Mitsuko Ochiai

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.

Increased expression of long pentraxin PTX3 in inflammatory bowel diseases.

The aims of this study were to investigate the expression of pentraxin-3 in inflamed gastrointestinal tissue in patients with inflammatory bowel diseases and to elucidate the usefulness of plasma pentraxin-3 level as an inflammation marker in patients with inflammatory bowel diseases. Pentraxin-3 immunoreactivity was found in infiltrating neutrophils and vessels in the inflamed gut. Plasma pentraxin-3 concentration in patients with active inflammatory bowel diseases was significantly higher than that of normal subjects and patients with inactive inflammatory bowel diseases. Significant positive correlations of clinical disease activity with plasma pentraxin-3 concentration and serum CRP concentration were found in patients with inflammatory bowel diseases. Pentraxin-3 is directly produced from the inflamed gut in inflammatory bowel diseases. In conclusion, plasma pentraxin-3 concentration is a useful marker for understanding the disease activity in patients with inflammatory bowel diseases.

Apelin-12 stimulates acid secretion through an increase of histamine release in rat stomachs

BACKGROUND Apelin is a peptide that was originally isolated from bovine stomach extract and has been demonstrated to be an endogenous ligand for orphan receptor APJ. Both apelin and the APJ receptor are widely distributed in the whole body. Apelin is supposed to have important regulatory roles in the function of many organs such as in the cardiovascular system; however, the mechanism of apelin function has not been elucidated. In this study, we studied the action of apelin in acid secretion and demonstrated its mechanism of action. METHODS Gastric lumen-perfused rats were prepared and their stomachs were perfused with a saline solution using a peristaltic pump. Apelin-12, 36 or Pyr(1)-apelin-13, were intravenously injected to examine their effects on acid secretion in rats. In some experiments, rats were pretreated with famotidine (0.33 mg/kg) or atropine sulfate (0.1mg/kg) intravenously injected 5 or 15 min before apelin injection. Furthermore, isolated vascularly perfused rat stomachs were prepared to examine the effect of apelin on histamine release, which was assayed in the effluent by radioimmunoassay. Messenger RNA of histidine decarboxylase (HDC) in gastric mucosa of isolated stomach was measured by real-time RT-PCR. RESULTS Apelin-12 (20-100 μg/kg) dose-dependently increased gastric acid secretion, with a maximum of 203% at 100 μg/kg (n=5). Neither Pyr(1)-apelin-13 nor apelin-36 caused a significant increase in acid secretion. Famotidine completely blocked the stimulatory action of apelin on acid secretion. Apelin-12 (100 μg/20 ml/10 min) markedly increased histamine release from isolated vascularly perfused rat stomachs by 278%, and also increased the mRNA of HDC by 480% of the control. Atropine sulfate did not abolish the effect of apelin on the secretion of gastric acid. Apelin-12 amplified an increase of acid secretion stimulated by gastrin injection. CONCLUSION These results indicate that apelin-12 stimulates gastric acid secretion through an increase in histamine release and synthesis from gastric mucosa, suggesting that apelin might play a role in the secretion of gastric acid or serve as a regulating factor of the secretion of gastric acid.

Increased pentosidine, an advanced glycation end-product, in urine and tissue reflects disease activity in inflammatory bowel diseases.

Background:  Under inflammatory conditions with strong oxidative stresses, advanced glycation end‐products (AGE), carbonyl compounds, are produced. The concentration of pentosidine, an AGE, reportedly correlates with complications of diabetes mellitus and worsening of rheumatoid arthritis, but its role in the pathogenesis of inflammatory bowel diseases (IBD) is unclear.

Peripheral α2-β1 adrenergic interactions mediate the ghrelin response to brain urocortin 1 in rats

