Psychological stress in aged female mice causes acute hypophagia independent of central serotonin 2C receptor activation

Sex differences exist in the activation of the hypothalamic-pituitary-adrenal axis following exposure to stress, and the stress response is further affected by aging. This study was conducted to elucidate the mechanism of hypophagia in aged female mice exposed to stress. Immediately after a stress load, aged female mice exhibited acute hypophagia and a rise in plasma corticosterone levels. The administration of a serotonin 2C receptor (5-T2CR) antagonist suppressed plasma corticosterone but did not affect the reduction in food intake. In contrast, an endogenous ghrelin enhancer, rikkunshito (RKT), significantly inhibited the reduction in food intake. An increase in peripheral acylated ghrelin levels during fasting, which occurs in young mice, was not observed in aged female mice. Moreover, in these mice, significantly increased levels of ghrelin and gastric preproghrelin mRNA expression were observed in the fed status. Moreover, plasma ghrelin levels were elevated by RKT and not by the 5-HT2CR antagonist. In female mice, the hypothalamic non-edited (INI) and partially edited mRNA 5-HT2CR isoforms (VNV, VNI, VSV or VSI) decreased with age, while in male mice, the editing isoform was unchanged by aging or stress. Estrogen receptor alpha (ER alpha)-positive cell counts in the arcuate nucleus of young male mice exposed to stress and control aged male mice were increased compared with those in young control mice. In aged male mice exposed to stress, the number of ER alpha-expressing cells in the paraventricular nucleus were significantly increased compared with those in aged control mice; in female mice, there was no increase in the number of ER alpha-positive cells. Hypophagia in aged female mice exposed to stress may be independent of 5-HT2CR activation. It seems likely that the mechanisms may be caused by sex dependent, differential regulation in 5-HT2CR mRNA expression, peripheral acylated ghrelin secretion and/or hypothalamic ER alpha expression

CRF receptor 1 antagonism and brain distribution of active components contribute to the ameliorative effect of rikkunshito on stress-induced anorexia

Rikkunshito (RKT), a Kampo medicine, has been reported to show an ameliorative effect on sustained hypophagia after novelty stress exposure in aged mice through serotonin 2C receptor (5-HT2CR) antagonism. We aimed to determine (1) whether the activation of anorexigenic neurons, corticotropin-releasing factor (CRF), and pro-opiomelanocortin (POMC) neurons, is involved in the initiation of hypophagia induced by novelty stress in aged mice; (2) whether the ameliorative effect of RKT is associated with CRF and POMC neurons and downstream signal transduction; and (3) the plasma and brain distribution of the active components of RKT. The administration of RKT or 5-HT2CR, CRF receptor 1 (CRFR1), and melanocortin-4 receptor antagonists significantly restored the decreased food intake observed in aged male C57BL/6 mice in the early stage after novelty stress exposure. Seven components of RKT exhibited antagonistic activity against CRFR1. Hesperetin and isoliquiritigenin, which showed antagonistic effects against both CRFR1 and 5-HT2CR, were distributed in the plasma and brain of male Sprague-Dawley rats after a single oral administration of RKT. In conclusion, the ameliorative effect of RKT in this model is assumed to be at least partly due to brain-distributed active components possessing 5-HT2CR and CRFR1 antagonistic activities

A New Strategy Using Rikkunshito to Treat Anorexia and Gastrointestinal Dysfunction

Because the clinical condition of gastrointestinal dysfunction, including functional dyspepsia, involves tangled combinations of pathologies, there are some cases of insufficient curative efficacy. Thus, traditional herbal medicines (Kampo medicines) uniquely developed in Japan are thought to contribute to medical treatment for upper gastrointestinal symptoms. Rikkunshito is a Kampo medicine often used to treat dyspeptic symptoms. Over the past few years, several studies have investigated the efficacy of rikkunshito for dysmotility, for example, upper abdominal complaints, in animals and humans. Rikkunshito ameliorated the decrease in gastric motility and anorexia in cisplatin-treated rats, stress-loaded mice, and selective serotonin reuptake inhibitor-treated rats by enhancing plasma ghrelin levels via serotonin2B/2C receptor antagonism. In addition, rikkunshito ameliorated the decrease in food intake in aged mice and stress-loaded decreased gastric motility via enhanced ghrelin receptor signaling. Several clinical studies revealed that rikkunshito was effective in ameliorating upper gastrointestinal symptoms, including dyspepsia, epigastric pain, and postprandial fullness. In this review, we discuss these studies and propose additional evidence-based research that may promote the clinical use of Kampo medicines, particularly rikkunshito, for treating anorexia and gastrointestinal dysfunction

