione and GPx which are antioxidant enzyme, antioxidant enzymes in Ovx group much lower than in Sham group. But they were significantly increased in each substance such as GTS and GW, administered group. Based on the results, it is supposed that more produced free radicals decreased antioxidant enzyme. And it is also thought that extracts of ginseng can inhibit aging by reducing antioxidant enzyme.

Role of benzodiazepine–GABA A receptor complex in attenuation of U-50,488H-induced analgesia and inhibition of tolerance to its analgesia by ginseng total saponin in mice

In the present study, the role of benzodiazepine–GABA A receptor complex in the attenuation of U-50,488H (U50), a selective kappa opioid agonist-induced analgesia and inhibition of tolerance to its analgesia by ginseng total saponin (GTS) was investigated using the mice tail–flick test. The intraperitoneal (i.p.) treatment of GTS (100 and 200 mg/kg) and diazepam (0.1–1 mg/kg) dose-dependently attenuated the U50 (40 mg/kg, i.p.)-induced analgesia. GTS (0.001–10 μg/ml) did not alter binding of [ 3H]naloxone to mice whole brain membrane. The attenuation effect of GTS (100 mg/kg) and diazepam (0.5 mg/kg) on U50-induced analgesia was blocked by flumazenil (0.1 mg/kg, i.p.), a benzodiazepine receptor antagonist, and picrotoxin (1 mg/kg, i.p.), a GABA A-gated chloride channel blocker. However, bicuculline (1 mg/kg, i.p.), a GABA A receptor antagonist blocked the attenuation effect of diazepam (0.5 mg/kg) but not GTS (100 mg/kg) on U50-induced analgesia. Chronic treatment (day 4–day 6) of GTS (50–200 mg/kg) and diazepam (0.1–1 mg/kg) dose-dependently inhibited the tolerance to U50-induced analgesia. Flumazenil (0.1 mg/kg) and picrotoxin (1 mg/kg) on chronic treatment blocked the inhibitory effect of GTS (100 mg/kg) and diazepam (0.5 mg/kg) on tolerance to U50-induced analgesia. On the other hand, chronic treatment of bicuculline (1 mg/kg) blocked the inhibitory effect of diazepam (0.5 mg/kg) but not GTS (100 mg/kg) on tolerance to U50-induced analgesia. In conclusion, the findings suggest that GTS attenuates U50-induced analgesia and inhibits tolerance to its analgesia and this action involves benzodiazepine receptors and GABA A-gated chloride channels.

Ginseng total saponin potentiates acute U-50,488H-induced analgesia and inhibits tolerance to U-50,488H-induced analgesia in mice

In the present study, an attempt has been made to investigate whether the potentiating effect of U-50,488H (U50)-induced analgesia by ginseng total saponin (GTS) is playing a role in inhibiting the tolerance to U50-induced analgesia as measured using the tail-flick test in mice. GTS (100 and 200 mg/kg ip), on acute administration, potentiated the U50 (40 mg/kg ip)-induced analgesia in U50-naive mice. Twice daily administration of U50 (40 mg/kg ip) for 6 days resulted in tolerance to U50-induced analgesia in mice. Chronic administration (Days 4–6) of GTS (50, 100, and 200 mg/kg ip) to U50-tolerant mice dose-dependently inhibited the tolerance to U50-induced analgesia. On the other hand, chronic administration of GTS (50, 100, and 200 mg/kg ip) dose-dependently potentiated the U50-induced analgesia in U50-naive mice. The dose–response curve to U50-induced analgesia in U50-tolerant mice was shifted rightward (2.6-fold) as compared to U50-naive mice, indicating the development of tolerance to U50-induced analgesia. GTS (100 mg/kg ip od), on chronic administration, prevented the rightward shift of dose–response curve to U50-induced analgesia in U50-tolerant mice, whereas in U50-naive mice it resulted in leftward shift (0.6-fold). It can be concluded that acute and chronic administration of GTS potentiates the U50-induced analgesia in U50-naive mice. The potentiating effect of GTS on U50-induced analgesia may be partially responsible in the inhibition of tolerance to U50-induced analgesia in mice.

