Traditional Japanese Medicine Yokukansan Research Articles

Yokukansan, a Traditional Japanese Medicine, Enhances the L-DOPA-Induced Rotational Response in 6-Hydroxydopamine-Lesioned Rats: Possible Inhibition of COMT.

The aim of the present study was to investigate the effects of the traditional Japanese medicine yokukansan (YKS) on the function of dopamine (DA) in the rat nigrostriatal system. Unilateral 6-hydroxydopamine lesions were produced in the rat nigrostriatal system. Despite a marked loss in the striatal immunoreactivity of tyrosine hydroxylase on the lesion side, striatal serotonin (5-HT) immunoreactivity was not affected. Treatment using L-3,4-dihydroxyphenylalanine (L-DOPA) in conjunction with benserazide for 15 d induced abnormal involuntary movements (AIMs) such as locomotive (rotational response), axial, forelimb, and orolingual movements in the lesioned rats. The L-DOPA-induced locomotive and axial, but not forelimb and orolingual, AIMs were significantly increased and prolonged by the pre-administration of YKS. We next investigated the effects of YKS on the production of DA from L-DOPA in 5-HT synthetic RIN 14B cells. RIN 14B cells produced DA and its metabolite, 3-methoxytyramine (3-MT), following L-DOPA treatment. YKS significantly augmented DA production and inhibited its metabolism to 3-MT in a manner similar to the catechol-O-methyltransferase (COMT) inhibitor entacapone. YKS and some alkaloids (corynoxeine: CX, geissoschizine methyl ether: GM) in Uncaria hook, a constituent herb of YKS, also inhibited COMT activity, indicating that the augmenting effect of YKS on L-DOPA-induced DA production in 5-HT synthetic cells was due to the inhibition of COMT by CX and GM. Our results suggest that YKS facilitates the DA supplemental effect of L-DOPA, and that COMT inhibition by CX and GM contributes, at least in part, to the effects of YKS.

In vitro identification of human cytochrome P450 isoforms involved in the metabolism of Geissoschizine methyl ether, an active component of the traditional Japanese medicine Yokukansan

1. Yokukansan (YKS) is a traditional Japanese medicine also called kampo, which has been used to treat neurosis, insomnia, and night crying and peevishness in children. Geissoschizine methyl ether (GM), a major indole alkaloid found in Uncaria hook, has been identified as a major active component of YKS with psychotropic effects. Recently, GM was reported to have a partial agonistic effect on serotonin 5-HT1A receptors. However, there is little published information on GM metabolism in humans, although several studies reported the blood kinetics of GM in rats and humans. In this study, we investigated the GM metabolic pathways and metabolizing enzymes in humans.2. Using recombinant human cytochrome P450 (CYP) isoforms and polyclonal antibodies to CYP isoforms, we found that GM was metabolized into hydroxylated, dehydrogenated, hydroxylated+dehydrogenated, demethylated and water adduct forms by some CYP isoforms.3. The relative activity factors in human liver microsomes were calculated to determine the relative contributions of individual CYP isoforms to GM metabolism in human liver microsomes (HLMs). We identified CYP3A4 as the CYP isoform primarily responsible for GM metabolism in human liver microsomes.4. These findings provide an important basis for understanding the pharmacokinetics and pharmacodynamics of GM and YKS.

Yokukansan Increases 5-HT1A Receptors in the Prefrontal Cortex and Enhances 5-HT1A Receptor Agonist-Induced Behavioral Responses in Socially Isolated Mice.

