Differential Metabolic Responses to Adipose Atrophy Associated with Cancer Cachexia and Caloric Restriction in Rats and the Effect of Rikkunshito in Cancer Cachexia.

Despite the similar phenotypes, including weight loss, reduction of food intake, and lower adiposity, associated with caloric restriction (CR) and cancer cachexia (CC), CC is a progressive wasting syndrome, while mild CR improves whole body metabolism. In the present study, we compared adipose metabolic changes in a novel rat model of CC, mild CR (70% of the food intake of control rats, which is similar to the food consumption of CC rats), and severe CR (30% of the food intake of controls). We show that CC and severe CR are associated with much smaller adipocytes with significantly lower mitochondrial DNA content; but, that mild CR is not. CC and both mild and severe CR similarly upregulated proteins involved in lipolysis. CC also downregulated proteins involved in fatty acid biosynthesis, but mild CR upregulated these. These findings suggest that CC might impair de novo fatty acid biosynthesis and reduce mitochondrial biogenesis, similar to severe CR. We also found that rikkunshito, a traditional Japanese herbal medicine, does not ameliorate the enhanced lipolysis and mitochondrial impairment, but rather, rescues de novo fatty acid biosynthesis, suggesting that rikkunshito administration might have partially similar effects to mild CR.

Development of ghrelin resistance in a cancer cachexia rat model using human gastric cancer-derived 85As2 cells and the palliative effects of the Kampo medicine rikkunshito on the model.

Cancer cachexia (CC) is a multifactorial disease characterized by decreased food intake and loss of body weight due to reduced musculature with or without loss of fat mass. Patients with gastric cancer have a high incidence of cachexia. We previously established a novel CC rat model induced by human gastric cancer-derived 85As2 cells in order to examine the pathophysiology of CC and identify potential therapeutics. In patients with CC, anorexia is often observed, despite elevation of ghrelin, suggesting that ghrelin resistance may develop in these patients. In this study, we aimed to clarify the occurrence of ghrelin resistance in CC rats accompanied by anorexia and we investigated whether rikkunshito (RKT), a traditional Japanese Kampo medicine that potentiates ghrelin signaling, ameliorated CC-related anorexia through alleviation of ghrelin resistance. 85As2-tumor-bearing rats developed severe CC symptoms, including anorexia and loss of body weight/musculature, with the latter symptoms being greater in cachectic rats than in non-tumor-bearing or pair-fed rats. CC rats showed poor responses to intraperitoneal injection of ghrelin. In CC rats, plasma ghrelin levels were elevated and hypothalamic anorexigenic peptide mRNA levels were decreased, whereas hypothalamic growth hormone secretagogue receptor (GHS-R) mRNA was not affected. In vitro, RKT directly enhanced ghrelin-induced GHS-R activation. RKT administrated orally for 7 days partly alleviated the poor response to ghrelin and ameliorated anorexia without affecting the elevation of plasma ghrelin levels in CC rats. The expression of hypothalamic orexigenic neuropeptide Y mRNA but not hypothalamic GHS-R mRNA was increased by RKT. Thus, the 85As2 cell-induced CC rat model developed ghrelin resistance, possibly contributing to anorexia and body weight loss. The mechanism through which RKT ameliorated anorexia in the CC rat model may involve alleviation of ghrelin resistance by enhancement of ghrelin signaling. These findings suggest that RKT may be a promising agent for the treatment of CC.

Hydroxy-α sanshool induces colonic motor activity in rat proximal colon: a possible involvement of KCNK9.