Summary The autonomic nervous system (ANS) conveys neuronal input from the brain to the stomach. We investigated mechanisms through which urocortin 1 (UCN1) injected intracerebroventricularly (ICV, 300 pmol/rat) inhibits circulating ghrelin in rats. This was achieved by assessing (1) the induction of c-fos gene expression as a marker of neuronal activation in specific hypothalamic and caudal brainstem regulating ANS; (2) the influence of vagotomy and pharmacological blockade of central and peripheral α- and β-adrenergic receptor (AR) on ICV UCN1 -induced reduction of plasma ghrelin levels (determined by ELISA); and (3) the relevance of this pathway in the feeding response to a fast in rats. UCN1 increased c-fos mRNA expression in key brain sites influencing sympathetic activity namely the hypothalamic paraventricular and ventromedial nuclei, locus coeruleus, nucleus of the solitary tract, and rostral ventrolateral medulla, by 16-, 29-, 6-, 37-, and 13-fold, respectively. In contrast, the dorsal motor nucleus of the vagus had little c-fos mRNA expression and ICV UCN1 induced a similar reduction in acylated ghrelin in the sham-operated (31%) and vagotomized (41%) rats. An intraperitoneal (IP) injection of either a non-selective α- or selective α2-AR antagonist reduced, while a selective α2-AR agonist enhanced ICV UCN1-induced suppression of plasma acylated ghrelin levels. In addition, IP injection of a non-selective β- or selective β1-AR agonist blocked, and selective β1-AR antagonist augmented, the ghrelin response to ICV UCN1. The IP injections of a selective α1- or non-selective β or β2-AR antagonists, or any of the pretreatments given ICV had no effect. ICV UCN1 reduced the 2-h food intake in response to a fast by 80%, and this effect was partially prevented by a selective α2-AR antagonist. These data suggest that ICV UCN1 reduces plasma ghrelin mainly through the brain sympathetic component of the ANS and peripheral AR specifically α2-AR activation and inactivation of β1-AR. The α2-AR pathway contributes to the associated reduction in food intake.

Urocortin1-induced anorexia is regulated by activation of the serotonin 2C receptor in the brain.

This study was conducted to determine the mechanisms by which serotonin (5-hydroxytryptamine, 5-HT) receptors are involved in the suppression of food intake in a rat stress model and to observe the degree of activation in the areas of the brain involved in feeding. In the stress model, male Sprague-Dawley rats (8 weeks old) were given intracerebroventricular injections of urocortin (UCN) 1. To determine the role of the 5-HT2c receptor (5-HT2cR) in the decreased food intake in UCN1-treated rats, specific 5-HT2cR or 5-HT2b receptor (5-HT2bR) antagonists were administered. Food intake was markedly reduced in UCN1-injected rats compared with phosphate buffered saline treated control rats. Intraperitoneal administration of a 5-HT2cR antagonist, but not a 5-HT2bR antagonist, significantly inhibited the decreased food intake. To assess the involvement of neural activation, we tracked the expression of c-fos mRNA as a neuronal activation marker. Expression of the c-fos mRNA in the arcuate nucleus, ventromedial hypothalamic nucleus (VMH) and rostral ventrolateral medulla (RVLM) in UNC1-injected rats showed significantly higher expression than in the PBS-injected rats. Increased c-fos mRNA was also observed in the paraventricular nucleus (PVN), the nucleus of the solitary tract (NTS), and the amygdala (AMG) after injection of UCN1. Increased 5-HT2cR protein expression was also observed in several areas. However, increased coexpression of 5-HT2cR and c-fos was observed in the PVN, VMH, NTS, RVLM and AMG. Whereas, pro-opiomelanocortin mRNA expression was not changed. In an UNC1-induced stress model, 5-HT2cR expression and activation was found in brain areas involved in feeding control.

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

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.

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.

Sa2021 The Stress Hormone Urocortin 1 Induces Gastric Dysfunction by α2-Adrenergic Receptor-Mediated Decrease in Ghrelin Signal in Rats

