Psychotropic effects of ginseng saponins on agonistic behavior between resident and intruder mice

Oxytocin and CD38 in the paraventricular nucleus play a critical role in paternal aggression in mice

In mammals, the development of healthy offspring requires maternal care. Behavior by lactating mothers toward other individuals is an important component of maternal aggression. However, it is unclear whether fathers display aggression primed by pups (an external factor), and the protection mechanism is poorly understood. To address this question, we examined paternal aggression in the ICR mouse strain. We found that sires exposed to cues from pups and lactating dams showed stronger aggression toward intruders than did sires that were deprived of family cues or exposed to nonlactating mates. c-Fos immunohistochemistry showed that cells in both the paraventricular and supraoptic nuclei (PVN and SON, respectively) in the hypothalamus of sires exposed to any cues were highly activated. However, c-Fos activation in oxytocinergic neurons was increased only in sires exposed to pup cues and solely in the PVN. In Cd38-knockout sires, the presence of pups induced no or reduced parental aggression; however, this phenotype was recovered, that is, aggression increased to the wild-type level, after intraperitoneal administration of oxytocin (OT). Specific c-Fos activation patterns induced by pup cues were not found in the PVN of knockout sires. These results demonstrate that the PVN is one of the primary hypothalamic areas involved in paternal aggression and suggest that a CD38-dependent OT mechanism in oxytocinergic neurons is critical for part of the behavior associated with the protection of offspring by nurturing male mice.

Effects of Panax ginseng C.A. Meyer extract on the offspring of adult mice with maternal immune activation

To understand maternal immune activation (MIA) during prenatal development, the synthetic double-stranded RNA polyriboinosinic-polyribocytidylic acid [poly(I:C)] has been widely used in animal models to induce behavioral deficits similar to those in schizophrenia and other psychotic disorders. Panax ginseng C.A. Meyer (PG) extract is widely used to treat various kinds of nervous system disorders in Asia particularly China and Korea. The present study aimed to examine the effects of PG extract on MIA offspring using behavioral activity tests and protein expression analyses. Pregnant mice were exposed to poly(I:C) (5 mg/kg) or vehicle treatment on gestation day 9, and the resulting MIA offspring were subjected to vehicle or PG (300 mg/kg) treatment. In the acoustic startle response test, MIA-induced sensorimotor gating deficit was ameliorated by PG. The majority of behavioral parameters measured in the social interaction (non-aggressive or/and aggressive pattern), open field (number/duration of behavior) and forced swimming test (immobility behavior) were significantly altered in the MIA offspring. Western blot and immunohistochemical analyses of the medial prefrontal cortex indicated that the expression levels of certain neurodevelopmental proteins, including dihydropyrimidinase-related 2, LIM and SH3 domain 1, neurofilament medium, and discs large homolog 4, were decreased in the untreated MIA offspring, whereas PG treatment improved behavioral impairments and increased neurodevelopmental protein expression in MIA offspring. These results suggested that PG may be useful in neurodevelopmental disorder therapy, including psychiatric disorders such as schizophrenia, owing to its antipsychotic effects.

Effects of ginsenoside on pacemaker potentials of cultured interstitial cells of Cajal clusters from the small intestine of mice

Ginsenoside, one of the active ingredients of Panax ginseng, has a variety of physiological and pharmacological actions in various organs. However, little is known about the effects of ginsenosides on gastrointestinal (GI) motility. We studied the modulation of pacemaker potentials by ginsenoside in the interstitial cells of Cajal (ICCs) using the whole-cell patch clamp technique in the current clamp mode. Among ginsenosides, we investigated the effects of ginsenoside Rb1, Rg3 and Rf. While externally applied Rb1 and Rg3 had no effects on pacemaker potentials, Rf caused membrane depolarization. The application of flufenamic acid or niflumic acid abolished the generation of pacemaker potentials and inhibited the Rf-induced membrane depolarization. Membrane depolarization induced by Rf was not inhibited by intracellular application of guanosine 5'-[β-thio]diphosphate trilithium salt. Pretreatment with a Ca(2+)-free solution, thapsigargin, a Ca(2+)-ATPase inhibitor of the endoplasmic reticulum, U-73122, a phospholipase C inhibitor, or 2-APB, an IP3 receptor inhibitor, abolished the generation of pacemaker potentials and suppressed Rfinduced actions. However, treatment with chelerythrine and calphostin C, protein kinase C inhibitors, did not block Rf-induced effects on pacemaker potentials. These results suggest that ginsenoside Rf modulates the pacemaker activities of ICCs and thereby regulates intestinal motility.

