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Sample records for ghrelin induces fos

  1. Peripheral injection of ghrelin induces Fos expression in the dorsomedial hypothalamic nucleus in rats

    PubMed Central

    Kobelt, Peter; Wisser, Anna-Sophia; Stengel, Andreas; Goebel, Miriam; Inhoff, Tobias; Noetzel, Steffen; Veh, Rüdiger W.; Bannert, Norbert; van der Voort, Ivo; Wiedenmann, Bertram; Klapp, Burghard F.; Taché, Yvette; Mönnikes, Hubert

    2009-01-01

    Peripheral ghrelin has been shown to act as a gut–brain peptide exerting a potent orexigenic effect on food intake. The dorsomedial nucleus of the hypothalamus (DMH) is innervated by projections from other brain areas being part of the network of nuclei controlling energy homeostasis, among others NPY/AgRP-positive fibers arising from the arcuate nucleus (ARC). The aim of the study was to determine if peripherally administered ghrelin affects neuronal activity in the DMH, as assessed by Fos expression. The number of Fos positive neurons was determined in the DMH, paraventricular nucleus of the hypothalamus (PVN), ARC, ventromedial hypothalamic nucleus (VMH), nucleus of the solitary tract (NTS) and in the area postrema(AP) in non-fasted Sprague–Dawley rats in response to intraperitoneally (ip) injected ghrelin (3 nmol/rat) or vehicle (0.15 M NaCl). Peripheral ghrelin induced a significant increase in the number of Fos-ir positive neurons/section compared with vehicle in the ARC (mean±SEM: 49±2 vs. 23±2 neurons/section, p=0.001), PVN (69±5 vs. 34±3, p=0.001), and DMH (142±5 vs. 83±5, p<0.001). Fos-ir positive neurons were mainly localized within the ventral part of the DMH. No change in Fos expression was observed in the VMH (53±8 vs. 48±6, p=0.581), NTS (42±2 vs.40±3, p=0.603), and in the AP (7±1 vs. 5±1, p=0.096). Additional double-labelling with anti-Fos and anti-AgRP revealed that Fos positive neurons in the DMH were encircled by a network of AgRP-ir positive fibers. These data indicate that peripheral ghrelin activates DMH neurons and that NPY-/AgRP-positive fibers may be involved in the response. PMID:18329635

  2. Activation of c-fos expression in the rat inferior olivary nucleus by ghrelin.

    PubMed

    Zhang, Weizhen; Lin, Theodore R; Hu, Yuexian; Fan, Yongyi; Zhao, Lili; Mulholland, Michael W

    2003-12-26

    Ghrelin, a novel 28-amino-acid hormone secreted by gastric oxyntic glands, stimulates food intake and induces adiposity. We examined whether ghrelin activates the inferior olivary nucleus. Systemic administration of ghrelin (37 nmol/kg) induced the expression of c-fos immunoreactivity in inferior olive neurons (n=6 rats). The number of neurons containing c-fos staining was significantly increased in the ghrelin-treated rats (65+/-14 vs.11+/-6 positive neurons, n=5). No significant difference in c-fos-positive neurons was observed between left (32+/-5) and right (33+/-6) inferior olivary nuclei. The number of c-fos-positive neurons in rats with bilateral vagotomy was not significantly different from those with intact vagal nerves. The present study demonstrates that ghrelin induces c-fos expression in inferior olivary nucleus via a central mechanism.

  3. A circulating ghrelin mimetic attenuates light-induced phase delay of mice and light-induced Fos expression in the suprachiasmatic nucleus of rats.

    PubMed

    Yi, Chun-Xia; Challet, Etienne; Pévet, Paul; Kalsbeek, Andries; Escobar, Carolina; Buijs, Ruud M

    2008-04-01

    Anatomical evidence suggests that the ventromedial arcuate nucleus (vmARC) is a route for circulating hormonal communications to the suprachiasmatic nucleus (SCN). Whether this vmARC-SCN connection is involved in the modulation of circadian activity of the SCN is not yet known. We recently demonstrated, in rats, that intravenous (i.v.) injection of a ghrelin mimetic, GHRP-6, during the daytime activated neurons in the vmARC and reduced the normal endogenous daytime Fos expression in the SCN. In the present study we show that i.v. administration of GHRP-6 decreases light-induced Fos expression at ZT13 in the rat SCN by 50%, indicating that light-induced changes in the SCN Fos expression can also be reduced by GHRP-6. Because it is difficult to study light-induced phase changes in rats, we examined the functional effects of GHRP-6 on light-induced phase shifts in mice and demonstrated that peripherally injected GHRP-6 attenuates light-induced phase delays at ZT13 by 45%. However, light-induced Fos expression in the mice SCN was not blocked by GHRP-6. These results illustrate that acute stimulation of the ghrelinergic system may modulate SCN activity, but that its effect on light-induced phase shifts and Fos expression in the SCN might be species related.

  4. Peptide YY directly inhibits ghrelin-activated neurons of the arcuate nucleus and reverses fasting-induced c-Fos expression.

    PubMed

    Riediger, Thomas; Bothe, Christine; Becskei, Csilla; Lutz, Thomas A

    2004-01-01

    The hypothalamic arcuate nucleus (Arc) monitors and integrates hormonal and metabolic signals involved in the maintenance of energy homeostasis. The orexigenic peptide ghrelin is secreted from the stomach during negative status of energy intake and directly activates neurons of the medial arcuate nucleus (ArcM) in rats. In contrast to ghrelin, peptide YY (PYY) is released postprandially from the gut and reduces food intake when applied peripherally. Neurons in the ArcM express ghrelin receptors and neuropeptide Y receptors. Thus, PYY may inhibit feeding by acting on ghrelin-sensitive Arc neurons. Using extracellular recordings, we (1) characterized the effects of PYY on the electrical activity of ghrelin-sensitive neurons in the ArcM of rats. In order to correlate the effect of PYY on neuronal activity with the energy status, we (2) investigated the ability of PYY to reverse fasting-induced c-Fos expression in Arc neurons of mice. In addition, we (3) sought to confirm that PYY reduces food intake under our experimental conditions. Superfusion of PYY reversibly inhibited 94% of all ArcM neurons by a direct postsynaptic mechanism. The PYY-induced inhibition was dose-dependent and occurred at a threshold concentration of 10(-8)M. Consistent with the opposite effects of ghrelin and PYY on food intake, a high percentage (50%) of Arc neurons was activated by ghrelin and inhibited by PYY. In line with this inhibitory action, peripherally injected PYY partly reversed the fasting-induced c-Fos expression in Arc neurons of mice. Similarly, refeeding of food-deprived mice reversed the fasting-induced activation in the Arc. Furthermore, peripherally injected PYY reduced food intake in 12-hour fasted mice. Thus the activity of Arc neurons correlated with the feeding status and was not only reduced by feeding but also by administration of PYY in non-refed mice. In conclusion, our current observations suggest that PYY may contribute to signaling a positive status of energy intake

  5. Actions of Agonists and Antagonists of the ghrelin/GHS-R Pathway on GH Secretion, Appetite, and cFos Activity

    PubMed Central

    Hassouna, Rim; Labarthe, Alexandra; Zizzari, Philippe; Videau, Catherine; Culler, Michael; Epelbaum, Jacques; Tolle, Virginie

    2012-01-01

    The stimulatory effects of ghrelin, a 28-AA acylated peptide originally isolated from stomach, on growth hormone (GH) secretion and feeding are exclusively mediated through the growth hormone secretagogue 1a receptor (GHS-R1a), the only ghrelin receptor described so far. Several GHS-R1a agonists and antagonists have been developed to treat metabolic or nutritional disorders but their mechanisms of action in the central nervous system remain poorly understood. In the present study, we compared the activity of BIM-28163, a GHS-R1a antagonist, and of several agonists, including native ghrelin and the potent synthetic agonist, BIM-28131, to modulate food intake, GH secretion, and cFos activity in arcuate nucleus (ArcN), nucleus tractus solitarius (NTS), and area postrema (AP) in wild-type and NPY-GFP mice. BIM-28131 was as effective as ghrelin in stimulating GH secretion, but more active than ghrelin in inducing feeding. It stimulated cFos activity similarly to ghrelin in the NTS and AP but was more powerful in the ArcN, suggesting that the super-agonist activity of BIM-28131 is mostly mediated in the ArcN. BIM-28163 antagonized ghrelin-induced GH secretion but not ghrelin-induced food consumption and cFos activation, rather it stimulated food intake and cFos activity without affecting GH secretion. The level of cFos activation was dependent on the region considered: BIM-28163 was as active as ghrelin in the NTS, but less active in the ArcN and AP. All compounds also induced cFos immunoreactivity in ArcN NPY neurons but BIM-28131 was the most active. In conclusion, these data demonstrate that two peptide analogs of ghrelin, BIM-28163, and BIM-28131, are powerful stimulators of appetite in mice, acting through pathways and key brain regions involved in the control of appetite that are only partially superimposable from those activated by ghrelin. A better understanding of the molecular pathways activated by these compounds could be useful in devising future therapeutic

  6. Anti-ghrelin Spiegelmer inhibits exogenous ghrelin-induced increases in food intake, hoarding, and neural activation, but not food deprivation-induced increases

    PubMed Central

    Teubner, Brett J. W.

    2013-01-01

    Circulating concentrations of the stomach-derived “hunger-peptide” ghrelin increase in direct proportion to the time since the last meal. Exogenous ghrelin also increases food intake in rodents and humans, suggesting ghrelin may increase post-fast ingestive behaviors. Food intake after food deprivation is increased by laboratory rats and mice, but not by humans (despite dogma to the contrary) or by Siberian hamsters; instead, humans and Siberian hamsters increase food hoarding, suggesting the latter as a model of fasting-induced changes in human ingestive behavior. Exogenous ghrelin markedly increases food hoarding by ad libitum-fed Siberian hamsters similarly to that after food deprivation, indicating sufficiency. Here, we tested the necessity of ghrelin to increase food foraging, food hoarding, and food intake, and neural activation [c-Fos immunoreactivity (c-Fos-ir)] using anti-ghrelin Spiegelmer NOX-B11–2 (SPM), an l-oligonucleotide that specifically binds active ghrelin, inhibiting peptide-receptor interaction. SPM blocked exogenous ghrelin-induced increases in food hoarding the first 2 days after injection, and foraging and food intake at 1–2 h and 2–4 h, respectively, and inhibited hypothalamic c-Fos-ir. SPM given every 24 h across 48-h food deprivation inconsistently inhibited food hoarding after refeeding and c-Fos-ir, similarly to inabilities to do so in laboratory rats and mice. These results suggest that ghrelin may not be necessary for food deprivation-induced foraging and hoarding and neural activation. A possible compensatory response, however, may underlie these findings because SPM treatment led to marked increases in circulating ghrelin concentrations. Collectively, these results show that SPM can block exogenous ghrelin-induced ingestive behaviors, but the necessity of ghrelin for food deprivation-induced ingestive behaviors remains unclear. PMID:23804279

  7. Anti-ghrelin Spiegelmer inhibits exogenous ghrelin-induced increases in food intake, hoarding, and neural activation, but not food deprivation-induced increases.

    PubMed

    Teubner, Brett J W; Bartness, Timothy J

    2013-08-15

    Circulating concentrations of the stomach-derived "hunger-peptide" ghrelin increase in direct proportion to the time since the last meal. Exogenous ghrelin also increases food intake in rodents and humans, suggesting ghrelin may increase post-fast ingestive behaviors. Food intake after food deprivation is increased by laboratory rats and mice, but not by humans (despite dogma to the contrary) or by Siberian hamsters; instead, humans and Siberian hamsters increase food hoarding, suggesting the latter as a model of fasting-induced changes in human ingestive behavior. Exogenous ghrelin markedly increases food hoarding by ad libitum-fed Siberian hamsters similarly to that after food deprivation, indicating sufficiency. Here, we tested the necessity of ghrelin to increase food foraging, food hoarding, and food intake, and neural activation [c-Fos immunoreactivity (c-Fos-ir)] using anti-ghrelin Spiegelmer NOX-B11-2 (SPM), an l-oligonucleotide that specifically binds active ghrelin, inhibiting peptide-receptor interaction. SPM blocked exogenous ghrelin-induced increases in food hoarding the first 2 days after injection, and foraging and food intake at 1-2 h and 2-4 h, respectively, and inhibited hypothalamic c-Fos-ir. SPM given every 24 h across 48-h food deprivation inconsistently inhibited food hoarding after refeeding and c-Fos-ir, similarly to inabilities to do so in laboratory rats and mice. These results suggest that ghrelin may not be necessary for food deprivation-induced foraging and hoarding and neural activation. A possible compensatory response, however, may underlie these findings because SPM treatment led to marked increases in circulating ghrelin concentrations. Collectively, these results show that SPM can block exogenous ghrelin-induced ingestive behaviors, but the necessity of ghrelin for food deprivation-induced ingestive behaviors remains unclear.

  8. Diet-induced obesity causes ghrelin resistance in arcuate NPY/AgRP neurons.

    PubMed

    Briggs, Dana I; Enriori, Pablo J; Lemus, Moyra B; Cowley, Michael A; Andrews, Zane B

    2010-10-01

    Circulating ghrelin is decreased in obesity, and peripheral ghrelin does not induce food intake in obese mice. We investigated whether ghrelin resistance was a centrally mediated phenomenon involving dysregulated neuropeptide Y (NPY) and agouti-related peptide (AgRP) circuits. We show that diet-induced obesity (DIO) (12 wk) suppresses the neuroendocrine ghrelin system by decreasing acylated and total plasma ghrelin, decreasing ghrelin and Goat mRNA in the stomach, and decreasing expression of hypothalamic GHSR. Peripheral (ip) or central (intracerebroventricular) ghrelin injection was able to induce food intake and arcuate nucleus Fos immunoreactivity in chow-fed but not high-fat diet-fed mice. DIO decreased expression of Npy and Agrp mRNA, and central ghrelin was unable to promote expression of these genes. Ghrelin did not induce AgRP or NPY secretion in hypothalamic explants from DIO mice. Injection of NPY intracerebroventricularly increased food intake in both chow-fed and high-fat diet-fed mice, indicating that downstream NPY/AgRP neural targets are intact and that defective NPY/AgRP function is a primary cause of ghrelin resistance. Ghrelin resistance in DIO is not confined to the NPY/AgRP neurons, because ghrelin did not stimulate growth hormone secretion in DIO mice. Collectively, our data suggests that DIO causes ghrelin resistance by reducing NPY/AgRP responsiveness to plasma ghrelin and suppressing the neuroendocrine ghrelin axis to limit further food intake. Ghrelin has a number of functions in the brain aside from appetite control, including cognitive function, mood regulation, and protecting against neurodegenerative diseases. Thus, central ghrelin resistance may potentiate obesity-related cognitive decline, and restoring ghrelin sensitivity may provide therapeutic outcomes for maintaining healthy aging.

  9. Diet-induced obesity causes peripheral and central ghrelin resistance by promoting inflammation.

    PubMed

    Naznin, Farhana; Toshinai, Koji; Waise, T M Zaved; NamKoong, Cherl; Md Moin, Abu Saleh; Sakoda, Hideyuki; Nakazato, Masamitsu

    2015-07-01

    Ghrelin, a stomach-derived orexigenic peptide, transmits starvation signals to the hypothalamus via the vagus afferent nerve. Peripheral administration of ghrelin does not induce food intake in high fat diet (HFD)-induced obese mice. We investigated whether this ghrelin resistance was caused by dysfunction of the vagus afferent pathway. Administration (s.c.) of ghrelin did not induce food intake, suppression of oxygen consumption, electrical activity of the vagal afferent nerve, phosphorylation of ERK2 and AMP-activated protein kinase alpha in the nodose ganglion, or Fos expression in hypothalamic arcuate nucleus of mice fed a HFD for 12 weeks. Administration of anti-ghrelin IgG did not induce suppression of food intake in HFD-fed mice. Expression levels of ghrelin receptor mRNA in the nodose ganglion and hypothalamus of HFD-fed mice were reduced. Inflammatory responses, including upregulation of macrophage/microglia markers and inflammatory cytokines, occurred in the nodose ganglion and hypothalamus of HFD-fed mice. A HFD blunted ghrelin signaling in the nodose ganglion via a mechanism involving in situ activation of inflammation. These results indicate that ghrelin resistance in the obese state may be caused by dysregulation of ghrelin signaling via the vagal afferent.

  10. DESACYL GHRELIN INHIBITS THE OREXIGENIC EFFECT OF PERIPHERALLY INJECTED GHRELIN IN RATS

    PubMed Central

    Inhoff, Tobias; Mönnikes, Hubert; Noetzel, Steffen; Stengel, Andreas; Goebel, Miriam; Dinh, Q. Thai; Riedl, Andrea; Bannert, Norbert; Wisser, Anna-Sophia; Wiedenmann, Bertram; Klapp, Burghard F.; Taché, Yvette

    2008-01-01

    Studies showed that the metabolic unlike the neuroendocrine effects of ghrelin could be abrogated by co-administered unacylated ghrelin. The aim was to investigate the interaction between ghrelin and desacyl ghrelin administered intraperitoneally on food intake and neuronal activity (c-Fos) in the arcuate nucleus in non-fasted rats. Ghrelin (13 μg/kg) significantly increased food intake within the first 30 min post injection. Desacyl ghrelin at 64 and 127 μg/kg injected simultaneously with ghrelin abolished the stimulatory effect of ghrelin on food intake. Desacyl ghrelin alone at both doses did not alter food intake. Both doses of desacyl ghrelin injected separately in the light phase had no effects on food intake when rats were fasted for 12 h. Ghrelin and desacyl ghrelin (64 μg/kg) injected alone increased the number of Fos positive neurons in the arcuate nucleus compared to vehicle. The effect on neuronal activity induced by ghrelin was significantly reduced when injected simultaneously with desacyl ghrelin. Double labeling revealed that nesfatin-1 immunoreactive neurons in the arcuate nucleus are activated by simultaneous injection of ghrelin and desacyl ghrelin. These results suggest that desacyl ghrelin suppresses ghrelin-induced food intake by curbing ghrelin-induced increased neuronal activity in the arcuate nucleus and recruiting nesfatin-1 immunopositive neurons. PMID:18938204

  11. Ghrelin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The gut hormone ghrelin was discovered in 1999. In the last 15 years, ample data have been generated on ghrelin. Bedsides its hallmark function as an appetite stimulator, ghrelin also has many other important functions. In this review, we discussed ghrelin's functions in learning and memory, gut mov...

  12. Cisplatin-induced anorexia and ghrelin.

    PubMed

    Hattori, Tomohisa; Yakabi, Koji; Takeda, Hiroshi

    2013-01-01

    Cisplatin, a formidable anticancer treatment, is used for several varieties of cancer. There are, however, many cases in which treatment must be abandoned due to a decrease in the patient's quality of life from loss of appetite associated with vomiting and nausea. There is a moderate degree of improvement in prevention of cisplatin-induced nausea and vomiting when serotonin (5-HT) 3 receptor antagonists, neurokinin 1 receptor antagonists, and steroids-either alone or in combination-are administered. The mechanism of action for anorexia, which continues during or after treatment, is, however, still unclear. This anorexia is, similar to the onset of vomiting and nausea, caused by the action of large amounts of 5-HT released as a result of cisplatin administration on tissue 5-HT receptors. Among the 5-HT receptors, the activation of 5-HT2b and 5-HT2c receptors, in particular, seems to play a major role in cisplatin-induced anorexia. Following activation of these two receptors, there is reduced gastric and hypothalamic secretion of the appetite-stimulating hormone ghrelin. There is ample evidence of the usefulness of exogenous ghrelin, synthetic ghrelin agonists, and the endogenous ghrelin signal-enhancer rikkunshito, which are expected to play significant roles in the clinical treatment and prevention of anorexia in future.

  13. Evidence that diet-induced hyperleptinemia, but not hypothalamic gliosis, causes ghrelin resistance in NPY/AgRP neurons of male mice.