The traditional Japanese medicine yokukansan has an anxiolytic effect, which occurs after repeated administration. In this study, to investigate the underlying mechanisms, we examined the effects of repeated yokukansan administration on serotonin 1A (5-HT1A) receptor density and affinity and its expression at both mRNA and protein levels in the prefrontal cortex (PFC) of socially isolated mice. Moreover, we examined the effects of yokukansan on a 5-HT1A receptor-mediated behavioral response. Male mice were subjected to social isolation stress for 6 weeks and simultaneously treated with yokukansan. Thereafter, the density and affinity of 5-HT1A receptors were analyzed by a receptor-binding assay. Levels of 5-HT1A receptor protein and mRNA were also measured. Furthermore, (±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT; a 5-HT1A receptor agonist) was injected intraperitoneally, and rearing behavior was examined. Social isolation stress alone did not affect 5-HT1A receptor density or affinity. However, yokukansan significantly increased receptor density and decreased affinity concomitant with unchanged protein and mRNA levels. Yokukansan also enhanced the 8-OH-DPAT-induced decrease in rearing behavior. These results suggest that yokukansan increases 5-HT1A receptors in the PFC of socially isolated mice and enhances their function, which might underlie its anxiolytic effects.

Protective effects of glycycoumarin and procyanidin B1, active components of traditional Japanese medicine yokukansan, on amyloid β oligomer-induced neuronal death

Ethnopharmacological relevanceYokukansan, a traditional Japanese (Kampo) medicine, is composed of seven medicinal herbs, and has been traditionally used to treat neurosis, insomnia, and night crying and irritability in children. Yokukansan and its constituent herbs, Glycyrrhiza and Uncaria Hook, have recently been shown to have protective effects against amyloid β (Aβ) oligomer-induced apoptosis by suppressing the activation of caspase-3 in primary cultured neurons. The aim of the present study was to identify the effective components of Glycyrrhiza and Uncaria Hook against Aβ oligomer-induced neurotoxicity. We also attempted to clarify the mechanisms by which yokukansan and these herbs, as well as their components, suppressed the activation of caspase-3 in Aβ oligomer-treated neurons. Materials and methodsRat primary cultured cortical neurons were treated with Aβ oligomer (3μM). The protective effects of 16 components derived from Glycyrrhiza or Uncaria Hook against Aβ oligomer-induced neurotoxicity were determined using the MTT reduction assay 48h after the treatment. The suppressive effects of the test substances, i.e., yokukansan, Glycyrrhiza, Uncaria Hook, and screened components, on the Aβ oligomer-induced activation of caspase-3(/7) were evaluated using the caspase-Glo assay 48h after the Aβ oligomer treatment. The suppressive effects of the test substances on the activation of caspase-8 and -9, both of which are located upstream of caspase-3, were also examined 24h after the Aβ oligomer treatment. ResultsTwo of the 16 components tested, glycycoumarin derived from Glycyrrhiza and procyanidin B1 derived from Uncaria Hook, significantly inhibited Aβ oligomer-induced neuronal death in a dose-dependent manner. Glycyrrhiza, Uncaria Hook, and yokukansan significantly suppressed the Aβ oligomer-induced activation of caspase-3 as well as caspase-8 and -9. Glycycoumarin also suppressed the activation of caspase-3, but not caspase-8 and -9. Procyanidin B1 suppressed the activation of caspase-3, -8, and -9. ConclusionsOur results demonstrated that glycycoumarin and procyanidin B1 had ameliorative effects on Aβ oligomer-induced neurotoxicity. The neuroprotective effects of glycycoumarin are thought to be due to the attenuated activation of caspase-3, but not caspase-8 or -9. Procyanidin B1, as well as yokukansan, Glycyrrhiza, and Uncaria Hook, may attenuate the activation of caspase-3 by inhibiting that of caspase-8 and -9.

