Koji Ataka

Centrally administered nesfatin-1 inhibits feeding behaviour and gastroduodenal motility in mice.

Nesfatin-1 was recently identified as a peptide with anorexigenic effects that is localized in the hypothalamus and adipocytes. Not much is known about the effect of nesfatin-1 on gut motility. Food intake was measured after intracerebroventricular administration of nesfatin-1 in food-deprived mice. Antral and duodenal motility was assessed by using a manometric method in conscious fed mice. We found that centrally administered nesfatin-1 decreased food intake and inhibited gastroduodenal motility in mice. These results suggest that nesfatin-1 influences gut motility and feeding behaviour.

Obestatin inhibits motor activity in the antrum and duodenum in the fed state of conscious rats

Obestatin is a novel peptide encoded by the ghrelin precursor gene; however, its effects on gastrointestinal motility remain controversial. Here we have examined the effects of obestatin on fed and fasted motor activities in the stomach and duodenum of freely moving conscious rats. We examined the effects of intravenous (IV) injection of obestatin on the percentage motor index (%MI) and phase III-like contractions in the antrum and duodenum. The brain mechanism mediating the action of obestatin on gastroduodenal motility and the involvement of vagal afferent pathway were also examined. Between 30 and 90 min after IV injection, obestatin decreased the %MI in the antrum and prolonged the time taken to return to fasted motility in the duodenum in fed rats given 3 g of chow after 18 h of fasting. Immunohistochemical analysis demonstrated that corticotropin-releasing factor- and urocortin-2-containing neurons in the paraventricular nucleus in the hypothalamus were activated by IV injection of obestatin. Intracerebroventricular injection of CRF type 1 and type 2 receptor antagonists prevented the effects of obestatin on gastroduodenal motility. Capsaicin treatment blocked the effects of obestatin on duodenal motility but not on antral motility. Obestatin failed to antagonize ghrelin-induced stimulation of gastroduodenal motility. These results suggest that, in the fed state, obestatin inhibits motor activity in the antrum and duodenum and that CRF type 1 and type 2 receptors in the brain might be involved in these effects of obestatin on gastroduodenal motility.

Bone Marrow-Derived Microglia Infiltrate into the Paraventricular Nucleus of Chronic Psychological Stress-Loaded Mice

Abstract Background Microglia of the central nervous system act as sentinels and rapidly react to infection or inflammation. The pathophysiological role of bone marrow-derived microglia is of particular interest because they affect neurodegenerative disorders and neuropathic pain. The hypothesis of the current study is that chronic psychological stress (chronic PS) induces the infiltration of bone marrow-derived microglia into hypothalamus by means of chemokine axes in brain and bone marrow. Methods and Findings Here we show that bone marrow-derived microglia specifically infiltrate the paraventricular nucleus (PVN) of mice that received chronic PS. Bone marrow derived-microglia are CX3CR1lowCCR2+CXCR4high, as distinct from CX3CR1highCCR2-CXCR4low resident microglia, and express higher levels of interleukin-1β (IL-1β) but lower levels of tumor necrosis factor-α (TNF-α). Chronic PS stimulates the expression of monocyte chemotactic protein-1 (MCP-1) in PVN neurons, reduces stromal cell-derived factor-1 (SDF-1) in the bone marrow and increases the frequency of CXCR4+ monocytes in peripheral circulation. And then a chemokine (C-C motif) receptor 2 (CCR2) or a β3-adrenoceptor blockade prevents infiltration of bone marrow-derived microglia in the PVN. Conclusion Chronic PS induces the infiltration of bone marrow-derived microglia into PVN, and it is conceivable that the MCP-1/CCR2 axis in PVN and the SDF-1/CXCR4 axis in bone marrow are involved in this mechanism.

Chronic foot-shock stress potentiates the influx of bone marrow-derived microglia into hippocampus

For several years, a new population of microglia derived from bone marrow has been described in multiple settings such as infection, trauma, and neurodegenerative disease. The aim of this study was to investigate the migration of bone marrow‐derived cells to the brain parenchyma after stress exposure. Stress exposure was performed in mice that had received bone marrow transplantation from GFP mice, allowing identification of blood‐derived elements within the brain. Electric foot‐shock exposure was chosen because of its ability to serve as fundamental and physical stress in mice. Bone marrow‐derived GFP+ cells migrated to the ventral part of the hippocampus and acquired a ramified microglia‐like morphology. Microglia marker Iba1 was expressed by 100% of the ramified cells, whereas ramified cells were negative for the astrocyte marker GFAP. Compared with the case in the control group, ramified cells significantly increased after chronic exposure to stress (5 days). One month after 5 days of stress exposure, ramified cells significantly decreased in ventral hippocampus compared with the group examined immediately after the last stress exposure. We report for the first time the migration of bone marrow‐derived cells to the ventral hippocampus after stress exposure. These cells have the characteristics of microglia. Mechanisms responsible for this migration and their roles in the brain remain to be determined.