Vulnerability to psychological stress-induced anorexia in female mice depends on blockade of ghrelin signal in nucleus tractus solitarius

Background and Purpose Women have a higher incidence of eating disorders than men. We investigated whether the effects of ghrelin on feeding are affected by sex and stress, and to elucidate the mechanisms that may cause sex differences in stress-mediated anorexia, focusing on ghrelin. Experimental Approach Acylated ghrelin was administered to naive and psychologically stressed male and female C57BL/6J mice, followed by measurements of food intake and plasma hormone levels. Ovariectomy was performed to determine the effects of ovary-derived oestrogen on stress-induced eating disorders in female mice. The numbers ofAgrporc-FosmRNA-positive cells and estrogen receptor alpha/c-Fos protein-double-positive cells were assessed. Key Results Ghrelin administration to naive female mice caused a higher increase in food intake, growth hormone secretion,AgrpmRNA expression in the arcuate nucleus andc-Fosexpression in the nucleus tractus solitarius (NTS) than in male mice. In contrast, psychological stress caused a more sustained reduction in food intake in females than males. The high sensitivity of naive females to exogenous ghrelin was attenuated by stress exposure. The stress-induced decline in food intake was not abolished by ovariectomy. Estrogen receptor-alpha but not -beta antagonism prevented the decrease in food intake under stress. Estrogen receptor-alpha/c-Fos-double-positive cells in the NTS were significantly increased by stress only in females. Conclusion and Implications Stress-mediated eating disorders in females may be due to blockade of ghrelin signalling via estrogen receptor-alpha activation in the NTS. Targeting the ghrelin signal in the brain could be a new treatment strategy to prevent these disorders

Usefulness of a Kampo Medicine on Stress-Induced Delayed Gastric Emptying in Mice

Anxiety and depression often occur with gastrointestinal symptoms. Although the Japanese traditional medicine (Kampo medicine) bukuryoingohangekobokuto (BGH) is approved for treating anxiety, neurotic gastritis, and heartburn, its effect on gastrointestinal motility remains poorly known. This study aimed to examine the effect of BGH on delayed gastric emptying in stress model mice and clarified its action mechanism. Seven-week-old C57BL/6 male mice were acclimated for a week and fasted overnight. Stress hormone, corticotropin-releasing factor (CRF), was intracerebroventricularly injected to mice, and solid nutrient meal (ground chow and distilled water) was orally administered 1 hour after. Gastric contents were collected to evaluate gastric emptying rates by measuring its dry weight. Injection of CRF (0.3 or 1.0 μg/mouse) significantly delayed the 2-hour gastric emptying in mice. BGH (1.0 g/kg), which was administered 30 minutes before the CRF injection, significantly ameliorated the delayed gastric emptying induced by CRF (0.3 μg/mouse). BGH (0.5, 1.0 g/kg) significantly enhanced the 1-hour gastric emptying and slightly increased the 2-hour gastric emptying in mice without CRF injection. In vitro functional assays showed that components of BGH antagonized or inhibited CRF type-2, dopamine D2/D3, neuropeptide Y Y2 receptors, or acetylcholinesterase. In conclusion, the components of BGH may exert synergistic effects on improving gastric emptying via various targets. BGH is considered to be potentially useful for treating gastrointestinal dysmotility with psychological symptoms