Geissoschizine Methyl Ether, an Alkaloid from the Uncaria Hook, Improves Remyelination After Cuprizone-Induced Demyelination in Medial Prefrontal Cortex of Adult Mice

Accumulating evidence indicates that the medial prefrontal cortex (mPFC) is a site of myelin and oligodendrocyte abnormalities that contribute to psychotic symptoms of schizophrenia. The development of therapeutic approaches to enhance remyelination, a regenerative process in which new myelin sheaths are formed on demyelinated axons, may be an attractive remedial strategy. Geissoschizine methyl ether (GM) in the Uncaria hook, a galenical constituent of the traditional Japanese medicine yokukansan (Yi-gan san), is one of the active components responsible for the psychotropic effects of yokukansan, though little is known about the mechanisms underlying the effects of either that medicine or GM itself. In the present study, we employed a cuprizone (CPZ)-induced demyelination model and examined the cellular changes in response to GM administration during the remyelination phase in the mPFC of adult mice. Using the mitotic marker 5-bromo-2'-deoxyuridine (BrdU), we demonstrated that CPZ treatment significantly increased the number of BrdU-positive NG2 cells, as well as microglia and mature oligodendrocytes in the mPFC. Newly formed oligodendrocytes were increased by GM administration after CPZ exposure. In addition, GM attenuated a decrease in myelin basic protein immunoreactivity caused by CPZ administration. Taken together, our findings suggest that GM administration ameliorated the myelin deficit by mature oligodendrocyte formation and remyelination in the mPFC of CPZ-fed mice. The present findings provide experimental evidence supporting the role for GM and its possible use as a remedy for schizophrenia symptoms by promoting the differentiation of progenitor cells to and myelination by oligodendrocytes.

Glycyrrhiza and Uncaria Hook contribute to protective effect of traditional Japanese medicine yokukansan against amyloid β oligomer-induced neuronal death

Ethnopharmacological relevanceYokukansan, a traditional Japanese (Kampo) medicine, composed of seven medicinal herbs has been traditionally used to treat neurosis, insomnia, and night crying and irritability in children. Recently, this medicine has been reported to improve the behavioral and psychological symptoms of dementia (BPSD) that often become problematic in patients with Alzheimer's disease (AD). Aim of the studyAmyloid β (Aβ) oligomers, which are extremely toxic to neurons, are involved in neurodegeneration in AD. In animals, yokukansan has been proven to improve memory impairments and BPSD-like behavior in transgenic mice overexpressing amyloid precursor protein and mice intracerebroventricularly injected with Aβ oligomers. These results suggest that yokukansan is potentially able to reduce the neurotoxicity of Aβ oligomers. Therefore, the present study aimed to explore the improving effects brought by yokukansan that consists of seven herbs for Aβ oligomer-induced neurotoxicity in vitro and to identify the candidate herbs in yokukansan's action. Materials and methodsPrimary cultured rat cortical neurons were used. Neurotoxicity induced by Aβ oligomers (3µM) and improving effects of yokukansan (300–1000µg/mL) and its constituent herbs were evaluated in MTT assay, DNA fragmentation analysis, and electron microscopic analysis at 48h after treatment with Aβ oligomers and drugs. Moreover, changes in expression of genes related to endoplasmic reticulum (ER) stress and in caspase-3 activity that is the enzyme closely related to apoptosis were analyzed to investigate the underlying mechanisms. ResultsYokukansan ameliorated Aβ oligomer-induced neuronal damage in a dose-dependent manner in the MTT assay. This drug also suppressed DNA fragmentation caused by Aβ oligomers. Electron microscopic analysis suggested that yokukansan reduced karyopyknosis and the expansion of rough ER caused by Aβ oligomers. However, neither Aβ oligomers nor yokukansan affected the mRNA expression of any ER stress-related genes, including CHOP and GRP78. On the other hand, yokukansan dose-dependently suppressed Aβ oligomer-induced activation of caspase-3. Among the seven constituents of yokukansan, Glycyrrhiza and Uncaria Hook (60–200µg/mL) suppressed Aβ oligomer-induced neuronal damage, DNA fragmentation, karyopyknosis, and caspase-3 activation to almost the same extent as yokukansan. ConclusionsThe present results suggest that yokukansan possesses an ameliorative effect against Aβ oligomer-induced neuronal apoptosis through the suppression of caspase-3 activation. Glycyrrhiza and Uncaria Hook may, at least in part, contribute to the neuroprotective effect of yokukansan. These mechanisms may underlie the improving effects of yokukansan on memory impairment and BPSD-like behaviors induced by Aβ oligomers.

