Kamikihi-to, a Kampo medicine, ameliorates impairment of spatial memory in rats

Kamikihito reduces β-amyloid25-35-induced axon damage via neurotrophic factors

The Japanese herbal medicine kamikihito (KKT) is widely used for insomnia, anorexia, anemia, and depression. Recently, the efficacy of KKT against Alzheimer's disease (AD) has been demonstrated in clinical and non-clinical studies. To address the mechanism underlying the effect of KKT on AD, we examined the effects of KKT in β-amyloid (Aβ)25-35-exposed primary cultured neurons. The effects of KKT on Aβ25-35-induced neurotoxicity were assessed by immunocytochemical assays and Sholl analysis of neurites, and the influence of KKT on neurotrophic factor (NF) gene expression was examined using RT-PCR analysis. As a result, Aβ25-35 exposure attenuated the arborization of neurites of single cultured hippocampal neurons, and KKT treatment for 3 days ameliorated the Aβ25-35-induced impairment of tau-positive axon outgrowth. This ameliorative effect of KKT was largely abolished by the Trk inhibitor K252a, and expression of NFs, nerve growth factor (Ngf), brain-derived neurotrophic factor (Bdnf), neurotrophin-3 (NT-3) was significantly increased by KKT. These results indicate that KKT ameliorates axonal atrophy via NFs signaling, providing a mechanistic basis for treatment of AD with KKT.

Effects of Kami Guibi-tang in patients with mild cognitive impairment: study protocol for a phase III, randomized, double-blind, and placebo-controlled trial

BACKGROUND

Amnestic mild cognitive impairment (aMCI) is often considered a precursor to Alzheimer's disease (AD) and represents a key therapeutic target for early intervention of AD. However, no treatments have been approved for MCI at present. Our previous pilot study has shown that Kami Guibi-tang (KGT), a traditional herbal prescription widely used in Korean medicine for treating amnesia, might be beneficial for improving general cognitive function of aMCI patients. We will conduct a larger-scale clinical trial to validate the findings of our pilot study and further examine the efficacy and safety of KGT in aMCI.

METHODS

This trial is designed as a randomized, double-blind, placebo-controlled clinical trial. A total of 84 aMCI patients will be recruited and randomized into the treatment and control groups. Participants will be administered either KGT or placebo granules for 24 weeks, with a follow-up period of 12 weeks after the last treatment. Primary outcomes will include changes in cognitive performance assessed using a neuropsychological test battery, called the Seoul Neuropsychological Screening Battery, between the baseline, post-intervention visit, and follow-up visit (24th and 36th week, respectively). Secondary outcomes will involve the rate of progression to AD, changes in neuroimaging signals assessed using structural magnetic resonance imaging (MRI), resting-state functional MRI (rs-fMRI), and task-based fMRI, and changes in blood biomarkers measured by the ratio of plasma amyloid-β 42/40 levels (Aβ42/Aβ40) between the baseline and post-intervention visit (24th week). For safety assessments, blood chemistry tests and electrocardiograms (ECG) will also be performed.

DISCUSSION

This study aims to provide confirmatory evidence of the effect of the Korean herbal medicine, KGT, on improving cognitive function in patients with aMCI. We will identify the possible mechanisms underlying the effects of KGT using neuroimaging signals and blood biomarkers.

TRIAL REGISTRATION

Korean Clinical Trial Registry ( https://cris.nih.go.kr/cris/search/detailSearch.do/16918; Registration number: KCT0007039; Date of registration: February 24, 2022).

