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.

Increased ghrelin signaling prolongs survival in mouse models of human aging through activation of sirtuin1.

Caloric restriction (CR) is known to retard aging and delay functional decline as well as the onset of diseases in most organisms. Ghrelin is secreted from the stomach in response to CR and regulates energy metabolism. We hypothesized that in CR ghrelin has a role in protecting aging-related diseases. We examined the physiological mechanisms underlying the ghrelin system during the aging process in three mouse strains with different genetic and biochemical backgrounds as animal models of accelerated or normal human aging. The elevated plasma ghrelin concentration was observed in both klotho-deficient and senescence-accelerated mouse prone/8 (SAMP8) mice. Ghrelin treatment failed to stimulate appetite and prolong survival in klotho-deficient mice, suggesting the existence of ghrelin resistance in the process of aging. However, ghrelin antagonist hastened death and ghrelin signaling potentiators rikkunshito and atractylodin ameliorated several age-related diseases with decreased microglial activation in the brain and prolonged survival in klotho-deficient, SAMP8 and aged ICR mice. In vitro experiments, the elevated sirtuin1 (SIRT1) activity and protein expression through the cAMP-CREB pathway was observed after ghrelin and ghrelin potentiator treatment in ghrelin receptor 1a-expressing cells and human umbilical vein endothelial cells. Furthermore, rikkunshito increased hypothalamic SIRT1 activity and SIRT1 protein expression of the heart in the all three mouse models of aging. Pericarditis, myocardial calcification and atrophy of myocardial and muscle fiber were improved by treatment with rikkunshito. Ghrelin signaling may represent one of the mechanisms activated by CR, and potentiating ghrelin signaling may be useful to extend health and lifespan.

Ghrelin enhancer, rikkunshito, improves postprandial gastric motor dysfunction in an experimental stress model.

BACKGROUND: Functional dyspepsia (FD) is one of the most common disorders of gastrointestinal (GI) diseases. However, no curable treatment is available for FD because the detailed mechanism of GI dysfunction in stressed conditions remains unclear. We aimed to clarify the association between endogenous acylated ghrelin signaling and gastric motor dysfunction and explore the possibility of a drug with ghrelin signal-enhancing action for FD treatment. METHODS: Solid gastric emptying (GE) and plasma acylated ghrelin levels were evaluated in an urocortin1 (UCN1) -induced stress model. To clarify the role of acylated ghrelin on GI dysfunction in the model, exogenous acylated ghrelin, an endogenous ghrelin enhancer, rikkunshito, or an α2 -adrenergic receptor (AR) antagonist was administered. Postprandial motor function was investigated using a strain gauge force transducer in a free-moving condition. KEY RESULTS: Exogenous acylated ghrelin supplementation restored UCN1-induced delayed GE. Alpha2 -AR antagonist and rikkunshito inhibited the reduction in plasma acylated ghrelin and GE in the stress model. The action of rikkunshito on delayed GE was blocked by co-administration of the ghrelin receptor antagonist. UCN1 decreased the amplitude of contraction in the antrum while increasing it in the duodenum. The motility index of the antrum but not the duodenum was significantly reduced by UCN1 treatment, which was improved by acylated ghrelin or rikkunshito. CONCLUSIONS & INFERENCES: The UCN1-induced gastric motility dysfunction was mediated by abnormal acylated ghrelin dynamics. Supplementation of exogenous acylated ghrelin or enhancement of endogenous acylated ghrelin secretion by rikkunshito may be effective in treating functional GI disorders.

Rikkunshito induces gastric relaxation via the ß-adrenergic pathway in Suncus murinus.