Identification of antidepressant-like ingredients in ginseng root (Panax ginseng C.A. Meyer) using a menopausal depressive-like state in female mice: participation of 5-HT2A receptors

RATIONALE

After reports of adverse effects with hormone replacement therapy, such as reproductive and breast cancer and coronary heart disease, much attention has been given to the development of new remedies to alleviate menopausal depression in women, but methods for their preclinical evaluation have not been clarified. We previously developed a procedure to predict the drug effect on the menopausal depressive-like state in female mice.

OBJECTIVES

We attempted to identify psychoactive components from ginseng root, one of the earliest known materials for menopausal disorder, and to clarify the possible mechanism involved.

METHODS

As an index of a depressive-like state, we used the prolongation of immobility time induced by an ovariectomy during the forced swimming test. Chronic treatment with the candidate substance began the day after ovariectomy and continued for 14 days. To examine whether the 5-HT(2A) receptor antagonist ritanserin antagonized the antidepressant-like effect of ginsenoside Rb(1), ritanserin was given as pretreatment 15 min before the daily administration of ginsenoside Rb(1) and the antagonistic effect was compared with ginsenoside Rb(1) alone.

RESULTS

Ginsenoside Rb(1) and compound K were active ingredients that dose-dependently prevented the prolongation of immobility time induced by ovariectomy. Co-administration of ritanserin, a 5-HT(2A)-receptor antagonist, antagonized the effect of ginsenoside Rb(1).

CONCLUSIONS

We suggest that ginsenoside Rb(1) and its metabolite, compound K, are antidepressant-like components of the ginseng root, and that 5-HT(2A) receptors may play an important role in mediating the antidepressant-like effect of ginsenoside Rb(1).

Antidepressant-like effects of the active acidic polysaccharide portion of ginseng in mice

AIM OF THE STUDY

The biological of activity of Panax ginseng C.A. Meyer (ginseng) is complex but some of its known effects are related to affective and anxiety disorders, including the enhancement of neuroprotection, cellular resilience and plasticity. Whereas such effects suggest that ginseng might have antidepressant activity, previous studies show incongruent results. The sources of contrasting results might be many but one possibility is the utilization of different ginseng preparations in different studies. The current study was therefore designed to examine the effects of a very specific component of ginseng extract, the acidic polysaccharide portion of the plant (WGPA), containing arabinogalactan, type-I rhamnogalacturonan (RG-I)- and homogalacturonan (HG)-rich pectins.

MATERIALS AND METHODS

WGPA was extracted from ginseng roots and administered orally to mice at 100 mg/kg and 200 mg/kg doses. WGPA was administered chronically, once daily for 1 week before the start of experiments and throughout the behavioral tests battery. Mice were tested for spontaneous activity, social interactions, anxiety-like behavior in the elevated plus-maze (EPM) and despair-like behavior in the forced swim test (FST).

RESULTS

WGPA had no effects on spontaneous activity or behavior in the EPM. In contrast, 100 mg/kg (but not the 200 mg/kg) WGPA significantly reduced immobility time in the FST and both doses significantly increased social interactions and decreased aggressive behaviors in mice.

CONCLUSION

These results suggest that chronic WGPA treatment might have antidepressant-like effects that are unrelated to generalized behavioral changes. The results are discussed in the context of the known ability of the active ingredients of ginseng to increase neuroprotection, similar to many of the current antidepressant and mood stabilizing drugs.