Neuroprotective Effects of Ginseng Total Saponin and Ginsenosides Rb1 and Rg1 on Spinal Cord Neurons in Vitro

Spinal cord injury is a major cause of disability and results in many serious physical, psychological, and social difficulties. Numerous studies have shown that traumatic spinal cord injuries (SCI) lead to neuronal loss and axonal degeneration in and around the injury site that cause partial disability or complete paralysis. An important strategy in the treatment of SCI is to promote neuron survival and axon outgrowth, making possible the recovery of neural connections. Using an in vitro survival assay, we have identified ginsenosides Rb1 and Rg1, extracted from ginseng root (Panax ginseng C. A. Meyer), as efficient neuroprotective agents for spinal cord neurons. These compounds protect spinal neurons from excitotoxicity induced by glutamate and kainic acid, as well as oxidative stress induced by H2O2. The neuroprotective effects are dose-dependent. The optimal doses are 20–40 μM for ginsenosides Rb1 and Rg1. The effects are specific for Rb1 and Rg1, since a third ginsenoside, Re, did not exhibit any activity. Ginseng has been used for thousands of years in the treatment of neurological disorders and other diseases in Asia. Ginsenosides Rb1 and Rg1 represent potentially effective therapeutic agents for spinal cord injuries.

Ginseng and ginsenoside Rg 3, a newly identified active ingredient of ginseng, modulate Ca 2+ channel currents in rat sensory neurons

There is increasing evidence that ginseng influences pain modulation. In spite of extensive behavior studies, the detailed mechanism of ginseng actions at the cellular level and the identity of the active substance have not been elucidated yet. Whole-cell patch-clamp recordings were used to examine the modulation of high-voltage-activated Ca 2+ channel currents by ginseng total saponins and its various individual ginsenosides in rat dorsal root ganglion neurons. Application of ginseng total saponins suppressed Ca 2+ channel currents in a dose-dependent manner. Occlusion experiments using selective blockers revealed that ginseng total saponins could modulate L-, N-, and P-type currents. The co-application of ginseng total saponins and the μ-opioid receptor agonist, d-Ala 2, N-MePhe 4, Gly 5-ol-enkephalin (DAMGO), produced non-additive effects in most cells tested and each effect was significantly relieved by a depolarizing prepulse. Overnight treatment of cells with pertussis toxin profoundly reduced the inhibition. Furthermore, we now report that ginsenoside Rg 3, among the major fractions of ginseng saponins, is a newly identified active component for the inhibition. These results suggest that the modulation of Ca 2+ channels by ginseng total saponins, in particular by ginsenoside Rg 3, could be part of the pharmacological basis of ginseng-mediated antinociception.

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.

Effect of ginseng total saponin on extracellular dopamine release elicited by local infusion of nicotine into the striatum of freely moving rats.

We investigated the effect of ginseng total saponin (GTS) on nicotine-induced dopamine (DA) release in the striatum of freely moving rats using an in vivo microdialysis technique. In order to further characterize the mechanism by which GTS affects DA release, the effect of GTS on K(+)-induced DA release was also examined. Local infusion of nicotine (1, 5, and 10 mM) into the striatum produced a dose-dependent increase in extracellular DA in dialysate samples (maximal response = 154.0 +/- 10.8%, 308.1 +/- 55.7%, and 499.9 +/- 77.9% over basal levels, respectively). GTS (100 mg/kg i.p.) had no effect on basal levels of extracellular DA. However, GTS inhibited maximal DA release induced by intrastriatal infusion of nicotine (1, 5, and 10 mM) by 35.3%, 36.6%, and 58.5%, respectively. Intra-striatal infusion of high K+ solution (100 mM) produced an increase in extracellular DA in the striatum (maximal response = 796.6 +/- 98.8% over basal levels). However, GTS had no effect on the K(+)-induced increase in extracellular DA. The present study demonstrated that GTS inhibited striatal DA release stimulated by local infusion of nicotine. This may reflect the blocking effect of GTS on the striatum-related behavior induced by nicotine as well as other psychostimulants. The results also suggest that GTS may act on presynaptic nicotinic acetylcholine receptors or receptor-operated Na+ channels in dopaminergic nerve terminals, but not on voltage-sensitive ion channels.

Modulatory role of ginsenosides injected intrathecally or intracerebroventricularly in the production of antinociception induced by kappa-opioid receptor agonist administered intracerebroventricularly in the mouse.