    PubMed

    Briggs, Dana I; Lockie, Sarah H; Benzler, Jonas; Wu, Qunli; Stark, Romana; Reichenbach, Alex; Hoy, Andrew J; Lemus, Moyra B; Coleman, Harold A; Parkington, Helena C; Tups, Alex; Andrews, Zane B

    2014-07-01

    High-fat diet (HFD) feeding causes ghrelin resistance in arcuate neuropeptide Y (NPY)/Agouti-related peptide neurons. In the current study, we investigated the time course over which this occurs and the mechanisms responsible for ghrelin resistance. After 3 weeks of HFD feeding, neither peripheral nor central ghrelin increased food intake and or activated NPY neurons as demonstrated by a lack of Fos immunoreactivity or whole-cell patch-clamp electrophysiology. Pair-feeding studies that matched HFD calorie intake with chow calorie intake show that HFD exposure does not cause ghrelin resistance independent of body weight gain. We observed increased plasma leptin in mice fed a HFD for 3 weeks and show that leptin-deficient obese ob/ob mice are still ghrelin sensitive but become ghrelin resistant when central leptin is coadministered. Moreover, ob/ob mice fed a HFD for 3 weeks remain ghrelin sensitive, and the ability of ghrelin to induce action potential firing in NPY neurons was blocked by leptin. We also examined hypothalamic gliosis in mice fed a chow diet or HFD, as well as in ob/ob mice fed a chow diet or HFD and lean controls. HFD-fed mice exhibited increased glial fibrillary acidic protein-positive cells compared with chow-fed mice, suggesting that hypothalamic gliosis may underlie ghrelin resistance. However, we also observed an increase in hypothalamic gliosis in ob/ob mice fed a HFD compared with chow-fed ob/ob and lean control mice. Because ob/ob mice fed a HFD remain ghrelin sensitive, our results suggest that hypothalamic gliosis does not underlie ghrelin resistance. Further, pair-feeding a HFD to match the calorie intake of chow-fed controls did not increase body weight gain or cause central ghrelin resistance; thus, our evidence suggests that diet-induced hyperleptinemia, rather than diet-induced hypothalamic gliosis or HFD exposure, causes ghrelin resistance.

  14. Ghrelin

    PubMed Central

    Müller, T.D.; Nogueiras, R.; Andermann, M.L.; Andrews, Z.B.; Anker, S.D.; Argente, J.; Batterham, R.L.; Benoit, S.C.; Bowers, C.Y.; Broglio, F.; Casanueva, F.F.; D'Alessio, D.; Depoortere, I.; Geliebter, A.; Ghigo, E.; Cole, P.A.; Cowley, M.; Cummings, D.E.; Dagher, A.; Diano, S.; Dickson, S.L.; Diéguez, C.; Granata, R.; Grill, H.J.; Grove, K.; Habegger, K.M.; Heppner, K.; Heiman, M.L.; Holsen, L.; Holst, B.; Inui, A.; Jansson, J.O.; Kirchner, H.; Korbonits, M.; Laferrère, B.; LeRoux, C.W.; Lopez, M.; Morin, S.; Nakazato, M.; Nass, R.; Perez-Tilve, D.; Pfluger, P.T.; Schwartz, T.W.; Seeley, R.J.; Sleeman, M.; Sun, Y.; Sussel, L.; Tong, J.; Thorner, M.O.; van der Lely, A.J.; van der Ploeg, L.H.T.; Zigman, J.M.; Kojima, M.; Kangawa, K.; Smith, R.G.; Horvath, T.; Tschöp, M.H.

    2015-01-01

    Background The gastrointestinal peptide hormone ghrelin was discovered in 1999 as the endogenous ligand of the growth hormone secretagogue receptor. Increasing evidence supports more complicated and nuanced roles for the hormone, which go beyond the regulation of systemic energy metabolism. Scope of review In this review, we discuss the diverse biological functions of ghrelin, the regulation of its secretion, and address questions that still remain 15 years after its discovery. Major conclusions In recent years, ghrelin has been found to have a plethora of central and peripheral actions in distinct areas including learning and memory, gut motility and gastric acid secretion, sleep/wake rhythm, reward seeking behavior, taste sensation and glucose metabolism. PMID:26042199

  15. The Hormone Ghrelin Prevents Traumatic Brain Injury Induced Intestinal Dysfunction

    PubMed Central

    Bansal, Vishal; Ryu, Seok Yong; Blow, Chelsea; Costantini, Todd; Loomis, William; Eliceiri, Brian; Baird, Andrew; Wolf, Paul

    2010-01-01

    Abstract Intestinal barrier breakdown following traumatic brain injury (TBI) is characterized by increased intestinal permeability, leading to bacterial translocation, and inflammation. The hormone ghrelin may prevent intestinal injury and have anti-inflammatory properties. We hypothesized that exogenous ghrelin prevents intestinal injury following TBI. A weight-drop model created severe TBI in three groups of anesthetized Balb/c mice. Group TBI: animals underwent TBI only; Group TBI/ghrelin: animals were given 10 μg of ghrelin intraperitoneally prior and 1 h following TBI; Group sham: no TBI or ghrelin injection. Intestinal permeability was measured 6 h following TBI by detecting serum levels of FITC-Dextran after injection into the intact ileum. The terminal ileum was harvested for histology, expression of the tight junction protein MLCK and inflammatory cytokine TNF-α. Permeability increased in the TBI group compared to the sham group (109.7 ± 21.8 μg/mL vs. 32.2 ± 10.1 μg/mL; p < 0.002). Ghrelin prevented TBI-induced permeability (28.3 ± 4.2 μg/mL vs. 109.7 ± 21.8 μg/mL; p < 0.001). The intestines of the TBI group showed blunting and necrosis of villi compared to the sham group, while ghrelin injection preserved intestinal architecture. Intestinal MLCK increased 73% compared to the sham group (p < 0.03). Ghrelin prevented TBI-induced MLCK expression to sham levels. Intestinal TNF-α increased following TBI compared to the sham group (46.2 ± 7.1 pg/mL vs. 24.4 ± 2.2 pg/mL p < 0.001). Ghrelin reduced TNF-α to sham levels (29.2 ± 5.0 pg/mL; p = NS). We therefore conclude that ghrelin prevents TBI-induced injury, as determined by intestinal permeability, histology, and intestinal levels of TNF-α. The mechanism for ghrelin mediating intestinal protection is likely multifactorial, and further studies are needed to delineate these possibilities. PMID:20858122

  16. Interleukin-1 beta-induced anorexia is reversed by ghrelin.

    PubMed

    Gonzalez, Patricia Verónica; Cragnolini, Andrea Beatriz; Schiöth, Helgi Birgir; Scimonelli, Teresa Nieves

    2006-12-01

    Interleukins, in particular interleukin-1beta (IL-1beta), reduce food intake after peripheral and central administration, which suggests that they contribute to anorexia during various infectious, neoplastic, and autoimmune diseases. On the other hand, ghrelin stimulates food intake by acting on the central nervous system (CNS) and is considered an important regulator of food intake in both rodents and humans. In the present study, we investigated if ghrelin could reverse IL-1beta-induced anorexia. Intracerebroventricular (i.c.v.) injection of 15, 30 or 45 ng/microl of IL-1beta caused significant suppression of food intake in 20 h fasting animals. This effect lasted for a 24h period. Ghrelin (0.15 nmol or 1.5 nmol/microl) produced a significant increase in cumulative food intake in normally fed animals. However, it did not alter food intake in 20 h fasting animals. Central administration of ghrelin reduced the anorexic effect of IL-1beta (15 ng/microl). The effect was observed 30 min after injection and lasted for the next 24h. This study provides evidence that ghrelin is an orexigenic peptide capable of antagonizing IL-1beta-induced anorexia.

  17. Ghrelin knockout mice show decreased voluntary alcohol consumption and reduced ethanol-induced conditioned place preference.

    PubMed

    Bahi, Amine; Tolle, Virginie; Fehrentz, Jean-Alain; Brunel, Luc; Martinez, Jean; Tomasetto, Catherine-Laure; Karam, Sherif M

    2013-05-01

    Recent work suggests that stomach-derived hormone ghrelin receptor (GHS-R1A) antagonism may reduce motivational aspects of ethanol intake. In the current study we hypothesized that the endogenous GHS-R1A agonist ghrelin modulates alcohol reward mechanisms. For this purpose ethanol-induced conditioned place preference (CPP), ethanol-induced locomotor stimulation and voluntary ethanol consumption in a two-bottle choice drinking paradigm were examined under conditions where ghrelin and its receptor were blocked, either using ghrelin knockout (KO) mice or the specific ghrelin receptor (GHS-R1A) antagonist "JMV2959". We showed that ghrelin KO mice displayed lower ethanol-induced CPP than their wild-type (WT) littermates. Consistently, when injected during CPP-acquisition, JMV2959 reduced CPP-expression in C57BL/6 mice. In addition, ethanol-induced locomotor stimulation was lower in ghrelin KO mice. Moreover, GHS-R1A blockade, using JMV2959, reduced alcohol-stimulated locomotion only in WT but not in ghrelin KO mice. When alcohol consumption and preference were assessed using the two-bottle choice test, both genetic deletion of ghrelin and pharmacological antagonism of the GHS-R1A (JMV2959) reduced voluntary alcohol consumption and preference. Finally, JMV2959-induced reduction of alcohol intake was only observed in WT but not in ghrelin KO mice. Taken together, these results suggest that ghrelin neurotransmission is necessary for the stimulatory effect of ethanol to occur, whereas lack of ghrelin leads to changes that reduce the voluntary intake as well as conditioned reward by ethanol. Our findings reveal a major, novel role for ghrelin in mediating ethanol behavior, and add to growing evidence that ghrelin is a key mediator of the effects of multiple abused drugs.

  18. Anti‐ghrelin Spiegelmer NOX‐B11 inhibits neurostimulatory and orexigenic effects of peripheral ghrelin in rats

    PubMed Central

    Kobelt, P; Helmling, S; Stengel, A; Wlotzka, B; Andresen, V; Klapp, B F; Wiedenmann, B; Klussmann, S; Mönnikes, H

    2006-01-01

    Background and aims Ghrelin, the natural ligand of the growth hormone secretagogue receptor 1a, is the most powerful peripherally active orexigenic agent known. In rodents, ghrelin administration stimulates growth hormone release, food intake, and adiposity. Because of these effects, blocking of ghrelin has been widely discussed as a potential treatment for obesity. Spiegelmer NOX‐B11 is a synthetic l‐oligonucleotide, which was previously shown to bind ghrelin. We examined the effects of NOX‐B11 on ghrelin induced neuronal activation and food intake in non‐fasted rats. Methods Animals received various doses of NOX‐B11, inactive control Spiegelmer, or vehicle intravenously. Ghrelin or vehicle was administered intraperitoneally 12 hours later and food intake was measured over four hours. Neuronal activation was assessed as c‐Fos‐like immunoreactivity in the arcuate nucleus. Results Treatment with NOX‐B11 30 nmol suppressed ghrelin induced c‐Fos‐like immunoreactivity in the arcuate nucleus and blocked the ghrelin induced increase in food intake within the first half hour after ghrelin injection (mean 1.13 (SEM 0.59) g/kg body weight; 4.94 (0.63) g/kg body weight versus 0.58 (0.58) g/kg body weight; p<0.0001). Treatment with NOX‐B11 1 nmol or control Spiegelmer had no effect whereas treatment with NOX‐B11 10 nmol showed an intermediate effect on ghrelin induced food intake. Conclusions Spiegelmer NOX‐B11 suppresses ghrelin induced food intake and c‐Fos induction in the arcuate nucleus in rats. The use of an anti‐ghrelin Spiegelmer could be an innovative new approach to inhibit the biological action of circulating ghrelin. This may be of particular relevance to conditions associated with elevated plasma ghrelin, such as the Prader‐Willi syndrome. PMID:15994217

  19. Diet-induced obesity causes ghrelin resistance in reward processing tasks.

    PubMed

    Lockie, Sarah H; Dinan, Tara; Lawrence, Andrew J; Spencer, Sarah J; Andrews, Zane B

    2015-12-01

    Diet-induced obesity (DIO) causes ghrelin resistance in hypothalamic Agouti-related peptide (AgRP) neurons. However, ghrelin promotes feeding through actions at both the hypothalamus and mesolimbic dopamine reward pathways. Therefore, we hypothesized that DIO would also establish ghrelin resistance in the ventral tegmental area (VTA), a major site of dopaminergic cell bodies important in reward processing. We observed reduced sucrose and saccharin consumption in Ghrelin KO vs Ghrelin WT mice. Moreover, DIO reduced saccharin consumption relative to chow-fed controls. These data suggest that the deletion of ghrelin and high fat diet both cause anhedonia. To assess if these are causally related, we tested whether DIO caused ghrelin resistance in a classic model of drug reward, conditioned place preference (CPP). Chow or high fat diet (HFD) mice were conditioned with ghrelin (1mg/kg in 10ml/kg ip) in the presence or absence of food in the conditioning chamber. We observed a CPP to ghrelin in chow-fed mice but not in HFD-fed mice. HFD-fed mice still showed a CPP for cocaine (20mg/kg), indicating that they maintained the ability to develop conditioned behaviour. The absence of food availability during ghrelin conditioning sessions induced a conditioned place aversion, an effect that was still present in both chow and HFD mice. Bilateral intra-VTA ghrelin injection (0.33μg/μl in 0.5μl) robustly increased feeding in both chow-fed and high fat diet (HFD)-fed mice; however, this was correlated with body weight only in the chow-fed mice. Our results suggest that DIO causes ghrelin resistance albeit not directly in the VTA. We suggest there is impaired ghrelin sensitivity in upstream pathways regulating reward pathways, highlighting a functional role for ghrelin linking appropriate metabolic sensing with reward processing.

  20. Acyl Ghrelin Induces Insulin Resistance Independently of GH, Cortisol, and Free Fatty Acids

    PubMed Central

    Vestergaard, Esben T.; Jessen, Niels; Møller, Niels; Jørgensen, Jens Otto Lunde

    2017-01-01

    Ghrelin produced in the gut stimulates GH and ACTH secretion from the pituitary and also stimulates appetite and gastric emptying. We have shown that ghrelin also induces insulin resistance via GH-independent mechanisms, but it is unknown if this effect depends on ambient fatty acid (FFA) levels. We investigated the impact of ghrelin and pharmacological antilipolysis (acipimox) on insulin sensitivity and substrate metabolism in 8 adult hypopituitary patients on stable replacement with GH and hydrocortisone using a 2 × 2 factorial design: Ghrelin infusion, saline infusion, ghrelin plus short-term acipimox, and acipimox alone. Peripheral and hepatic insulin sensitivity was determined with a hyperinsulinemic euglycemic clamp in combination with a glucose tracer infusion. Insulin signaling was assayed in muscle biopsies. Peripheral insulin sensitivity was reduced by ghrelin independently of ambient FFA concentrations and was increased by acipimox independently of ghrelin. Hepatic insulin sensitivity was increased by acipimox. Insulin signaling pathways in skeletal muscle were not consistently regulated by ghrelin. Our data demonstrate that ghrelin induces peripheral insulin resistance independently of GH, cortisol, and FFA. The molecular mechanisms remain elusive, but we speculate that ghrelin is a hitherto unrecognized direct regulator of substrate metabolism. We also suggest that acipimox per se improves hepatic insulin sensitivity. PMID:28198428

  1. Ghrelin secretion is not reduced by increased fat mass during diet-induced obesity.

    PubMed

    Qi, Xiang; Reed, Jason T; Wang, Guiyun; Han, Song; Englander, Ella W; Greeley, George H

    2008-08-01

    Ghrelin is a stomach hormone that stimulates growth hormone (GH) secretion, adiposity, and food intake. Gastric ghrelin production and secretion are regulated by caloric intake; ghrelin secretion increases during fasting, decreases with refeeding, and is reduced by diet-induced obesity. The aim of the present study was to test the hypotheses that 1) an increase in body adiposity will play an inhibitory role in the reduction of gastric ghrelin synthesis and secretion during chronic ingestion of a high-fat (HF) diet and 2) chronic ingestion of an HF diet will suppress the rise in circulating ghrelin levels in response to acute fasting. Adult male Sprague-Dawley rats were fed a standard AIN-76A (approximately 5-12% of calories from fat) or an HF (approximately 45% of calories from fat) diet. The effect of increased adiposity on gastric ghrelin homeostasis was assessed by comparison of stomach ghrelin production and plasma ghrelin levels in obese and nonobese rats fed the HF diet. HF diet-fed, nonobese rats were generated by administration of triiodothyronine to lower body fat accumulation. Our findings indicate that an increased fat mass per se does not exert an inhibitory effect on ghrelin homeostasis during ingestion of the HF diet. Additionally, the magnitude of change in plasma ghrelin in response to fasting was not blunted, indicating that a presumed, endogenous signal for activation of ingestive behavior remains intact, despite excess stored calories in HF-fed rats.

  2. Ghrelin-induced sleep responses in ad libitum fed and food-restricted rats.

    PubMed

    Szentirmai, E; Hajdu, I; Obal, F; Krueger, James M

    2006-05-09

    Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor and a well-characterized food intake regulatory peptide. Hypothalamic ghrelin-, neuropeptide Y (NPY)-, and orexin-containing neurons form a feeding regulatory circuit. Orexins and NPY are also implicated in sleep-wake regulation. Sleep responses and motor activity after central administration of 0.2, 1, or 5 microg ghrelin in free-feeding rats as well as in feeding-restricted rats (1 microg dose) were determined. Food and water intake and behavioral responses after the light onset injection of saline or 1 microg ghrelin were also recorded. Light onset injection of ghrelin suppressed non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS) for 2 h. In the first hour, ghrelin induced increases in behavioral activity including feeding, exploring, and grooming and stimulated food and water intake. Ghrelin administration at dark onset also elicited NREMS and REMS suppression in hours 1 and 2, but the effect was not as marked as that, which occurred in the light period. In hours 3-12, a secondary NREMS increase was observed after some doses of ghrelin. In the feeding-restricted rats, ghrelin suppressed NREMS in hours 1 and 2 and REMS in hours 3-12. Data are consistent with the notion that ghrelin has a role in the integration of feeding, metabolism, and sleep regulation.

  3. Diet-induced obesity suppresses ghrelin in rat gastrointestinal tract and serum.

    PubMed

    Sahin, Ibrahim; Aydin, Suleyman; Ozkan, Yusuf; Dagli, Adile Ferda; Akin, Kadir Okhan; Guzel, Saadet Pilten; Catak, Zekiye; Ozercan, Mehmet Resat

    2011-09-01

    The aims of the present study were to examine ghrelin expression in serum and gastrointestinal tract (GIT) tissues, and to measure tissue ghrelin levels and obesity-related alterations in some serum biochemical variables in rats with diet-induced obesity (DIO). The study included 12 male rats, 60 days old. The rats were randomly allocated to two groups (n = 6). Rats in the DIO group were fed a cafeteria-style diet to induce obesity, while those in the control group were fed on standard rat pellets. After a 12 week diet program including an adaptation period all rats were decapitated, tissues were individually fixed, ghrelin expression was examined by immunohistochemistry , and tissue and serum ghrelin levels were measured by radioimmunoassay. Serum biochemical variables were measured using an autoanalyzer. When the baseline and week 12 body mass index and GIT ghrelin expression were compared between DIO and control rats, BMI had increased and ghrelin expression decreased due to obesity. The RIA results were consistent with these findings. Serum glucose, LDL cholesterol, and total cholesterol levels were elevated and HDL cholesterol significantly decreased in the DIO group. A comparison of GIT tissues between the control and obese groups demonstrated that ghrelin was decreased in all tissues of the latter. This decrease was brought about a decline in the circulating ghrelin pool. This suggests that rather than being associated with a change in a single tissue, obesity is a pathological condition in which ghrelin expression is changed in all tissues.