Simultaneous quantitative analyses of indole and oxindole alkaloids of Uncaria Hook in rat plasma and brain after oral administration of the traditional Japanese medicine Yokukansan using high‐performance liquid chromatography with tandem mass spectrometry

Uncaria Hook (UH) alkaloids are involved in the beneficial effects of Yokukansan. However, the pharmacokinetics of UH alkaloids after oral administration of Yokukansan has not yet been sufficiently investigated. Therefore, we developed and validated a sensitive and specific high-performance liquid chromatography with tandem mass spectrometry (LC/MS/MS) method for the simultaneous quantitation of seven UH alkaloids (corynoxeine, isocorynoxeine, rhynchophylline, isorhynchophylline, hirsutine, hirsuteine and geissoschizine methyl ether) in rat plasma and brain. After protein precipitation with acetonitrile, chromatographic separation was performed using an Ascentis Express RP-amide column, with gradient elution with 0.2% formic acid and acetonitrile at 0.3 mL/min. All analytes in the plasma and brain showed good linearity over a wide concentration range (r > 0.995). Intra-day and inter-day variations of each constituent were 8.6 and 8.0% or less in the plasma, and 14.9 and 15.0% or less in the brain, respectively. The validated LC/MS/MS method was applied in the pharmacokinetic studies of UH alkaloids after oral administration of Yokukansan to rats. In the plasma, rhynchophylline, hirsutine, hirsuteine and geissoschizine methyl ether were detected, but only geissoschizine methyl ether was detected in the brain. These results suggest that geissoschizine methyl ether is an important constituent of the pharmacological effects of Yokukansan.

The Blood–Brain Barrier Permeability of 18β-Glycyrrhetinic Acid, a Major Metabolite of Glycyrrhizin in Glycyrrhiza Root, a Constituent of the Traditional Japanese Medicine Yokukansan

18β-Glycyrrhetinic acid (GA) is a major metabolite of glycyrrhizin (GL), which is one of the components of glycyrrhiza root, a constituent herb of the traditional Japanese medicine yokukansan. It is well known that most GL is metabolized to GA in the intestine by bacteria. A previous in vitro study using cultured rat cortical astrocytes suggested that GA activates glutamate transport, which is a putative mechanism of the psychotropic effect of yokukansan. To activate the glutamate transport in the brain, GA must be absorbed into the blood after oral administration of yokukansan and then cross the blood-brain barrier (BBB) to reach the brain. However, there is no data on the BBB permeability of GA derived from yokukansan. In the present study, the BBB permeability of GA was investigated in both in vivo and in vitro studies. In the in vivo study, GA was detected in the plasma, brain, and cerebrospinal fluid of rats orally administered yokukansan. In the in vitro study using a BBB model composed of co-culture of endothelial cells, pericytes, and astrocytes, the permeability rate and apparent permeability coefficient of GA were found to be 13.3 ± 0.5 % and 16.5 ± 0.7 × 10(-6) cm/s. These in vivo and in vitro results suggest that GL in orally administered yokukansan is absorbed into the blood as GA, and then reaches the brain through the BBB. This evidence further supports the possibility that GA is an active component in the psychotropic effect of yokukansan.