We examined the effects of ginseng total saponin and several ginsenosides injected intrathecally (i.t.) or intracerebroventricularly (i.c.v.) on the antinociception induced by U50, 488H (trans-3,4-dichloro-N-methyl-N-[2- (1-pyrrolidinyl)cyclohexyl]benzeocetamide; a kappa opioid receptor agonist) administered i.c.v. The tail-flick test was used as an analgesic assay. Total saponin fraction at doses of 0.1 to 20 micrograms, which when administered intrathecally (i.t.) or intracerebroventricularly (i.c.v.) alone did not affect the latencies of tail-flick threshold, attenuated dose-dependently the inhibition of the tail-flick response induced by U50, 488H (60 micrograms) administered i.c.v. The duration of antagonistic action of total saponin fraction against U50, 488H-induced antinociception lasted at least for 6 h. Various doses (from 0.1 to 1 microgram) of ginsenosides Rb1, Rb2, Rc, Rd, and Rg1, but not Re, injected i.t. dose-dependently attenuated antinociception induced by U50, 488H administered i.c.v. Furthermore, various doses (from 1 to 10 micrograms) of ginsenosides Rb2 and Re, but not Rb1, Rc, Rd, and Rg1, injected i.c.v. dose-dependently attenuated antinociception induced by U50, 488H administered i.c.v. In summary, ginsenosides Rb1, Rb2, Rc, Rd, and Rg1 administered spinally appear to be responsible for blocking the antinociception induced by U50, 488H administered supraspinally, whereas ginsenosides Rb2 and Re administered supraspinally appear to be responsible for blocking the antinociception induced by U50, 488H administered supraspinally.

Modulatory effect of ginseng total saponin on dopamine release and tyrosine hydroxylase gene expression induced by nicotine in the rat

Several studies have demonstrated that behavioral activation induced by psychostimulants is prevented by ginseng total saponin (GTS), which has been known to act on the central dopaminergic system. In an attempt to investigate whether the effect of GTS is through its inhibitory action on the elevated dopaminergic transmission, we examined the effect of GTS on nicotine-induced dopamine (DA) release in the nucleus accumbens (NA) of freely moving rats using in vivo microdialysis. Systemic injection of nicotine (3 mg/kg; i.p.) produced a mild increase in extracellular DA of dialysates samples in the NA (132±13% over basal levels at the peak). GTS (100 mg/kg; i.p.) had no effect on resting levels of extracelluar DA. However, an increase in accumbens DA release produced by systemic nicotine was completely blocked by systemic pre-treatment with GTS (100 mg/kg; i.p.). In addition, the effect of GTS on nicotine-induced tyrosine hydroxylase (TH) and immediate early gene expression in ventral tegmental area (VTA) or NA regions was examined. A single injection of nicotine increased TH mRNA level at VTA region. GTS, which did not affect the basal TH mRNA expression, attenuated nicotine-induced TH mRNA expression. Nicotine slightly increased both c-fos and c-jun mRNA level and GTS, which did not affect the basal c-fos and c-jun mRNA expression, further enhanced nicotine-induced c-fos and c-jun mRNA level at both VTA and NA regions. Our results suggest that GTS may have an inhibitory action against nicotine-induced DA release in NA region and TH mRNA expression in VTA region. GTS may exert an potentiative effect on both c-fos and c-jun mRNA expression at NA region through inhibiting the release of DA in NA.

Effects of red ginseng saponins and nootropic drugs on impaired acquisition of ethanol-treated rats in passive avoidance performance

Effects of single and repeated administration of red ginseng total saponins (ROTS) and nootropic drugs were examined on impairment of acquisition induced by single oral administration of 3 g/kg ethanol (EtOH) in a step through test. The inhibitory effect of EtOH on acquisition was significantly reduced following single or repeated RGTS administration. The nootropic drugs, piracetam and N-methyl- d-glucamine, given orally significantly reduced impairment of acquisition induced by EtOH. On the other hand, the inhibitory effect of repeated RGTS on the EtOH-induced amnesia was blocked by the pretreatment of α-methyl-ρ-tyrosine (α-MT), an inhibitor of catecholamine synthesis, in a dose-dependent manner but not ρ-chlorophenylalanine (PCPA), an inhibitor of serotonin synthesis, whereas the inhibitory effect of repeated N-methyl- d-glucamine on the EtOH-induced amnesia was blocked neither by α-MT nor PCPA. These results suggest that repeated RGTS and N-methyl- d-glucamine ameliorate the impairing effect of EtOH on acquisition, and the effect of RGTS on EtOH-induced amnesia is dependent on the catecholaminergic but not serotonergic neuronal activity, while RGTS and N-methyl- d-glucamine seem to have a different mechanism on EtOH-induced amnesia.