Various colonic motor activities are thought to mediate propulsion and mixing/absorption of colonic content. The Japanese traditional medicine daikenchuto (TU-100), which is widely used for postoperative ileus in Japan, accelerates colonic emptying in healthy humans. Hydroxy-α sanshool (HAS), a readily absorbable active ingredient of TU-100 and a KCNK3/KCNK9/KCNK18 blocker as well as TRPV1/TRPA1 agonist, has been investigated for its effects on colonic motility. Motility was evaluated by intraluminal pressure and video imaging of rat proximal colons in an organ bath. Distribution of KCNKs was investigated by RT-PCR, in situ hybridization, and immunohistochemistry. Current and membrane potential were evaluated with use of recombinant KCNK3- or KCNK9-expressing Xenopus oocytes and Chinese hamster ovary cells. Defecation frequency in rats was measured. HAS dose dependently induced strong propulsive "squeezing" motility, presumably as long-distance contraction (LDC). TRPV1/TRPA1 agonists induced different motility patterns. The effect of HAS was unaltered by TRPV1/TRPA1 antagonists and desensitization. Lidocaine (a nonselective KCNK blocker) and hydroxy-ß sanshool (a geometrical isomer of HAS and KCNK3 blocker) also induced colonic motility as a rhythmic propagating ripple (RPR) and a LDC-like motion, respectively. HAS-induced "LDC," but not lidocaine-induced "RPR," was abrogated by a neuroleptic agent tetrodotoxin. KCNK3 and KCNK9 were located mainly in longitudinal smooth muscle cells and in neural cells in the myenteric plexus, respectively. Administration of HAS or TU-100 increased defecation frequency in normal and laparotomy rats. HAS may evoke strong LDC possibly via blockage of the neural KCNK9 channel in the colonic myenteric plexus.

New cancer cachexia rat model generated by implantation of a peritoneal dissemination-derived human stomach cancer cell line.

Cancer cachexia (CC), a syndrome characterized by anorexia and body weight loss due to low fat-free mass levels, including reduced musculature, markedly worsens patient quality of life. Although stomach cancer patients have the highest incidence of cachexia, few experimental models for the study of stomach CC have been established. Herein, we developed stomach CC animal models using nude rats subcutaneously implanted with two novel cell lines, i.e., MKN45c185, established from the human stomach cancer cell line MKN-45, and 85As2, derived from peritoneal dissemination of orthotopically implanted MKN45c185 cells in mice. Both CC models showed marked weight loss, anorexia, reduced musculature and muscle strength, increased inflammatory markers, and low plasma albumin levels; however, CC developed earlier and was more severe in rats implanted with 85As2 than in those implanted with MKN45cl85. Moreover, human leukemia inhibitory factor (LIF), a known cachectic factor, and hypothalamic orexigenic peptide mRNA levels increased in the models, whereas hypothalamic anorexigenic peptide mRNA levels decreased. Surgical removal of the tumor not only abolished cachexia symptoms but also reduced plasma LIF levels to below detectable limits. Importantly, oral administration of rikkunshito, a traditional Japanese medicine, substantially ameliorated CC-related anorexia and body composition changes. In summary, our novel peritoneal dissemination-derived 85As2 rat model developed severe cachexia, possibly caused by LIF from cancer cells, that was ameliorated by rikkunshito. This model should provide a useful tool for further study into the mechanisms and treatment of stomach CC.

A review of traditional Japanese medicines and their potential mechanism of action.

Traditional Japanese herbal, or Kampo medicine was developed and modified from Chinese herbal medicine. After the Japanese government approved Kampo for clinical use, much attention has been paid to establishing scientific evidence for the effectiveness of these medicines. Recent progress has been made in elucidating the mechanisms of action of some types of Kampo medicine, including rikkunshito (RKT), daikenchuto, and yokukansan. In this review, we focused on identifying the target molecules and the active ingredients of RKT. Thus far, many target molecules have been implicated in the mechanism of action of Kampo medicines, such as ion channels, enzymes, and receptors. In particular, G protein-coupled receptors are attractive candidates for explaining herbal medicine activity. This is particularly true of RKT, which is composed of 8 independent, crude drug extracts. Recent reports have shown that RKT elicits its effects through dual action to the G protein-coupled receptors: inhibition of serotonergic 5-HT2C and 5-HT2B receptors and activation of ghrelin receptors via specific ingredients of RKT. In addition, we suggest that the identification of the effective ingredients from Kampo medicines could contribute to the discovery and development of new drugs by means of modern high-throughput drug screening technology.