Kampo Formulae for the Treatment of Neuropathic Pain ∼ Especially the Mechanism of Action of Yokukansan ∼

Unraveling the pathogenesis of myelosuppression and therapeutic potential of natural products

BACKGROUND

Myelosuppression is a serious and common complication of radiotherapy and chemotherapy in cancer patients and is characterized by a reduction of peripheral blood cells. This condition not only compromises the efficacy of treatment but also increases the risk of patient death. Natural products are emerging as promising adjuvant therapies due to their antioxidant properties, ability to modulate immune responses, and capacity to stimulate haematopoietic stem cell proliferation. These therapies demonstrate significant potential in ameliorating myelosuppression.

METHODS

A systematic review of the literature was performed utilizing the search terms "natural products," "traditional Chinese medicine," and "myelosuppression" across prominent databases, including Google Scholar, PubMed, and Web of Science. All pertinent literature was meticulously analysed and summarized. The objective of this study was to perform a pertinent analysis to elucidate the mechanisms underlying myelosuppression and to categorize and synthesize information on natural products and traditional Chinese medicines employed for the therapeutic management of myelosuppression.

RESULTS

Myelosuppression resulting from drug and radiation exposure, viral infections, and exosomes is characterized by multiple underlying mechanisms involving immune factors, target genes, and the activation of diverse signalling pathways, including the (TGF-β)/Smad pathway. Recently, traditional Chinese medicine monomers and compounds, including more than twenty natural products, such as Astragalus and Angelica, have shown promising potential as therapeutics for ameliorating myelosuppression. These natural products exert their effects by modulating haematopoietic stem cells, immune factors, and critical signalling pathways.

CONCLUSIONS

Understanding the various mechanisms of myelosuppression facilitates the exploration of natural product therapies and biological target identification for evaluating herbal medicine efficacy. This study aimed to establish a foundation for the clinical application of natural products and provide methodologies and technical support for exploring additional treatments for myelosuppression.

Serotonin-Mediated Anti-Allodynic Effect of Yokukansan on Diabetes-Induced Neuropathic Pain

Background: Diabetic neuropathic pain is a known complication of diabetes mellitus (DM) and results from the complex interaction of various factors affecting the nervous system. Yokuansan (YKS) is a versatile traditional Japanese herbal medicine with a wide range of applications, especially in pain management and neurological manifestations. YKS has analgesic properties for nerve damage and is a potential treatment for DM-induced neuropathic pain, especially in patients with diabetic neuropathy. Thus, we examined the anti-allodynic effect of YKS on DM-induced neuropathic pain. Methods: All experiments were performed on 6-week-old male Sprague-Dawley rats. DM and diabetic neuropathy were induced in rats with streptozotocin. Mechanical allodynia was assessed using dynamic plantar esthesiometry. Additionally, we conducted an immunological assessment of microglia cell changes in the spinal cord and an experiment to clarify the involvement of serotonin. Results: Diabetes significantly reduced withdrawal thresholds in rats during the initial two weeks of the experiment, which stabilized thereafter. However, this effect was not investigated in the control group. We assessed, using the dynamic plantar test, the anti-allodynic effects of orally administered YKS (1 g/kg). Daily YKS administration significantly increased the withdrawal threshold in DM animals. Additionally, oral YKS reduced the expression of Ibal-1-positive microglia. To elucidate the mechanism of action of YKS, we explored the involvement of serotonin (5-hydroxytryptamine [5-HT]) receptors in mediating its effects. Intrathecal administration of 5-HT receptor antagonists (WAY-100635, ketanserin, and ondansetron) inhibited the protective effects of YKS. Conclusions: YKS exhibited an anti-allodynic effect, suggesting that YKS may activate 5-HT receptors in the spinal cord, thereby alleviating diabetic neuropathic pain.

