Rikkunshito and isoliquiritigenin counteract 5-HT-induced 2C receptor-mediated activation of pro-opiomelanocortin neurons in the hypothalamic arcuate nucleus

Antiemetic Effect of Rikkunshito, a Japanese Kampo Herbal Medicine, on Cisplatin-induced Nausea and Vomiting: A Nationwide Database Study in Japan

Objective The effect of Rikkunshito, a Japanese herbal Kampo medicine, on chemotherapy-induced nausea and vomiting (CINV) has been evaluated in several small prospective studies, with mixed results. We retrospectively evaluated the antiemetic effects of Rikkunshito in patients undergoing cisplatin-based chemotherapy using a large-scale database in Japan. Methods The Diagnosis Procedure Combination inpatient database from July 2010 to March 2019 was used to compare adult patients with malignant tumors who had received Rikkunshito on or before the day of cisplatin administration (Rikkunshito group) and those who had not (control group). Antiemetics on days 2 and 3 and days 4 and beyond following cisplatin administration were used as surrogate outcomes for CINV. Patient backgrounds were adjusted using the stabilized inverse probability of treatment weighting, and outcomes were compared using univariable regression models. Results We identified 669 and 123,378 patients in the Rikkunshito and control groups, respectively. There were significantly fewer patients using intravenous 5-HT3-receptor antagonists in the Rikkunshito group (odds ratio, 0.38; 95% confidence interval, 0.16-0.87; p=0.023) on days 2 and 3 of cisplatin-based chemotherapy. Conclusion The reduced use of antiemetics on day 2 and beyond of cisplatin administration suggested a beneficial effect of Rikkunshito in palliating the symptoms of CINV.

Mechanism of gastrointestinal injury in COVID-19 and potential use of ghrelin therapy

In Corona Virus Disease 2019 (COVID-19), the most obvious symptoms occur in the respiratory and digestive systems, posing a serious threat to the health of patients. Decreased appetite is the most common digestive system symptom and is an important predictor of mortality. A large number of patients have decreased appetite after infection and do not show obvious organic disease characteristics. Currently, no drugs can directly alleviate such symptom. In order to reduce the number of severe and critically ill patients and decrease the hospitalization rate, it is very important to understand the pathogenic mechanism of appetite loss caused by COVID-19 and manage such symptom. Ghrelin is a key gastric hormone that has anti-inflammatory, neuroprotective, and antidepressant effects. In this paper, we will review the progress in the understanding of the mechanism of appetite loss associated with COVID-19, and introduce a potential therapeutic drug, ghrelin.

Neuropeptide Y modifies a part of diencephalic catecholamine but not indolamine metabolism in chicks depending on feeding status

The role of the monoaminergic system in the feeding behavior of neonatal chicks has been reported, but the functional relationship between the metabolism of monoamines and appetite-related neuropeptides is still unclear. This study aimed to investigate the changes in catecholamine and indolamine metabolism in response to the central action of neuropeptide Y (NPY) in different feeding statuses and the underlying mechanisms. In Experiment 1, the diencephalic concentrations of amino acids and monoamines following the intracerebroventricular (ICV) injection of NPY (375 pmol/10 μl/chick), saline solution under ad libitum, and fasting conditions for 30 min were determined. Central NPY significantly decreased L-tyrosine concentration, the precursor of catecholamines under feeding condition, but not under fasting condition. Central NPY significantly increased dopamine metabolites, including 3,4-dihydroxyphenylacetic acid and homovanillic acid (HVA). The concentration of 3-methoxy-4-hydroxyphenylglycol was significantly reduced under feeding condition, but did not change under fasting condition by NPY. However, no effects of NPY on indolamine metabolism were found in either feeding status. Therefore, the mechanism of action of catecholamines with central NPY under feeding condition was elucidated in Experiment 2. Central NPY significantly attenuated diencephalic gene expression of catecholaminergic synthetic enzymes, such as tyrosine hydroxylase, L-aromatic amino acid decarboxylase, and GTP cyclohydrolase I after 30 min of feeding. In Experiment 3, co-injection of α-methyl-L-tyrosine, an inhibitor of tyrosine hydroxylase with NPY, moderately attenuated the orexigenic effect of NPY, accompanied by a significant positive correlation between food intake and HVA levels. In Experiment 4, there was a significant interaction between NPY and clorgyline, an inhibitor of monoamine oxidase A with ICV co-injection which implies that co-existence of NPY and clorgyline enhances the orexigenic effect of NPY. In conclusion, central NPY modifies a part of catecholamine metabolism, which is illustrated by the involvement of dopamine transmission and metabolism under feeding but not fasting conditions.