Suppression of bone marrow–derived microglia in the amygdala improves anxiety-like behavior induced by chronic partial sciatic nerve ligation in mice

Summary Bone marrow–derived microglia aggregated in the central nucleus of the amygdala are involved in the chronic neuropathic pain–induced anxiety. ABSTRACT Chronic neuropathic pain causes abnormal sensitivities such as hyperalgesia and allodynia, and emotional abnormalities such as anxiety and depression. Although spinal cord microglia are involved in abnormal sensitivity to neuropathic pain, no previous studies have examined the mechanism of neuropathic pain–induced anxiety. Here, we examined the involvement of bone marrow (BM)–derived microglia aggregated in the amygdalae of mice with chronic neuropathic pain in the development of anxiety‐like behavior. We prepared partial sciatic nerve ligations (PSNL) in mice that received bone marrow transplantation from green fluorescent protein (GFP)–Tg mice after irradiation with head protection, and examined GFP‐positive microglia in the central nuclei of the amygdalae (CeA). On day 28 after PSNL, BM‐derived microglia aggregated in the CeA concurrent with anxiety‐like behavior. BM‐derived microglia in the CeA highly expressed interleukin (IL)–1&bgr; and C‐C chemokine receptor type 2 (CCR2). In addition, neurons in the CeA highly expressed monocyte chemotactic protein–1 (MCP‐1), a ligand for CCR2, in PSNL‐treated mice compared to sham‐operated mice, suggesting that the MCP‐1/CCR2 axis is involved in the recruitment of BM‐derived microglia. Oral administration of a CCR2 antagonist decreased the number of BM‐derived microglia in the CeA, and successfully reversed the anxiety‐like behavior and hypersensitivity to mechanical stimuli in PSNL‐treated mice. Microinjections of an IL‐1&bgr; receptor antagonist directly into the CeA successfully reversed the anxiety‐like behavior in the PSNL‐treated mice even though the neuropathic pain persisted. These results suggest that the recruitment of BM‐derived microglia to the CeA via the MCP‐1/CCR2 axis and neuron–microglia interactions might be important in the pathogenesis of neuropathic pain–induced anxiety.

Ghrelin, Des-Acyl Ghrelin, and Obestatin: Regulatory Roles on the Gastrointestinal Motility

Ghrelin, des-acyl ghrelin, and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. To examine the regulatory roles of these peptides, we applied the manometric measurement of gastrointestinal motility in freely moving conscious rat or mouse model. Ghrelin exerts stimulatory effects on the motility of antrum and duodenum in both fed and fasted state of animals. Des-acyl ghrelin exerts inhibitory effects on the motility of antrum but not on the motility of duodenum in the fasted state of animals. Obestatin exerts inhibitory effects on the motility of antrum and duodenum in the fed state but not in the fasted state of animals. NPY Y2 and Y4 receptors in the brain may mediate the action of ghrelin, CRF type 2 receptor in the brain may mediate the action of des-acyl ghrelin, whereas CRF type 1 and type 2 receptors in the brain may mediate the action of obestatin. Vagal afferent pathways might be involved in the action of ghrelin, but not involved in the action of des-acyl ghrelin, whereas vagal afferent pathways might be partially involved in the action of obestatin.

Regulation of Gastroduodenal Motility: Acyl Ghrelin, Des-Acyl Ghrelin and Obestatin and Hypothalamic Peptides

Real-time measurements for gut motility in conscious rats or mice combined with intracerebroventricular or intravenous injection of peptide agonists or antagonists allow us to understand the regulatory mechanism of gastrointestinal motility. Neuropeptide Y (NPY) in the arcuate nucleus in the hypothalamus stimulates the fasted motility in the duodenum, while urocortin in the paraventricular nucleus inhibits fed and fasted motility in the antrum and duodenum. Acyl ghrelin exerts stimulatory effects on the motility of the antrum and duodenum in both the fed and fasted state of animals. NPY Y2 and Y4 receptors in the brain may mediate the action of acyl ghrelin, and vagal afferent pathways might be involved in this mechanism. Des-acyl ghrelin exerts inhibitory effects on the motility of the antrum but not on the motility of the duodenum in the fasted state of animals. CRF type 2 receptor in the brain may mediate the action of des-acyl ghrelin, and vagal afferent pathways might not be involved in this mechanism. Obestatin exerts inhibitory effects on the motility of the antrum and duodenum in the fed state but not in the fasted state of animals. CRF type 1 and type 2 receptors in the brain may mediate the action of obestatin, and vagal afferent pathways might be partially involved in this mechanism.

