Preventive effect of rikkunshito on gastric motor function inhibited by L-dopa in rats

[Oral microbiota and liver]

The liver has many important biological functions for the body, as it is involved in the storage and distribution of nutrients (carbohydrates to glycogen, lipids to triglycerides), the digestion of fats, the synthesis of blood proteins, and the detoxification of alcohol and drugs. The liver can be affected by various diseases such as viral or drug-induced hepatitis, fibrosis and cirrhosis, in which damaged hepatocytes are progressively replaced by scar tissue.

Influence of food on the gastric motor effect of the Kampo medicine rikkunshito in rat

BACKGROUND

Rikkunshito, one of the Kampo medicines, is widely prescribed as a remedy for various upper gastrointestinal syndromes. The effect of rikkunshito is related to endogenous ghrelin and its active ingredient atractylodin enhances ghrelin receptor signaling. Kampo medicines are traditionally administered before or between meals; however, no definitive benefit of the timing of administration has been proven yet. To clarify the influence of food on the pharmacological action of rikkunshito, we investigated the gastric motor activity and pharmacokinetic profiles of atractylodin after the administration of rikkunshito in fasted and fed rats.

METHODS

Phase III-like contractions in the gastric antrum after an injection of ghrelin were measured using a strain gauge force transducer. Rikkunshito was administered to rats during fasting or after a nutrient test meal. Ghrelin was injected 30 minutes later and gastric motility was evaluated. Furthermore, after rikkunshito administration, the pharmacokinetic profiles of atractylodin in the plasma and brain of fasted and free-fed rats were assessed.

KEY RESULTS

Rikkunshito administration potentiated ghrelin-induced phase III-like contractions under fasting conditions. This effect was attenuated in animals fed a test meal. Atractylodin was detected pharmacokinetically in the plasma and brain after rikkunshito administration in rats, and free-fed rats exhibited a decreased maximum concentration of plasma atractylodin and a delayed time to reach the maximum concentration.

CONCLUSIONS & INFERENCES

We show that the pharmacological action of rikkunshito is influenced by food in rats. The efficacy of rikkunshito may be associated with decreased absorption of its active ingredient atractylodin when food is in the stomach.

Critical Evaluation of Animal Models of Gastrointestinal Disorders

Preclinical research remains an important tool for discovery and validation of novel therapeutics for gastrointestinal disorders. While in vitro assays can be used to verify receptor-ligand interactions and test for structural activity of new compounds, only whole-animal studies can demonstrate drug efficacy within the gastrointestinal system. Most major gastrointestinal disorders have been modeled in animals; however the translational relevance of each model is not equal. The purpose of this chapter is to provide a critical evaluation of common animal models that are being used to develop pharmaceuticals for gastrointestinal disorders. For brevity, the models are presented for upper gastrointestinal disorders involving the esophagus, stomach, and small intestine and lower gastrointestinal disorders that focus on the colon. Particular emphasis is used to explain the face and construct validity of each model, and the limitations of each model, including data interpretation, are highlighted. This chapter does not evaluate models that rely on surgical or other non-pharmacological interventions for treatment.

Open Label Trial of the Efficacy and Safety Profile of Rikkunshito used for the Treatment of Gastrointestinal Symptoms in Patients with Parkinson's Disease: A Pilot Study

BACKGROUND

Patients with Parkinson's disease (PD) usually experience distress related not only to motor dysfunction, but also to nonmotor symptoms, including gastrointestinal dysfunction.

OBJECTIVE

The purpose of this pilot study was to evaluate the efficacy and safety profile of a traditional Japanese medicine, rikkunshito (RKT), used for the treatment of gastrointestinal symptoms, associated with anorexia and dyspepsia, in patients with PD.

METHODS

Patients were randomly assigned to either Group A (4-week treatment period with 7.5 g/d RKT followed by a 4-week off-treatment period) or Group B (4-week off-treatment period followed by a 4-week treatment period with 7.5 g/d RKT). Appetite, quality of life for gastrointestinal symptoms, and depression were assessed using a visual analog scale, the Gastrointestinal Symptom Rating Scale and the Self-Rating Depression Scale, respectively. The gastric emptying examination and assay of plasma acylated ghrelin level were performed using the ¹³C-acetate breath test and commercially available assay kits, respectively.