Medicine and food with particular reference to chinpi, dried citrus peel, and a component of Ninjin'yoeito

Kampo medicines contain many kinds of herbal drugs. Chinpi and Kippi, dried citrus peels, are components of a substantial number of Kampo medicine. They contain abundant flavonoids and studies on hesperidin, narirutin, and nobiletin as active ingredient have been conducted. Conversely, in Kagoshima prefecture, located in the southwestern part of the Japanese Islands, various citrus products are cultivated. Among them, Tankan and Daimasaki are specialies. In this study, we conducted high- performance liquid chromatography to determine the difference in flavonoid contents among Tankan, Daimasaki, Tankan related product, Chinpi, and Kippi. As a result, several active components, such as hesperidin, narirutin, nobiletin, and tangeretin, in common with crude drug, Chinpi, were detected in local citrus fruits. In addition, some active components little or not found in Chinpi, for example hesperetin and rutin, were detected in the local products. A detailed analysis of active components considering their genetic origin, the time of fruit collection, and different parts of the fruit used (peel, albedo, edible parts, and the whole) will need to be discussed to get the most out of the citrus fruits or make best use of them for health and longevity.

Rikkunshito as a Therapeautic Agent for Functional Dyspepsia and its Prokinetic and Non-Prokinetic Effects

Prokinetics is one of the therapeutic agents for functional and motility disorders of the stomach. However, its efficacy is limited. Kampo medicine is a unique medical system that was developed in Japan. In Kampo medicine, herbal medicine is prescribed based on the patient’s condition. Therefore, even for functional and motility disorders of the stomach, some herbal medicines are considered as a therapeutic option. Recently, there has been an increase in evidence for the efficacy or the mechanism of herbal medicine for functional and motility disorders of the stomach. Among these, rikkunshito is a well-studied herbal medicine that could be used as an alternative to prokinetics. In this review, we discuss the possibilities of rikkunshito for functional dyspepsia with its prokinetic and non-prokinetic effects and provide an overview of their current use with a focus on their therapeutic mechanism.

The Role of Ghrelin in Anorexia Nervosa

Ghrelin, a 28-amino acid peptide hormone expressed in X/A-like endocrine cells of the stomach, is the only known peripherally produced and centrally acting peptide that stimulates food intake and therefore attracted a lot of attention with one major focus on the treatment of conditions where an increased energy intake or body weight gain is desired. Anorexia nervosa is an eating disorder characterized by a pronounced reduction of body weight, a disturbed body image and hormonal alterations. Ghrelin signaling has been thoroughly investigated under conditions of anorexia nervosa. The present review will highlight these alterations of ghrelin in anorexia and discuss possible treatment strategies targeting ghrelin signaling. Lastly, gaps in knowledge will be mentioned to foster future research.

The Leptin, Dopamine and Serotonin Receptors in Hypothalamic POMC-Neurons of Normal and Obese Rodents