Analgesic effects of oral Yokukansan on acute postoperative pain and involvement of the serotonin nervous system: a mouse model study

BACKGROUND

Yokukansan, a traditional Japanese medicine (Kampo), has been widely used to treat neurosis, dementia, and chronic pain. Previous in vitro studies have suggested that Yokukansan acts as a partial agonist of the 5-HT1A receptor, resulting in amelioration of chronic pain through inhibition of nociceptive neuronal activity. However, its effectiveness for treating postoperative pain remains unknown, although its analgesic mechanism of action has been suggested to involve serotonin and glutamatergic neurotransmission. This study aimed to investigate the effect of Yokukansan on postoperative pain in an animal model.

METHODS

A mouse model of postoperative pain was created by plantar incision, and Yokukansan was administered orally the day after paw incision. Pain thresholds for mechanical and heat stimuli were examined in a behavioral experiment. In addition, to clarify the involvement of the serotonergic nervous system, we examined the analgesic effects of Yokukansan in mice that were serotonin-depleted by para-chlorophenylalanine (PCPA) treatment and intrathecal administration of NAN-190, 5-HT1A receptor antagonist.

RESULTS

Orally administered Yokukansan increased the pain threshold dose-dependent in postoperative pain model mice. Pretreatment of para-chlorophenylalanine dramatically suppressed serotonin immunoreactivity in the spinal dorsal horn without changing the pain threshold after the paw incision. The analgesic effect of Yokukansan tended to be attenuated by para-chlorophenylalanine pretreatment and significantly attenuated by intrathecal administration of 2.5 µg of NAN-190 compared to that in postoperative pain model mice without para-chlorophenylalanine treatment and NAN-190 administration.

CONCLUSION

This study demonstrated that oral administration of Yokukansan has acute analgesic effects in postoperative pain model mice. Behavioral experiments using serotonin-depleted mice and mice intrathecally administered with a 5-HT1A receptor antagonist suggested that Yokukansan acts as an agonist at the 5-HT1A receptor, one of the serotonin receptors, to produce analgesia.

Advanced researches of traditional uses, phytochemistry, pharmacology, and toxicology of medical Uncariae Ramulus Cum Uncis

ETHNOPHARMACOLOGICAL RELEVANCE

Medical Uncariae Ramulus Cum Uncis consists of Uncaria rhynchophylla (Miq.) Miq. ex Havil, Uncaria macrophylla Wall, Uncaria sinensis (Oliv.) Havil, Uncaria hirsuta Havil, and Uncaria sessilifructus Roxb, which belongs to the species widely used in the genus Uncaria. These species resource widely distributed in China and abroad, and the hook-bearing stem is the primary constituent enrichment site. There are many different forms and architectures of chemicals, depending on the extraction site. Traditional remedies employing URCU had been used widely in antiquity and were first compiled in renowned ancient masterpiece 'Mingyi Bielu ()' written by Hongjing Tao. In modern pharmacological studies, both the total extracts and the phytoconstituents isolated from URCU have been shown to have neuroprotective, antioxidant, anti-inflammatory, anticancer, antibacterial, and autophagy-enhancer properties.

AIM OF THE STUDY

This review concentrates on the traditional uses, phytochemistry, pharmacology, toxicology, and nanomaterials studies of URCU, with a perspective to assist with further research and advance.

MATERIAL AND METHODS

The Chinese and English literature studies of this review are based on these database searches including Science Direct, CNKI, Wiley online library, Spring Link, Web of Science, PubMed, Medalink, Google scholar, Elsevier, ACS Publications, iPlant, Missouri Botanical Garden, Plant of the World Online. The pertinent data on URCU was gathered.

RESULTS

Based on the examination of the genus Uncaria, 107 newly marked chemical compositions have been identified from URCU from 2015 to present, including alkaloids, terpenoids, flavonoids, steroids, and others. Pharmacological studies have demonstrated that URCU has a variety of benefits in diseases such as neurodegenerative diseases, cancer, cardiovascular diseases, diabetes, and migraine, due to its neuroprotective, anti-inflammatory, antioxidant, anti-tumor, anti-bacterial and anti-viral properties. According to metabolic and toxicological studies, the dosage, frequency, and interactions of the drugs that occur in vivo are of great significance for determining whether the organic bodies can perform efficacy or produce toxicity. The research on URCU-mediated nanomaterials is expanding and increasing in order to address the inadequacies of conventional Chinese medicine. The alkaloids in URCU have the capability to self-assemble with other classes of components in addition to being biologically active.