Effects of ginseng total saponins on pacemaker currents of interstitial cells of Cajal from the small intestine of mice

Although ginsenosides have a variety of physiologic or pharmacologic functions in various regions, there are only a few reports on the effects of ginsenosides on gastrointestinal (GI) motility. We studied the modulation of pacemaker activities by ginseng total saponins in the interstitial cells of Cajal (ICC) using the whole cell patch-clamp technique. Externally applied ginseng total saponins (GTS) produced membrane depolarization in the current-clamp mode and increased tonic inward pacemaker currents in the voltage-clamp mode. The application of flufenamic acid or niflumic acid abolished the generation of pacemaker currents, but only treatment with flufenamic acid inhibited the GTS-induced tonic inward currents. The tonic inward currents induced by GTS were not inhibited by the intracellular application of guanosine 5'-[beta-thio]diphosphate trilithium salt. Pretreatment with a Ca(2+)-free solution, with U-73122, an active phospholipase C inhibitor, and with thapsigargin, a Ca(2')-ATPase inhibitor of the endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the GTS-induced action. However, treatment with chelerythrine and calphostin C, protein kinase C inhibitors, did not block the GTS-induced effects on the pacemaker currents. These results suggest that ginsenosides modulate the pacemaker activities of the ICC, and the ICC can be targets for ginsenosides, and their interaction can affect intestinal motility.

Anxiolytic effect of saponins from Panax quinquefolium in mice

The anxiolytic effect of the saponins from Aniliaeea Panax quinquefolium L. (PQS) was studied in male mice by using a number of experimental paradigms of anxiety and compared with that of the known anxiolytic compound diazepam. Use of the elevated plus-maze test revealed that PQS (50 mg/kg, p.o.) and diazepam (2.5 mg/kg, p.o.) increased the percentage of time and entries spent in open arms. In the light/dark test, PQS (50 and 100 mg/kg, p.o.) and diazepam (2.5 mg/kg, p.o.) prolonged the time spent in the light area. In the hole-board test, PQS (50 and 100 mg/kg, p.o.) and diazepam (2.5 mg/kg, p.o.) significantly increased both head-dip counts and head-dip duration. Both PQS (50 and 100 mg/kg, p.o.) and diazepam (2.5 mg/kg, p.o.) decreased the total fighting time in the isolation-induced aggressive test. Since PQS, in contrast to diazepam, had no effect on locomotion in these tests, its side-effect profile might be considered superior to the benzodiazepines. Thus, the present findings suggest that PQS might be a potential candidate for use as an anxiolytic drug.

Identification of anxiolytic ingredients in ginseng root using the elevated plus-maze test in mice

Ginseng root has been widely used for the management of anxiety and emotional instability, but there is little experimental evidence supporting these clinical applications. We pharmacologically identified the anxiolytic components in ginseng root, using the elevated plus-maze test. Male ICR albino mice and the following drugs were used: diazepam (0.5, 1 and 1.5 mg/kg, p.o.); red ginseng powder (300, 600 and 1200 mg/kg, p.o.); crude saponin and non-saponin ginseng fractions (50, 100 and 200 mg/kg, i.p., for each preparation); and pure ginsenoside Rb1, Rg1, and Ro (2.5, 5 and 10 mg/kg, i.p., for each preparation). Ginseng powder and crude saponin ginseng fraction significantly increased the frequency and duration of open arm entries. Among the three types of pure ginsenoside, only ginsenoside Rb1 significantly increased both the frequency and duration of open arm entries. Our results clearly indicate that ginsenoside Rb1 is one of the active anxiolytic components of ginseng root.

Correlation of aggression with serum IgM level in autoimmune-prone NZB mice

Neurological symptoms are often found in patients with systemic lupus erythematosus, an autoimmune disease. We found an enhanced aggression in young autoimmune-prone NZB mice before expression of autoimmune hemolytic anemia, which was accompanied by an increase in neural activity in the accessory olfactory bulb. The performance of aggressive behavior was correlated with serum IgM level. These results indicate that IgM class autoantibodies could be implicated in brain dysfunction without apparent pathological changes of autoimmune disease.

