Tomohisa Hattori

Decreased plasma ghrelin contributes to anorexia following novelty stress

We hypothesized that anorexia induced by novelty stress caused by exposure to a novel environment may be due to activation of corticotropin-releasing factor (CRF) and subsequently mediated by decreasing peripheral ghrelin concentration via serotonin (5-HT) and melanocortin-4 receptors (MC4R). Each mouse was transferred from group-housed cages to individual cages to establish the novelty stress. We observed the effect of changes in feeding behavior in a novel environment using the method of transferring group-housed mice to individual cages. We investigated the effect of an intracerebroventricular injection of antagonists/agonists of CRF1/2 receptors (CRF1/2Rs), 5-HT(1B)/(2C) receptors (5-HT(1B)/(2C)R), and MC4R to clarify the role of each receptor on the decrease in food intake. Plasma ghrelin levels were also measured. The novelty stress caused a reduction in food intake that was abolished by administering a CRF1R antagonist. Three hours after the novelty stress, appetite reduction was associated with reduced levels of neuropeptide Y/agouti-related peptide mRNA, increased levels of proopiomelanocortin mRNA in the hypothalamus, and a decrease in plasma ghrelin level. Administering a CRF1R antagonist, a 5-HT(1B)/(2C)R antagonist, an MC4R antagonist, exogenous ghrelin, and an enhancer of ghrelin secretion, rikkunshito, resolved the reduction in food intake 3 h after the novelty stress by enhancing circulating ghrelin concentrations. We showed that anorexia during a novelty stress is a process in which CRF1R is activated at the early stage of appetite loss and is subsequently activated by a 5-HT(1B)/(2C)R and MC4R stimulus, leading to decreased peripheral ghrelin concentrations.

Rikkunshito Ameliorates the Aging-Associated Decrease in Ghrelin Receptor Reactivity via Phosphodiesterase III Inhibition

Aging is associated with decreased food intake, a phenomenon termed the anorexia of aging. In this study, we sought to clarify changes in peripheral and central appetite-related factors in aged mice. Furthermore, we investigated the effects of rikkunshito, a traditional Japanese medicine, on age-related anorexia. C57BL/6J mice that were 6 or 75 wk old were studied. We investigated changes in food intake, ghrelin and leptin levels, and the expression of appetite-related genes with age. In addition, we verified the effects of ghrelin, rikkunshito, phosphodiesterase 3 (PDE3), and phosphoinositide 3-kinase inhibitors on appetite. Food intake was significantly decreased in 75-wk-old mice compared with the 6-wk-old mice. In 75-wk-old mice, plasma acylated ghrelin levels under fasting conditions were lower than in 6-wk-old mice, whereas leptin levels under feeding conditions were substantially higher. The expression levels of hypothalamic preproghrelin under feeding conditions and the expression levels of neuropeptide Y and agouti-related protein under fasting conditions were lower compared with those of the 6-wk-old mice. Ghrelin supplementation (33 microg/kg) failed to increase food intake in 75-wk-old mice. Conversely, oral administration of LY294002, a phosphoinositide 3-kinase inhibitor, and cilostamide, a PDE3 inhibitor, increased food intake in 75-wk-old mice. Moreover, rikkunshito increased food intake in aged mice. The components of rikkunshito (nobiletin, isoliquiritigenin, and heptamethoxyflavone) had inhibitory effects on PDE3. These results suggest that dysregulation of ghrelin secretion and ghrelin resistance in the appetite control system occurred in aged mice and that rikkunshito ameliorated aging-associated anorexia via inhibition of PDE3.

Rikkunshito and 5-HT2C receptor antagonist improve cisplatin-induced anorexia via hypothalamic ghrelin interaction.