BACKGROUND: Rikkunshito (RKT) is a gastroprotective herbal medicine. In this study, we investigated the role of RKT in the relaxation of the gastric body (fundus and corpus) and antrum. METHODS: We used Suncus murinus, a unique small model animal with similar gastrointestinal motility to humans and dogs. RKT was added at 0.1, 1.0, and 5.0 mg/mL to induce relaxation in vitro; the outcome measure was the intensity of relaxation. The number of spontaneous antral contractions in the absence or the presence of RKT was also counted. KEY RESULTS: Rikkunshito induced the relaxation of the gastric body and antrum and decreased the number of spontaneous antral contractions in a dose-dependent manner. The responses to RKT (1.0 mg/mL) were not affected by pretreatment with atropine, N-nitro-l-arginine methyl ester, ritanserin, or ondansetron. On the other hand, timolol almost completely reversed the relaxation induced by RKT (1.0 mg/mL) on the gastric body and antrum and the occurrence of the spontaneous antral contractions. Both butoxamine, a ß(2) -adrenoreceptor antagonist, and L 748337, a ß(3) -adrenoreceptor antagonist, but not CGP 20712, a ß(1) -adrenoreceptor antagonist, significantly reversed the RKT-induced (1.0 mg/mL) gastric relaxation. CONCLUSIONS & INFERENCES: These results indicate that RKT stimulates and modulates gastric relaxation through ß(2) - and ß(3) -adrenergic, but not ß(1) -adrenergic, pathways in S. murinus.

Potentiation of ghrelin signaling attenuates cancer anorexia-cachexia and prolongs survival.

Cancer anorexia-cachexia syndrome is characterized by decreased food intake, weight loss, muscle tissue wasting and psychological distress, and this syndrome is a major source of increased morbidity and mortality in cancer patients. This study aimed to clarify the gut-brain peptides involved in the pathogenesis of the syndrome and determine effective treatment for cancer anorexia-cachexia. We show that both ghrelin insufficiency and resistance were observed in tumor-bearing rats. Corticotropin-releasing factor (CRF) decreased the plasma level of acyl ghrelin, and its receptor antagonist, α-helical CRF, increased food intake of these rats. The serotonin 2c receptor (5-HT2cR) antagonist SB242084 decreased hypothalamic CRF level and improved anorexia, gastrointestinal (GI) dysmotility and body weight loss. The ghrelin receptor antagonist (D-Lys3)-GHRP-6 worsened anorexia and hastened death in tumor-bearing rats. Ghrelin attenuated anorexia-cachexia in the short term, but failed to prolong survival, as did SB242084 administration. In addition, the herbal medicine rikkunshito improved anorexia, GI dysmotility, muscle wasting, and anxiety-related behavior and prolonged survival in animals and patients with cancer. The appetite-stimulating effect of rikkunshito was blocked by (D-Lys3)-GHRP-6. Active components of rikkunshito, hesperidin and atractylodin, potentiated ghrelin secretion and receptor signaling, respectively, and atractylodin prolonged survival in tumor-bearing rats. Our study demonstrates that the integrated mechanism underlying cancer anorexia-cachexia involves lowered ghrelin signaling due to excessive hypothalamic interactions of 5-HT with CRF through the 5-HT2cR. Potentiation of ghrelin receptor signaling may be an attractive treatment for anorexia, muscle wasting and prolong survival in patients with cancer anorexia-cachexia.

Suppression of glycogen consumption during acute exercise by dietary branched-chain amino acids in rats.

The effects of a diet supplemented with branched-chain amino acids (BCAA; 4.8% or 6.2%) on BCAA catabolism and glycogen metabolism in rats were examined. Rats were fed a BCAA diet or control diet for 4 wk and part of the rats were subjected to exercise training during the experimental period. Feeding the BCAA diet increased serum BCAA concentrations and activity of the hepatic branched-chain alpha-keto acid dehydrogenase complex, the rate-limiting enzyme in the catabolism of BCAA, suggesting that dietary BCAA promotes BCAA catabolism. Although the serum glucose concentration and glycogen contents in the liver and gastrocnemius muscle of rested rats were not significantly affected by feeding of the BCAA diet, those in rats exhausted by acute exercise were 2-4-fold higher in rats fed the BCAA diet than in rats fed the control diet. The activity of pyruvate dehydrogenase complex in the liver and gastrocnemius muscle after acute exercise showed reverse trends; the complex activities (especially in liver) tended to be less in the BCAA diet group than in the control diet group. These results suggest that dietary BCAA spares glycogen stores in liver and skeletal muscle during exercise and that the decrease in pyruvate dehydrogenase complex activity in these tissues by dietary BCAA is involved in the mechanisms.

Dietary maltitol decreases the incidence of 1,2-dimethylhydrazine-induced cecum and proximal colon tumors in rats.