RESULTS

RKT treatment produced a significant increase in the appetite score (1.84 [2.34]; P < 0.05), compared to a decrease in the score over the off-treatment period (-1.36 [2.94]). The mean score for abdominal pain, on the Gastrointestinal Symptom Rating Scale, and for self-reported depression, on the Self-Rating Depression Scale, also decreased significantly with RKT treatment (P < 0.05), compared with the off-treatment period scores. No effect of RKT on plasma acylated ghrelin level and rate of gastric emptying was identified.

CONCLUSIONS

RKT may improve anorexia in patients with PD. The positive effects of RKT on depression and anorexia may improve the overall quality of life of these patients. The benefits of RKT identified in our pilot study will need to be confirmed in a randomized, double-blind, controlled trial. UMIN Clinical Trial Registry identifier: UMIN000009626.

Patterns of Brain Activation and Meal Reduction Induced by Abdominal Surgery in Mice and Modulation by Rikkunshito

Abdominal surgery inhibits food intake and induces c-Fos expression in the hypothalamic and medullary nuclei in rats. Rikkunshito (RKT), a Kampo medicine improves anorexia. We assessed the alterations in meal microstructure and c-Fos expression in brain nuclei induced by abdominal surgery and the modulation by RKT in mice. RKT or vehicle was gavaged daily for 1 week. On day 8 mice had no access to food for 6–7 h and were treated twice with RKT or vehicle. Abdominal surgery (laparotomy-cecum palpation) was performed 1–2 h before the dark phase. The food intake and meal structures were monitored using an automated monitoring system for mice. Brain sections were processed for c-Fos immunoreactivity (ir) 2-h after abdominal surgery. Abdominal surgery significantly reduced bouts, meal frequency, size and duration, and time spent on meals, and increased inter-meal interval and satiety ratio resulting in 92–86% suppression of food intake at 2–24 h post-surgery compared with control group (no surgery). RKT significantly increased bouts, meal duration and the cumulative 12-h food intake by 11%. Abdominal surgery increased c-Fos in the prelimbic, cingulate and insular cortexes, and autonomic nuclei, such as the bed nucleus of the stria terminalis, central amygdala, hypothalamic supraoptic (SON), paraventricular and arcuate nuclei, Edinger-Westphal nucleus (E-W), lateral periaqueduct gray (PAG), lateral parabrachial nucleus, locus coeruleus, ventrolateral medulla and nucleus tractus solitarius (NTS). RKT induced a small increase in c-Fos-ir neurons in the SON and E-W of control mice, and in mice with surgery there was an increase in the lateral PAG and a decrease in the NTS. These findings indicate that abdominal surgery inhibits food intake by increasing both satiation (meal duration) and satiety (meal interval) and activates brain circuits involved in pain, feeding behavior and stress that may underlie the alterations of meal pattern and food intake inhibition. RKT improves food consumption post-surgically that may involve modulation of pain pathway.

Complementary and synergistic therapeutic effects of compounds found in Kampo medicine: analysis of daikenchuto

Herbal medicines have been used in Japan for more than 1500 years and traditional Japanese medicines (Kampo medicines) are now fully integrated into the modern healthcare system. In total, 148 Kampo formulae are officially approved as prescription drugs and covered by the national health insurance system in Japan. However, despite their long track record of clinical use, the multi-targeted, multi-component properties of Kampo medicines, which are fundamentally different from Western medicines, have made it difficult to create a suitable framework for conducting well-designed, large-scale clinical trials. In turn, this has led to misconceptions among western trained physicians concerning the paucity of scientific evidence for the beneficial effects of Kampo medicines. Fortunately, there has been a recent surge in scientifically robust data from basic and clinical studies for some of the Kampo medicines, e.g., daikenchuto (TU-100). Numerous basic and clinical studies on TU-100, including placebo-controlled double-blind studies for various gastrointestinal disorders, and absorption, distribution, metabolism and excretion (ADME) studies, have been conducted or are in the process of being conducted in both Japan and the USA. Clinical studies suggest that TU-100 is beneficial for postoperative complications, especially ileus and abdominal bloating. ADME and basic studies indicate that the effect of TU-100 is a composite of numerous actions mediated by multiple compounds supplied via multiple routes. In addition to known mechanisms of action via enteric/sensory nerve stimulation, novel mechanisms via the TRPA1 channel and two pore domain potassium channels have recently been elucidated. TU-100 compounds target these channels with and without absorption, both before and after metabolic activation by enteric flora, with different timings and possibly with synergism.

