Yokukansan Alleviates Cancer Pain by Suppressing Matrix Metalloproteinase-9 in a Mouse Bone Metastasis Model

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.

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

Kampo medicine has been practiced as traditional medicine (TM) in Japan. Kampo medicine uses Kampo formulae that are composed of multiple crude drugs to make Kampo formulae. In Japan, Kampo formulae are commonly used instead of or combined with Western medicines. If drug therapy that follows the guidelines for neuropathic pain does not work or cannot be taken due to side effects, various Kampo formulae are considered as the next line of treatment. Since Kampo formulae are composed of two or more kinds of natural crude drugs, and their extracts contain many ingredients with pharmacological effects, one Kampo formula usually has multiple effects. Therefore, when selecting a formula, we consider symptoms other than pain. This review outlines the Kampo formulae that are frequently used for pain treatment and their crude drugs and the basic usage of each component. In recent years, Yokukansan (YKS) has become one of the most used Kampo formulae for pain treatment with an increasing body of baseline research available. We outline the known and possible mechanisms by which YKS exerts its pharmacologic benefits as an example of Kampo formulae's potency and holistic healing properties.

Analgesic Effect of Combined Therapy with the Japanese Herbal Medicine "Yokukansan" and Electroacupuncture in Rats with Acute Inflammatory Pain

Background: Japanese herbal medicine, called Kampo medicine, and acupuncture are mainly used in Japanese traditional medicine. In this experiment, the analgesic effect of Yokukansan (YKS) alone and a combination of YKS and electroacupuncture (EA) on inflammatory pain induced by formalin injection were examined. Methods: Animals were divided into four groups: a control group, formalin injection group (formalin), YKS-treated formalin group (YKS), and YKS- and EA-treated formalin group (YKS + EA). The duration of pain-related behaviors and extracellular signal-regulated protein kinase (ERK) activation in the spinal cord after formalin injection in the right hind paw were determined. Results: The duration of pain-related behaviors was dramatically prolonged in the late phase (10–60 min) in the formalin group. The YKS treatment tended to reduce (p = 0.08), whereas YKS + EA significantly suppressed the pain-related behaviors (p < 0.01). Immunohistochemical and Western blot analyses revealed that the number of phosphorylated ERK1/2 (pERK1/2)-positive cells and the pERK expression level, which were increased by formalin injection, were significantly inhibited by YKS (p < 0.05) and YKS + EA (p < 0.01). Conclusions: The YKS + EA combination therapy elicited an analgesic effect on formalin-induced acute inflammatory pain.