Maltitol is fermented in the colon due to only partial hydrolysis in the small intestine. In the present study, we examined effects of dietary maltitol on dimethylhydrazine-induced intestinal tumor in rats. In experiment 1, rats were fed a fiber-free diet or diets supplemented with 1 or 5 g/100 g maltitol for 27 wk. Each group of rats was injected with dimethylhydrazine or vehicle alone for the first 14 wk of the experimental period. Maltitol supplementation at 1 g/100 g of the diet significantly reduced tumor incidence in the cecum and the 5% supplement reduced tumor incidence in both the cecum and proximal colon in dimethylhydrazine-treated rats. In experiment 2, we investigated the effect of the 1 g/100 g maltitol diet on the short chain fatty acid concentrations in cecal contents of placebo and dimethylhydrazine-treated rats. Intake of the 1 g/100 g maltitol diet doubled (P < 0.05) the concentration of butyrate but did not affect acetate or propionate in the cecal contents. These results suggest that dietary maltitol has a protective effect against dimethylhydrazine-induced tumors in rat cecum and proximal colon and that butyrate produced by bacterial fermentation of maltitol in the cecum may be involved in the protection.

[Effects of onpi-to (TJ-8117) and (-)epicatechin-3-O-gallate on the proliferating changes in glomeruli of 5/6 nephrectomized rats].

Onpi-to (TJ-8117) is a herbal medicine composed of five crude drugs (Rhei Rhizoma, Glycyrrhizae Radix, Ginseng Radix, Zingiberis Rhizoma and Aconiti Tuber). Our previous experiments have demonstrated that TJ-8117 suppressed the development of glomerulosclerosis and retarded the deterioration of renal function in 5/6 nephrectomised rats. In the present study, the effects of TJ-8117 and (-)Epicatechin-3-O-gallate (ECG), which is a component of Rhei Rhizoma, on glomerular cell proliferation, extracellular matrix accumulation and glomerular hypertrophy were investigated in 5/6 nephrectomized rats. Male Wistar rats (170-180 g) were subjected to 5/6 nephrectomy, and TJ-8117 (0.32%, 0.64%) or angiotensin-converting enzyme inhibitor, captopril (CAP 0.08%) was administered daily by mixing in normal chow and ECG (2 mg, 8 mg/100 ml) by drinking water from the day after 5/6 nephrectomy. Following 5/6 nephrectomy, glomerular cell poliferation was increased and reached a maximum at 1 week in the untreated control rats, but was suppressed significantly at 1 and 2 weeks after treatment with TJ-8117 and at only 1 week after treatment with CAP. Extracellular matrix accumulation was detected after 1 week and increased gradually until 4 weeks in the control rats, whereas it was significantly inhibited in both the TJ-8117- and CAP-treated rats. In addition, immunohistochemistry revealed that TJ-8117 significantly inhibited the increase of fibronectin, and tended to reduce type I and type IV collagen at 4 weeks. Furthermore, TJ-8117 suppressed glomerular hypertrophy at 4 weeks. Systolic blood pressure (SBP) and urinary protein excretion (UP) were higher in the control rats than sham-operated rats. TJ-8117 prevented this increase of SBP and UP at 1 week. ECG also suppressed glomerular cell proliferation and the increase of SBP and UP at 1 week after 5/6 nephrectomy. These findings suggest that ECG was one of active components of TJ-8117. These results suggest that TJ-8117 suppressed proliferating changes in glomeruli at an early stage in 5/6 nephrectomized rats, and inhibited the development of glomerulosclerosis.

[Protective effect of onpi-to (TJ-8117) on the expression of apoptosis in 5/6 nephrectomized rats].