Endoscopic treatment of gastroparesis

Gastroparesis has traditionally been a largely medically managed disease with refractory symptoms typically falling under the umbrella of the surgical domain. Surgical options include, but are not limited to, gastrostomy, jejunostomy, pyloromyotomy, or pyloroplasty, and the Food and Drug Administration approved gastric electrical stimulation implantation. Endoscopic management of gastroparesis most commonly involves intrapyloric botulinum toxin injection; however, there exists a variety of endoscopic approaches on the horizon that have the potential to radically shift standard of care. Endoscopic management of gastroparesis seeks to treat delayed gastric emptying with a less invasive approach compared to the surgical approach. This review will serve to highlight such innovative and potentially transformative, endoscopic interventions available to gastroenterologists in the management of gastroparesis.

Rikkunshito, a ghrelin potentiator, ameliorates anorexia-cachexia syndrome

Anorexia–cachexia syndrome develops during the advanced stages of various chronic diseases in which patients exhibit a decreased food intake, weight loss, and muscle tissue wasting. For these patients, this syndrome is a critical problem leading to an increased rate of morbidity and mortality. The present pharmacological therapies for treating anorexia–cachexia have limited effectiveness. The Japanese herbal medicine rikkunshito is often prescribed for the treatment of anorexia and upper gastrointestinal (GI) disorders. Thus, rikkunshito is expected to be beneficial for the treatment of patients with anorexia–cachexia syndrome. In this review, we summarize the effects of rikkunshito and its mechanisms of action on anorexia–cachexia. Persistent loss of appetite leads to a progressive depletion of body energy stores, which is frequently associated with cachexia. Consequently, regulating appetite and energy homeostasis is critically important for treating cachexia. Ghrelin is mainly secreted from the stomach, and it plays an important role in initiating feeding, controlling GI motility, and regulating energy expenditure. Recent clinical and basic science studies have demonstrated that the critical mechanism of rikkunshito underlies endogenous ghrelin activity. Interestingly, several components of rikkunshito target multiple gastric and central sites, and regulate the secretion, receptor sensitization, and degradation of ghrelin. Rikkunshito is effective for the treatment of anorexia, body weight loss, muscle wasting, and anxiety-related behavior. Furthermore, treatment with rikkunshito was observed to prolong survival in an animal model of cachexia. The use of a potentiator of ghrelin signaling, such as rikkunshito, may represent a novel approach for the treatment of anorexia–cachexia syndrome.

New ghrelin agonist, HM01 alleviates constipation and L-dopa-delayed gastric emptying in 6-hydroxydopamine rat model of Parkinson's disease

BACKGROUND

Constipation and L-dopa-induced gastric dysmotility are common gastrointestinal (GI) symptoms in Parkinson's disease (PD). We investigated the novel ghrelin agonist, HM01 influence on GI motor dysfunctions in 6-hydroxydopamine (6-OHDA) rats.

METHODS

HM01 pharmacological profiles were determined in vitro and in vivo in rats. We assessed changes in fecal output and water content, and gastric emptying (GE) in 6-OHDA rats treated with orogastric (og) HM01 and L-dopa/carbidopa (LD/CD, 20/2 mg/kg). Fos immunoreactivity (ir) cells in specific brain and lumbosacral spinal cord were quantified.