Expression of oxytocin in hypothalamus and reduction of nociceptive stress following administration of Kamikihi-to in female rats

Hypothalamo-neurohypophysial oxytocin (OXT) plays an essential role in reproduction and in several socio-physiological functions, including stress reduction, anxiety relief, feeding suppression, social recognition, and trust building. Recent studies suggest that the central OXT system is also involved in antinociceptive and anti-inflammatory functions. Kamikihi-to (KKT), a Japanese traditional herbal (Kampo) medicine composed of 14 herbal ingredients, is clinically prescribed for patients with psychological symptoms, including anxiety, depression, and insomnia, and it has been associated with OXT expression. We investigated the antinociceptive response and OXT expression according to sex and the effects of KKT pre administration in a rat model. We found that nociceptive responses measured via the hot plate and formalin tests were attenuated following the administration of KKT-enriched feed for 4 weeks. The observation of mRFP1 fluorescence in OXT-mRFP1 transgenic rats revealed that KKT-administered rats showed increased expression of OXT in the magnocellular and parvocellular paraventricular nucleus of the hypothalamus. Food intake in the KKT-pre-administered group significantly decreased after cholecystokinin (CCK)-8 administration. Our results suggest that KKT is involved in the attenuation of nociceptive stress in female rats by enhancing the expression of OXT in the hypothalamus.

Treatment evaluation of Kami Guibi-tang on participants with amnestic mild cognitive impairment using magnetic resonance imaging on brain metabolites, gamma-aminobutyric acid, and cerebral blood flow

Purpose

To evaluate the effectiveness of Kami Guibi‐tang (KGT) in the treatment of mild cognitive impairment (MCI) using magnetic resonance imaging (MRI) on brain metabolites, neurotransmitter, and cerebral blood flow (CBF).

Methods

We randomly allocated a total of 30 MCI patients to a KGT (N = 16) or a placebo (N = 14) group and performed MRI scans before and after 24 weeks of treatment. The participants underwent brain magnetic resonance spectroscopy and MRI scans to obtain brain metabolites using Point‐RESolved Spectroscopy (PRESS) single‐voxel spectroscopy, gamma‐aminobutyric acid (GABA) neurotransmitter using Mescher–Garwood PRESS, and CBF using pseudocontinuous arterial spin labeling sequences using a 3.0 Tesla MRI system. We analyzed metabolite and neurotransmitter levels and CBF using repeated‐measure analysis of variance to evaluate between‐subject group effect, within‐subject treatment condition effect, and interaction of group by condition (group x condition).

Results

The GABA+/creatine (Cr) ratio values were not significantly different between the before and after treatment conditions. The glutamate complex/Cr ratio difference before and after treatment was lower in the KGT group than in the placebo group, but was not statistically significant (p = 0.077). The result of region of interest–based CBF measurement showed that CBF values were significantly lower after treatment at Cluster 2 for the KGT group (p = 0.003) and the placebo group (p = 0.011), at hippocampus for the KGT group (p = 0.004) and the placebo group (p = 0.008), and at the fusiform gyrus for the KGT group (p = 0.002). Furthermore, the absolute CBF difference before and after treatment in the fusiform gyrus was significantly lower in the KGT group than in the placebo group (p = 0.024).

Conclusions

Although a KGT treatment of 24 weeks showed some significant impact on the level of CBF, the Korean version of the mini‐mental state examination score was not significantly different between before and after treatment conditions, indicating that there was no memory function improvement after treatment in amnestic MCI patients. Therefore, further studies should be performed with a relatively larger population and extending the duration of the KGT treatment.

Kamikihito Enhances Cognitive Functions and Reward-Related Behaviors of Aged C57BL/6J Mice in an Automated Behavioral Assay System