CONCLUSION

URCU plants are widely distributed, abundant in chemical constituents, and widely used in both traditional and modern medicine for a variety of pharmacological effects. The utilization of herbal medicines can be raised by assessing the pharmacological distinctions among several species within the same genus and may accelerate the modernization of traditional Chinese medicine. Controlling the concentration of drug administration, monitoring metabolic markers, and inventing novel nanotechnologies are effective strategies for synergistic influence and detoxification to alleviate the main obstacles that toxicity, low bioavailability, and poor permeability. This review can assist further research and advances.

Analgesic Effect of the Kampo Formula Yokukansan via the Suppression of Substance P in an Experimental Rat Model of Hunner-Type Interstitial Cystitis

INTRODUCTION

Yokukansan (YKS), a Kampo formula used in traditional Japanese medicine, has an analgesic effect, and is used for various pain disorders. This study investigated its analgesic effects on Hunner-type interstitial cystitis (HIC) and its mechanism of action in animal models.   Methods: Rats with toll-like receptor-7 agonist (loxoribine)-induced HIC were used. Eight-week-old female Wistar rats were divided into three groups: control, HIC, and HIC-administered YKS (YKS + HIC). Bladder pain was assessed based on escape behavior using the von Frey test. Three days after HIC induction, the bladder and spinal cord were excised, and the expression of substance P (SP) was examined.   Results: The pain threshold decreased significantly in the HIC group compared to that in the control group, but this decrease was suppressed by further YKS administration. The expression of SP in the bladder wall and spinal cord increased significantly in the HIC group compared to that in the control group; however, this increase was suppressed by YKS administration.

CONCLUSION

SP is involved in the onset of bladder pain via neurokinin 1 receptors in bladder tissue. YKS may be useful for managing HIC-induced pain, and the suppression of SP secretion is one of its mechanisms of action.

Traditional uses, chemical compounds, pharmacological activities and clinical studies on the traditional Chinese prescription Yi-Gan San

ETHNOPHARMACOLOGICAL RELEVANCE

A widely used traditional prescription, Yi-Gan San (YGS) is a remedy for neurodegenerative disorders. The formulation consists of seven Chinese medicinal materials in specific proportions, namely Uncariae Ramulus cum Uncis (Uncaria rhynchophylla (Miq.) Miq. ex Havil.), Bupleuri Radix (Bupleurum chinense DC.), Angelicae Sinensis Radix (Angelica sinensis (Oliv.) Diels), Chuanxiong Rhizoma (Ligusticum wallichii Franch.), Poria (Poria cocos (Schw.) Wolf), Atractylodis Macrocephalae Rhizoma (Atractylodes macrocephala Koidz.) and Glycyrrhizae Radix et Rhizoma (Glycyrrhiza uralensis Fisch.). Using YGS has been shown to alleviate various behavioural and psychological symptoms of dementia (BPSD).

AIM OF THIS REVIEW

The goal of this review is to give up-to-date information about the traditional uses, chemistry, pharmacology and clinical efficacy of YGS based on the scientific literature and to learn the current focus and provide references in the next step.

MATERIALS AND METHODS

The database search room was accessed using the search terms "Yi-Gan San" and "Yokukansan" to obtain results from resources such as Web of Science, PubMed, Google Scholar and Sci Finder Scholar. We not only consulted the literature of fellow authors for this review but also explored classical medical books.