Ginseng enhances contextual fear conditioning and neurogenesis in rats

Panax Ginseng is a commonly used galenical known to have an enhancing effect on learning. Neurogenesis in the hippocampus has been shown to be necessary for hippocampus/amygdala-dependent learning tasks. To investigate the role of Ginseng in neurogenesis and learning of rats, we administered both Ginseng and BrdU for five consecutive days. As a result, Ginseng increased the number of BrdU-positive cells in the dentate gyrus in a dose-dependent manner. Further, we administered one dose of BrdU after Ginseng treatment for five consecutive days, and the number of BrdU-positive cells did not increase significantly. However, when one dose of BrdU was given 1 day before the following five consecutive days of Ginseng treatment, the number of BrdU-positive cells markedly increased in the hippocampus. Therefore, it is likely that Ginseng enhances not proliferation but survival of newly generated neurons in the hippocampus. Second, we administered both Ginseng and BrdU to rats for five consecutive days. One day after the last Ginseng and BrdU co-administration, contextual fear conditioning (CFC) was conducted. Ginseng in a dose-dependent manner increased the % freezing time and the number of BrdU-positive cells in the dentate gyrus of rats that received CFC. Thus, an increase in CFC-related neurogenesis may be one mechanism of Ginseng's properties to enhance learning ability.

Immunocytochemical analyses and targeted gene disruption of GTPBP1

We previously identified a gene encoding a putative GTPase, GTPBP1, which is structurally related to elongation factor 1alpha, a key component of protein biosynthesis machinery. The primary structure of GTPBP1 is highly conserved between human and mouse (97% identical at the amino acid level). Expression of this gene is enhanced by gamma interferon in a monocytic cell line, THP-1. Although counterparts of this molecule in Caenorhabditis elegans and Ascaris suum have also been identified, the function of this molecule remains to be clarified. In the present study, our immunohistochemical analyses on mouse tissues revealed that GTPBP1 is expressed in some neurons and smooth muscle cells of various organs as well as macrophages. Immunofluorescence analyses revealed that GTPBP1 is localized exclusively in cytoplasm and shows a diffuse granular network forming a gradient from the nucleus to the periphery of the cells in smooth muscle cell lines and macrophages. To investigate the physiological role of GTPBP1, we used targeted gene disruption in embryonic stem cells to generate GTPBP1-deficient mice. The mutant mice were born at the expected Mendelian frequency, developed normally, and were fertile. No manifest anatomical or behavioral abnormality was observed in the mutant mice. Functions of macrophages, including chemotaxis, phagocytosis, and nitric oxide production, in mutant mice were equivalent to those seen in wild-type mice. No significant difference was observed in the immune response to protein antigen between mutant mice and wild-type mice, suggesting normal function of antigen-presenting cells of the mutant mice. The absence of an eminent phenotype in GTPBP1-deficient mice may be due to functional compensation by GTPBP2, a molecule we recently identified which is similar to GTPBP1 in structure and tissue distribution.

Protection of ischemic hippocampal neurons by ginsenoside Rb1, a main ingredient of ginseng root

Our previous study showed that the oral administration of red ginseng powder before but not after transient forebrain ischemia prevented delayed neuronal death in gerbils, and that a neuroprotective molecule within red ginseng powder was ginsenoside Rb1. However, it remains to be clarified whether or not ginsenoside Rb1 acts directly on the ischemic brain, and the mechanism by which ginsenoside Rb1 protects the ischemic CA1 neurons is not determined. Without elucidation of the pharmacological property of ginsenoside Rb1, the drug would not be accepted as a neuroprotective agent. The present study demonstrated that the intracerebroventricular infusion of ginsenoside Rb1 after 3.5 min or 3 min forebrain ischemia, precluded significantly the ischemia-induced shortening of response latency in a step-down passive avoidance task and rescued a significant number of hippocampal CA1 neurons from lethal ischemic damage. The intracerebroventricular infusion of ginsenoside Rb1 did not affect hippocampal blood flow or hippocampal temperature except that it caused a slight increase in hippocampal blood flow at 5 min after transient forebrain ischemia. Furthermore, ginsenoside Rb1 at concentrations of 0.1-100 fg/ml (0.09-90 fM) rescued hippocampal neurons from lethal damage caused by the hydroxyl radical-promoting agent FeSO4 in vitro, and the Fenton reaction system containing p-nitrosodimethylaniline confirmed the hydroxyl radical-scavenging activity of ginsenoside Rb1. These findings suggest that the central infusion of ginsenoside Rb1 after forebrain ischemia protects hippocampal CA1 neurons against lethal ischemic damage possibly by scavenging free radicals which are overproduced in situ after brain ischemia and reperfusion. The present study may validate the empirical usage of ginseng root over thousands of years for the prevention of cerebrovascular diseases.