  4. The Anti-apoptotic Effect of Ghrelin on Restraint Stress-Induced Thymus Atrophy in Mice

    PubMed Central

    Kim, Tae-Jin; Kim, Jie Wan; Yoon, Jeong Seon; Kim, Hyuk Soon

    2016-01-01

    Thymic atrophy is a complication that results from exposure to many environmental stressors, disease treatments, and microbial challenges. Such acute stress-associated thymic loss can have a dramatic impact on the host's ability to replenish the necessary naïve T cell output to reconstitute the peripheral T cell numbers and repertoire to respond to new antigenic challenges. We have previously reported that treatment with the orexigenic hormone ghrelin results in an increase in the number and proliferation of thymocytes after dexamethasone challenge, suggesting a role for ghrelin in restraint stress-induced thymic involution and cell apoptosis and its potential use as a thymostimulatory agent. In an effort to understand how ghrelin suppresses thymic T cell apoptosis, we have examined the various signaling pathways induced by receptor-specific ghrelin stimulation using a restraint stress mouse model. In this model, stress-induced apoptosis in thymocytes was effectively blocked by ghrelin. Western blot analysis demonstrated that ghrelin prevents the cleavage of pro-apoptotic proteins such as Bim, Caspase-3, and PARP. In addition, ghrelin stimulation activates the Akt and Mitogen-activated protein kinases (MAPK) signaling pathways in a time/dose-dependent manner. Moreover, we also revealed the involvement of the FoxO3a pathway in the phosphorylation of Akt and ERK1/2. Together, these findings suggest that ghrelin inhibits apoptosis by modulating the stress-induced apoptotic signal pathway in the restraint-induced thymic apoptosis. PMID:27574503

  5. A ghrelin-growth hormone axis drives stress-induced vulnerability to enhanced fear

    PubMed Central

    Meyer, Retsina M.; Burgos-Robles, Anthony; Liu, Elizabeth; Correia, Susana S.; Goosens, Ki A.

    2014-01-01

    Hormones in the hypothalamus-pituitary-adrenal (HPA) axis mediate many of the bodily responses to stressors, yet there is not a clear relationship between the levels of these hormones and stress-associated mental illnesses such as post-traumatic stress disorder (PTSD). Therefore, other hormones are likely to be involved in this effect of stress. Here we used a rodent model of PTSD in which rats repeatedly exposed to a stressor display heightened fear learning following auditory Pavlovian fear conditioning. Our results show that stress-related increases in circulating ghrelin, a peptide hormone, are necessary and sufficient for stress-associated vulnerability to exacerbated fear learning and these actions of ghrelin occur in the amygdala. Importantly, these actions are also independent of the classic HPA stress axis. Repeated systemic administration of a ghrelin receptor agonist enhanced fear memory but did not increase either corticotropin releasing factor (CRF) or corticosterone. Repeated intra-amygdala infusion of a ghrelin receptor agonist produced a similar enhancement of fear memory. Ghrelin receptor antagonism during repeated stress abolished stress-related enhancement of fear memory without blunting stress-induced corticosterone release. We also examined links between ghrelin and growth hormone (GH), a major downstream effector of the ghrelin receptor. GH protein was upregulated in the amygdala following chronic stress, and its release from amygdala neurons was increased by ghrelin receptor stimulation. Virus-mediated overexpression of GH in the amygdala was also sufficient to increase fear. Finally, virus-mediated overexpression of a GH receptor antagonist was sufficient to block the fear enhancing effects of repeated ghrelin receptor stimulation. Thus, ghrelin requires GH in the amygdala to exert fear-enhancing effects. These results suggest that ghrelin mediates a novel branch of the stress response and highlight a previously unrecognized role for ghrelin

  6. The Influence of Ghrelin on the Development of Dextran Sodium Sulfate-Induced Colitis in Rats.

    PubMed

    Matuszyk, Aleksandra; Ceranowicz, Dagmara; Warzecha, Zygmunt; Ceranowicz, Piotr; Fyderek, Krzysztof; Gałązka, Krystyna; Cieszkowski, Jakub; Bonior, Joanna; Jaworek, Jolanta; Pihut, Małgorzata; Dembiński, Artur

    2015-01-01

    Ghrelin has protective and therapeutic effects in the gut. The aim of present studies was to investigate the effect of treatment with ghrelin on the development of colitis evoked by dextran sodium sulfate (DSS). Methods. Studies have been performed on rats. Colitis was induced by adding 5% DSS to the drinking water for 5 days. During this period animals were treated intraperitoneally twice a day with saline or ghrelin given at the dose of 8 nmol/kg/dose. On the sixth day, animals were anesthetized and the severity of colitis was assessed. Results. Treatment with ghrelin during administration of DSS reduced the development of colitis. Morphological features of colonic mucosa exhibited a reduction in the area and deep of mucosal damage. Ghrelin reversed the colitis-induced decrease in blood flow, DNA synthesis, and superoxide dismutase activity in colonic mucosa. These effects were accompanied by a decrease in the colitis-evoked increase in mucosal concentration of interleukin-1β and malondialdehyde. Treatment with ghrelin reversed the DSS-induced reduction in body weight gain. Conclusions. Administration of ghrelin exhibits the preventive effect against the development of DSS-induced colitis. This effect seems to be related to ghrelin's anti-inflammatory and antioxidative properties.

  7. The Influence of Ghrelin on the Development of Dextran Sodium Sulfate-Induced Colitis in Rats

    PubMed Central

    Matuszyk, Aleksandra; Ceranowicz, Dagmara; Warzecha, Zygmunt; Ceranowicz, Piotr; Fyderek, Krzysztof; Gałązka, Krystyna; Cieszkowski, Jakub; Bonior, Joanna; Jaworek, Jolanta; Pihut, Małgorzata; Dembiński, Artur

    2015-01-01

    Ghrelin has protective and therapeutic effects in the gut. The aim of present studies was to investigate the effect of treatment with ghrelin on the development of colitis evoked by dextran sodium sulfate (DSS). Methods. Studies have been performed on rats. Colitis was induced by adding 5% DSS to the drinking water for 5 days. During this period animals were treated intraperitoneally twice a day with saline or ghrelin given at the dose of 8 nmol/kg/dose. On the sixth day, animals were anesthetized and the severity of colitis was assessed. Results. Treatment with ghrelin during administration of DSS reduced the development of colitis. Morphological features of colonic mucosa exhibited a reduction in the area and deep of mucosal damage. Ghrelin reversed the colitis-induced decrease in blood flow, DNA synthesis, and superoxide dismutase activity in colonic mucosa. These effects were accompanied by a decrease in the colitis-evoked increase in mucosal concentration of interleukin-1β and malondialdehyde. Treatment with ghrelin reversed the DSS-induced reduction in body weight gain. Conclusions. Administration of ghrelin exhibits the preventive effect against the development of DSS-induced colitis. This effect seems to be related to ghrelin's anti-inflammatory and antioxidative properties. PMID:26713317

  8. Mice lacking ghrelin receptors resist the development of diet-induced obesity

    PubMed Central

    Zigman, Jeffrey M.; Nakano, Yoshihide; Coppari, Roberto; Balthasar, Nina; Marcus, Jacob N.; Lee, Charlotte E.; Jones, Juli E.; Deysher, Amy E.; Waxman, Amanda R.; White, Ryan D.; Williams, Todd D.; Lachey, Jennifer L.; Seeley, Randy J.; Lowell, Bradford B.; Elmquist, Joel K.

    2005-01-01

    Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHSR; ghrelin receptor). Since its discovery, accumulating evidence has suggested that ghrelin may play a role in signaling and reversing states of energy insufficiency. For example, ghrelin levels rise following food deprivation, and ghrelin administration stimulates feeding and increases body weight and adiposity. However, recent loss-of-function studies have raised questions regarding the physiological significance of ghrelin in regulating these processes. Here, we present results of a study using a novel GHSR-null mouse model, in which ghrelin administration fails to acutely stimulate food intake or activate arcuate nucleus neurons. We show that when fed a high-fat diet, both female and male GHSR-null mice eat less food, store less of their consumed calories, preferentially utilize fat as an energy substrate, and accumulate less body weight and adiposity than control mice. Similar effects on body weight and adiposity were also observed in female, but not male, GHSR-null mice fed standard chow. GHSR deletion also affected locomotor activity and levels of glycemia. These findings support the hypothesis that ghrelin-responsive pathways are an important component of coordinated body weight control. Moreover, our data suggest that ghrelin signaling is required for development of the full phenotype of diet-induced obesity. PMID:16322794

  9. Ghrelin induces abdominal obesity via GHS-R-dependent lipid retention.

    PubMed

    Davies, Jeffrey S; Kotokorpi, Pia; Eccles, Sinan R; Barnes, Sarah K; Tokarczuk, Pawel F; Allen, Sophie K; Whitworth, Hilary S; Guschina, Irina A; Evans, Bronwen A J; Mode, Agneta; Zigman, Jeffrey M; Wells, Timothy

    2009-06-01

    Circulating ghrelin elevates abdominal adiposity by a mechanism independent of its central orexigenic activity. In this study we tested the hypothesis that peripheral ghrelin induces a depot-specific increase in white adipose tissue (WAT) mass in vivo by GH secretagogue receptor (GHS-R(1a))-mediated lipolysis. Chronic iv infusion of acylated ghrelin increased retroperitoneal and inguinal WAT volume in rats without elevating superficial sc fat, food intake, or circulating lipids and glucose. Increased retroperitoneal WAT mass resulted from adipocyte enlargement probably due to reduced lipid export (ATP-binding cassette transporter G1 mRNA expression and circulating free fatty acids were halved by ghrelin infusion). In contrast, ghrelin treatment did not up-regulate biomarkers of adipogenesis (peroxisome proliferator-activated receptor-gamma2 or CCAAT/enhancer binding protein-alpha) or substrate uptake (glucose transporter 4, lipoprotein lipase, or CD36) and although ghrelin elevated sterol-regulatory element-binding protein 1c expression, WAT-specific mediators of lipogenesis (liver X receptor-alpha and fatty acid synthase) were unchanged. Adiposity was unaffected by infusion of unacylated ghrelin, and the effects of acylated ghrelin were abolished by transcriptional blockade of GHS-R(1a), but GHS-R(1a) mRNA expression was similar in responsive and unresponsive WAT. Microarray analysis suggested that depot-specific sensitivity to ghrelin may arise from differential fine tuning of signal transduction and/or lipid-handling mechanisms. Acylated ghrelin also induced hepatic steatosis, increasing lipid droplet number and triacylglycerol content by a GHS-R(1a)-dependent mechanism. Our data imply that, during periods of energy insufficiency, exposure to acylated ghrelin may limit energy utilization in specific WAT depots by GHS-R(1a)-dependent lipid retention.

  10. Nitric oxide mediates Fos expression in the spinal cord induced by mechanical noxious stimulation.

    PubMed

    Lee, J H; Wilcox, G L; Beitz, A J

    1992-10-01

    Immunocytochemical localization of Fos protein was used to analyze the involvement of nitric oxide (NO) in the expression of Fos in the spinal cord, induced by mechanical noxious stimulation (NS). Mechanical NS was applied to the left hindpaw 30 minutes after intrathecal administration of the NO synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME) and the resulting Fos expression in the spinal cord dorsal horn was compared with that obtained in rats exposed only to the mechanical NS. Pretreatment with L-NAME but not its stereoisomer N omega-nitro-D-arginine methyl ester (D-NAME), produced a dose-dependent suppression of Fos expression induced by mechanical noxious stimulation. These results indicate that NO modulates the expression of Fos in the dorsal horn induced by mechanical noxious stimulation and further support the hypothesis that NO is involved in nociceptive events occurring in the spinal cord in response to a peripheral noxious stimulus.

  11. Protective effects of ghrelin on cisplatin-induced nephrotoxicity in mice.

    PubMed

    Nojiri, Takashi; Hosoda, Hiroshi; Kimura, Toru; Tokudome, Takeshi; Miura, Koichi; Takabatake, Hiroyuki; Miyazato, Mikiya; Okumura, Meinoshin; Kangawa, Kenji

    2016-08-01

    Cisplatin is a potent chemotherapeutic agent that has activity against malignant tumors. However, cisplatin causes various adverse effects, such as nephrotoxicity, which are associated with high morbidity and mortality. Recent studies have revealed that the mechanism of cisplatin nephrotoxicity includes a robust inflammatory response. Since ghrelin has been shown to have anti-inflammatory properties, we hypothesized that ghrelin might have protective effects against cisplatin nephrotoxicity. Mice were randomly divided into three groups: control, cisplatin with vehicle, and cisplatin with ghrelin. Ghrelin (0.8μg/kg/min via osmotic-pump, subcutaneously) or vehicle administration was started one day before cisplatin injection. At 72h after cisplatin administration (20mg/kg, intraperitoneally), we measured serum blood urea nitrogen and creatinine, urine albumin/creatinine, renal mRNA levels of monocyte chemoattractant protein-1, interleukin-6, tumor necrosis factor-α, interleukin-1β, kidney injury molecule-1, and neutrophil gelatinase-associated lipocalin by real-time polymerase chain reaction, and histological changes. Ghrelin significantly attenuated the increase in serum blood urea nitrogen and creatinine induced by cisplatin. Ghrelin tended to attenuate the increase in urine albumin/creatinine, although not significantly. Cisplatin-induced renal tubular injury and apoptosis were significantly attenuated by ghrelin pretreatment. Consequently, ghrelin significantly attenuated renal mRNA levels of monocyte chemoattractant protein-1, interleukin-6, kidney injury molecule-1, and neutrophil gelatinase-associated lipocalin. In conclusion, ghrelin produces protective effects in cisplatin-induced nephrotoxicity through inhibition of inflammatory reactions. Pretreatment with ghrelin may become a new prophylactic candidate for cisplatin-induced nephrotoxicity.

  12. MTII attenuates ghrelin- and food deprivation-induced increases in food hoarding and food intake.

    PubMed

    Keen-Rhinehart, Erin; Bartness, Timothy J

    2007-12-01

    Food deprivation triggers a constellation of physiological and behavioral changes including increases in peripherally-produced ghrelin and centrally-produced agouti-related protein (AgRP). Upon refeeding, food intake is increased in most species, however hamsters primarily increase food hoarding. Food deprivation-induced increases in food hoarding by Siberian hamsters are mimicked by peripheral ghrelin and central AgRP injections. Because food deprivation stimulates ghrelin as well as AgRP synthesis/release, food deprivation-induced increases in hoarding may be mediated by melanocortin 3 or 4 receptor (MC3/4-R) antagonism via AgRP, the MC3/4-R inverse agonist. Therefore, we asked: Can a MC3/4-R agonist block food deprivation- or ghrelin-induced increases in foraging, food hoarding and food intake? This was accomplished by injecting melanotan II (MTII), a synthetic MC3/4-R agonist, into the 3rd ventricle in food deprived, fed or peripheral ghrelin injected hamsters and housed in a running wheel-based food delivery foraging system. Three foraging conditions were used: a) no running wheel access, non-contingent food, b) running wheel access, non-contingent food or c) a foraging requirement for food (10 revolutions/pellet). Food deprivation was a more potent stimulator of foraging and hoarding than ghrelin. Concurrent injections of MTII completely blocked food deprivation- and ghrelin-induced increases in food intake and attenuated, but did not always completely block, food deprivation- and ghrelin-induced increases in food hoarding. Collectively, these data suggest that the MC3/4-R are involved in ghrelin- and food deprivation-induced increases in food intake, but other neurochemical systems, such as previously demonstrated with neuropeptide Y, also are involved in increases in food hoarding as well as foraging.

  13. Exogenous Ghrelin Accelerates the Healing of Acetic Acid-Induced Colitis in Rats.

    PubMed

    Matuszyk, Aleksandra; Ceranowicz, Piotr; Warzecha, Zygmunt; Cieszkowski, Jakub; Ceranowicz, Dagmara; Gałązka, Krystyna; Bonior, Joanna; Jaworek, Jolanta; Bartuś, Krzysztof; Gil, Krzysztof; Olszanecki, Rafał; Dembiński, Artur

    2016-09-01

    Previous studies have shown that ghrelin reduces colonic inflammation induced by trinitrobenzene sulfonic acid and dextran sodium sulfate. In the present study we determined the effect of treatment with ghrelin on the course of acetic acid-induced colitis in rats. Rectal administration of 3% acetic acid solution led to induction of colitis in all animals. Damage of the colonic wall was accompanied by an increase in mucosal concentration of pro-inflammatory interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), as well mucosal activity of myeloperoxidase. Moreover, induction of colitis led to a reduction in colonic blood flow and DNA synthesis. Administration of ghrelin after induction of colitis led to faster regeneration of the colonic wall and reduction in colonic levels of IL-1β, TNF-α, and myeloperoxidase. In addition, treatment with ghrelin improved mucosal DNA synthesis and blood flow. Our study disclosed that ghrelin exhibits a strong anti-inflammatory and healing effect in acetic acid-induced colitis. Our current observation in association with previous findings that ghrelin exhibits curative effect in trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis suggest that therapeutic effect of ghrelin in the colon is universal and independent of the primary cause of colitis.

  14. Exogenous Ghrelin Accelerates the Healing of Acetic Acid-Induced Colitis in Rats

    PubMed Central

    Matuszyk, Aleksandra; Ceranowicz, Piotr; Warzecha, Zygmunt; Cieszkowski, Jakub; Ceranowicz, Dagmara; Gałązka, Krystyna; Bonior, Joanna; Jaworek, Jolanta; Bartuś, Krzysztof; Gil, Krzysztof; Olszanecki, Rafał; Dembiński, Artur

    2016-01-01

    Previous studies have shown that ghrelin reduces colonic inflammation induced by trinitrobenzene sulfonic acid and dextran sodium sulfate. In the present study we determined the effect of treatment with ghrelin on the course of acetic acid-induced colitis in rats. Rectal administration of 3% acetic acid solution led to induction of colitis in all animals. Damage of the colonic wall was accompanied by an increase in mucosal concentration of pro-inflammatory interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), as well mucosal activity of myeloperoxidase. Moreover, induction of colitis led to a reduction in colonic blood flow and DNA synthesis. Administration of ghrelin after induction of colitis led to faster regeneration of the colonic wall and reduction in colonic levels of IL-1β, TNF-α, and myeloperoxidase. In addition, treatment with ghrelin improved mucosal DNA synthesis and blood flow. Our study disclosed that ghrelin exhibits a strong anti-inflammatory and healing effect in acetic acid-induced colitis. Our current observation in association with previous findings that ghrelin exhibits curative effect in trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis suggest that therapeutic effect of ghrelin in the colon is universal and independent of the primary cause of colitis. PMID:27598133

  15. Therapeutic effect of ghrelin in the course of cerulein-induced acute pancreatitis in rats.

    PubMed

    Warzecha, Z; Ceranowicz, P; Dembinski, A; Cieszkowski, J; Kusnierz-Cabala, B; Tomaszewska, R; Kuwahara, A; Kato, I

    2010-08-01

    Recent studies have shown that pretreatment with ghrelin exhibits protective effect in the gut. Administration of ghrelin reduces gastric mucosal damage, as well as inhibits the development of experimental pancreatitis. However, this protective effect requires administration of ghrelin before gastric or pancreatic damage and thus has a limited clinical value. The aim of present study was to assess the influence of ghrelin administered after development of acute pancreatitis on the course of this disease. Acute pancreatitis was induced by cerulein. Ghrelin was administered twice a day for 1, 2, 4, 6 or 9 days at the dose of 4, 8 or 16 nmol/kg/dose. The first dose of ghrelin was given 24 hours after last injection of cerulein. The severity of acute pancreatitis was assessed between 0 h and 10 days after cessation of cerulein administration. Administration of caerulein led to the development of acute edematous pancreatitis and maximal severity of this disease was observed 24 hours after induction of pancreatitis. Treatment with ghrelin reduced morphological signs of pancreatic damage such as pancreatic edema, leukocyte infiltration and vacuolization of acinar cells, and led to earlier regeneration of the pancreas. Also biochemical indexes of the severity of acute pancreatitis, serum activity of lipase and amylase were significantly reduced in animals treated with ghrelin. These effects were accompanied by an increase in the pancreatic DNA synthesis and a decrease in serum level of pro-inflammatory interleukin-1b. Administration of ghrelin improved pancreatic blood flow in rats with acute pancreatitis. We conclude that: (1) treatment with ghrelin exhibits therapeutic effect in caerulein-induced experimental acute pancreatitis; (2) this effect is related, at least in part, to the improvement of pancreatic blood flow, reduction in proinflammatory interleukin-1beta and stimulation of pancreatic cell proliferation.