Circulating ghrelin concentration regulates appetite behavior, but no study thus far has focused on the role of central ghrelin in anorexia after chemotherapy. To clarify the action mechanisms of rikkunshito (RKT), a traditional Japanese medicine, on cisplatin-induced anorexia, we attempted to elucidate its effect on hypothalamic ghrelin receptor expression in cisplatin-induced anorexia. We first examined the effects of an intracerebroventricular (ICV) injection of exogenous ghrelin on food intake with or without cisplatin treatment, and the effects of cisplatin or m-chlorophenylpiperazine (mCPP), a 5-HT2C receptor agonist, on hypothalamic growth hormone secretagogue receptor 1a (GHS-R1a) mRNA expression. To identify the mechanism of cisplatin-induced decrease in hypothalamic GHS-R1a mRNA expression, we evaluated the effects of SB242084HCl, a 5-HT2C receptor antagonist, and RKT on hypothalamic GHS-R1a gene expression, along with the effect of coadministration of a GHS-R1a antagonist on decreased food intake. Compared to vehicle controls, an ICV-injected rat ghrelin failed to inhibit the decrease in food intake in cisplatin-treated rats. Hypothalamic GHS-R1a gene expression was significantly reduced after cisplatin or mCPP treatment, and the induced decrease was reversed by SB242084HCl or RKT, but not granisetron or ondansetron, both of which are 5-HT3 receptor antagonists. Their suppressive effect on the decrease in food intake was abolished by coadministration of the GHS-R1a antagonist. Administration of RKT or SB242084HCl reversed the decrease in food intake induced by mCPP injection. The improvement by RKT on decreased food intake after cisplatin treatment was partly mediated by hesperidin and isoliquiritigenin, components of RKT. Cisplatin-induced anorexia may worsen because of decreased hypothalamic GHS-R1a gene expression. A 5-HT2C receptor antagonist and RKT suppressed cisplatin-induced anorexia by inhibiting reduction of GHS-R1a signal transduction in the hypothalamus.

Urocortin 1 reduces food intake and ghrelin secretion via CRF2 receptors

Although it is known that urocortin 1 (UCN) acts on both corticotropin-releasing factor receptors (CRF(1) and CRF(2)), the mechanisms underlying UCN-induced anorexia remain unclear. In contrast, ghrelin, the endogenous ligand for the growth hormone secretagogue receptor, stimulates food intake. In the present study, we examined the effects of CRF(1) and CRF(2) receptor antagonists (CRF(1)a and CRF(2)a) on ghrelin secretion and synthesis, c-fos mRNA expression in the caudal brain stem, and food intake following intracerebroventricular administration of UCN. Eight-week-old, male Sprague-Dawley rats were used after 24-h food deprivation. Acylated and des-acylated ghrelin levels were measured by enzyme-linked immunosorbent assay. The mRNA expressions of preproghrelin and c-fos were measured by real-time RT-PCR. The present study provided the following important insights into the mechanisms underlying the anorectic effects of UCN: 1) UCN increased acylated and des-acylated ghrelin levels in the gastric body and decreased their levels in the plasma; 2) UCN decreased preproghrelin mRNA levels in the gastric body; 3) UCN-induced reduction of plasma ghrelin and food intake were restored by CRF(2)a but not CRF(1)a; 4) UCN-induced increase of c-fos mRNA levels in the caudal brain stem containing the nucleus of the solitary tract (NTS) was inhibited by CRF(2)a; and 5) UCN-induced reduction of food intake was restored by exogenous ghrelin and rikkunshito, an endogenous ghrelin secretion regulator. Thus, UCN increases neuronal activation in the caudal brain stem containing NTS via CRF(2) receptors, which may be related to UCN-induced inhibition of both ghrelin secretion and food intake.

Apoptosis and expression of Bax protein and Fas antigen in glomeruli of a remnant-kidney model.