The cognitive and psychological domains of frailty in the elderly have drawn increasing attention given the aging of society. However, therapeutics to treat minor deficits in cognition and mental state in the elderly remain an unmet need. Kamikihito (KKT), a traditional Japanese Kampo medicine indicated for neuroses, anxiety, and insomnia, is effective for treating cognitive dysfunction and depressive-like behaviors in animal models, suggesting that it may have therapeutic potential for treating cognitive and/or mental frailty. In this study, we first validated the known anxiolytic effects of KKT in a conventional maze test. We then introduced an automated behavioral assay system, IntelliCage, to evaluate the therapeutic potential of KKT for age-related and diverse central functions by performing sequential behavioral tasks in young and aged mice to assess basal activities, cognitive functions, perseveration, and hedonic-related behaviors. Although young mice treated with KKT did not exhibit changes in diurnal variation, KKT-administered aged mice exhibited an accelerated decline in voluntary activity during the early part of the light period, implying that KKT may promote sleep onset in aged mice. Neither place learning acquisition for gaining rewards nor subsequent behavioral flexibility performance was altered by KKT in the young group, whereas the aged KKT group exhibited significantly enhanced performance in both phases of learning relative to age-matched controls. Conversely, perseverative nose-pokes (NPs) to gain rewards observed during place learning, indicative of compulsivity, were attenuated by KKT in both age groups. Regarding hedonic processing, aged mice exhibited a decreased preference for sweet solutions compared to young mice, which was effectively reversed by KKT treatment. Furthermore, KKT elevated high-effort choices for high-value reward in an effort-based decision-making paradigm in both age groups, implying augmentation of motivational behaviors by KKT. Collectively, KKT exerted various beneficial effects in cognitive and emotional domains, several of which were more evident in aged mice than in young mice, suggesting the potential of KKT for treating cognitive and mental frailty.

The effectiveness and safety of Kami Guibi-tang for mild cognitive impairment: study protocol of a pilot, randomized, placebo-controlled, double-blind trial

Background

Mild cognitive impairment (MCI) is an intermediate phase between normal aging and dementia. Since a majority of amnestic MCI (aMCI) cases progress to Alzheimer’s disease (AD), it is considered the prodromal stage of AD and, therefore, a treatment target for the prevention of further cognitive decline. However, there is no approved treatment for MCI at present. Kami Guibi-tang (KGT) is a herbal drug used in Korean medicine to treat amnesia, insomnia, loss of appetite, and depression. We will explore the effectiveness and safety of KGT in amnestic MCI in this trial.

Methods/design

The study will be a single-center, randomized, placebo-controlled, double-blind trial. Eligible participants diagnosed with amnestic MCI will be randomly allocated to a treatment or control group. Participants will take KGT or placebo granules, three times a day, for 24 weeks. The primary outcomes will be changes in Seoul Neuropsychological Screening Battery (SNSB) scores, and magnetic resonance imaging (MRI) measurements including those of brain metabolites, neurotransmitters, and cerebral blood flow. The secondary outcomes will include the safety assessment, measured by changes in blood chemistry, changes in blood protein and cholesterol levels related to AD pathology, and a comparison of MRI changes between the two groups, using age and genotype as covariates.

Discussion

This study will be the first clinical trial to identify the therapeutic potential of Kami Guibi-tang for amnestic MCI. The findings will provide insight into the feasibility of large-scale trials to gather evidence for KGT as a treatment for MCI.

Trial registration

Korean Clinical Trial Registry, ID: KCT0002407. Registered on 30 March 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3567-1) contains supplementary material, which is available to authorized users.

New Treatment for Alzheimer's Disease, Kamikihito, Reverses Amyloid-β-Induced Progression of Tau Phosphorylation and Axonal Atrophy

Aims. We previously reported that kamikihito (KKT), a traditional Japanese medicine, improved memory impairment and reversed the degeneration of axons in the 5XFAD mouse model of Alzheimer's disease (AD). However, the mechanism underlying the effects of KKT remained unknown. The aim of the present study was to investigate the mechanism by which KKT reverses the progression of axonal degeneration. Methods. Primary cultured cortical neurons were treated with amyloid beta (A β ) fragment comprising amino acid residues (25-35) (10  μ M) in an in vitro AD model. KKT (10  μ g/mL) was administered to the cells before or after A β treatment. The effects of KKT on A β -induced tau phosphorylation, axonal atrophy, and protein phosphatase 2A (PP2A) activity were investigated. We also performed an in vivo assay in which KKT (500 mg/kg/day) was administered to 5XFAD mice once a day for 15 days. Cerebral cortex homogenates were used to measure PP2A activity. Results. KKT improved A β -induced tau phosphorylation and axonal atrophy after they had already progressed. In addition, KKT increased PP2A activity in vitro and in vivo. Conclusions. KKT reversed the progression of A β -induced axonal degeneration. KKT reversed axonal degeneration at least in part through its role as an exogenous PP2A stimulator.