  16. Ghrelin and feedback systems.

    PubMed

    Nonogaki, Katsunori

    2008-01-01

    Ghrelin is produced primarily in the stomach in response to hunger, and circulates in the blood. Plasma ghrelin levels increase during fasting and decrease after ingesting glucose and lipid, but not protein. The efferent vagus nerve contributes to the fasting-induced increase in ghrelin secretion. Ghrelin secreted by the stomach stimulates the afferent vagus nerve and promotes food intake. Ghrelin also stimulates pituitary gland secretion of growth hormone (GH) via the afferent vagus nerve. GH inhibits stomach ghrelin secretion. These findings indicate that the vagal circuit between the central nervous system and stomach has a crucial role in regulating plasma ghrelin levels. Moreover, body mass index modulates plasma ghrelin levels. In a lean state and anorexia nervosa, plasma ghrelin levels are increased, whereas in obesity, except in Prader-Willi syndrome, plasma ghrelin levels are decreased and the feeding- and sleeping-induced decline in plasma ghrelin levels is disrupted. There are two forms of ghrelin: active n-octanoyl-modified ghrelin and des-acyl ghrelin. Fasting increases both ghrelin types compared with the fed state. Hyperphagia and obesity are likely to decrease plasma des-acyl ghrelin, but not n-octanoyl-modified ghrelin levels. Hypothalamic serum and glucocorticoid-inducible kinase-1 and serotonin 5-HT2C/1B receptor gene expression levels are likely to be proportional to plasma des-acyl ghrelin levels during fasting, whereas they are likely to be inversely proportional to plasma des-acyl ghrelin levels in an increased energy storage state such as obesity. Thus, a dysfunction of the ghrelin feedback systems might contribute to the pathophysiology of obesity and eating disorders.

  17. Ghrelin Protects against Renal Damages Induced by Angiotensin-II via an Antioxidative Stress Mechanism in Mice

    PubMed Central

    Fujimura, Keiko; Wakino, Shu; Minakuchi, Hitoshi; Hasegawa, Kazuhiro; Hosoya, Koji; Komatsu, Motoaki; Kaneko, Yuka; Shinozuka, Keisuke; Washida, Naoki; Kanda, Takeshi; Tokuyama, Hirobumi; Hayashi, Koichi; Itoh, Hiroshi

    2014-01-01

    We explored the renal protective effects by a gut peptide, Ghrelin. Daily peritoneal injection with Ghrelin ameliorated renal damages in continuously angiotensin II (AngII)-infused C57BL/6 mice as assessed by urinary excretion of protein and renal tubular markers. AngII-induced increase in reactive oxygen species (ROS) levels and senescent changes were attenuated by Ghrelin. Ghrelin also inhibited AngII-induced upregulations of transforming growth factor-β (TGF-β) and plasminogen activator inhibitor-1 (PAI-1), ameliorating renal fibrotic changes. These effects were accompanied by concomitant increase in mitochondria uncoupling protein, UCP2 as well as in a key regulator of mitochondria biosynthesis, PGC1α. In renal proximal cell line, HK-2 cells, Ghrelin reduced mitochondria membrane potential and mitochondria-derived ROS. The transfection of UCP2 siRNA abolished the decrease in mitochondria-derived ROS by Ghrelin. Ghrelin ameliorated AngII-induced renal tubular cell senescent changes and AngII-induced TGF-β and PAI-1 expressions. Finally, Ghrelin receptor, growth hormone secretagogue receptor (GHSR)-null mice exhibited an increase in tubular damages, renal ROS levels, renal senescent changes and fibrosis complicated with renal dysfunction. GHSR-null mice harbored elongated mitochondria in the proximal tubules. In conclusion, Ghrelin suppressed AngII-induced renal damages through its UCP2 dependent anti-oxidative stress effect and mitochondria maintenance. Ghrelin/GHSR pathway played an important role in the maintenance of ROS levels in the kidney. PMID:24747517

  18. Inhibition of ghrelin O-acyltransferase attenuates food deprivation-induced increases in ingestive behavior.

    PubMed

    Teubner, Brett J W; Garretson, John T; Hwang, Yousang; Cole, Philip A; Bartness, Timothy J

    2013-04-01

    Ghrelin is an orexigenic hormone produced by the stomach in direct proportion to the time since the last meal and has therefore been called a 'hunger signal'. The octanoylation of ghrelin is critical for its orexigenic functions and is dependent upon ghrelin O-acyltransferase (GOAT) catalyzation. The GOAT inhibitor, GO-CoA-Tat, decreases the circulating concentrations of octanoylated ghrelin and attenuates weight gain on a high fat diet in mice. Unlike rats and mice, Siberian hamsters and humans do not increase food intake after food deprivation, but increase food hoarding after food deprivation. In Siberian hamsters, exogenous ghrelin increases ingestive behaviors similarly to 48-56 h food deprivation. Therefore, we tested the necessity of increased ghrelin in food-deprived Siberian hamsters to stimulate ingestive behaviors. To do so we used our simulated natural housing system that allows hamsters to forage for and hoard food. Animals were given an injection of GO-CoA-Tat (i.p., 11 μmol/kg) every 6h because that is the duration of its effective inhibition of octanoylated ghrelin concentrations during a 48 h food deprivation. We found that GO-CoA-Tat attenuated food foraging (0-1h), food intake (0-1 and 2-4h), and food hoarding (0-1h and 2 and 3 days) post-refeeding compared with saline treated animals. This suggests that increased octanoylated ghrelin concentrations play a role in the food deprivation-induced increases in ingestive behavior. Therefore, ghrelin is a critical aspect of the multi-faceted mechanisms that stimulate ingestive behaviors, and might be a critical point for a successful clinical intervention scheme in humans.

  19. Ghrelin inhibits LPS-induced release of IL-6 from mouse dopaminergic neurones

    PubMed Central

    2013-01-01

    Background Ghrelin is an orexigenic stomach hormone that acts centrally to increase mid-brain dopamine neurone activity, amplify dopamine signaling and protect against neurotoxin-induced dopamine cell death in the mouse substantia nigra pars compacta (SNpc). In addition, ghrelin inhibits the lipopolysaccharide (LPS)-induced release of pro-inflammatory cytokines from peripheral macrophages, T-cells and from LPS stimulated microglia. Here we sought to determine whether ghrelin attenuates pro-inflammatory cytokine release from dopaminergic neurones. Findings The dopaminergic SN4741 cell-line, which derives from the mouse substantia nigra (SN) and expresses the ghrelin-receptor (growth hormone secretagogue receptor (GHS-R)) and the ghrelin-O-acyl transferase (GOAT) enzyme, was used to determine the neuro-immunomodulatory action of ghrelin. We induced innate immune activation via LPS challenge (1 μg/ml) of SN4741 neurones that had been pre-cultured in the presence or absence of ghrelin (1, 10, 100 nM) for 4 h. After 24 h supernatants were collected for detection of IL-1 beta (IL-1β ), TNF alpha (TNF-α) and IL-6 cytokines via enzyme linked immunosorbent assay (ELISA) analysis. Nuclear translocation of the transcription factor nuclear factor kappa B (NF-κB) was analyzed by Western blotting, and to determine viability of treatments a cell viability assay and caspase-3 immunohistochemistry were performed. We provide evidence that while IL-1β and TNF-α were not detectable under any conditions, SN4741 neurones constitutively released IL-6 under basal conditions and treatment with LPS significantly increased IL-6 secretion. Pre-treatment of neurones with ghrelin attenuated LPS-mediated IL-6 release at 24 h, an affect that was inhibited by the GHS-R antagonist [D-Lys3]-GHRP-6. However, while ghrelin pre-treatment attenuated the LPS-mediated increase in NF-κB, there was no alteration in its nuclear translocation. Cell viability assay and caspase-3 immunocytochemistry

  20. fra-1: a serum-inducible, cellular immediate-early gene that encodes a fos-related antigen.

    PubMed Central

    Cohen, D R; Curran, T

    1988-01-01

    A set of proteins antigenically related to the c-fos protein (Fos) are induced by serum in fibroblasts. To isolate cDNA clones of genes encoding such proteins, a lambda gt11 expression cDNA library constructed from serum-stimulated rat fibroblasts was screened with antibodies raised against a hydrophilic region (amino acids 127 to 152) of Fos. One of the positive clones identified, termed fra-1 (Fos-related antigen) was characterized. It encoded a protein that shared several regions of extensive amino acid homology with Fos (including the region that showed similarity to both the yeast GCN4 regulatory protein and the protein encoded by the jun oncogene), although its nucleotide sequence was considerably diverged from that of the c-fos gene. Only a subset of the agents and conditions that activated c-fos also induced fra-1. Induction of fra-1 expression following serum stimulation was delayed compared with that of c-fos. However, like c-fos, fra-1 was induced rapidly by serum in the presence of protein synthesis inhibitors. Thus, a family of Fos-related, inducible genes are involved in the cellular immediate-early transcriptional response to extracellular stimuli. Images PMID:3133553

  1. Mechanically induced c-fos expression is mediated by cAMP in MC3T3-E1 osteoblasts

    NASA Technical Reports Server (NTRS)

    Fitzgerald, J.; Hughes-Fulford, M.

    1999-01-01

    In serum-deprived MC3T3-E1 osteoblasts, mechanical stimulation caused by mild (287 x g) centrifugation induced a 10-fold increase in mRNA levels of the proto-oncogene, c-fos. Induction of c-fos was abolished by the cAMP-dependent protein kinase inhibitor H-89, suggesting that the transient c-fos mRNA increase is mediated by cAMP. Down-regulation of protein kinase C (PKC) activity by chronic TPA treatment failed to significantly reduce c-fos induction, suggesting that TPA-sensitive isoforms of PKC are not responsible for c-fos up-regulation. In addition, 287 x g centrifugation increased intracellular prostaglandin E2 (PGE2) levels 2.8-fold (P<0. 005). Since we have previously shown that prostaglandin E2 (PGE2) can induce c-fos expression via a cAMP-mediated mechanism, we asked whether the increase in c-fos mRNA was due to centrifugation-induced PGE2 release. Pretreatment with the cyclooxygenase inhibitors indomethacin and flurbiprofen did not hinder the early induction of c-fos by mechanical stimulation. We conclude that c-fos expression induced by mild mechanical loading is dependent primarily on cAMP, not PKC, and initial induction of c-fos is not necessarily dependent on the action of newly synthesized PGE2.

  2. The atypical dopamine D1 receptor agonist SKF 83959 induces striatal Fos expression in rats.

    PubMed

    Wirtshafter, David; Osborn, Catherine V

    2005-12-28

    The effects of dopamine D1 receptor agonists are often presumed to result from an activation of adenylyl cyclase, but dopamine D1 receptors may also be linked to other signal transduction cascades and the relative importance of these various pathways is currently unclear. SKF 83959 is an agonist at dopamine D1 receptors linked to phospholipase C, but has been reported to be an antagonist at receptors linked to adenylyl cyclase. The current report demonstrates that SKF 83959 induces pronounced, nonpatchy, expression of the immediate-early gene product Fos in the striatum of intact rats which can be converted to a patchy pattern by pretreatment with the dopamine D2-like receptor agonist quinpirole. In rats with unilateral 6-hydroxydopamine lesions SKF 83959 induces strong behavioral rotation and a greatly potentiated Fos response. All of the responses to SKF 83959, in both intact and dopamine-depleted animals, can be blocked by pretreatment with the dopamine D1 receptor antagonist SCH-23390. In intact subjects, SKF 83959 induced Fos expression less potently than the standard dopamine D1 receptor agonist SKF 82958, but the two drugs were approximately equipotent in deinnervated animals. These results demonstrate for the first time that possession of full efficacy at dopamine D1 receptors linked to adenylyl cyclase is not a necessary requirement for the induction of striatal Fos expression in intact animals and suggest that alternative signal transduction pathways may play a role in dopamine agonist induced Fos expression, especially in dopamine-depleted subjects.

  3. Ghrelin Induces Leptin Resistance by Activation of Suppressor of Cytokine Signaling 3 Expression in Male Rats: Implications in Satiety Regulation

    PubMed Central

    Heldsinger, Andrea; Grabauskas, Gintautas; Wu, Xiaoyin; Zhou, ShiYi; Lu, Yuanxu; Song, Il

    2014-01-01

    The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) –bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior. PMID:25060362

  4. Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation.

    PubMed

    Heldsinger, Andrea; Grabauskas, Gintautas; Wu, Xiaoyin; Zhou, ShiYi; Lu, Yuanxu; Song, Il; Owyang, Chung

    2014-10-01

    The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.

  5. Lipopolysaccharide induces delayed FosB/DeltaFosB immunostaining within the mouse extended amygdala, hippocampus and hypothalamus, that parallel the expression of depressive-like behavior

    PubMed Central

    Frenois, François; Moreau, Maïté; Connor, Jason O’; Lawson, Marc; Micon, Charlotte; Lestage, Jacques; Kelley, Keith W.; Dantzer, Robert; Castanon, Nathalie

    2007-01-01

    Proinflammatory cytokines induce both sickness behavior and depression, but their respective neurobiological correlates are still poorly understood. The aim of the present study was therefore to identify in mice the neural substrates of sickness and depressive-like behavior induced by lipopolysaccharide (LPS, 830 μg/kg, intraperitoneal). LPS-induced depressive-like behavior was dissociated from LPS-induced sickness by testing mice either at 6 h (at which time sickness was expected to be maximal) or at 24 h post-LPS (at which time sickness was expected to be minimal and not to bias the measurement of depressive-like behavior). Concurrently, the expression of acute and chronic cellular reactivity markers (c-Fos and FosB/ΔFosB respectively) was mapped by immunohistochemistry at these two time points. In comparison to saline, LPS decreased motor activity in a new cage at 6 but not at 24 h. In contrast, the duration of immobility in the tail suspension test was increased at both 6 and 24 h. This dissociation between decreased motor activity and depressive-like behavior was confirmed at 24 h post-LPS in the forced swim test. LPS also decreased sucrose consumption at 24 and 48 h, despite normal food and water consumption by that time. At 24 h post-LPS, LPS-induced depressive-like behavior was associated with a delayed cellular activity (as assessed by FosB/ΔFosB immunostaining) in specific brain structures, particularly within the extended amygdala, hippocampus and hypothalamus, whereas c-Fos labeling was markedly decreased by that time in all the brain areas at 6 h post-LPS. These results provide the first evidence in favor of a functional dissociation between the brain structures that underlie cytokine-induced sickness behavior and cytokine-induced depressive-like behavior, and provide important cues about the neuroanatomical brain circuits through which cytokines could have an impact on affect. PMID:17482371

  6. Bicuculline, a GABAA-receptor antagonist, blocked HPA axis activation induced by ghrelin under an acute stress.

    PubMed

    Gastón, M S; Cid, M P; Salvatierra, N A

    2017-03-01

    Ghrelin is a peptide of 28 amino acids with a homology between species, which acts on the central nervous system to regulate different actions, including the control of growth hormone secretion and metabolic regulation. It has been suggested that central ghrelin is a mediator of behavior linked to stress responses and induces anxiety in rodents and birds. Previously, we observed that the anxiogenic-like behavior induced by ghrelin injected into the intermediate medial mesopallium (IMM) of the forebrain was blocked by bicuculline (a GABAA receptor competitive antagonist) but not by diazepam (a GABAA receptor allosteric agonist) in neonatal meat-type chicks (Cobb). Numerous studies have indicated that hypothalamic-pituitary-adrenal (HPA) axis activation mediates the response to stress in mammals and birds. However, it is still unclear whether this effect of ghrelin is associated with HPA activation. Therefore, we investigated whether anxiety behavior induced by intra-IMM ghrelin and mediated through GABAA receptors could be associated with HPA axis activation in the neonatal chick. In the present study, in an Open Field test, intraperitoneal bicuculline methiodide blocked anxiogenic-like behavior as well as the increase in plasma ACTH and corticosterone levels induced by ghrelin (30pmol) in neonatal chicks. Moreover, we showed for the first time that a competitive antagonist of GABAA receptor suppressed the HPA axis activation induced by an anxiogenic dose of ghrelin. These results show that the anxiogenic ghrelin action involves the activation of the HPA axis, with a complex functional interaction with the GABAA receptor.

  7. d-LSD-induced c-Fos expression occurs in a population of oligodendrocytes in rat prefrontal cortex.

    PubMed

    Reissig, Chad J; Rabin, Richard A; Winter, Jerrold C; Dlugos, Cynthia A

    2008-03-31

    Induction of mRNA or protein for immediate-early genes, such as c-fos, is used to identify brain areas, specific cell types, and neuronal circuits that become activated in response to various stimuli including psychoactive drugs. The objective of the present study was to identify the cell types in the prefrontal cortex in which lysergic acid diethylamide (d-LSD) induces c-Fos expression. Systemic administration of d-LSD resulted in a dose-dependent increase in c-Fos immunoreactivity. Although c-Fos-positive cells were found in all cortical layers, they were most numerous in layers III, IV, and V. d-LSD-induced c-Fos immunoreactivity was found in cells co-labeled with anti-neuron-specific enolase or anti-oligodendrocyte Oligo1. The Oligo1-labeled cells had small, round bodies and nuclear diameters characteristic of oligodendrocytes. Studies using confocal microscopy confirmed colocalization of c-Fos-labeled nuclei in NeuN-labeled neurons. Astrocytes and microglia labeled with glial fibrillary acidic protein antibody and OX-42 antibody, respectively, did not display LSD-induced c-Fos expression. Pyramidal neurons labeled with anti-neurofilament antibody also did not show induction of c-Fos immunoreactivity after systemic d-LSD administration. The present study demonstrates that d-LSD induced expression of c-Fos in the prefrontal cortex occurs in subpopulations of neurons and in oligodendrocytes, but not in pyramidal neurons, astrocytes, and microglia.

  8. Lysergic acid diethylamide-induced Fos expression in rat brain: role of serotonin-2A receptors.

    PubMed

    Gresch, P J; Strickland, L V; Sanders-Bush, E

    2002-01-01

    Lysergic acid diethylamide (LSD) produces altered mood and hallucinations in humans and binds with high affinity to serotonin-2A (5-HT(2A)) receptors. Although LSD interacts with other receptors, the activation of 5-HT(2A) receptors is thought to mediate the hallucinogenic properties of LSD. The goal of this study was to identify the brain sites activated by LSD and to determine the influence of 5-HT(2A) receptors in this activation. Rats were pretreated with the 5-HT(2A) receptor antagonist MDL 100907 (0.3 mg/kg, i.p.) or vehicle 30 min prior to LSD (500 microg/kg, i.p.) administration and killed 3 h later. Brain tissue was examined for Fos protein expression by immunohistochemistry. LSD administration produced a five- to eight-fold increase in Fos-like immunoreactivity in medial prefrontal cortex, anterior cingulate cortex, and central nucleus of amygdala. However, in dorsal striatum and nucleus accumbens no increase in Fos-like immunoreactivity was observed. Pretreatment with MDL 100907 completely blocked LSD-induced Fos-like immunoreactivity in medial prefrontal cortex and anterior cingulate cortex, but only partially blocked LSD-induced Fos-like immunoreactivity in amygdala. Double-labeled immunohistochemistry revealed that LSD did not induce Fos-like immunoreactivity in cortical cells expressing 5-HT(2A) receptors, suggesting an indirect activation of cortical neurons. These results indicate that the LSD activation of medial prefrontal cortex and anterior cingulate cortex is mediated by 5-HT(2A) receptors, whereas in amygdala 5-HT(2A) receptor activation is a component of the response. These findings support the hypothesis that the medial prefrontal cortex, anterior cingulate cortex, and perhaps the amygdala, are important regions involved in the production of hallucinations.