Mesenchymal stem cell therapy ameliorates diabetic hepatocyte damage in mice by inhibiting infiltration of bone marrow–derived cells

Although mesenchymal stem cells (MSCs) have been implicated in hepatic injury, the mechanism through which they contribute to diabetic liver disease has not been clarified. In this study, we investigated the effects of MSC therapy on diabetic liver damage with a focus on the role of bone‐marrow–derived cells (BMDCs), which infiltrate the liver, and elucidated the mechanism mediating this process. Rat bone‐marrow (BM)‐derived MSCs were administered to high‐fat diet (HFD)‐induced type 2 diabetic mice and streptozotocin (STZ)‐induced insulin‐deficient diabetic mice. MSC‐conditioned medium (MSC‐CM) was also administered to examine the trophic effects of MSCs on liver damage. Therapeutic effects of MSCs were analyzed by assessing serum liver enzyme levels and histological findings. Kinetic and molecular profiles of BMDCs in the liver were evaluated using BM‐chimeric mice. Curative effects of MSC and MSC‐CM therapies were similar because both ameliorated the aggravation of aspartate aminotransferase and alanine aminotransferase at 8 weeks of treatment, despite persistent hyperlipidemia and hyperinsulinemia in HFD‐diabetic mice and persistent hyperglycemia in STZ‐diabetic mice. Furthermore, both therapies suppressed the abnormal infiltration of BMDCs into the liver, reversed excessive expression of proinflammatory cytokines in parenchymal cells, and regulated proliferation and survival signaling in the liver in both HFD‐ and STZ‐diabetic mice. In addition to inducing hepatocyte regeneration in STZ‐diabetic mice, both therapies also prevented excessive lipid accumulation and apoptosis of hepatocytes and reversed insulin resistance (IR) in HFD‐diabetic mice. Conclusion: MSC therapy is a powerful tool for repairing diabetic hepatocyte damage by inhibiting inflammatory reactions induced by BMDCs and IR. These effects are likely the result of humoral factors derived from MSCs. (Hepatology 2014;59:1816–1829)

Wood creosote prevents CRF-induced motility via 5-HT3 receptors in proximal and 5-HT4 receptors in distal colon in rats.

Wood creosote has been used as an herbal medicine against acute diarrhea caused by food poisoning and has an inhibitory effect on colonic motility and enterotoxin-induced ion secretion. Since no previous studies have examined the effects of wood creosote on stress-induced alteration of colonic motility, we examined the effects on the colonic motility altered by intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF), which is a key mediator in responses to stress. We recorded motor activity in proximal and distal colon of unrestrained conscious rats via two manometory catheters. The frequencies of phase III-like contraction and the % motor indices in both proximal and distal colon were measured. At the same time the number of fecal pellets excreted was counted. I.c.v. injection of CRF increased the motor activity in both proximal and distal colon, and these effects were completely antagonized by i.c.v. injection of a selective CRF type 1 antagonist but not by a CRF type 2 antagonist. Changes in colonic motility induced by CRF were reversed by intravenously administered wood creosote. Intraluminal administration of the 5-HT(3) receptor antagonist granisetron, or the 5-HT(4) receptor antagonist SB 204070 blocked the increase in colonic motility induced by i.c.v. injection of CRF. Wood creosote prevented the increase in colonic motility induced by the 5-HT(3) receptor agonist SR57227A in the proximal colon, while it prevented the increase in colonic motility induced by the 5-HT(4) receptor agonist RS67506 in the distal colon. These results indicate that wood creosote prevents the increase in colonic motility induced by CRF via 5-HT(3) receptors in the proximal colon, and via 5-HT(4) receptors in the distal colon, suggesting that wood creosote might be useful to treat stress-induced diarrhea.

Ghrelin, des-acyl ghrelin and obestatin on the gastrointestinal motility

Ghrelin, des-acyl ghrelin and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. Ghrelin exerts stimulatory effects on the motility of antrum and duodenum in both fed and fasted state of animals. On the other hand, des-acyl ghrelin exerts inhibitory effects on the motility of antrum but not on the motility of duodenum in the fasted state of animals. Obestatin exerts inhibitory effects on the motility of antrum and duodenum in the fed state but not in the fasted state of animals. NPY Y2 and Y4 receptors in the brain may mediate the action of ghrelin, CRF type 2 receptor in the brain may mediate the action of des-acyl ghrelin, whereas CRF type 1 and type 2 receptors in the brain may mediate the action of obestatin.