Inhibitory effects of ginseng total saponin on nicotine-induced hyperactivity, reverse tolerance and dopamine receptor supersensitivity

A single administration of a low dose of nicotine produced hyperactivity in mice. A repeated administration of nicotine developed reverse tolerance to the ambulation-accelerating activity of nicotine and also developed postsynaptic dopamine (DA) receptor supersensitivity. The development of reverse tolerance was evidenced by an increased ambulatory response to nicotine, and the development of postsynaptic DA receptor supersensitivity was evidenced by the enhanced response in ambulatory activity to apomorphine, a DA receptor agonist. Administration of ginseng total saponin (GTS) prior to and during the nicotine treatment in mice inhibited not only nicotine-induced hyperactivity and reverse tolerance, but also postsynaptic DA receptor supersensitivity in nicotine-induced reverse tolerant mice. These results suggest that inhibition by GTS of nicotine-induced hyperactivity and reverse tolerance may be closely related with the inhibition of the dopaminergic activation induced by nicotine and that the development of nicotine-induced reverse tolerance may be associated with enhanced DA receptor sensitivity.

Panax ginseng blocks morphine-induced thymic apoptosis by lowering plasma corticosterone level

The effects of Panax ginseng on morphine-induced immune suppression were studied. Morphine (20 mg/kg, SC, 4 days) decreased body weight increment rate and caused atrophy of thymus and spleen. These changes were partly reversed by concomitant administration of ginseng total saponin (GTS, 100 mg/kg, oral, 9 days). Morphine elevated the serum corticosterone level and caused the DNA fragmentation of thymocytes. These sequential events were completely blocked by a concomitant administration of GTS. Flow cytometry analysis showed that GTS specifically blocked morphine-induced apoptosis of thymocytes.

Ginseng total saponin inhibits nicotine-induced hyperactivity and conditioned place preference in mice

A single or repeated administration of nicotine in mice produced hyperactivity and conditioned place preference (CPP). Postsynaptic dopamine (DA) receptor supersensitivity was also developed in nicotine-induced CPP mice. The hyperactivity induced by nicotine was evidenced by measuring the enhanced ambulatory activity using a tilting-type ambulometer. CPP effects were evaluated assessing the increased time spent by the mice to nicotine and the inhibition of CPP by the decreased time spent by the mice in the nonpreferred compartment. Postsynaptic DA receptor supersensitivity was evidenced by the enhanced response in ambulatory activity to the apomorphine, a DA receptor agonist. Administration of ginseng total saponin (GTS) prior to and during the nicotine treatment in mice inhibited not only nicotine-induced hyperactivity and CPP but also postsynaptic DA receptor supersensitivity in nicotine-induced CPP mice. These results suggest that inhibition by GTS of the nicotine-induced hyperactivity and CPP may be closely related with the inhibition of dopaminergic activation induced by nicotine and that the development of nicotine-induced CPP may be associated with the enhanced DA receptor supersensitivity. From these results, it is presumed that GTS may be useful for the prevention and therapy of these adverse actions of nicotine.

Acute and Chronic Effects of Ginseng Total Saponin and Amphetamine on Fixed-Interval Performance of Rats

The effect of ginseng total saponin (GTS) on amphetamine (AMPH)-induced disruption of fixed-interval (Fl) responding in rats was examined. GTS (50 mg/kg) significantly improved the temporal responding impaired by 2 mg/kg of AMPH. A higher dose of 100 mg/kg GTS disrupted performance when given alone; this disruption was reversed by a low dose of AMPH (0.5 mg/kg) and tolerance developed to the effects of GTS with its repeated administration. Neurochemical analysis revealed that GTS (50 mg/kg) attenuated the increase in striatal dopamine caused by AMPH leading to the conclusion that brain dopamine may partially mediate the behavioral effects of GTS.

Effect of ginseng total saponin on bovine adrenal tyrosine hydroxylase.

Ginseng total saponin (GTS) can modulate dopaminergic activity at both presynaptic and postsynaptic dopamine receptors (Kim et al., 1998). The present study investigated the effect of GTS on the bovine adrenal tyrosine hydroxylase (TH), which catalyze L/tyrosine to DOP. GTS inhibited the bovine adrenal TH by 42.4, 51.5 and 55.3% at concentrations of 40, 80 and 100 micrograms/ml, respectively. The IC50 value of GTS was 77.5 micrograms/ml. GTS exhibited noncompetitive inhibition with a substrate L-tyrosine. The Ki value was 155 micrograms/ml.

Inhibition of stress-induced plasma corticosterone levels by ginsenosides in mice: involvement of nitric oxide.