Effects of yokukansan on behavioral and psychological symptoms of vascular dementia: An open-label trial

Previous clinical trials suggest that the traditional Japanese medicine yokukansan has beneficial effects on the behavioral and psychological symptoms of dementia (BPSD). The present study was conducted to elucidate the efficacy of yokukansan on BPSD in patients with vascular dementia. Thirteen Japanese patients (9 men and 4 women) who were diagnosed as having vascular dementia (VaD) according to the diagnostic criteria of NINDS-AIREN were subjected to the open-label clinical trial in which yokukansan (7.5g/day) has been given for 4 weeks. Their mean age was 71.2±6.5 years. The BPSD was evaluated using the Neuropsychiatric Inventory (NPI), cognitive function was evaluated by the Mini-Mental State Examination (MMSE), the activities of daily living was evaluated by Barthel index (BI) and Disability Assessment for Dementia (DAD), and the extrapyramidal signs were evaluated by United Parkinson's Disease Rating Scale (UPDRS). The mean NPI was 33.0±17.3 and 23.6±13.9 for the baseline and after treatment, respectively. It was significantly improved after treatment (p<0.05). In the NPI-subcategories, there was a significant improvement in agitation and disinhibition after the treatment. There was no significant change in MMSE, BI, DAD or UPDRS before and after the treatment. There was no adverse effect during the treatment period. The present results suggest that yokukansan is beneficial for the treatment of BPSD in VaD patients.

The Blood–Brain Barrier Permeability of Geissoschizine Methyl Ether in Uncaria Hook, a Galenical Constituent of the Traditional Japanese Medicine Yokukansan

Geissoschizine methyl ether (GM) in Uncaria hook, a galenical constituent of yokukansan is thought to be one of active components in the psychotropic effect of yokukansan, a traditional Japanese medicine (kampo medicine). However, there is no data on the blood-brain barrier (BBB) permeability of Uncaria hook-derived alkaloids containing GM. In this study, we investigated the BBB permeability of seven Uncaria hook alkaloids (GM, isocorynoxeine, isorhynchophylline, hirsuteine, hirsutine, rhynchophylline, and corynoxeine) using in vivo and in vitro methods. In the in vivo experiment, seven alkaloids in the plasma and brain of rats orally administered with yokukansan were measured by liquid chromatography-mass spectroscopy/mass spectrometric multiple reaction monitoring assay. In the in vitro experiment, the BBB permeability of seven alkaloids were examined using the BBB model composed of co-culture of endothelial cells, pericytes, and astrocytes. In the in vivo study, six components containing GM but not isocorynoxeine were detected in the plasma, and three (GM, hirsuteine, and corynoxeine) of components were detected in the brain. The in vitro BBB permeability data indicated that seven alkaloids were able to cross brain endothelial cells in culture conditions and that the BBB permeability of GM was higher than those of the other six alkaloids. These results suggest that target ingredient GM in yokukansan administered orally is absorbed into the blood and then reaches the brain through the BBB. This evidence further supports the possibility that GM is an active component in the psychotropic effect of yokukansan.

Ameliorative effect of traditional Japanese medicine yokukansan on age-related impairments of working memory and reversal learning in rats

Aging is thought to impair prefrontal cortical (PFC) structure-sensitive cognitive functions and flexibility, such as working memory and reversal learning. A traditional Japanese medicine, yokukansan (YKS), is frequently used to treat age-related neurodegenerative disorders such as Alzheimer's disease in Japan, but its pharmacological properties have not been elucidated. The present study was designed to examine whether YKS improves age-related cognitive deficits using aged rats. YKS was administered to 21-month-old rats for 3 months. The ability to learn initially a reward rule for a T-maze discrimination task (initial learning) was examined in young control (4-month-old), aged control (24-month-old) and YKS-treated aged (24-month-old) rats. Subsequently, working memory and reversal learning were examined in delayed alternation and reversal discrimination T-maze tasks, respectively. Locomotor activity was also measured in new environments. Although performance accuracy in the initial learning procedure did not differ among any experimental groups, accuracy in the delayed alternation task was significantly decreased in aged rats compared to young rats. Aged rats also showed significant decreases in accuracy in the reversal discrimination task. YKS treatment significantly ameliorated the age-related decreases in accuracy in the delayed alternation and reversal discrimination tasks. The ameliorative effects of YKS on impaired delayed alternation performance were reduced by intracranial infusions of a dopamine D1 receptor antagonist, SCH 23390, into the prelimbic cortical region of the PFC, and the YKS effects on impaired reversal learning were done by the infusions into the orbitofrontal cortex (OFC). Locomotor activity did not change in any experimental group. Thus, YKS ameliorated age-related impairments of working memory and reversal learning, which might be mediated by a dopaminergic mechanism in the PFC structure. These investigations provide information important for the treatment of brain dysfunctions in the elderly people.