G1 phase-specific suppression of the Cdk2 activity by ginsenoside Rh2 in cultured murine cells

Ginsenoside Rh2, a plant glycoside with a dammarane skeleton resembling a steroid skeleton as an aglycone, has anticancer potentials in vitro or in vivo. To elucidate the molecular mechanisms of the effects of Rh2, we have examined the Cyclin-dependent kinase-2 (Cdk2) activity in G1 arrested B16 melanoma cells and in S phase-arrested Meth-A sarcoma cells, that have been treated with Rh2. The kinase activity was suppressed in B16 cells but not in Meth-A cells. In addition, Rh2 was found to induce G1 arrest and concomitantly suppress the Cdk2 activity in carcinogen-susceptible BALB/c 3T3 A31-1-1 and A31-1-13 cell lines. Thus, Rh2 has a G1 phase-specific suppressive effect on the Cdk2 activity, supporting further evaluation of Rh2 and its related compounds in cancer chemoprevention studies.

The effect of ginseng extract on locomotor sensitization and conditioned place preference induced by methamphetamine and cocaine in mice

Repeated i.p. injections of 2 mg/kg methamphetamine (MA) or 20 mg/kg cocaine at 48-h intervals induced reverse tolerance to their ambulation-enhancing effects (behavioral sensitization). Furthermore, the reappearance of the sensitized state was observed at the time of readministration of MA or cocaine even after a 30-day discontinuation of drug administration. A concomitant injection of ginseng extract (GE), 200 mg/kg, i.p., suppressed the development of reverse tolerance and the reappearance of sensitization to MA and cocaine. Conditioned place preference to MA (1, 2, and 4 mg/kg, i.p.) and cocaine (1, 4, 10, and 20 mg/kg, i.p.), was completely blocked by GE, 200 mg/kg, i.p. combined treatment with MA of cocaine. Meanwhile, spontaneous motor activity and place preference were not affected by GE alone. These results provide evidence that GE may be useful clinically for the prevention of adverse actions of MA and cocaine.

Effects of ginsenosides on impaired performance induced in the rat by scopolamine in a radial-arm maze

The effects of ginsenosides Rg1, Rd and Rb1 on impaired performance induced in the rat by scopolamine were examined in a radial-arm maze. Scopolamine caused a reduction in the number of initial correct responses in the maze. A single IP injection of Rg1, but not Rd or Rb1, prevented the reduction. The inhibition of the reduction in initial correct responses was associated with a bell-shaped dose-response curve for Rg1. A lesion in the medial septum caused spatial learning deficits. Rg1 did not overcome these deficits. It is suggested that cholinergic neurons in the medial septum are involved in the ameliorative effect of Rg1 on impaired performance induced by scopolamine.

Evaluation of the ergogenic properties of ginseng

Ginseng has been used for several thousand years in the Orient as a tonic, prophylactic agent and 'restorative'. However, its efficacy has been established primarily through clinical experience as opposed to scientific verification of its pharmacological effects. Ginseng has been used by athletes as an ergogenic aid for many years, but there is an absence of compelling research evidence in support of its use for this purpose. Indeed, most of the support favouring the use of ginseng to enhance physical performance is of a testimonial nature. While studies with animals show that ginseng or its active components may prolong survival to physical or chemical stress, there is, generally, a lack of controlled research demonstrating the ability of ginseng to improve or prolong performance in fatigued humans.