  9. Age-dependent reduction of ghrelin- and motilin-induced contractile activity in the chicken gastrointestinal tract.

    PubMed

    Kitazawa, Takio; Yoshida, Akiko; Tamano, Takuya; Teraoka, Hiroki; Kaiya, Hiroyuki

    2013-05-01

    Ghrelin is an endogenous ligand for growth hormone secretagogue-receptor 1a (GHS-R1a) and stimulates gastrointestinal (GI) motility in the chicken. Since ghrelin stimulates GH release, which regulates growth, it might be interesting to compare ghrelin-induced responses in GI tract of different-aged chickens. Motilin is a ghrelin-related gut peptide that induces strong contraction in the small intestine. Aim of this study was to clarify age-dependent changes in ghrelin- and motilin-induced contractions of the chicken GI tract and expression of their receptor mRNAs. Chicken ghrelin caused contraction of the crop and proventriculus. Ghrelin-induced contraction in the proventriculus decreased gradually up to 100 days after hatching, but the responses to ghrelin in the crop were the same during the growth period. GHS-R1a mRNA expression in the crop tended to increase, but that in the proventriculus decreased depending on the age. Chicken motilin caused contraction of the chicken GI tract. Atropine decreased the responses to motilin in the proventriculus but not in the ileum. Motilin-induced contraction in the proventriculus but not that in the ileum decreased depending on post-hatching days. On the other hand, motilin receptor mRNA expression in every region of the GI tract decreased with age, but the decrease was more marked in the proventriculus than in the ileum. In conclusion, ghrelin- and motilin-induced GI contractions selectively decreased in the chicken proventriculus depending on post-hatching days, probably due to the age-related decrease in respective receptors expression. The results suggest an age-related contribution of ghrelin and motilin to the regulation of chicken GI motility.

  10. The influence of pretreatment with ghrelin on the development of acetic-acid-induced colitis in rats.

    PubMed

    Maduzia, D; Matuszyk, A; Ceranowicz, D; Warzecha, Z; Ceranowicz, P; Fyderek, K; Galazka, K; Dembinski, A

    2015-12-01

    Ghrelin has been primarily shown to exhibit protective and therapeutic effect in the gut. Pretreatment with ghrelin inhibits the development of acute pancreatitis and accelerates pancreatic recovery in the course of this disease. In the stomach, ghrelin reduces gastric mucosal damage induced by ethanol, stress or alendronate, as well as accelerates the healing of acetic acid-induced gastric and duodenal ulcer. The aim of present studies was to investigate the effect of pretreatment with ghrelin on the development of acetic acid-induced colitis. Studies have been performed on male Wistar rats. Animals were treated intraperitoneally with saline (control) or ghrelin (4, 8 or 16 nmol/kg/dose). Saline or ghrelin was given twice: 8 and 1 h before induction of colitis. Colitis was induced by a rectal enema with 1 ml of 4% solution of acetic acid and the severity of colitis was assessed 1 or 24 hours after induction of inflammation. Rectal administration of acetic acid induced colitis in all animals. Damage of colonic wall was seen at the macroscopic and microscopic level. This effect was accompanied by a reduction in colonic blood flow and mucosal DNA synthesis. Moreover, induction of colitis significantly increased mucosal concentration of pro-inflammatory interleukin-1β (IL-1β), activity of myeloperoxidase and concentration of malondialdehyde (MDA). Mucosal activity of superoxide dismutase (SOD) was reduced. Pretreatment with ghrelin reduced the area and grade of mucosal damage. This effect was accompanied by an improvement of blood flow, DNA synthesis and SOD activity in colonic mucosa. Moreover, ghrelin administration reduced mucosal concentration of IL-1β and MDA, as well as decreased mucosal activity of myeloperoxidase. Administration of ghrelin protects the large bowel against the development of the acetic acid-induced colitis and this effect seems to be related to the ghrelin-evoked anti-inflammatory and anti-oxidative effects.

  11. Ghrelin counteracts salt-induced hypertension via promoting diuresis and renal nitric oxide production in Dahl rats.

    PubMed

    Aoki, Hirotaka; Nakata, Masanori; Dezaki, Katsuya; Lu, Ming; Gantulga, Darambazar; Yamamoto, Keiji; Shimada, Kazuyuki; Kario, Kazuomi; Yada, Toshihiko

    2013-01-01

    Ghrelin is the endogenous ligand for the growth hormone-secretagogue receptor expressed in various tissues including the heart, blood vessels and kidney. This study sought to determine the effects of long-term treatment with ghrelin (10 nmol/kg, twice a day, intraperitoneally) on the hypertension induced by high salt (8.0% NaCl) diet in Dahl salt-sensitive hypertensive (DS) rats. Systolic blood pressure (SBP) was measured by a tail cuff method. During the treatment period for 3 weeks, high salt diet increased blood pressure compared to normal salt (0.3% NaCl) diet, and this hypertension was partly but significantly (P<0.01) attenuated by simultaneous treatment with ghrelin. Ghrelin significantly increased urine volume and tended to increase urine Na⁺ excretion. Furthermore, ghrelin increased urine nitric oxide (NO) excretion and tended to increase renal neuronal nitric oxide synthase (nNOS) mRNA expression. Ghrelin did not alter the plasma angiotensin II level and renin activity, nor urine catecholamine levels. Furthermore, ghrelin prevented the high salt-induced increases in heart thickness and plasma ANP mRNA expression. These results demonstrate that long-term ghrelin treatment counteracts salt-induced hypertension in DS rats primarily through diuretic action associated with increased renal NO production, thereby exerting cardio-protective effects.

  12. Context-Induced Reinstatement of Methamphetamine Seeking Is Associated with Unique Molecular Alterations in Fos-Expressing Dorsolateral Striatum Neurons

    PubMed Central

    Rubio, F. Javier; Liu, Qing-Rong; Li, Xuan; Cruz, Fabio C.; Leão, Rodrigo M.; Warren, Brandon L.; Kambhampati, Sarita; Babin, Klil R.; McPherson, Kylie B.; Cimbro, Raffaello; Bossert, Jennifer M.; Shaham, Yavin

    2015-01-01

    Context-induced reinstatement of drug seeking is a well established animal model for assessing the neural mechanisms underlying context-induced drug relapse, a major factor in human drug addiction. Neural activity in striatum has previously been shown to contribute to context-induced reinstatement of heroin, cocaine, and alcohol seeking, but not yet for methamphetamine seeking. In this study, we found that context-induced reinstatement of methamphetamine seeking increased expression of the neural activity marker Fos in dorsal but not ventral striatum. Reversible inactivation of neural activity in dorsolateral but not dorsomedial striatum using the GABA agonists muscimol and baclofen decreased context-induced reinstatement. Based on our previous findings that Fos-expressing neurons play a critical role in conditioned drug effects, we assessed whether context-induced reinstatement was associated with molecular alterations selectively induced within context-activated Fos-expressing neurons. We used fluorescence-activated cell sorting to isolate reinstatement-activated Fos-positive neurons from Fos-negative neurons in dorsal striatum and used quantitative PCR to assess gene expression within these two populations of neurons. Context-induced reinstatement was associated with increased expression of the immediate early genes Fos and FosB and the NMDA receptor subunit gene Grin2a in only Fos-positive neurons. RNAscope in situ hybridization confirmed that Grin2a, as well as Grin2b, expression were increased in only Fos-positive neurons from dorsolateral, but not dorsomedial, striatum. Our results demonstrate an important role of dorsolateral striatum in context-induced reinstatement of methamphetamine seeking and that this reinstatement is associated with unique gene alterations in Fos-expressing neurons. PMID:25855177

  13. Context-induced reinstatement of methamphetamine seeking is associated with unique molecular alterations in Fos-expressing dorsolateral striatum neurons.

    PubMed

    Rubio, F Javier; Liu, Qing-Rong; Li, Xuan; Cruz, Fabio C; Leão, Rodrigo M; Warren, Brandon L; Kambhampati, Sarita; Babin, Klil R; McPherson, Kylie B; Cimbro, Raffaello; Bossert, Jennifer M; Shaham, Yavin; Hope, Bruce T

    2015-04-08

    Context-induced reinstatement of drug seeking is a well established animal model for assessing the neural mechanisms underlying context-induced drug relapse, a major factor in human drug addiction. Neural activity in striatum has previously been shown to contribute to context-induced reinstatement of heroin, cocaine, and alcohol seeking, but not yet for methamphetamine seeking. In this study, we found that context-induced reinstatement of methamphetamine seeking increased expression of the neural activity marker Fos in dorsal but not ventral striatum. Reversible inactivation of neural activity in dorsolateral but not dorsomedial striatum using the GABA agonists muscimol and baclofen decreased context-induced reinstatement. Based on our previous findings that Fos-expressing neurons play a critical role in conditioned drug effects, we assessed whether context-induced reinstatement was associated with molecular alterations selectively induced within context-activated Fos-expressing neurons. We used fluorescence-activated cell sorting to isolate reinstatement-activated Fos-positive neurons from Fos-negative neurons in dorsal striatum and used quantitative PCR to assess gene expression within these two populations of neurons. Context-induced reinstatement was associated with increased expression of the immediate early genes Fos and FosB and the NMDA receptor subunit gene Grin2a in only Fos-positive neurons. RNAscope in situ hybridization confirmed that Grin2a, as well as Grin2b, expression were increased in only Fos-positive neurons from dorsolateral, but not dorsomedial, striatum. Our results demonstrate an important role of dorsolateral striatum in context-induced reinstatement of methamphetamine seeking and that this reinstatement is associated with unique gene alterations in Fos-expressing neurons.

  14. Ghrelin Protects against Dexamethasone-Induced INS-1 Cell Apoptosis via ERK and p38MAPK Signaling

    PubMed Central

    2016-01-01

    Glucocorticoid excess induces apoptosis of islet cells, which may result in diabetes. In this study, we investigated the protective effect of ghrelin on dexamethasone-induced INS-1 cell apoptosis. Our data showed that ghrelin (0.1 μM) inhibited dexamethasone-induced (0.1 μM) apoptosis of INS-1 cells and facilitated cell proliferation. Moreover, ghrelin upregulated Bcl-2 expression, downregulated Bax expression, and decreased caspase-3 activity. The protective effect of ghrelin against dexamethasone-induced INS-1 cell apoptosis was mediated via growth hormone secretagogue receptor 1a. Further studies revealed that ghrelin increased ERK activation and decreased p38MAPK expression after dexamethasone treatment. Ghrelin-mediated protection of dexamethasone-induced apoptosis of INS-1 cells was attenuated using the ERK inhibitor U0126 (10 μM), and cell viability increased using the p38MAPK inhibitor SB203580 (10 μM). In conclusion, ghrelin could protect against dexamethasone-induced INS-1 cell apoptosis, at least partially via GHS-R1a and the signaling pathway of ERK and p38MAPK. PMID:27190513

  15. Parathyroid hormone induces c-fos and c-jun messenger RNA in rat osteoblastic cells

    NASA Technical Reports Server (NTRS)

    Clohisy, J. C.; Scott, D. K.; Brakenhoff, K. D.; Quinn, C. O.; Partridge, N. C.

    1992-01-01

    PTH is a potent regulator of osteoblast gene expression, yet the nuclear events that mediate PTH action are poorly understood. We were interested in identifying immediate early genes which may regulate PTH-altered gene expression in the osteoblast. Therefore, we examined the effects of PTH on c-fos and c-jun gene expression in a rat osteoblastic cell line (UMR 106-01). Under control conditions, c-fos and c-jun mRNAs were present at low basal levels. After PTH treatment, c-fos mRNA abundance dramatically increased, with a maximal and transient response at 30 min. PTH also stimulated an increase in c-jun mRNA, but in a biphasic manner, with maximal levels at 30 min and 2 h. These responses were dose dependent, not altered by cotreatment with the protein synthesis inhibitor cycloheximide, and preceded PTH-induced expression of matrix metallo-proteinase-1 mRNA. Nuclear run-on assays demonstrated an increased rate of c-fos and c-jun transcription after PTH exposure. To determine the signal transduction pathways involved, second messenger analogs were tested for their ability to mimic the effects of PTH. 8-Bromo-cAMP and phorbol 12-myristate 13-acetate (PMA) caused increases in the abundance of c-fos and c-jun transcripts. Ionomycin had no effect on the expression of these genes. Pretreatment of the cells with PMA resulted in a decrease in basal c-jun expression, but did not alter the PTH-mediated increase in c-fos, c-jun, or matrix metalloproteinase-1 mRNAs.(ABSTRACT TRUNCATED AT 250 WORDS).

  16. Lack of estradiol modulation of sleep deprivation-induced c-Fos in the rat brain.

    PubMed

    Mashoodh, Rahia; Stamp, Jennifer A; Wilkinson, Michael; Rusak, Benjamin; Semba, Kazue

    2008-11-28

    Women recover from sleep deprivation more efficiently than men, but the mechanism for this difference is unknown. Effects of estrogen on sleep suggest that it could play a role, but the brain targets on which estrogen may act to have this effect have not been identified. Sleep deprivation increases levels of the immediate-early gene protein c-Fos in selected brain regions, but it is unknown whether estrogen modulates this response. We investigated the influence of different levels of exogenous estradiol on the c-Fos response to sleep deprivation in ovariectomized female rats. Female rats were treated with low or high levels of estradiol (mimicking diestrous and proestrous levels, respectively) delivered via subcutaneous silastic tubes. Control ovariectomized females and sham-operated males were implanted with tubes filled with cholesterol. One week after surgery, half of the rats underwent a 3 h period of sleep deprivation during the light phase in a motorized Wahmann activity wheel that rotated constantly at a slow speed, while half were confined to fixed wheels. Immediately after sleep deprivation, animals were killed and their brains processed to detect c-Fos using immunohistochemistry. Sleep deprivation increased the number of c-Fos positive cells in a number of brain areas, including the caudate putamen, medial preoptic area, perifornical hypothalamus, and anterior paraventricular thalamic nucleus. Other areas, including the suprachiasmatic nucleus, posterior paraventricular hypothalamic nucleus, posterior paraventricular thalamic nucleus, arcuate nucleus, and central amygdala, did not respond to 3 h sleep deprivation with a significant increase in c-Fos levels. Levels of c-Fos induced in the selected brain regions by sleep deprivation were not modulated by estrogen levels, nor by sex.

  17. Intracerebroventricular urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats

    PubMed Central

    Yeh, Chun; Ting, Ching-Heng; Doong, Ming-Luen; Chi, Chin-Wen; Lee, Shou-Dong; Chen, Chih-Yen

    2016-01-01

    Purpose Urocortin 3 is a key neuromodulator in the regulation of stress, anxiety, food intake, gut motility, and energy homeostasis, while ghrelin elicits feeding behavior and enhances gastric emptying, adiposity, and positive energy balance. However, the interplays between urocortin 3 and ghrelin on food intake and gastric emptying remain uninvestigated. Methods We examined the differential effects of central O-n-octanoylated ghrelin, des-Gln14-ghrelin, and urocortin 3 on food intake, as well as on charcoal nonnutrient semiliquid gastric emptying in conscious rats that were chronically implanted with intracerebroventricular (ICV) catheters. The functional importance of corticotropin-releasing factor (CRF) receptor 2 in urocortin 3-induced responses was examined by ICV injection of the selective CRF receptor 2 antagonist, astressin2-B. Results ICV infusion of urocortin 3 opposed central acyl ghrelin-elicited hyperphagia via CRF receptor 2 in satiated rats. ICV injection of O-n-octanoylated ghrelin and des-Gln14-ghrelin were equally potent in accelerating gastric emptying in fasted rats, whereas ICV administration of urocortin 3 delayed gastric emptying. In addition, ICV infusion of urocortin 3 counteracted central acyl ghrelin-induced gastroprokinetic effects via CRF receptor 2 pathway. Conclusion ICV-infused urocortin 3 counteracts central acyl ghrelin-induced hyperphagic and gastroprokinetic effects via CRF receptor 2 in rats. Our results clearly showed that enhancing ghrelin and blocking CRF receptor 2 signaling in the brain accelerated gastric emptying, which provided important clues for a new therapeutic avenue in ameliorating anorexia and gastric ileus found in various chronic wasting disorders. PMID:27757017

  18. Effects of intrahippocampal injection of ghrelin on spatial memory in PTZ-induced seizures in male rats.

    PubMed

    Babri, Shirin; Amani, Mohammad; Mohaddes, Gisou; Mirzaei, Fariba; Mahmoudi, Fariba

    2013-10-01

    Ghrelin (gh) is a peptide hormone that may affect learning and memory. There is some evidence that ghrelin can have antiepileptic effects. So we decided to investigate the possible effects of ghrelin on spatial memory following PTZ-induced seizures in male rats. Ninety male rats were divided into 9 groups including control, saline, ghrelin (0.3, 1.5 or 3 nmol) and pentylenetetrazol (PTZ, 50 mg/kg, i.p.) plus saline or ghrelin (0.3, 1.5 or 3 nmol). All groups were trained in Morris water maze (MWM) for two consecutive days. Our results showed that ghrelin significantly improves spatial memory at the doses of 1.5 or 3 nmol (P<0.05) in normal rats. We also demonstrated the significant impairment of spatial memory in PTZ group (P<0.05). Intrahippocampal injection of ghrelin at the dose of 3 nmol significantly improved spatial memory in PTZ+gh group compared to PTZ group (P<0.05). These findings suggest that ghrelin as a neuropeptide can improve spatial memory in PTZ-treated rats.

  19. NPY Y1 receptor is involved in ghrelin- and fasting-induced increases in foraging, food hoarding, and food intake.

    PubMed

    Keen-Rhinehart, Erin; Bartness, Timothy J

    2007-04-01

    Fasting triggers a constellation of physiological and behavioral changes, including increases in peripherally produced ghrelin and centrally produced hypothalamic neuropeptide Y (NPY). Refeeding stimulates food intake in most species; however, hamsters primarily increase foraging and food hoarding with smaller increases in food intake. Fasting-induced increases in foraging and food hoarding in Siberian hamsters are mimicked by peripheral ghrelin, central NPY, and NPY Y1 receptor agonist injections. Because fasting stimulates ghrelin and subsequently NPY synthesis/release, it may be that fasting-induced increased hoarding is mediated by NPY Y1 receptor activation. Therefore, we asked: Can an Y1 receptor antagonist block fasting- or ghrelin-induced increases in foraging, food hoarding, and food intake? This was accomplished by injecting the NPY Y1 receptor antagonist 1229U91 intracerebroventricularly in hamsters fasted, fed, or given peripheral ghrelin injections and housed in a running wheel-based food delivery foraging system coupled with simulated-burrow housing. Three foraging conditions were used: 1) no running wheel access, free food, 2) running wheel access, free food, or 3) foraging requirement (10 revolutions/pellet) for food. Fasting was a more potent stimulator of foraging and food hoarding than ghrelin. Concurrent injections of 1229U91 completely blocked fasting- and ghrelin-induced increased foraging and food intake and attenuated, but did not always completely block, fasting- and ghrelin-induced increases in food hoarding. Collectively, these data suggest that the NPY Y1 receptor is important for the effects of ghrelin- and fasting-induced increases in foraging and food intake, but other NPY receptors and/or other neurochemical systems are involved in increases in food hoarding.

  20. Fos immunoreactivity in the rat forebrain induced by electrical stimulation of the dorsolateral periaqueductal gray matter.

    PubMed

    Lim, Lee Wei; Temel, Yasin; Visser-Vandewalle, Veerle; Blokland, Arjan; Steinbusch, Harry

    2009-10-01

    Electrical stimulation of the dorsolateral periaqueductal gray (dlPAG) matter induces panic- or fear-like responses with intense emotional distress and severe anxiety. In this study, we evoked panic-like behaviour by dlPAG stimulation and evaluated the effect on neuronal activation in different brain regions. The number of c-Fos immunoreactive (c-Fos-ir) cells was measured semi-quantitatively through series of stained rat brain sections. Our results demonstrate strong neural activation in the medial prefrontal cortex, orbital cortex, anterior olfactory nuclei, secondary motor cortex, and the somatosensory cortex. Moderate increases in the number of c-Fos-ir cells were detected in various regions, including the hypothalamus, amygdala, and striatum. Additionally, there was mild expression of c-Fos-ir cells in the hippocampus, thalamus, and habenula regions. In conclusion, we have shown that deep brain stimulation of the dlPAG produced a distinctive pattern of neuronal activation across forebrain regions as compared to the sham and control animals.

  1. Ghrelin Receptor Deficiency does not Affect Diet-Induced Atherosclerosis in Low-Density Lipoprotein Receptor-Null Mice

    PubMed Central

    Habegger, Kirk M.; Grant, Erin; Pfluger, Paul Thomas; Perez-Tilve, Diego; Daugherty, Alan; Bruemmer, Dennis; Tschöp, Matthias H.; Hofmann, Susanna M.