The pro-opiomelanocortin (POMC)-expressing neurons of the hypothalamic arcuate nucleus (ARC) are involved in the control of food intake and metabolic processes. It is assumed that, in addition to leptin, the activity of these neurons is regulated by serotonin and dopamine, but only subtype 2C serotonin receptors (5-HT_2CR) was identified earlier on the POMC-neurons. The aim of this work was a comparative study of the localization and number of leptin receptors (LepR), types 1 and 2 dopamine receptors (D₁R, D₂R), 5-HT_1BR and 5-HT_2CR on the POMC-neurons and the expression of the genes encoding them in the ARC of the normal and diet-induced obese (DIO) rodents and the agouti mice (A ^y /a) with the melanocortin obesity. As shown by immunohistochemistry (IHC), all the studied receptors were located on the POMC-immunopositive neurons, and their IHC-content was in agreement with the expression of their genes. In DIO rats the number of D₁R and D₂R in the POMC-neurons and their expression in the ARC were reduced. In DIO mice the number of D₁R and D₂R did not change, while the number of LepR and 5-HT_2CR was increased, although to a small extent. In the POMC-neurons of agouti mice the number of LepR, D₂R, 5-HT_1BR and 5-HT_2CR was increased, and the D₁R number was reduced. Thus, our data demonstrates for the first time the localization of different types of the serotonin and dopamine receptors on the POMC-neurons and a specific pattern of the changes of their number and expression in the DIO and melanocortin obesity.

Total gastrectomy-induced reductions in food intake and weight are counteracted by rikkunshito by attenuating glucagon-like peptide-1 elevation in rats

BACKGROUND

Decrease in appetite and weight after total gastrectomy in patients with gastric cancer leads to a decrease in quality of life, increased mortality, and may necessitate discontinuation of adjuvant chemotherapy. The aim of this study is to determine whether rikkunshito, a Japanese herbal medicine, increases food intake and weight after gastrectomy in rats.

METHODS

Male rats underwent gastrectomy followed by roux-en-Y reconstruction or sham operation and were then treated with rikkunshito for 14 days starting on postoperative day 3. Daily food intake, weight, plasma glucagon-like peptide-1 (GLP-1), and ghrelin levels were measured. A pilot study to measure pre- and postoperative plasma GLP-1 levels was conducted in patients who underwent total gastrectomy for gastric cancer.

RESULTS

Administration of rikkunshito after gastrectomy in rats significantly increased food intake and weight, which continued for at least 2 weeks after treatment. Both fasting and postprandial plasma GLP-1 levels were increased markedly after gastrectomy compared with sham-operated animals. Increased GLP-1 levels in rats after gastrectomy were suppressed markedly by rikkunshito. rikkunshito had no significant effect on plasma ghrelin levels after gastrectomy. Treatment with a GLP-1 receptor antagonist significantly improved food intake and weight after gastrectomy. Plasma fasting GLP-1 levels in patients with gastric cancer were increased greatly after gastrectomy on postoperative day 1.

CONCLUSION

Administration of rikkunshito suppresses plasma GLP-1 levels after total gastrectomy, which is associated with recovery from reduced food intake and weight in rats.

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.

Isoliquiritigenin is a potent inhibitor of NLRP3 inflammasome activation and diet-induced adipose tissue inflammation

Inflammasome activation initiates the development of many inflammatory diseases, including obesity and type 2 diabetes. Therefore, agents that target discrete activation steps could represent very important drugs. We reported previously that ILG, a chalcone from Glycyrrhiza uralensis, inhibits LPS-induced NF-κB activation. Here, we show that ILG potently inhibits the activation of NLRP3 inflammasome, and the effect is independent of its inhibitory potency on TLR4. The inhibitory effect of ILG was stronger than that of parthenolide, a known inhibitor of the NLRP3 inflammasome. GL, a triterpenoid from G. uralensis, had similar inhibitory effects on NLRP3 activity, but high concentrations of GL were required. In contrast, activation of the AIM2 inflammasome was inhibited by GL but not by ILG. Moreover, GL inhibited NLRP3- and AIM2-activated ASC oligomerization, whereas ILG inhibited NLRP3-activated ASC oligomerization. Low concentrations of ILG were highly effective in IAPP-induced IL-1β production compared with the sulfonylurea drug glyburide. In vivo analyses revealed that ILG potently attenuated HFD-induced obesity, hypercholesterolemia, and insulin resistance. Furthermore, ILG treatment improved HFD-induced macrovesicular steatosis in the liver. Finally, ILG markedly inhibited diet-induced adipose tissue inflammation and IL-1β and caspase-1 production in white adipose tissue in ex vivo culture. These results suggest that ILG is a potential drug target for treatment of NLRP3 inflammasome-associated inflammatory diseases.