KEY RESULTS

HM01 displayed a high binding affinity to ghrelin receptor (Ki: 1.42 ± 0.36 nM), 4.3 ± 1.0 h half-life and high brain/plasma ratio. 6-OHDA rats had reduced daily fecal output (22%) and water intake (23%) compared to controls. HM01 (3 and 10 mg/kg) similarly reversed the decreased 4-h fecal weight and water content in 6-OHDA rats. Basal GE was not modified in 6-OHDA rats, however, LD/CD (once or daily for 8 days) delayed GE in 6-OHDA and control rats that was prevented by HM01 (3 mg/kg acute or daily before LD/CD). HM01 increased Fos-ir cell number in the area postrema, arcuate nucleus, nucleus tractus solitarius, and lumbosacral intermediolateral column of 6-OHDA rats where 6-OHDA had a lowering effect compared to controls.

CONCLUSIONS & INFERENCES

6-OHDA rats display constipation- and adipsia-like features of PD and L-dopa-inhibited GE. The new orally active ghrelin agonist, HM01 crosses the blood-brain barrier and alleviates these alterations suggesting a potential benefit for PD with GI disorders.

Gastric dysregulation induced by microinjection of 6-OHDA in the substantia nigra pars compacta of rats is determined by alterations in the brain-gut axis

Idiopathic Parkinson's disease (PD) is a late-onset, chronic, and progressive motor dysfunction attributable to loss of nigrostriatal dopamine neurons. Patients with PD experience significant gastrointestinal (GI) issues, including gastroparesis. We aimed to evaluate whether 6-hydroxy-dopamine (6-OHDA)-induced degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) induces gastric dysmotility via dysfunctions of the brain-gut axis. 6-OHDA microinjection into the SNpc induced a >90% decrease in tyrosine hydroxylase-immunoreactivity (IR) on the injection site. The [13C]-octanoic acid breath test showed a delayed gastric emptying 4 wk after the 6-OHDA treatment. In control rats, microinjection of the indirect sympathomimetic, tyramine, in the dorsal vagal complex (DVC) decreased gastric tone and motility; this inhibition was prevented by the fourth ventricular application of either a combination of α1- and α2- or a combination of D1 and D2 receptor antagonists. Conversely, in 6-OHDA-treated rats, whereas DVC microinjection of tyramine had reduced effects on gastric tone or motility, DVC microinjection of thyrotropin-releasing hormone induced a similar increase in motility as in control rats. In 6-OHDA-treated rats, there was a decreased expression of choline acetyl transferase (ChAT)-IR and neuronal nitric oxide synthase (NOS)-IR in DVC neurons but an increase in dopamine-β-hydroxylase-IR in the A2 area. Within the myenteric plexus of the esophagus, stomach, and duodenum, there were no changes in the total number of neurons; however, the percentage of NOS-IR neurons increased, whereas that of ChAT-IR decreased. Our data suggest that the delayed gastric emptying in a 6-OHDA rat model of PD may be caused by neurochemical and neurophysiological alterations in the brain-gut axis.

Standardized herbal treatments on functional bowel disorders: moving from putative mechanisms of action to controlled clinical trials

Symptom relief in functional gastrointestinal disorders (FGID) is frequently sought with complementary and alternative medicine, and various herbal medicine compounds are popular in different parts of the world. Only a few products, however, are standardized and are backed by scientific evidence. This review mainly focuses on mechanistic and clinical data in support of the Japanese traditional compound Rikkunshi-to (RKT) and of STW-5. Their effects on gut sensori-motor function, neurohormonal network, and controlled clinical data in FGID are revised. RKT and STW-5 appear to possess some degree of gastroprokinetic, visceral analgesic properties, and seem to increase the gastric accommodation response. Controlled trials of RKT and STW-5 support at least a modest effect on symptoms of functional dyspepsia and irritable bowel syndrome, with low side effects profile. With the widespread use of herbals and the relative paucity of effective pharmacological options for FGID, rigorous studies to further elucidate pharmacological actions and clinical applications of herbal compounds are a priority.