Ginseng total saponins (GTS) injected intracerebroventricularly (i.c.v.) at doses of 0.1-1 microg inhibited the i.c.v. injection stress-induced plasma corticosterone levels in mice. The inhibitory action of GTS was blocked by co-administered N(G)-nitro-L-arginine methyl ester (L-NAME; 1.5 microg, i.c.v.), an inhibitor of nitric oxide synthase (NOS). Of the ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, 20(S)-Rg3 and 20(R)-Rg3 injected i.c.v. at doses of 0.01-1 microg, 20(S)-Rg3 and Rc significantly inhibited the i.c.v. injection stress-induced plasma corticosterone levels. The inhibitory actions of 20(S)-Rg3 and Rc were blocked by co-administered L-NAME (1.5 microg, i.c.v.). These results suggest that GTS, 20(S)-Rg3 and Rc may inhibit the i.c.v. injection stress-induced hypothalamo-pituitary-adrenal response by inducing NO production in the brain.

Effects of ginsenosides on Ca 2 channels and membrane capacitance in rat adrenal chromaffin cells

We investigated the effects of ginseng total saponins (GTS) and five ginsenosides on voltage-dependent Ca 2+ channels and membrane capacitance using rat adrenal chromaffin cells. In this study, cells were voltage-clamped in a whole-cell recording mode and a perforated patch-clamp technique was used. The inward Ca 2+ currents (I Ca) was elicited by depolarization and the change in cell membrane capacitance (ΔC m) was monitored. The application of GTS (100 μg/ml) induced rapid and reversible inhibition of the Ca 2+ current by 38.8 ± 3.6% ( n = 16). To identify the particular single component that seems to be responsible for Ca 2+ current inhibition, the effects of five ginsenosides (ginsenoside Rb 1, Rc, Re, Rf, and Rg 1) on the Ca 2+ current were examined. The inhibitions to the Ca 2+ current by Rb 1, Rc, Re, Rf, and Rg 1 were 15.3 ± 2.2% ( n = 5); 36.9 ± 2.4% ( n = 7); 28.1 ± 1.9% ( n = 12); 19.0 ± 2.5% ( n = 10); and 16.3 ± 1.6% ( n = 15), respectively. The order of inhibitory potency (100 μM) was Rc > Re > Rf > Rg 1 > Rb 1. A software based phase detector technique was used to monitor membrane capacitance change (ΔC m). The application of GTS (100 μg/ml) induced inhibitory effects on ΔC m by 60.8 ± 9.7% ( n = 10). The inhibitions of membrane capacitance by Rb 1, Rc, Re, Rf, and Rg 1 were 35.3 ± 5.5% ( n = 7); 41.8 ± 7.0% ( n = 8); 40.5 ± 5.9% ( n = 9); 51.2 ± 7.6% ( n = 9); and 35.9 ± 5.1% ( n = 10), respectively. The inhibitory potencies of the ginsenosides on ΔC m were Rf > Rc > Re > Rg 1 > Rb 1. Therefore, we found that GTS and ginsenosides exerted inhibitory effects on both Ca 2+ currents and ΔC m in rat adrenal chromaffin cells. These results suggest that ginseng saponins regulate catecholamine secretion from adrenal chromaffin cells and this regulation could be the cellular basis of antistress effects induced by ginseng.

Effects of ginseng total saponin on morphine-induced hyperactivity and conditioned place preference in mice

A single or repeated administration of morphine in mice produced hyperactivity, conditioned place preference (CPP) and postsynaptic dopamine (DA) receptor supersensitivity. The hyperactivity induced by morphine was evidenced by measuring the enhanced ambulatory activity using a tilting-type ambulometer. CPP effects were evaluated assessing the increased time spent by the mice to morphine and the inhibition of CPP by the decreased time spent by the mice in the white compartment. Postsynaptic DA receptor supersensitivity in mice displaying a morphine-induced CPP was evidenced by the enhanced response in ambulatory activity to the DA agonist, apomorphine (2 mg/kg, s.c.). The intraperitoneal injection of ginseng total saponin (GTS) from the root of Panax ginseng C.A. Meyer ( Araliaceae), prior to and during the morphine treatment in mice inhibited morphine-induced hyperactivity and CPP. GTS inhibited the development of postsynaptic DA receptor supersensitivity. A single dose administration of GTS also inhibited apomorphine-induced climbing behavior, showing the antidopaminergic action of GTS at the postsynaptic DA receptor. These results suggest that the development of morphine-induced CPP may be associated with the enhanced DA receptor sensitivity and that GTS inhibition of the morphine-induced hyperactivity and CPP may be closely related with the inhibition of dopaminergic activation induced by morphine.