RESULTS

YGS has been used to cure neurosis, sleeplessness, night weeping and restlessness in infants. Its chemical components primarily consist of triterpenes, flavonoids, phenolics, lactones, alkaloids and other types of compounds. These active ingredients displayed diverse pharmacological activities to ameliorate BPSD by regulating serotonergic, glutamatergic, cholinergic, dopaminergic, adrenergic, and GABAergic neurotransmission. In addition, YGS showed neuroprotective, antistress, and anti-inflammatory effects. The majority of cases of neurodegenerative disorders are treated with YGS, including Alzheimer's disease and dementia with Lewy bodies.

CONCLUSIONS

Based on previous studies, YGS has been used as a traditional prescription in East Asia, such as Japan, Korea and China, and it has diverse chemical compounds and multiple pharmacological activities. Nevertheless, few experimental studies have focused on chemical and quantitative YGS studies, suggesting that further comprehensive research on its chemicals and quality assessments is critical for future evaluations of drug efficacy.

The Japanese Herbal Medicine Yokukansan Exerted Antioxidant and Analgesic Effects in an Experimental Rat Model of Hunner-Type Interstitial Cystitis

Background and Objectives: The Japanese herbal medicine Yokukansan (YKS) has analgesic properties and is used for various pain disorders. The purpose of the present study was to investigate the effects of YKS in Hunner-type interstitial cystitis (HIC) using an experimental rat model of HIC and to explore its antioxidant activity and role as the underlying mechanism of action. Materials and Methods: The antioxidant capacity of YKS was evaluated by determining its hydroxyl radical (·OH) scavenging capacity using electron spin resonance (ESR). Next, the effects of YKS administration were explored using a toll-like receptor-7 agonist-induced rat model of HIC. The von Frey test was performed to assess bladder pain. Three days after HIC induction, the bladder was removed, and the expression of oxidative stress parameters in the bladder wall was investigated (reactive oxygen metabolites (ROMs), ·OH, and 8-hydroxy-2′-deoxyguanosine (8-OhdG)). Results: YKS had a ·OH scavenging capacity according to the ESR study. In the von Frey test, a significant decrease in the withdrawal threshold was observed in the HIC group compared with the control group; however, the decrease was ameliorated by the administration of YKS. Oxidative stress parameters showed increasing tendencies (ROMs test and 8-OHdG) or a significant increase (·OH) in the HIC group compared with the control group; however, the increase was significantly suppressed by the administration of YKS. Conclusions: These findings suggest that YKS is effective against HIC and that its antioxidant activity is involved in the mechanism of action.

Yokukansan Inhibits the Development of Morphine Tolerance by Regulating Presynaptic Proteins in DRG Neurons

Opioids, such as morphine, are used in clinical settings for the management of acute and chronic pain. However, long-term use of morphine leads to antinociceptive tolerance and hypersensitivity. The cellular and molecular mechanisms of morphine tolerance seem to be quite complex, with suggestions including internalization of the μ-opioid receptor (MOR), neuroinflammation with activation of microglia and astrocytes, and changes in synaptic function in the central nervous system. Yokukansan (YKS), a traditional Kampo medicine consisting of seven herbs, has been used to treat emotional instability, neurosis, and insomnia. Interestingly, recent studies have begun to reveal the inhibitory effect of YKS on the development of morphine tolerance. In the present study, we determined the effect of YKS on morphine tolerance formation and its mechanisms in a rat model, focusing on the synapses between primary sensory neurons and spinal dorsal horn secondary neurons. We found that morphine tolerance formation was significantly inhibited by YKS (0.3 or 1.0 g/kg/day) preadministration for 7 days. Repeated administration of morphine (10 mg/kg/day) increased the expression of presynaptic proteins, including synaptotagmin I, in the spinal cord, which was suppressed by YKS. Furthermore, these changes in presynaptic protein expression were more pronounced at isolectin B4 (IB4)-positive excitatory synapses around the lamina II of the dorsal horn. These results suggest that YKS suppresses the development of morphine tolerance by inhibiting the enhancement of presynaptic function of dorsal root ganglia neurons projecting to spinal dorsal horn neurons caused by continuous morphine administration.