The role of apoptosis in glomerular cell depletion associated with a decrease in renal function is still controversial. To examine the involvement of apoptosis in renal disease, the occurrence of apoptosis during the progression of renal insufficiency as well as the expression of Bax protein and Fas antigen that are related to the apoptosis were investigated using five-sixths nephrectomized rats, one of the progressive renal disease models. Serum creatinine was significantly elevated to a level approximately five-fold higher than that in the sham-operated group on day 1 after the five-sixths nephrectomy and then maintained at a level approximately two- to three-fold higher until day 56 and then elevated further to a level eight-fold higher on day 96 after nephrectomy as compared with the sham-operated group. The total number of glomerular cells was significantly increased from day 7 to day 56 after nephrectomy and then returned to the level of the sham-operated group by day 96. The number of PCNA-positive cells (a marker of proliferating cells) in the glomeruli was significantly increased from day 7 to day 28 after nephrectomy; the highest level was observed on day 7, and the numbers then decreased gradually. Apoptotic cells, which were represented by TUNEL-positive cells, as well as apoptotic bodies were persistenly increased with time after nephrectomy in the glomeruli of nephrectomized rats; apoptotic cells could hardly be observed in the sham-operated group. Therefore, glomerular cell proliferation appeared to begin immediately after nephrectomy and to continue until day 28 at a level high enough to overcome the decrease in the number of glomerular cells due to apoptosis, since the total number of glomerular cells was apparently high until day 56. On day 96, the decrease in the number of glomerular cells probably becomes predominant over cell proliferation, since apoptosis continuously increased with time after nephrectomy. The events on day 96 may be associated with the severely decreased renal function which was represented by the explosive increase in the serum creatinine level on the same day. The number of Fas antigen positive glomerular cells was increased from day 1 after nephrectomy and reached a plateau on day 21. The number of Bax protein positive glomerular cells was generally increased with time after nephrectomy, but the number was slightly decreased on day 21. The theory that the expression of Bax protein is correlated with apoptosis appears to fit the case of progressive renal disease. These results suggest that apoptosis is involved in the cell depletion of progressive renal insufficiency.

10-Gingerol, a component of rikkunshito, improves cisplatin-induced anorexia by inhibiting acylated ghrelin degradation

Rikkunshito (RKT), a Japanese traditional medicine, has been shown to stimulate food intake in rats with cisplatin-induced anorexia; however, the underlying mechanisms remain unknown. In this study, we investigated whether RKT is involved in the degradation of peripheral ghrelin. RKT inhibited decreases in plasma ghrelin level and enhanced acyl- to desacyl-ghrelin (A/D) ratio in cisplatin-treated rats. Several components of RKT demonstrated inhibitory activity against ghrelin deacylating enzymes. In addition, 10-gingerol, a component of RKT, inhibited exogenous ghrelin deacylation. Therefore, RKT may enhance plasma acyl-ghrelin level, at least in part, by inhibiting the circulating ghrelin degrading enzyme.

Rikkunshito, a traditional Japanese medicine, may relieve abdominal symptoms in rats with experimental esophagitis by improving the barrier function of epithelial cells in esophageal mucosa.

BackgroundA traditional Japanese medicine, rikkunshito, has been reported to relieve dyspepsia symptoms. We investigated the effect of rikkunshito on RE-induced abdominal dyspepsia, and performed experiments to elucidate the mechanism of that effect.Methods RE model rats were prepared using 8-week-old male Wistar rats, and rikkunshito was administered in drinking water. Voluntary movement was used as an index of RE-induced abdominal dyspepsia, which was monitored by an infrared sensor. On the tenth day after surgery, the total area of esophageal erosion was measured, and samples of nonerosive mucosa were collected. Using those samples, intercellular spaces of epithelial mucosa were examined by transmission electron microscopy, and the NP-40-soluble and -insoluble levels of the tight junction proteins claudin-1, -3 and -4 and their mRNAs were determined.ResultsRikkunshito did not reduce the average total area of erosive lesions in the esophageal mucosa of RE model rats. On day 10, voluntary movement was significantly decreased in the RE model rats and rikkunshito significantly increased it. Nonerosive esophageal mucosa from RE rats showed dilation of intercellular spaces in epithelium, and significantly decreased claudin-3 mRNA and protein levels. Rikkunshito significantly suppressed intercellular space dilation and significantly increased the level of NP-40-insoluble claudin-3, but it did not affect the mRNA level, suggesting that it promoted tight junction formation by facilitating the translocation of proteins.ConclusionRikkunshito increased voluntary movement in RE model rats. This may have been because rikkunshito ameliorated the symptoms of RE by improving the barrier function of esophageal mucosa.