The present study was designed to clarify the effects of TJ-8117 on apoptosis in the glomeruli of 5/6 nephrectomized rats. TJ-8117 (400 mg/kg/day), captopril (50 mg/kg/day) and nicardipine (50 mg/kg/day) were administered as drinking water from the 56th day after renal ablation, and continued throughout the experiment. All rats were sacrificed at 13 weeks and renal tissues were removed to quantify histopathological and apoptotic parameters in glomeruli. TJ-8117 inhibited proteinuria, matrix index and decrease in the number of total cells in glomeruli of nephrectomized rats. In addition, the increase in apoptotic body and DNA fragmentation was significantly inhibited in the TJ-8117-treated group. Captopril and nicardipine failed to inhibit both parameters. In 400 mg/kg of the TJ-8117 treated group, the number of Bcl -2 positive cells in the glomeruli was elevated compared with the 5/6 nephrectomized control group. In addition, the number of Bax positive cells in the TJ-8117 group was significantly suppressed in a dose-dependent manner. These results suggest that TJ-8117 may inhibit apoptosis in the late stage of this model by suppressing matrix accumulation and progression of glomerulosclerosis. The apoptosis-preventing effect may be mediated by decreased expression of Bax in the glomerular cells.

[Sairei-to may inhibit the synthesis of endothelin-1 in nephritic glomeruli].

In order to clarify the antinephritic mechanisms of Sairei-to (TJ-114), its effects on the synthesis and expression of endothelin-1 were evaluated in rats with anti-glomerular basement membrane (GBM) nephritis. TJ-114 was administered orally once daily from the 20th day after anti-GBM serum injection and was continued throughout the experiment. TJ-114 prevented proteinuria and histopathological changes in the glomeruli of nephritic rats. TJ-114 inhibited elevation of the endothelin-1 concentration in the supernatant from cultured glomeruli of nephritic rats and the endothelin-1 positive area in the glomeruli. TJ-114 inhibited the elevation of systolic blood pressure and the number of proliferating cell nuclear antigen (PCNA)-positive cells per glomeruli. We also found that the constitutive Kampo medicine in TJ-114, Gorei-san (TJ-17), inhibited the synthesis and expression of endothelin-1. In addition, the constitutive herbs TJ-17, alismatis rhizoma (Japanese name "Takusha") and hoelen (Japanese name "Bukuryou") inhibited the synthesis and expression of endothelin-1. These results indicate that the antinephritic actions of TJ-114 may be due partially to the inhibition of endothelin-1 synthesis in the glomeruli.

[Effect of Onpi-to (TJ-8117) on TGF-beta 1 in rats with 5/6 nephrectomized chronic renal failure].

We and others have already reported that Onpi-to (TJ-8117), a Kampo medicine composed mainly of Rhei Rhizoma, has a beneficial effect on an adenine-induced renal failure model and 5/6 nephrectomized renal failure. However, little is known about the detailed mechanism of this medicine when used for renal failure. The present study was designed to clarify whether or not TJ-8117 affects TGF-beta 1 production or activation in glomeruli of 5/6 nephrectomized rats. TJ-8117 (400 mg/kg/ day) and captopril (50 mg/kg/day) were administered as drinking water from the day immediately after the operation and continued throughout the experiment. All rats were sacrificed at 4 weeks and renal cortical tissue was removed to quantify the protein and activity of TGF-beta 1 and activities of metalloproteinase. TIMP expression and extracellular matrix (collagen type I, IV) in the glomeruli were analysed histologically. TJ-8117 inhibited proteinuria, and the accumulation of collagen type I and IV in glomeruli of nephrectomized rats. In addition, TJ-8117 inhibited the TGF-beta 1 positive area in the glomeruli and the elevation of mature TGF-beta 1 level in the renal cortex of nephrectomized rats. In the TJ-8117 treated group, activities of metalloproteinase 1, 2 or 9 in the renal cortex were elevated compared with the control group. Captopril failed to affect the TGF-beta 1 level. We also found that the constitutive herbs in TJ-8117, Rhei Rhizoma and Ginseng radix, inhibited the process from inactive TGF-beta 1 to mature TGF-beta 1.

[Effects of Onpi-to (TJ-8117) on mesangial injury induced by anti Thy-1 antibody].

We investigated the effect of Onpi-to (TJ-8117) on the mesangial injury induced by anti-Thy-1 antibody. TJ-8117 (400 mg/kg/day, p.o.) given from the 1st day (from the day of injection of the anti-thymocyte serum) or 4th day (after mesangial proliferation), markedly inhibited the mesangial proliferation and hypercellularity in glomeruli. TJ-8117 prevented the increase in the number of PCNA or ED-1 positive cells in glomeruli. These results suggest that TJ-8117 is effective against glomerular disease with mesangial injury.