    2011-01-01

    Objective: Ghrelin, a stomach-derived, secreted peptide, and its receptor (growth hormone secretagogue receptor, GHSR) are known to modulate food intake and energy homeostasis. The ghrelin system is also expressed broadly in cardiovascular tissues. Since ghrelin has been associated with anti-inflammatory and anti-atherogenic properties, but is also well known to promote obesity and impair glucose metabolism, we investigated whether ghrelin has any impact on the development of atherosclerosis. The hypothesis that endogenous ghrelin signaling may be involved in atherosclerosis has not been tested previously. Methods and Results: We crossed ghrelin receptor knockout mice (GHSr−/−) into a low-density lipoprotein receptor-null (Ldlr−/−) mouse line. In this model, atherosclerotic lesions were promoted by feeding a high-fat, high-cholesterol Western-type diet for 13 months, following a standard protocol. Body composition and glucose homeostasis were similar between Ldlr−/− and Ldlr/GHSR−/−ko mice throughout the study. Absence or presence of GHSr did not alter the apolipoprotein profile changes in response to diet exposure on an LDLRko background. Atherosclerotic plaque volume in the aortic arch and thoracic aorta were also not affected differentially in mice without ghrelin signaling due to GHSR gene disruption as compared to control LDLRko littermates. In light of the associations reported for ghrelin with cardiovascular disease in humans, the lack of a phenotype in these loss-of-function studies in mice suggests no direct role for endogenous ghrelin in either the inhibition or the promotion of diet-induced atherosclerosis. Conclusion: These data indicate that, surprisingly, the complex and multifaceted actions of endogenous ghrelin receptor mediated signaling on the cardiovascular system have minimal direct impact on atherosclerotic plaque progression as based on a loss-of-function mouse model of the disease. PMID:22649381

  2. Attenuation of systemic morphine-induced analgesia by central administration of ghrelin and related peptides in mice.

    PubMed

    Zeng, Ping; Chen, Jia-Xiang; Yang, Bei; Zhi, Xing; Guo, Fa-Xian; Sun, Meng-Li; Wang, Jing-Lei; Wei, Jie

    2013-12-01

    Ghrelin, an acylated 28-amino peptide secreted in the gastric endocrine cells, has been demonstrated to stimulate the release of growth hormone, increase food intake, and inhibit pro-inflammatory cascade, etc. Ghrelin mainly combines with its receptor (GHS-R1α) to play the role in physiological and pathological functions. It has been reported that ghrelin plays important roles in the control of pain through interaction with the opioid system in inflammatory pain and acute pain. However, very few studies show the effect of supraspinal ghrelin system on antinociception induced by intraperitoneal (i.p.) administration of morphine. In the present study, intracerebroventricular (i.c.v.) injection of ghrelin (0.1, 1, 10 and 100 nmol/L) produced inhibition of systemic morphine (6 mg/kg, i.p.) analgesia in the tail withdrawal test. Similarly, i.c.v. injection GHRP-6 and GHRP-2 which are the agonists of GHS-R1α, also decreased analgesia effect induced by morphine injected intraperitoneally in mice. Furthermore, these anti-opioid activities of ghrelin and related peptides were not blocked by pretreatment with the GHS-R1α selective antagonist [d-Lys(3)]-GHRP-6 (100 nmol/L, i.c.v.). These results demonstrated that central ghrelin and related peptides could inhibit the analgesia effect induced by intraperitoneal (i.p.) administration of morphine. The anti-opioid effects of ghrelin and related peptides do not interact with GHS-R1a. These findings may pave the way for a new strategy on investigating the interaction between ghrelin system and opioids on pain modulation.

  3. Immunomodulatory actions of central ghrelin in diet-induced energy imbalance.

    PubMed

    Stevanovic, Darko; Starcevic, Vesna; Vilimanovich, Urosh; Nesic, Dejan; Vucicevic, Ljubica; Misirkic, Maja; Janjetovic, Kristina; Savic, Emina; Popadic, Dusan; Sudar, Emina; Micic, Dragan; Sumarac-Dumanovic, Mirjana; Trajkovic, Vladimir

    2012-01-01

    We investigated the effects of centrally administered orexigenic hormone ghrelin on energy imbalance-induced inflammation. Rats were subjected for four weeks to three different dietary regimes: normal (standard food), high-fat (standard food with 30% lard) or food-restricted (70%, 50%, 40% and 40% of the expected food intake in 1st, 2nd, 3rd and 4th week, respectively). Compared to normal-weight controls, starved, but not obese rats had significantly higher levels of proinflammatory cytokines (TNF, IL-1β, IFN-γ) in the blood. When compared to normally fed animals, the hearts of starved and obese animals expressed higher levels of mRNAs encoding proinflammatory mediators (TNF, IL-1β, IL-6, IFN-γ, IL-17, IL-12, iNOS), while mRNA levels of the anti-inflammatory TGF-β remained unchanged. Intracerebroventricular (ICV) injection of ghrelin (1 μg/day) for five consecutive days significantly reduced TNF, IL-1β and IFN-γ levels in the blood of starved rats, as well as TNF, IL-17 and IL-12p40 mRNA expression in the hearts of obese rats. Conversely, ICV ghrelin increased the levels of IFN-γ, IL-17, IL-12p35 and IL-12p40 mRNA in the heart tissue of food-restricted animals. This was associated with an increase of immunosuppressive ACTH/corticosterone production in starved animals and a decrease of the immunostimulatory adipokine leptin both in food-restricted and high-fat groups. Ghrelin activated the energy sensor AMP-activated protein kinase (AMPK) in the hypothalamus and inhibited extracellular signal-regulated kinase (ERK) in the hearts of obese, but not starved rats. Therefore, central ghrelin may play a complex role in energy imbalance-induced inflammation by modulating HPA axis, leptin and AMPK/ERK signaling pathways.

  4. Ghrelin accelerates the healing of cysteamine-induced duodenal ulcers in rats

    PubMed Central

    Warzecha, Zygmunt; Ceranowicz, Dagmara; Dembiński, Artur; Ceranowicz, Piotr; Cieszkowski, Jakub; Kuwahara, Atsukazu; Kato, Ikuo; Dembiński, Marcin; Konturek, Peter C.

    2012-01-01

    Summary Background Previous studies have shown that administration of ghrelin exhibits protective and therapeutic effects in the gut. The aim of the present investigation was to examine the influence of ghrelin administration on the course of cysteamine-induced duodenal ulcers, as well as effects on mucosal production of oxygen free radicals and duodenal antioxidant defense. Material/Methods Duodenal ulcers were induced in male Wistar rats by cysteamine administered intragastrically at the dose of 200 mg/kg in 1 ml of saline, 3 times at 4-h intervals. Starting 24 h after the first dose of cysteamine, rats were treated intraperitoneally twice a day with saline or ghrelin given at the dose of 4, 8 or 16 nmol/kg/dose. Seven days after administration of the first dose of cysteamine, the study was terminated. Results Induction of ulcers by cysteamine was accompanied by a reduction in duodenal blood flow, mucosal DNA synthesis and mucosal activity of superoxide dismutase (SOD); whereas mucosal concentration of interleukin-1β and malonyldialdehyde (MDA – an index of lipid peroxidation) were increased. Treatment with ghrelin increased healing rate of duodenal ulcers and enhanced duodenal blood flow, mucosal DNA synthesis and mucosal activity of SOD, and reduced mucosal concentration of interleukin-1β and MDA. Conclusions Treatment with ghrelin increases the healing rate of duodenal ulcers and this effect is related, at least in part, to improvement of duodenal mucosal blood flow, mucosal cell proliferation and antioxidant defense, as well as being related to reduction in mucosal oxidative stress and inflammatory response. PMID:22534700

  5. Ghrelin prevents tumour- and cisplatin-induced muscle wasting: characterization of multiple mechanisms involved

    PubMed Central

    Chen, Ji-an; Splenser, Andres; Guillory, Bobby; Luo, Jiaohua; Mendiratta, Meenal; Belinova, Blaga; Halder, Tripti; Zhang, Guohua; Li, Yi-Ping; Garcia, Jose M

    2015-01-01

    Background Cachexia and muscle atrophy are common consequences of cancer and chemotherapy administration. The novel hormone ghrelin has been proposed as a treatment for this condition. Increases in food intake and direct effects on muscle proteolysis and protein synthesis are likely to mediate these effects, but the pathways leading to these events are not well understood. Methods We characterized molecular pathways involved in muscle atrophy induced by Lewis lung carcinoma (LLC) tumour implantation in c57/bl6 adult male mice and by administration of the chemotherapeutic agent cisplatin in mice and in C2C12 myotubes. The effects of exogenous ghrelin administration and its mechanisms of action were examined in these settings. Results Tumour implantation and cisplatin induced muscle atrophy by activating pro-inflammatory cytokines, p38-C/EBP-β, and myostatin, and by down-regulating Akt, myoD, and myogenin, leading to activation of ubiquitin-proteasome-mediated proteolysis and muscle weakness. Tumour implantation also increased mortality. In vitro, cisplatin up-regulated myostatin and atrogin-1 by activating C/EBP-β and FoxO1/3. Ghrelin prevented these changes in vivo and in vitro, significantly increasing muscle mass (P < 0.05 for LLC and P < 0.01 for cisplatin models) and grip strength (P = 0.038 for LLC and P = 0.001 for cisplatin models) and improving survival (P = 0.021 for LLC model). Conclusion Ghrelin prevents muscle atrophy by down-regulating inflammation, p38/C/EBP-β/myostatin, and activating Akt, myogenin, and myoD. These changes appear, at least in part, to target muscle cells directly. Ghrelin administration in this setting is associated with improved muscle strength and survival. PMID:26136189

  6. Mechanism of Ghrelin-Induced Gastric Contractions in Suncus murinus (House Musk Shrew): Involvement of Intrinsic Primary Afferent Neurons

    PubMed Central

    Mondal, Anupom; Aizawa, Sayaka; Sakata, Ichiro; Goswami, Chayon; Oda, Sen-ichi; Sakai, Takafumi

    2013-01-01

    Here, we have reported that motilin can induce contractions in a dose-dependent manner in isolated Suncus murinus (house musk shrew) stomach. We have also shown that after pretreatment with a low dose of motilin (10−10 M), ghrelin also induces gastric contractions at levels of 10−10 M to 10−7 M. However, the neural mechanism of ghrelin action in the stomach has not been fully revealed. In the present study, we studied the mechanism of ghrelin-induced contraction in vitro using a pharmacological method. The responses to ghrelin in the stomach were almost completely abolished by hexamethonium and were significantly suppressed by the administration of phentolamine, prazosin, ondansetron, and naloxone. Additionally, N-nitro-l-arginine methylester significantly potentiated the contractions. Importantly, the mucosa is essential for ghrelin-induced, but not motilin-induced, gastric contractions. To evaluate the involvement of intrinsic primary afferent neurons (IPANs), which are multiaxonal neurons that pass signals from the mucosa to the myenteric plexus, we examined the effect of the IPAN-related pathway on ghrelin-induced contractions and found that pretreatment with adenosine and tachykinergic receptor 3 antagonists (SR142801) significantly eliminated the contractions and GR113808 (5-hydroxytryptamine receptor 4 antagonist) almost completely eliminated it. The results indicate that ghrelin stimulates and modulates suncus gastric contractions through cholinergic, adrenergic, serotonergic, opioidergic neurons and nitric oxide synthases in the myenteric plexus. The mucosa is also important for ghrelin-induced gastric contractions, and IPANs may be the important interneurons that pass the signal from the mucosa to the myenteric plexus. PMID:23565235

  7. Compression Induces Ephrin-A2 in PDL Fibroblasts via c-fos

    PubMed Central

    Sen, S.; Diercke, K.; Zingler, S.; Lux, C. J.

    2015-01-01

    Ephrin-A2–EphA2 and ephrin-B2–EphB4 interactions have been implicated in the regulation of bone remodeling. We previously demonstrated a potential role for members of the Eph-ephrin family of receptor tyrosine kinases for bone remodeling during orthodontic tooth movement: compression-dependent upregulation of ephrin-A2 in fibroblasts of the periodontal ligament (PDL) attenuated osteogenesis in osteoblasts of the alveolar bone. However, factors affecting the regulation of ephrin-A2 expression upon the application of compressive forces remained unclear. Here, we report a mechano-dependent pathway of ephrin-A2 induction in PDL fibroblasts (PDLFs) involving extracellular signal–regulated kinases (ERK) 1/2 and c-fos. PDLF subjected to compressive forces (30.3 g/cm2) upregulated c-fos and ephrin-A2 mRNA and protein expression and displayed increased ERK1/2 phosphorylation. Inhibition of the MAP kinase kinase (MEK)/ERK1/2 pathway using the specific MEK inhibitor U0126 significantly reduced ephrin-A2 messenger RNA upregulation upon compression. Silencing of c-fos using a small interfering RNA approach led to a significant inhibition of ephrin-A2 induction upon the application of compressive forces. Interestingly, ephrin-A2 stimulation of PDLF induced c-fos expression and led also to the induction of ephrin-A2 expression. Using a reporter gene construct in murine 3T3 cells, we found that ephrin-A2 was able to stimulate serum response element (SRE)–dependent luciferase activity. As the regulation of c-fos is SRE dependent, ephrin-A2 might induce c-fos via SRE activation. Taken together, we provide evidence for an ERK1/2- and c-fos–dependent regulation of ephrin-A2 in compressed PDLF and suggest a novel pathway for ephrin-A2 induction emanating from ephrin-A2 itself. We showed previously that ephrin-A2 at compression sites might contribute to tooth movement by inhibiting osteogenic differentiation. The regulatory pathway of ephrin-A2 induction during tooth movement

  8. Decreased ghrelin-induced GH release in thyrotoxicosis: comparison with GH-releasing peptide-6 (GHRP-6) and GHRH.

    PubMed

    Nascif, Sergio Oliva; Correa-Silva, Silvia Regina; Silva, Marcos Roberto; Lengyel, Ana-Maria Judith

    2007-01-01

    In thyrotoxicosis GH response to several stimuli is impaired, but there is no data on ghrelin-induced GH release in these patients. Ghrelin is a potent GH secretagogue and it also increases glucose levels in men. The aim of this study was to evaluate the effects of ghrelin (1 microg/kg), GHRP-6 (1 mug/kg) and GHRH (100 microg), i.v., on GH levels in 10 hyperthyroid patients and in 8 controls. Glucose levels were also measured during ghrelin and GHRP-6 administration. In control subjects and hyperthyroid patients peak GH (microg/l; mean +/- SE) values after ghrelin injection (controls: 66.7 +/- 13.6; hyper: 19.3 +/- 2.4) were significantly higher than those obtained after GHRP-6 (controls: 26.7 +/- 5.1; hyper: 12.6 +/- 1.3) and GHRH (controls: 13.5 +/- 4.3; hyper: 5.3 +/- 1.3). There was a significant decrease in GH responsiveness to ghrelin, GHRP-6 and GHRH in the hyperthyroid group compared to controls. In control subjects and hyperthyroid patients basal glucose (mmol/l) values were 4.5 +/- 0.1 and 4.7 +/- 0.2, respectively. There was a significant increase in glucose levels 30 min after ghrelin injection (controls: 4.9 +/- 0.1; hyper: 5.2 +/- 0.2), which remained elevated up to 120 min. When the two groups were compared no differences in glucose values were observed. GHRP-6 administration was not able to increase glucose levels in both groups. Our data shows that GH release after ghrelin, GHRP-6 and GHRH administration is decreased in thyrotoxicosis. This suggests that thyroid hormone excess interferes with GH-releasing pathways activated by these peptides. Our results also suggest that ghrelin's ability to increase glucose levels is not altered in thyrotoxicosis.

  9. Impact of [d-Lys(3)]-GHRP-6 and feeding status on hypothalamic ghrelin-induced stress activation.

    PubMed

    Brockway, Emma T; Krater, Katherine R; Selva, Joaquín A; Wauson, Shelby E R; Currie, Paul J

    2016-05-01

    Ghrelin administration directly into hypothalamic nuclei, including the arcuate nucleus (ArcN) and the paraventricular nucleus (PVN), alters the expression of stress-related behaviors. In the present study we investigated the effect of feeding status on the ability of ghrelin to induce stress and anxiogenesis. Adult male Sprague Dawley rats were implanted with guide cannula targeting either the ArcN or PVN. In the first experiment we confirmed that ArcN and PVN ghrelin treatment produced anxiety-like behavior as measured using the elevated plus maze (EPM) paradigm. Ghrelin was administered during the early dark cycle. Immediately after microinjections rats were placed in the EPM for 5min. Both ArcN and PVN treatment reduced open arm exploration. The effect was attenuated by pretreatment with the ghrelin 1a receptor antagonist [d-Lys(3)]-GHRP-6. In a separate group of animals ghrelin was injected into either nucleus and rats were returned to their home cages for 60min with free access to food. An additional group of rats was returned to home cages with no food access. After 60min with or without food access all rats were tested in the EPM. Results indicated that food consumption just prior to EPM testing reversed the avoidance of the open arms of the EPM. In contrast, rats injected with ghrelin, placed in their home cage for 60min without food, and subsequently tested in the EPM, exhibited an increased avoidance of the open arms, consistent with stress activation. Overall, our findings demonstrate that ghrelin 1a receptor blockade and feeding status appear to impact the ability of ArcN and PVN ghrelin to elicit stress and anxiety-like behaviors.

  10. Unique gene alterations are induced in FACS-purified Fos-positive neurons activated during cue-induced relapse to heroin seeking.

    PubMed

    Fanous, Sanya; Guez-Barber, Danielle H; Goldart, Evan M; Schrama, Regina; Theberge, Florence R M; Shaham, Yavin; Hope, Bruce T

    2013-01-01

    Cue-induced heroin seeking after prolonged withdrawal is associated with neuronal activation and altered gene expression in prefrontal cortex (PFC). However, these previous studies assessed gene expression in all neurons regardless of their activity state during heroin seeking. Using Fos as a marker of neural activity, we describe distinct molecular alterations induced in activated versus non-activated neurons during cue-induced heroin seeking after prolonged withdrawal. We trained rats to self-administer heroin for 10 days (6 h/day) and assessed cue-induced heroin seeking in extinction tests after 14 or 30 days. We used fluorescent-activated cell sorting (FACS) to purify Fos-positive and Fos-negative neurons from PFC 90 min after extinction testing. Flow cytometry showed that Fos-immunoreactivity was increased in less than 10% of sparsely distributed PFC neurons. mRNA levels of the immediate early genes fosB, arc, egr1, and egr2, as well as npy and map2k6, were increased in Fos-positive, but not Fos-negative, neurons. In support of these findings, double-label immunohistochemistry indicated substantial coexpression of neuropeptide Y (NPY)- and Arc-immunoreactivity in Fos-positive neurons. Our data indicate that cue-induced relapse to heroin seeking after prolonged withdrawal induces unique molecular alterations within activated PFC neurons that are distinct from those observed in the surrounding majority of non-activated neurons.

  11. Central ghrelin increases food foraging/hoarding that is blocked by GHSR antagonism and attenuates hypothalamic paraventricular nucleus neuronal activation.

    PubMed

    Thomas, Michael A; Ryu, Vitaly; Bartness, Timothy J

    2016-02-01

    The stomach-derived "hunger hormone" ghrelin increases in the circulation in direct response to time since the last meal, increasing preprandially and falling immediately following food consumption. We found previously that peripheral injection of ghrelin potently stimulates food foraging (FF), food hoarding (FH), and food intake (FI) in Siberian hamsters. It remains, however, largely unknown if central ghrelin stimulation is necessary/sufficient to increase these behaviors regardless of peripheral stimulation of the ghrelin receptor [growth hormone secretagogue receptor (GHSR)]. We injected three doses (0.01, 0.1, and 1.0 μg) of ghrelin into the third ventricle (3V) of Siberian hamsters and measured changes in FF, FH, and FI. To test the effects of 3V ghrelin receptor blockade, we used the potent GHSR antagonist JMV2959 to block these behaviors in response to food deprivation or a peripheral ghrelin challenge. Finally, we examined neuronal activation in the arcuate nucleus and paraventricular hypothalamic nucleus in response to peripheral ghrelin administration and 3V GHSR antagonism. Third ventricular ghrelin injection significantly increased FI through 24 h and FH through day 4. Pretreatment with 3V JMV2959 successfully blocked peripheral ghrelin-induced increases in FF, FH, and FI at all time points and food deprivation-induced increases in FF, FH, and FI up to 4 h. c-Fos immunoreactivity was significantly reduced in the paraventricular hypothalamic nucleus, but not in the arcuate nucleus, following pretreatment with intraperitoneal JMV2959 and ghrelin. Collectively, these data suggest that central GHSR activation is both necessary and sufficient to increase appetitive and consummatory behaviors in Siberian hamsters.