Differential effects of ginsenoside Rb1 and malonylginsenoside Rb1 on long-term potentiation in the dentate gyrus of rats

Ginseng saponins are known to have various pharmacological actions on the central nervous system. In the present study, we investigated the effects of ginsenoside Rb1 (GRb1) and malonylginsenoside Rb1 (GRb1-m) on the induction of long-term potentiation (LTP) in the dentate gyrus using anesthetized rats. Injection (i.c.v.) of GRb1 did not affect the basal synaptic responses evoked by low-frequency test stimulation, but significantly attenuated the magnitude of LTP induced by strong tetanus (100 pulses at 100 Hz). The inhibitory effect of GRb1 depended on its doses (0.5-50 nmol, i.c.v.). On the other hand, GRb1-m did not affect the LTP induced by the strong tetanus, but facilitated the generation of LTP by the weak tetanus (20 pulses at 60 Hz) that produced only short-lasting potentiation in normal condition. The LTP-facilitating effect of GRb1-m was seen maximally at a dose of 5 nmol (i.c.v.) and diminished at a higher dose (50 nmol, i.c.v.). Since another ginseng saponin ginsenoside Rg1 did not affect the induction of LTP at all, the inhibition and facilitation of LTP induction are probably specific actions of GRb1 and GRb1-m, respectively. This is the first report providing direct evidence that ginseng saponins affect the activity-dependent synaptic plasticity in the brain.

The effect of Panax ginseng on the development of tolerance to the pharmacological actions of morphine in the rat

1. The effect of intraperitoneal administration of Panax ginseng on the development of tolerance to the analgesic and hyperthermic actions of morphine was determined in male Sprague-Dawley rats. Rats were rendered tolerant to morphine to different degrees by the subcutaneous implantation of either four pellets of morphine over a 3-day period or six pellets over a 7-day period. Each pellet contained 75 mg of morphine free base. Rats serving as controls were implanted with placebo pellets. 2. Daily administration of ginseng extract (6.25-50.0 mg/kg) for 3 days inhibited the development of tolerance to the analgesic effect but not to the hyperthermic effect of morphine in the four pellet schedule. 3. In six pellet schedule, daily administration of ginseng extract (25 and 50 mg/kg) for 7 days also inhibited the development of tolerance to the analgesic effect of morphine, but the 100 mg/kg dose had no effect. On the other hand, in six pellet schedule, the administration of ginseng extract (50 and 100 mg/kg) once daily for 7 days inhibited the development of tolerance to the hyperthermic effect of morphine. 4. It is concluded that in appropriate doses, ginseng extract has inhibitory activity on the development of tolerance to the pharmacological actions of morphine.

Antagonism of the acute pharmacological actions of morphine by panax ginseng extract

1. The effects of intraperitoneal administration of a standard extract of Panax ginseng alone and in combination with morphine were determined in male Sprague-Dawley rats. 2. Ginseng extract at 200 mg/kg produced analgesia and hypothermia. These effects of ginseng were not reversed by naltrexone. 3. A dose of morphine (8 mg/kg) produced analgesia and hyperthermia. The analgesic response to morphine was antagonized by 25 and 50 mg/kg doses of ginseng but not by 12.5, 100 and 200 mg/kg doses. 4. Morphine-induced hyperthermia was antagonized by 12.5-200 mg/kg doses of ginseng. 5. Administration of morphine (50 mg/kg) produced cataleptic effect which was antagonized by 25 mg/kg of ginseng. 6. The results suggest that ginseng extract at high doses produces analgesia and hypothermia in the rat by a non-opiate mechanism, and antagonizes the acute pharmacological effects of morphine.

Acute and chronic effects of ginseng saponins on maternal aggression in mice

The present study investigated the acute and chronic effects of crude ginseng saponin (CGS), pure ginsenoside Rb1 (GS-Rb1) and ginsenoside Rg1 (GS-Rg1) on maternal aggression in mice. Maternal aggression was determined on postpartum days 5 and 7 in female mice that had been housed alone since the end of the 4-day mating period. Acute intraperitoneal administration of CGS (50 and 100 mg/kg) and GS-Rb1 (2.5 and 5 mg/kg) significantly suppressed maternal aggression in a dose-dependent manner, whereas GS-Rg1 was ineffective. As compared with the vehicle-treated group, chronic treatment with CGS (50 mg/kg) and GS-Rb1 (2.5 mg/kg) significantly suppressed maternal aggression without causing motor dysfunction, whereas GS-Rg1 (2.5 mg/kg) showed a tendency to facilitate maternal aggression. These findings indicate that the root of Panax ginseng contains a psychoactive ingredient, GS-Rb1, which can suppress maternal aggression.