Yokukansan Inhibits Social Isolation-Induced Aggression and Methamphetamine-Induced Hyperlocomotion in Rodents

Behavioral and psychological symptoms of dementia (BPSD) are commonly seen in patients with Alzheimer's disease (AD) and other forms of senile dementia. BPSD have a serious impact on the quality of life of dementia patients, as well as on that of their caregivers. However, effective drug therapy for BPSD has not been established. Recently, the traditional Japanese medicine Yokukansan (YKS, Yi-gan san in Chinese) has been reported to improve BPSD, such as aggression, agitation, irritability, and hallucinations, in a randomized, single-blind, placebo-controlled study. However, the psychopharmacologic effects of YKS remain unexplored. In the present study, we investigated the effects of YKS on social isolation-induced aggressive behavior and methamphetamine- or MK-801-induced hyperlocomotion in rodents. Social isolation markedly induced aggressive behavior in male Wistar rats. Quetiapine at a dose of 10 mg/kg (per os (p.o.)) significantly inhibited this social isolation-induced aggressive behavior. YKS (100, 300 mg/kg, p.o.) also significantly inhibited the aggressive behavior. Moreover, risperidone (0.1 mg/kg, p.o.) significantly inhibited methamphetamine- or MK-801-induced hyperlocomotion in mice. YKS (300 mg/kg, p.o.) inhibited methamphetamine-induced hyperlocomotion, while YKS at the same dose had no effect on MK-801-induced hyperlocomotion. These findings suggest that YKS may be useful for the treatment of aggression and agitation, and that the psychopharmacologic effects of YKS might be mediated, in part, by inhibiting the activity of the dopaminergic system.

Repeated administration of Yokukansan inhibits DOI-induced head-twitch response and decreases expression of 5-hydroxytryptamine (5-HT) 2A receptors in the prefrontal cortex

Behavioral and psychological symptoms of dementia (BPSD) are commonly seen in patients with Alzheimer's disease (AD) and other forms of senile dementia. BPSD have a serious impact on the quality of life of dementia patients, as well as their caregivers. However, an effective drug therapy for BPSD has not been established. Recently, the traditional Japanese medicine Yokukansan (YKS, Yi-gan san in Chinese) has been reported to improve BPSD in a randomized, single-blind, placebo-controlled study. Moreover, abnormalities of the serotonin (5-HT) system such as 5-HT 2A receptors have been reported to be associated with BPSD of AD patients. In the present study, we investigated the effect of YKS on head-twitch response induced by 2,5-dimethoxy-4-iodoamphetamine (DOI, 5 mg/kg, i.p.) in mice, a behavioral response that is mediated, in part, by 5-HT 2A receptors. Acute treatment with YKS (100 and 300 mg/kg, p.o.) had no effect on the DOI-induced head-twitch response, whilst 14 days repeated treatment with YKS (300 mg/kg, p.o.) significantly inhibited this response. Moreover, repeated treatment with YKS (300 mg/kg, p.o.) decreased expression of 5-HT 2A receptors in the prefrontal cortex, which is part of the circuitry mediating the head-twitch response. These findings suggest that the inhibition of DOI-induced head-twitch response by YKS may be mediated, in part, by altered expression of 5-HT 2A receptors in the prefrontal cortex, which suggests the involvement of the 5-HT system in psychopharmacological effects of YKS.