Background/Aim: Excessive stress in modern society is associated with development of functional dyspepsia, which presents with symptoms of epigastric pain, early satiety and postprandial fullness. The central neural peptides, members of the corticotropin-releasing factor family, play key roles in response to stress. We previously reported that urocortin1 (UCN1) suppressed feeding behavior in fasted rats through an α2-adrenergic receptor (α2AR) activation, which decreases ghrelin secretion (DDW 2014). However, the influence of UCN1 on gastrointestinal (GI) function remains unclear. To elucidate this, we investigated the changes in gastric emptying and GI motility in UCN1-treated rats. Methods: UCN1 (300 pmol/rat) or phosphate-buffered saline (PBS) were intracerebroventricularly (ICV) injected to Sprague-Dawley rats, and gastric emptying and plasma ghrelin levels 2 h after oral administration of test meal were measured. The α2-AR antagonist, yohimbine (5 mg/kg) 15 min before ICV were intraperitoneal(IP) administered to UCN1-treated rats. Furthermore, ghrelin (3 nmol/rat, intravenous (IV)) were administered to UCN1-treated rats. In another set of experiment, the effects of co-administration of rikkunshito (RKT; 1000 mg/kg, which is an endogenous ghrelin enhancer) and with the ghrelin receptor antagonist ([D-Lys3] GHRP-6; 4 μmol/kg IV) was investigated. GI motility was investigated to determine the effects of ghrelin or RKT to UCN1-treated rats using a strain gauge force transducer in free-moving condition. Results: UCN1-treated rats exhibited significantly delayed gastric emptying. Administration of yohimbine improved gastric emptying (UCN1: 22.9±6.5 %, UCN1+yohimbine: 58.5±7.6 %, p<0.05) and significantly increased plasma ghrelin levels (UCN1:47.2±3.6 fmol/mL, UCN1+yohimbine: 81.9±7.8 fmol/mL, p<0.05). Exogenous administration of ghrelin restored delayed gastric empting. Administration of RKT significantly prevented delayed gastric empting and decreased plasma ghrelin levels. The gastric function of RKT was blocked by co-administration of the ghrelin receptor antagonist. ICV injection of UCN1 decreased the amplitude of contraction in the stomach while increasing the amplitude in the duodenum. Motility index of the stomach, but not the duodenum, was significantly reduced by treatment with UCN1 (PBS: 92.1 ± 10.1%, UCN1: 62.8 ± 4.7%), which was improved by the administration of ghrelin or RKT (99.03 ± 7.95%, p<0.05). Conclusions UCN1-induced gastric motility dysfunction with decrease in plasma ghrelin levels wasmediated byα2-AR activation. Disturbance in endogenous ghrelin dynamics play an important role in the functional abnormality of the upper GI tract under stressful conditions.

Su1253 Abnormal Dynamics of Endogenous Acylated Ghrelin Mediates Decreases in Gastric Phase III-Like Contraction, Leading to Delayed Gastric Emptying in Urocortin1-Induced Stress Rats

INTRODUCTION: Gastric acid suppression is justified to prevent severe gastro esophageal reflux (GER) disease related complications. However, it does not reduce the total amount and proximal extent of GER in the esophagus and non-acid components are able to induce (extra-esophageal) GER symptoms as well. No data on the composition of gastric juice (GJ) in children using gastric acid suppression exists. We therefore aimed to assess whether the composition of gastric juice in children using proton pump inhibitors (PPIs) differs, compared to that of their controls. METHODS: Infants and children (0-18 years) on proton pump inhibitors (PPIs) for at least six weeks and a control group not using anti reflux medication, were included. GJ was obtained through an existing nasogastric or a percutaneous endoscopic gastrostomy tube/ Mic-key gastrostomy. In the collected GJ (5 ml), pH, pepsin activity, bile salts and endotoxin (LPS) levels were determined. Pepsin was measured using a fluorometric assay using 4-Methyl-Coumaryl-7-Amide (MCA) substrate with/without pepstatin. Concentrations of deconjugated and taurine/glycine-conjugated bile salts were assessed by reversephase HPLC. Levels of LPS were determined using the spectrophotometric Limulus Amebocyte Lysate assay. RESULTS: GJ was analyzed from 16 children with (median: 3.8 yrs, range: 17.6 years) and 16 children (4.0 yrs, range: 16.0) without PPI therapy. Median duration of PPI treatment was 24 weeks (range: 514 weeks). Gastric pH was 5.0 (range: 5.0) and 1.0 (range: 4.5) in the PPI and control group respectively (p <0.001). Pepsin, unconjugated bile salts, and endotoxin were not significantly different in the two groups. Total taurine conjugated bile salts, and specifically taurocholate, was significantly higher in the PPI group (p=0.01 and p=0.005). pH and concentration of deconjugated bile and conjugated bile salts were significantly associated (p=0.006 and p=0.02). Endotoxin and bile salts were not significantly associated. CONCLUSION: Taurine conjugated bile acids are significantly higher in children chronically using PPIs compared to controls. Moreover acidity of gastric pH correlated negatively with deconjugated and conjugated bile salts. These findings imply that GJ under chronic proton pump inhibition contains nonacid components potentially harmful to esophageal mucosa and bronchial tissue.