  12. Ethanol-induced alterations of c-Fos immunoreactivity in specific limbic brain regions following ethanol discrimination training.

    PubMed

    Besheer, Joyce; Schroeder, Jason P; Stevenson, Rebekah A; Hodge, Clyde W

    2008-09-26

    The discriminative stimulus properties of ethanol are functionally regulated by ionotropic GABA(A) and NMDA receptors in specific limbic brain regions including the nucleus accumbens, amygdala, and hippocampus, as determined by microinjection studies. The purpose of the present work was to further investigate potential neural substrates of ethanol's discriminative stimulus effects by examining if ethanol discrimination learning produces changes in brain regional response to ethanol. To accomplish this goal, immunohistochemistry was used to assess the effects of ethanol (2 g/kg) on c-Fos immunoreactivity (Fos-IR). Comparisons in ethanol-induced Fos-IR were made between a group of rats that was trained to discriminate the stimulus properties of ethanol (2 g/kg, IG) from water (IG) and a drug/behavior-matched control group that did not receive differential reinforcement for lever selection, which precluded acquisition of discriminative stimulus control by ethanol. In some brain regions discrimination training had no effect on ethanol-induced Fos-IR changes (caudate putamen, bed nucleus of the stria terminalis, and CA1 region of the hippocampus). In contrast, discrimination training altered the pattern of ethanol-induced Fos-IR in the nucleus accumbens (core), medial septum, and the hippocampus (dentate and CA3). These results indicate that having behavior under the stimulus control of ethanol can change ethanol-induced Fos-IR in some brain regions. This suggests that learning about the subjective properties of ethanol produces adaptive changes in how the brain responds to acute ethanol exposure.

  13. Tactile Experience Induces c-fos Expression in Rat Barrel Cortex

    PubMed Central

    Filipkowski, Robert K.; Rydz, Marek; Berdel, Bozena; Morys, Janusz; Kaczmarek, Leszek

    2000-01-01

    Understanding gene expression that is responsive to sensory stimulation is central to elucidate molecular mechanisms underlying neuronal plasticity. In this study we demonstrate two new methods of stimulating whiskers that provide major sensory input to rat neocortex. In the first paradigm, animals were placed on the top of a cylinder and their vibrissae were brushed by hand. In the second paradigm, animals were placed for a brief period of time into a new, wired cage resulting in vibrissae stimulation when they explored the new environment. Both approaches induced c-Fos expression in barrel cortex corresponding to the stimulated vibrissae, especially in layer IV. Layers II/III and V/VI also showed c-Fos induction, but there were no detectable changes in layer VIb. The majority of c-Fos-expressing cells are probably not inhibitory neurons, because they do not show parvalbumin staining. Both paradigms, in contrast to the previous methods, are simple to use and do not require anesthesia, restraint of animals, or elaborate experimental setups. PMID:10753978

  14. Protective effect of leptin and ghrelin against toxicity induced by amyloid-β oligomers in a hypothalamic cell line.

    PubMed

    Gomes, S; Martins, I; Fonseca, A C R G; Oliveira, C R; Resende, R; Pereira, C M F

    2014-03-01

    In addition to cognitive decline, Alzheimer's disease (AD) patients also exhibit an unexplained weight loss that correlates with disease progression. In young and middle-aged AD patients, large amounts of amyloid-β (Aβ) deposits were observed in the hypothalamus, a brain region involved in the control of feeding and body weight through the action of peripheral metabolic peptides, which have recently been shown to have neuroprotective effects. Moreover, levels of peripheral metabolic peptides, such as leptin and ghrelin, are changed in AD patients. The present study aimed to investigate the role of Aβ peptide in the survival of hypothalamic cells and to explore the receptor-mediated protective effect of leptin and ghrelin against Aβ-induced toxicity in these cells. Using the mHypoE-N42 cell line, we demonstrated for the first time that oligomeric Aβ is toxic to hypothalamic cells, leading to cell death. It was also demonstrated that leptin and ghrelin protect these cells against AβO-induced cell death through the activation of the leptin and ghrelin receptors, respectively. Furthermore, ghrelin and leptin prevented superoxide production, calcium rise and mitochondrial dysfunction triggered by AβO. Taken together, these results suggest that peripheral metabolic peptides, in particular leptin and ghrelin, might be considered as preventive strategies for ameliorating hypothalamic alterations in AD.

  15. Ghrelin may reduce radiation-induced mucositis and anorexia in head-neck cancer.

    PubMed

    Guney, Yildiz; Ozel Turkcu, Ummuhani; Hicsonmez, Ayse; Nalca Andrieu, Meltem; Kurtman, Cengiz

    2007-01-01

    Body weight loss is common in cancer patients, and is often associated with poor prognosis, it greatly impairs quality of life (QOL). Radiation therapy (RT) is used in head and neck cancers (HNC) either as a primary treatment or as an adjuvant therapy to surgery. Patients with HNC are most susceptible to malnutrition especially due to anorexia, which is aggravated by RT. Multiple pro-inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1beta (IL-1beta), interferon (IFN)-gamma and tumor necrosis factor-alpha(TNF-alpha), have been all associated with the development of both anorexia and oral mucositis. Radiation-induced mucositis occurs in almost all patients, who are treated for HNC, it could also cause weight loss. Ghrelin is a novel 28-amino acid peptide, which up-regulates body weight through appetite control, increase food intake, down-regulate energy expenditure and induces adiposity. Furthermore, ghrelin inhibits pro-inflammatory cytokines such as IL-1alpha, IL-1beta, TNF-alpha which may cause oral mucositis and aneroxia, which are the results of weight loss. Thus weight loss during RT is an early indicator of nutritional decline, we propose that recombinant ghrelin used prophylactically could be useful as an appetite stimulant; and preventive of mucositis because of its anti-inflammatory effect, it might help patients maintain weight over the course of curative RT of the HNC and can improve specific aspects of QOL. This issue warrants further studies.

  16. Overexpression of intraislet ghrelin enhances β-cell proliferation after streptozotocin-induced β-cell injury in mice.

    PubMed

    Bando, Mika; Iwakura, Hiroshi; Ariyasu, Hiroyuki; Koyama, Hiroyuki; Hosoda, Kiminori; Adachi, Souichi; Nakao, Kazuwa; Kangawa, Kenji; Akamizu, Takashi

    2013-07-01

    Previously, we reported that exogenous administration of ghrelin ameliorates glucose metabolism in a neonate streptozotocin (STZ)-induced diabetic rat model through enhancement of β-cell proliferation. However, it was not clear whether the observed β-cell proliferation was a direct or indirect effect (e.g., via orexigenic or growth hormone-stimulated pathways) of ghrelin activity. Here, we aimed to investigate whether ghrelin directly impacts β-cell proliferation after STZ-induced injury in mice. Seven-week-old male rat insulin II promoter-ghrelin internal ribosomal sequence ghrelin O-acyltransferase transgenic (RIP-GG Tg) mice, which have elevated pancreatic ghrelin levels, but only minor changes in plasma ghrelin levels when fed a medium-chain triglyceride-rich diet, were treated with STZ. Then, serum insulin, pancreatic insulin mRNA expression, and islet histology were evaluated. We found that the serum insulin levels, but not blood glucose levels, of RIP-GG Tg mice were significantly ameliorated 14 days post-STZ treatment. Pancreatic insulin mRNA expression was significantly elevated in RIP-GG Tg mice, and β-cell numbers in islets were increased. Furthermore, the number of phospho-histone H3⁺ or Ki67⁺ proliferating β-cells was significantly elevated in RIP-GG Tg mice, whereas the apoptotic indexes within the islets, as determined by TUNEL assay, were not changed. These results indicate that ghrelin can directly stimulate β-cell proliferation in vivo after β-cell injury even without its orexigenic or GH-stimulating activities, although it did not have enough impact to normalize the glucose tolerance in adult mice.

  17. GHRP-6 mimics ghrelin-induced stimulation of food intake and suppression of locomotor activity in goldfish.

    PubMed

    Yahashi, Satowa; Kang, Ki Sung; Kaiya, Hiroyuki; Matsuda, Kouhei

    2012-04-01

    Ghrelin was first identified and characterized from rat stomach as an endogenous ligand for the growth hormone secretagogue (GHS) receptor (GHS-R). Ghrelin also acts as an orexigenic factor and regulates energy balance in rodents. In goldfish, native ghrelin consists of 11 molecular variants, the major form being a 17-residue peptide with n-octanoic acid modification (n-octanoyl ghrelin17), and intraperitoneal (IP) administration of n-octanoyl ghrelin17 induces central actions such as stimulation of food intake and suppression of locomotor activity through capsaicin-sensitive afferents. Four types of GHS-Rs (1a-1, 1a-2, 2a-1 and 2a-2) have been identified in goldfish, and one GHS, GHRP-6, can activate only GHS-R2a-1 in vitro. However, there is no information about the effect of GHRP-6 on food intake and locomotor activity in goldfish in vivo. Therefore, in the present study, we examined whether IP-administered GHRP-6 would mimic the orexigenic action of n-octanoyl ghrelin17 and its suppression of locomotor activity. IP administration of GHRP-6 at 1pmol/g body weight (BW) stimulated food intake, and was equipotent to the orexigenic action of n-octanoyl ghrelin17 at 10 pmol/g BW. IP-injected GHRP-6 at 1 pmol/g BW also induced a significant decrease of locomotor activity, as was the case for IP-injected n-octanoyl ghrelin17 at 10 pmol/g BW. The action of GHRP-6 was blocked by IP-preinjected capsaicin at 160 nmol/g BW. These results suggest that the central action of GHRP-6 might be mediated via the GHS-R2a-1-signaling pathway, and subsequently through capsaicin-sensitive afferents in goldfish.

  18. Attenuation of Cocaine Induced Locomotor Sensitization in Rats Sustaining Genetic or Pharmacologic Antagonism of Ghrelin Receptors

    PubMed Central

    Clifford, P. Shane; Rodriguez, Juan; Schul, Destri; Hughes, Samuel; Kniffin, Tracey; Hart, Nigel; Eitan, Shoshana; Wellman, Paul J.; Brunel, Luc; Fehrentz, Jean-Alain; Martinez, Jean

    2011-01-01

    Systemic infusions of the orexigenic peptide ghrelin (GHR) increase dopamine levels within the nucleus accumbens and augment cocaine stimulated locomotion and conditioned place preference in rats; observations that suggest an important role for ghrelin and GHR receptors (GHR-Rs) in drug reinforcement. In the present studies, we examined the development of cocaine locomotor sensitization in rats sustaining either pharmacologic antagonism or genetic ablation of GHR-Rs. In a pharmacologic study, adult male rats were injected (i.p.) with either 0, 3 or 6 mg/kg JMV 2959 (a GHR-R1 receptor antagonist) and 20 minutes later with either vehicle or 10 mg/kg cocaine HCl on each of 7 consecutive days. Rats pretreated with JMV 2959 showed significantly attenuated cocaine-induced hyperlocomotion. In a second study, adult wild type (WT) or mutant rats sustaining ENU-induced knockout of GHR-R (GHR-R (−/−)) received daily injections (i.p) of vehicle (0.9% saline) or 10.0 mg/kg cocaine HCl for 14 successive days. GHR-R null rats treated repeatedly with cocaine showed diminished development of cocaine locomotor sensitization relative to WT rats treated with cocaine. To verify the lack of GHR-R function in the GHR-R (−/−) rats, a separate feeding experiment was conducted in which WT rats, but not GHR-R (−/−) rats, were noted to eat more after a systemic injection of 15 nmol ghrelin than after vehicle. These results suggest that GHR-R activity is required for the induction of locomotor sensitization to cocaine and complement an emerging literature implicating central GHR systems in drug reward. Ghrelin (GHR) is an orexigenic gut peptide that is transported across the blood brain barrier and interacts with GHR receptors (GHR-R) located on ventral tegmental dopamine neurons. PMID:21790898

  19. The appetite-inducing peptide, ghrelin, induces intracellular store-mediated rises in calcium in addiction and arousal-related laterodorsal tegmental neurons in mouse brain slices.

    PubMed

    Hauberg, Katrine; Kohlmeier, Kristi A

    2015-03-01

    Ghrelin, a gut and brain peptide, has recently been shown to be involved in motivated behavior and regulation of the sleep and wakefulness cycle. The laterodorsal tegmental nucleus (LDT) is involved in appetitive behavior and control of the arousal state of an organism, and accordingly, behavioral actions of ghrelin could be mediated by direct cellular actions within this nucleus. Consistent with this interpretation, postsynaptically mediated depolarizing membrane actions of ghrelin on LDT neurons have been reported. Direct actions were ascribed solely to closure of a potassium conductance however this peptide has been shown in other cell types to lead to rises in calcium via release of calcium from intracellular stores. To determine whether ghrelin induced intracellular calcium rises in mouse LDT neurons, we conducted calcium imaging studies in LDT brain slices loaded with the calcium binding dye, Fura-2AM. Ghrelin elicited TTX-insensitive changes in dF/F indicative of rises in calcium, and a portion of these rises were independent of membrane depolarization, as they persisted in conditions of high extracellular potassium solutions and were found to involve SERCA-pump mediated intracellular calcium stores. Involvement of the ghrelin receptor (GHR-S) in these actions was confirmed. Taken together with other studies, our data suggest that ghrelin has multiple cellular actions on LDT cells. Ghrelin's induction of calcium via intracellular release in the LDT could play a role in behavioral actions of this peptide as the LDT governs processes involved in stimulation of motivated behavior and control of cortical arousal.

  20. Ghrelin reverses experimental diabetic neuropathy in mice

    SciTech Connect

    Kyoraku, Itaru; Shiomi, Kazutaka; Kangawa, Kenji; Nakazato, Masamitsu

    2009-11-20

    Ghrelin, an acylated peptide produced in the stomach, increases food intake and growth hormone secretion, suppresses inflammation and oxidative stress, and promotes cell survival and proliferation. We investigated the pharmacological potential of ghrelin in the treatment of polyneuropathy in uncontrolled streptozotocin (STZ)-induced diabetes in mice. Ghrelin or desacyl-ghrelin was administered daily for 4 weeks after STZ-induced diabetic polyneuropathy had developed. Ghrelin administration did not alter food intake, body weight gain, blood glucose levels, or plasma insulin levels when compared with mice given saline or desacyl-ghrelin administration. Ghrelin administration ameliorated reductions in motor and sensory nerve conduction velocities in diabetic mice and normalized their temperature sensation and plasma concentrations of 8-isoprostaglandin {alpha}, an oxidative stress marker. Desacyl-ghrelin failed to have any effect. Ghrelin administration in a mouse model of diabetes ameliorated polyneuropathy. Thus, ghrelin's effects represent a novel therapeutic paradigm for the treatment of this otherwise intractable disorder.

  1. Examination of the tissue ghrelin expression of rats with diet-induced obesity using radioimmunoassay and immunohistochemical methods.

    PubMed

    Aydin, Suleyman; Sahin, Ibrahim; Ozkan, Yusuf; Dag, Ersel; Gunay, Ahmet; Guzel, Saadet Pilten; Catak, Zekiye; Ozercan, Mehmet Resat

    2012-06-01

    Currently, obesity is an important health problem in all countries, both developed and developing. Dietary habits and neurohormonal imbalances play a critical role in obesity. Circulating amounts of ghrelin, which is a neurohormonal hormone, decrease with obesity and increase with weight loss. Although it is known that both mRNA and peptide version of the ghrelin hormone are expressed in almost all tissues of both humans and animals, it is not known how obesity changes the expression of this hormone in the tissues, with the exception of the gastrointestinal system tissues. Therefore, the objective of the present study is to show how diet-induced obesity in rats changes ghrelin expression in all system tissues, and thus, to shed light on the etiopathology of obesity. The study included 12 male and 12 female 2-month-old Wistar albino species rats. The animals in the control group were fed on standard rat pellet, while those in the experiment group were fed ad libitum on a cafeteria-style diet for 2 months. When their body mass index reached 1 g/cm(2), diet-induced obese (DIO) rats were sacrificed in a sterile environment after one night fasting. Ghrelin localizations in the tissues were studied immunohistochemically using avidin-biotin-peroxidase complex (ABC) method, while tissue ghrelin amounts were analyzed using radioimmunoassay (RIA) method. When the ghrelin amounts in the urogenital system (with the exception of kidney tissues), sensory organs, respiratory system, immune system, skeletal muscle system, cardiovascular system, nervous system, and adipose tissue of rats analyzed by RIA method were compared to those in the control group, tissue ghrelin amounts in the DIO group were found lower. Immunohistochemical findings which showed a similar fall in ghrelin concentrations in the tissues were parallel to RIA results. In addition, ghrelin was shown to be synthesized in the cardiovascular system, heart muscle cells, tails of the sperms, hair follicles, lacrimal

  2. Differences in basal and morphine-induced FosB/DeltaFosB and pCREB immunoreactivities in dopaminergic brain regions of alcohol-preferring AA and alcohol-avoiding ANA rats.

    PubMed

    Kaste, Kristiina; Kivinummi, Tanja; Piepponen, T Petteri; Kiianmaa, Kalervo; Ahtee, Liisa

    2009-06-01

    Besides alcohol, alcohol-preferring AA and alcohol-avoiding ANA rats differ also with respect to other abused drugs. To study the molecular basis of these differences, we examined the expression of two transcription factors implicated in addiction, DeltaFosB and pCREB, in brain dopaminergic regions of AA and ANA rats. The effects of morphine and nicotine were studied to relate the behavioral and molecular changes induced by these drugs. Baseline FosB/DeltaFosB immunoreactivity (IR) in the nucleus accumbens core and pCREB IR in the prefrontal cortex (PFC) were elevated in AA rats. Morphine increased DeltaFosB-like IR more readily in the caudate-putamen of AA rats than in ANA rats. In the PFC morphine decreased pCREB IR in AA rats, but increased it in ANA rats. In addition to enhanced locomotor response, the development of place preference to morphine was enhanced in AA rats. The enhanced nicotine-induced locomotor sensitization found in AA compared with ANA rats seems to depend in addition to dopamine and DeltaFosB on other mechanisms. These findings suggest that enhanced sensitivity of AA rats to morphine is related to augmented morphine-induced expression of FosB/DeltaFosB and morphine-induced reduction of pCREB levels. Moreover, altered innate expression of FosB/DeltaFosB and pCREB in AA rats is likely to affect the sensitivity of these rats to abused drugs.

  3. Effects of monocular deprivation on the spatial pattern of visually induced expression of c-Fos protein.

    PubMed

    Nakadate, K; Imamura, K; Watanabe, Y

    2012-01-27

    We studied the pattern of expression of a protein product (c-Fos) of immediate-early gene (IEG) in the visual cortex of rats and mice. The basal expression of c-Fos was very low and visual exposure revealed a large number of c-Fos immunopositive cells in the visual cortex. We found that monocular deprivation during the sensitive period of ocular dominance (OD) plasticity significantly changed both the amount and pattern of c-Fos expression upon monocular stimulation of either eye. The number of immunopositive cells in layer IV of binocular subfields of the primary visual cortex (Oc1B) ipsilateral to the stimulated eye was found to be the most sensitive index of the effects of monocular deprivation during the sensitive period, that is, opened eye stimulation induced significantly larger numbers of c-Fos immunopositive cells, whereas closed eye stimulation induced significantly smaller numbers compared with those induced by monocular stimulation in control animals. In the lateral geniculate nucleus and superior colliculus, the pattern of expression of c-Fos following monocular stimulation was not affected by preceding monocular deprivation. Monocular deprivation imposed after the sensitive period did not affect the pattern of induction of c-Fos. Notably, in age-matched old animals that had been raised in total darkness and then experienced monocular deprivation, the distribution and numbers of c-Fos-expressing cells in visual cortex exhibited the same alterations as found in young animals during the sensitive period. These findings suggest that the present activity mapping method using c-Fos as a molecular marker is useful for examining the activity-dependent regulation of cortical plasticity, and provides an alternative method to conventional electrophysiological recording. This method is particularly powerful when applied to knockout or transgenic mice in which sampling biases in electrophysiological recording have been considered inevitable. Furthermore, these

  4. Effects of Intracerebroventricularly (ICV) Injected Ghrelin on Cardiac Inducible Nitric Oxide Synthase Activity/Expression in Obese Rats.