Impaired ghrelin signaling is associated with gastrointestinal dysmotility in rats with gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is often associated with decreased upper gastrointestinal motility, and ghrelin is an appetite-stimulating hormone known to increase gastrointestinal motility. We investigated whether ghrelin signaling is impaired in rats with GERD and studied its involvement in upper gastrointestinal motility. GERD was induced surgically in Wistar rats. Rats were injected intravenously with ghrelin (3 nmol/rat), after which gastric emptying, food intake, gastroduodenal motility, and growth hormone (GH) release were investigated. Furthermore, plasma ghrelin levels and the expression of ghrelin-related genes in the stomach and hypothalamus were examined. In addition, we administered ghrelin to GERD rats treated with rikkunshito, a Kampo medicine, and examined its effects on gastroduodenal motility. GERD rats showed a considerable decrease in gastric emptying, food intake, and antral motility. Ghrelin administration significantly increased gastric emptying, food intake, and antral and duodenal motility in sham-operated rats, but not in GERD rats. The effect of ghrelin on GH release was also attenuated in GERD rats, which had significantly increased plasma ghrelin levels and expression of orexigenic neuropeptide Y/agouti-related peptide mRNA in the hypothalamus. The number of ghrelin-positive cells in the gastric body decreased in GERD rats, but the expression of gastric preproghrelin and GH secretagogue receptor mRNA was not affected. However, when ghrelin was exogenously administered to GERD rats treated with rikkunshito, a significant increase in antral motility was observed. These results suggest that gastrointestinal dysmotility is associated with impaired ghrelin signaling in GERD rats and that rikkunshito restores gastrointestinal motility by improving the ghrelin response.

Studies on antinephritic effects of plant components in rats (2) : Effects of ginsenosides on original-type anti-GBM nephritis in rats and its mechanisms.

To clarify the antinephritic effects of ginsenosides, we investigated the effects of crude ginsenoside and ginsenosides Rg1 and Rb1 on original-type anti-GBM nephritis in rats. Crude ginsenoside at 1.0 mg and 5.0 mg/kg, i.p., and ginsenoside Rg1 at 1.0 mg/kg, i.p., prevented urinary protein excretion and elevation of serum cholesterol content, as well as histopathological changes such as hypercellularity and adhesion. On the other hand, ginsenoside Rb1 only inhibited the histopathological parameters. In order to clarify the antinephritic mechanisms of ginsenosides on this model, we investigated the effect of ginsenosides on platelet aggregation and renal blood flow. Crude ginsenoside markedly enhanced the renal blood flow. Ginsenoside Rg1 inhibited the platelet aggregation in vivo and enhanced the renal blood flow on the 1st day. These results suggest that crude ginsenoside and Rg1 exert their antinephritic action via increased renal blood flow.

Beneficial Effects of Rikkunshito, a Japanese Kampo Medicine, on Gastrointestinal Dysfunction and Anorexia in Combination with Western Drug: A Systematic Review

Background. Kampo medicines are traditional herbal medicines which have been approved for medicinal use by the Japanese Ministry of Health and Welfare and are currently being used more and more, often in combination with Western drugs. Thus, the need for investigation of interactions between Kampo medicines and Western drugs is now widely recognized. Aim. To summarize the effects and drug interactions of rikkunshito, a Kampo medicine often prescribed for upper gastrointestinal disorders and anorexia. Methods. Animal and human studies were systematically reviewed to identify published data on rikkunshito. Results describing its effects were abstracted, with an emphasis on drug interactions. Results and Discussion. Rikkunshito ameliorates anorexia induced by anticancer drugs, improves quality of life scores, and can even prolong survival compared with monotherapy. Rikkunshito combined with proton pump inhibitor therapy is shown to be useful in the treatment of PPI-refractory gastroesophageal reflux disease patients and patients with gastrointestinal symptoms after endoscopic submucosal dissection. Rikkunshito reduces antidepressant-induced adverse events and improves quality of life without influencing antidepressant effects. Conclusions. Rikkunshito shows ameliorative effects on adverse reactions induced by various Western drugs and can achieve better results (e.g., anticancer drugs and proton pump inhibitor) without influencing the efficacy and bioavailability of Western drugs.