Changes in Ghrelin-Related Factors in Gastroesophageal Reflux Disease in Rats

To examine gastrointestinal hormone profiles and functional changes in gastroesophageal reflux disease (GERD), blood levels of the orexigenic hormone ghrelin were measured in rats with experimentally induced GERD. During the experiment, plasma acyl ghrelin levels in GERD rats were higher than those in sham-operated rats, although food intake was reduced in GERD rats. Although plasma levels of the appetite-suppressing hormone leptin were significantly decreased in GERD rats, no changes were observed in cholecystokinin levels. Repeated administration of rat ghrelin to GERD rats had no effect on the reduction in body weight or food intake. Therefore, these results suggest that aberrantly increased secretion of peripheral ghrelin and decreased ghrelin responsiveness may occur in GERD rats. Neuropeptide Y and agouti-related peptide mRNA expression in the hypothalamus of GERD rats was significantly increased, whereas proopiomelanocortin mRNA expression was significantly decreased compared to that in sham-operated rats. However, melanin-concentrating hormone (MCH) and prepro-orexin mRNA expression in the hypothalamus of GERD rats was similar to that in sham-operated rats. These results suggest that although GERD rats have higher plasma ghrelin levels, ghrelin signaling in GERD rats may be suppressed due to reduced MCH and/or orexin synthesis in the hypothalamus

Decreased Motility of the Lower Esophageal Sphincter in a Rat Model of Gastroesophageal Reflux Disease May Be Mediated by Reductions of Serotonin and Acetylcholine Signaling

To elucidate the altered function of the lower esophageal sphincter (LES) in gastroesophageal reflux disease (GERD), we evaluated the motility proximal to LES using force transducers, contraction and relaxation responses to neurotransmitters in LES strips, and gene expression of neurotransmitter receptors in GERD rats. Force transducers were applied to the proximal LES, and contraction of the LES was monitored during free moving. In addition, LES was isolated from sham-operated and GERD rats to investigate the LES function in an organ bath, and to determine gene expression. The in vivo motility proximal to LES (% motility index) in conscious rats was decreased by atropine treatment and increased by cisapride (5-HT4 receptor agonist) treatment. Acetylcholine- and serotonin (5-HT)-induced LES contraction and sodium nitroprusside-induced relaxation in LES strips of GERD rats markedly decreased compared to sham-operated rats. The mRNA expressions of 5-HT4 and muscarinic acetylcholine 3 receptors were significantly reduced in esophageal LES strips of GERD rats compared with sham-operated rats. Intraperitoneal administration of cisapride improves the erosive damage in the esophagus in GERD rats. It is suggested that the reduction of 5-HT-induced contraction in LES strips in GERD rats may be partly due to the decrease in 5-HT4-receptor activation. The reduction of LES function may be due to the decrease in neurotransmitters signal transduction, leading to the deterioration of histopathological damage in GERD

Bcl-2-dependent autophagy disruption during aging impairs amino acid utilization that is restored by hochuekkito

Chronic undernutrition contributes to the increase in frailty observed among elderly adults, which is a pressing issue in the sector of health care for older people worldwide. Autophagy, an intracellular recycling system, is closely associated with age-related pathologies. Therefore, decreased autophagy in aging could be involved in the disruption of energy homeostasis that occurs during undernutrition; however, the physiological mechanisms underlying this process remain unknown. Here, we showed that 70% daily food restriction (FR) induced fatal hypoglycemia in 23-26-month-old (aged) mice, which exhibited significantly lower hepatic autophagy than 9-week-old (young) mice. The liver expressions of Bcl-2, an autophagy-negative regulator, and Beclin1-Bcl-2 binding, were increased in aged mice compared with young mice. The autophagy inducer Tat-Beclin1 D11, not the mTOR inhibitor rapamycin, decreased the plasma levels of the glucogenic amino acid and restored the blood glucose levels in aged FR mice. Decreased liver gluconeogenesis, body temperature, physical activity, amino acid metabolism, and hepatic mitochondrial dynamics were observed in the aged FR mice. These changes were restored by treatment with hochuekkito that is a herbal formula containing several autophagy-activating ingredients. Our results indicate that Bcl-2 upregulation in the liver during the aging process disturbs autophagy activation, which increases the vulnerability to undernutrition. The promotion of liver autophagy may offer clinical therapeutic benefits to frail elderly patients