    PubMed

    Sudar Milovanovic, E; Jovanovic, A; Misirkic-Marjanovic, M; Vucicevic, Lj; Janjetovic, K; Isenovic, E R

    2015-11-01

    The aim of this study was to examine the effects of ghrelin on regulation of cardiac inducible nitric oxide synthase (iNOS) activity/expression in high fat (HF), obese rats.For this study, male Wistar rats fed with HF diet (30% fat) for 4 weeks were injected every 24 h for 5 days intracerebroventricularly (ICV) with ghrelin (0.3 nmol/5 µl) or with an equal volume of phosphate buffered saline (PBS). Control rats were ICV injected with an equal volume of PBS. Glucose, insulin and nitric oxide (NO) concentrations were measured in serum, while arginase activity and citrulline concentrations were measured in heart lysate. Protein iNOS and regulatory subunit of nuclear factor-κB (NFκB-p65), phosphorylation of enzymes protein kinase B (Akt) at Ser(473), and extracellular signal-regulated kinases 1/2 (ERK1/2) at Tyr(202)/Tyr(204) were determined in heart lysate by Western blot. For gene expression of iNOS qRT-PCR was used.Results show significantly (p<0.01) higher serum NO production in ghrelin treated HF rats compared with HF rats. Ghrelin significantly reduced citrulline concentration (p<0.05) and arginase activity (p<0.01) in HF rats. In ghrelin treated HF rats, gene and protein expression of iNOS and NFκB-p65 levels were significantly (p<0.05) increased compared with HF rats. Increased phosphorylation of Akt (p<0.01) and decreased (p<0.05) ERK1/2 phosphorylation were detected in HF ghrelin treated rats compared with HF rats hearts.Results from this study indicate that exogenous ghrelin induces expression and activity of cardiac iNOS via Akt phosphorylation followed by NFκB activation in HF rats.

  5. Pharmacologic Antagonism of Ghrelin Receptors Attenuates Development of Nicotine Induced Locomotor Sensitization in Rats

    PubMed Central

    Wellman, Paul J.; Clifford, P. Shane; Rodriguez, Juan; Hughes, Samuel; Eitan, Shoshana; Brunel, Luc; Fehrentz, Jean-Alain; Martinez, Jean

    2011-01-01

    Aims Ghrelin (GHR) is an orexigenic gut peptide that interacts with ghrelin receptors (GHR-Rs) to modulate brain reinforcement circuits. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP) in rats, whereas genetic or pharmacological ablation of GHR-Rs has been shown to attenuate the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and to blunt the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. A key issue is whether pharmacological antagonism of GHR-Rs would similarly attenuate nicotine-induced locomotor sensitization. Method To examine the role of GHR-Rs in the behavioral sensitizing effects of nicotine, adult male rats were injected with either 0, 3 or 6 mg/kg of the GHR-R receptor antagonist JMV 2959 (i.p.) and 20 minutes later with either vehicle or 0.4 mg/kg nicotine hydrogen tartrate (s.c.) on each of 7 consecutive days. Results Rats treated with nicotine alone showed robust locomotor sensitization, whereas rats pretreated with JMV 2959 showed significantly attenuated nicotine-induced hyperlocomotion. Conclusions These results suggest that GHR-R activity is required for the induction of locomotor sensitization to nicotine and complement an emerging literature implicating central GHR systems in drug reward/reinforcement. PMID:21903141

  6. Social and environmental contexts modulate sleep deprivation-induced c-Fos activation in rats.

    PubMed

    Deurveilher, Samuel; Ryan, Nathan; Burns, Joan; Semba, Kazue

    2013-11-01

    People often sleep deprive themselves voluntarily for social and lifestyle reasons. Animals also appear to stay awake longer as a result of their natural curiosity to explore novel environments and interact socially with conspecifics. Although multiple arousal systems in the brain are known to act jointly to promote and maintain wakefulness, it remains unclear whether these systems are similarly engaged during voluntary vs. forced wakefulness. Using c-Fos immunohistochemistry, we compared neuronal responses in rats deprived of sleep for 2 h by gentle sensory stimulation, exploration under social isolation, or exploration with social interaction, and rats under undisturbed control conditions. In many arousal, limbic, and autonomic nuclei examined (e.g., anterior cingulate cortex and locus coeruleus), the two sleep deprivation procedures involving exploration were similarly effective, and both were more effective than sleep deprivation with sensory stimulation, in increasing the number of c-Fos immunoreactive neurons. However, some nuclei (e.g., paraventricular hypothalamic nucleus and select amygdala nuclei) were more responsive to exploration with social interaction, while others (e.g., histaminergic tuberomammillary nucleus) responded more strongly to exploration in social isolation. In the rostral basal forebrain, cholinergic and GABAergic neurons responded preferentially to exploration with social interaction, whereas resident neurons in general responded most strongly to exploration without social interaction. These results indicate that voluntary exploration with/without social interaction is more effective than forced sleep deprivation with gentle sensory stimulation for inducing c-Fos in arousal and limbic/autonomic brain regions, and suggest that these nuclei participate in different aspects of arousal during sustained voluntary wakefulness.

  7. Acylated and unacylated ghrelin protect MC3T3-E1 cells against tert-butyl hydroperoxide-induced oxidative injury: pharmacological characterization of ghrelin receptor and possible epigenetic involvement.

    PubMed

    Dieci, Elisa; Casati, Lavinia; Pagani, Francesca; Celotti, Fabio; Sibilia, Valeria

    2014-07-01

    Increasing evidence suggests a role for oxidative stress in age-related decrease in osteoblast number and function leading to the development of osteoporosis. This study was undertaken to investigate whether ghrelin, previously reported to stimulate osteoblast proliferation, counteracts tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in MC3T3-E1 osteoblastic cells as well as to characterize the ghrelin receptor (GHS-R) involved in such activity. Pretreatment with ghrelin (10(-7)-10(-11)M) significantly increased viability and reduced apoptosis of MC3T3-E1 cells cultured with t-BHP (250 μM) for three hours at the low concentration of 10(-9)M as shown by MTT assay and Hoechst-33258 staining. Furthermore, ghrelin prevented t-BHP-induced osteoblastic dysfunction and changes in the cytoskeleton organization evidenced by the staining of the actin fibers with Phalloidin-FITC by reducing reactive oxygen species generation. The GHS-R type 1a agonist, EP1572 (10(-7)-10(-11)M), had no effect against t-BHP-induced cytotoxicity and pretreatment with the selective GHS-R1a antagonist, D-Lys(3)-GHRP-6 (10(-7)M), failed to remove ghrelin (10(-9) M)-protective effects against oxidative injury, indicating that GHS-R1a is not involved in such ghrelin activity. Accordingly, unacylated ghrelin (DAG), not binding GHS-R1a, displays the same protective actions of ghrelin against t-BHP-induced cytotoxicity. Preliminary observations indicate that ghrelin increased the trimethylation of lys4 on histones H3, a known epigenetic mark activator, which may regulate the expression of some genes limiting oxidative damage. In conclusion, our data demonstrate that ghrelin and DAG promote survival of MC3T3-E1 cell exposed to t-BHP-induced oxidative damage. Such effect is independent of GHS-R1a and is likely mediated by a common ghrelin/DAG binding site.

  8. Striatal dopamine and glutamate receptors modulate methamphetamine-induced cortical Fos expression

    PubMed Central

    Gross, Noah B.; Marshall, John F.

    2009-01-01

    Methamphetamine (mAMPH) is a psychostimulant drug that increases extracellular levels of monoamines throughout the brain. It has previously been observed that a single injection of mAMPH increases immediate early gene (IEG) expression in both the striatum and cerebral cortex. Moreover, this effect is modulated by dopamine and glutamate receptors since systemic administration of dopamine or glutamate antagonists has been found to alter mAMPH-induced striatal and cortical IEG expression. However, because dopamine and glutamate receptors are found in extra-striatal as well as striatal brain regions, studies employing systemic injection of dopamine or glutamate antagonists fail to localize the effects of mAMPH-induced activation. In the present experiments, the roles of striatal dopamine and glutamate receptors in mAMPH-induced gene expression in the striatum and cerebral cortex were examined. The nuclear expression of Fos, the protein product of the IEG c-fos, was quantified in both the striatum and the cortex of animals receiving intrastriatal dopamine or glutamate antagonist administration. Intrastriatal infusion of dopamine (D1 or D2) or glutamate [N-methyl-D-aspartic acid (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)] antagonists affected not only mAMPH-induced striatal, but also cortical, Fos expression. Overall, the effects of the antagonists occurred dose-dependently, in both the infused and non-infused hemispheres, with greater influences occurring in the infused hemisphere. Finally, unilateral intrastriatal infusion of dopamine or glutamate antagonists changed the behavior of the rats from characteristic mAMPH-induced stereotypy to rotation ipsilateral to the infusion. These results demonstrate that mAMPH’s actions on striatal dopamine and glutamate receptors modulate the widespread cortical activation induced by mAMPH. It is hypothesized that dopamine release from nigrostriatal terminals modulates activity within striatal

  9. Ghrelin inhibition of ethanol-induced gastric epithelial cell apoptosis is mediated by miR-21

    PubMed Central

    Jiang, Miao; Gao, Peng-Fei; Li, Huan-Qing; Tian, Pei-Ying; Fan, Xiao-Ming

    2015-01-01

    Aim: To investigate the underlying mechanism of ghrelin-induced gastro-protection in a cell culture model of ethanol-induced gastric epithelial cell injury. Methods: The human gastric epithelial cell line GES-1 was incubated with ghrelin (0.01-1 µM), 1 µM ghrelin and 1 µM D-Lys3-growth hormone releasing peptide-6 (GHRP-6), or 1 µM ghrelin and 400 nM antagomiR-21 for 24 h, followed by treatment with 8% ethanol for 3 h to induce apoptosis. Cell viability was determined by MTT assays and flow cytometry was used for detection of apoptosis rates. miR-21 transcription was analyzed by qRT-PCR and Akt, Bcl-2, Bax and caspase 3 expressions were measured by Western blot. Results: Flow cytometry and a quantitative RT-PCR analysis of the expression of miR-21 showed that ghrelin inhibited apoptosis in a dose dependent manner through a signaling pathway that was both growth hormone secretagogue receptor (GHS-R) and miR-21 dependent, as the antiapoptotic effect of ghrelin was blocked by both D-Lys3-GHRP-6 and antagomiR-21, respectively. Western blotting of Akt, Bcl-2, Bax, and caspase 3 showed that the levels of the antiapoptotic proteins, Akt and Bcl-2, in the cells pretreated with ghrelin alone were higher than those in the cells pretreated with D-Lys3-GHRP-6 or antagomiR-21. By contrast, the levels of the proapoptotic proteins, Bax and caspase 3, in the cells pretreated with ghrelin alone were lower than those in the cells pretreated with D-Lys3-GHRP-6 or antagomiR-21. Conclusion: Ghrelin inhibits GES-1 cell apoptosis through GHS-R-dependent signaling in which miR-21 activates the PI3K/Akt pathway, which upregulates Bcl-2 and downregulates Bax and caspase 3 expression. PMID:26191156

  10. Neuronal deletion of ghrelin receptor almost completely prevents diet-induced obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ghrelin signaling has major effects on energy- and glucose-homeostasis, but it is unknown whether ghrelin's functions are centrally and/or peripherally mediated. The ghrelin receptor, Growth Hormone Secretagogue Receptor (GHS-R), is highly expressed in brain and detectable in some peripheral tissues...

  11. Ghrelin Protection against Lipopolysaccharide-Induced Gastric Mucosal Cell Apoptosis Involves Constitutive Nitric Oxide Synthase-Mediated Caspase-3 S-Nitrosylation

    PubMed Central

    Slomiany, Bronislaw L.; Slomiany, Amalia

    2010-01-01

    Ghrelin, a peptide hormone produced mainly in the stomach, has emerged as an important modulator of the inflammatory responses that are of significance to the maintenance of gastric mucosal integrity. Here, we report on the role of ghrelin in controlling the apoptotic processes induced in gastric mucosal cells by H. pylori lipopolysaccharide (LPS). The countering effect of ghrelin on the LPS-induced mucosal cell apoptosis was associated with the increase in constitutive nitric oxide synthase (cNOS) activity, and the reduction in caspase-3 and inducible nitric oxide synthase (NOS-2). The loss in countering effect of ghrelin on the LPS-induced changes in apoptosis and caspase-3 activity was attained with Src kinase inhibitor, PP2, as well as Akt inhibitor, SH-5, and cNOS inhibitor, L-NAME. Moreover, the effect of ghrelin on the LPS-induced changes in cNOS activity was reflected in the increased cNOS phosphorylation that was sensitive to SH-5. Furthermore, the ghrelin-induced up-regulation in cNOS activity was associated with the increase in caspase-3 S-nitrosylation that was susceptible to the blockage by L-NAME. Therefore, ghrelin protection of gastric mucosal cells against H. pylori LPS-induced apoptosis involves Src/Akt-mediated up-regulation in cNOS activation that leads to the apoptotic signal inhibition through the NO-induced caspase-3 S-nitrosylation. PMID:20369000

  12. Site specific effects of anosmia and cloacal gland anesthesia on Fos expression induced in male quail brain by sexual behavior

    PubMed Central

    Taziaux, Mélanie; Keller, Matthieu; Ball, Gregory F.; Balthazart, Jacques

    2008-01-01

    In rats, expression of the immediate early gene, c-fos observed in the brain following male copulatory behavior relates mostly to the detection of olfactory information originating from the female and to somatosensory feedback from the penis. However, quail, like most birds, are generally considered to have a relatively poorly developed sense of smell. Furthermore, quail have no intromittent organ (e.g., penis). It is therefore intriguing that expression of male copulatory behavior induces in quail and rats a similar pattern of c-fos expression in the medial preoptic area (mPOA), bed nucleus of the stria terminalis (BSTM) and parts of the amygdala. We analyzed here by immunocytochemistry Fos expression in the mPOA/BSTM/amygdala of male quail that had been allowed to copulate with a female during standardized tests. Before these tests, some of the males had either their nostrils plugged, or their cloacal area anesthetized, or both. A control group was not exposed to females. These manipulations did not affect frequencies of male sexual behavior and all birds exposed to a female copulated normally. In the mPOA, the increased Fos expression induced by copulation was not affected by the cloacal gland anesthesia but was markedly reduced in subjects deprived of olfactory input. Both manipulations affected copulation-induced Fos expression in the BSTM. No change in Fos expression was observed in the amygdala. Thus immediate early gene expression in the mPOA and BSTM of quail is modulated at least in part by olfactory cues and/or somatosensory stimuli originating from the cloacal gland. Future work should specify the nature of these stimuli and their function in the expression of avian male sexual behavior. PMID:18638505

  13. Endomorphins suppress nociception-induced c-Fos and Zif/268 expression in the rat spinal dorsal horn.

    PubMed

    Tateyama, Shingo; Ikeda, Tetsuya; Kosai, Kazuko; Nakamura, Tadashi; Kasaba, Toshiharu; Takasaki, Mayumi; Nishimori, Toshikazu

    2002-09-06

    We evaluated the potency of endomorphin-1 and -2 as endogenous ligands on c-Fos and Zif/268 expression in the spinal dorsal horn by formalin injection to the rat hind paw. Endomorphin-1, -2, or morphine was administered intrathecally or intracerebroventricularly 5 min before formalin injection (5%, 100 microl). All drugs produced marked reductions of formalin-induced c-Fos and Zif/268 immunoreactivity in laminae I and II, and laminae V and VI in the rat lumbar spinal cord. The reductions of Zif/268 expression by endomorphins were greater than those by morphine, while the reductions of c-Fos expression by endomorphins were smaller than those by morphine. These effects of endomorphins were attenuated by pretreatment with naloxone. These results indicate that endomorphin-1 and -2 act as endogenous ligands of mu-opioid receptor in neurons of the spinal dorsal horn and suppress the processing of nociceptive information in the central nervous system.

  14. Prenatal ethanol exposure alters ethanol-induced Fos immunoreactivity and dopaminergic activity in the mesocorticolimbic pathway of the adolescent brain.

    PubMed

    Fabio, M C; Vivas, L M; Pautassi, R M

    2015-08-20

    Prenatal ethanol exposure (PEE) promotes alcohol intake during adolescence, as shown in clinical and pre-clinical animal models. The mechanisms underlying this effect of prenatal ethanol exposure on postnatal ethanol intake remain, however, mostly unknown. Few studies assessed the effects of moderate doses of prenatal ethanol on spontaneous and ethanol-induced brain activity on adolescence. This study measured, in adolescent (female) Wistar rats prenatally exposed to ethanol (0.0 or 2.0g/kg/day, gestational days 17-20) or non-manipulated (NM group) throughout pregnancy, baseline and ethanol-induced cathecolaminergic activity (i.e., colocalization of c-Fos and tyrosine hydroxylase) in ventral tegmental area (VTA), and baseline and ethanol-induced Fos immunoreactivity (ir) in nucleus accumbens shell and core (AcbSh and AcbC, respectively) and prelimbic (PrL) and infralimbic (IL) prefrontal cortex. The rats were challenged with ethanol (dose: 0.0, 1.25, 2.5 or 3.25g/kg, i.p.) at postnatal day 37. Rats exposed to vehicle prenatally (VE group) exhibited reduced baseline dopaminergic tone in VTA; an effect that was inhibited by prenatal ethanol exposure (PEE group). Dopaminergic activity in VTA after the postnatal ethanol challenge was greater in PEE than in VE or NM animals. Ethanol-induced Fos-ir at AcbSh was found after 1.25g/kg and 2.5g/kg ethanol, in VE and PEE rats, respectively. PEE did not alter ethanol-induced Fos-ir at IL but reduced ethanol-induced Fos-ir at PrL. These results suggest that prenatal ethanol exposure heightens dopaminergic activity in the VTA and alters the response of the mesocorticolimbic pathway to postnatal ethanol exposure. These effects may underlie the enhanced vulnerability to develop alcohol-use disorders of adolescents with a history of in utero ethanol exposure.

  15. High ambient temperature increases 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy")-induced Fos expression in a region-specific manner.

    PubMed

    Hargreaves, G A; Hunt, G E; Cornish, J L; McGregor, I S

    2007-03-16

    3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a popular drug that is often taken under hot conditions at dance clubs. High ambient temperature increases MDMA-induced hyperthermia and recent studies suggest that high temperatures may also enhance the rewarding and prosocial effects of MDMA in rats. The present study investigated whether ambient temperature influences MDMA-induced expression of Fos, a marker of neural activation. Male Wistar rats received either MDMA (10 mg/kg i.p.) or saline, and were placed in test chambers for 2 h at either 19 or 30 degrees C. MDMA caused significant hyperthermia at 30 degrees C and a modest hypothermia at 19 degrees C. The 30 degrees C ambient temperature had little effect on Fos expression in vehicle-treated rats. However MDMA-induced Fos expression was augmented in 15 of 30 brain regions at the high temperature. These regions included (1) sites associated with thermoregulation such as the median preoptic nucleus, dorsomedial hypothalamus and raphe pallidus, (2) the supraoptic nucleus, a region important for osmoregulation and a key mediator of oxytocin and vasopressin release, (3) the medial and central nuclei of the amygdala, important in the regulation of social and emotional behaviors, and (4) the shell of the nucleus accumbens and (anterior) ventral tegmental area, regions associated with the reinforcing effects of MDMA. MDMA-induced Fos expression was unaffected by ambient temperature at many other sites, and was diminished at high temperature at one site (the islands of Calleja), suggesting that the effect of temperature on MDMA-induced Fos expression was not a general pharmacokinetic effect. Overall, these results indicate that high temperatures accentuate key neural effects of MDMA and this may help explain the widespread use of the drug under hot conditions at dance parties as well as the more hazardous nature of MDMA taken under such conditions.

  16. Involvement of cyclooxygenase-1 and cyclooxygenase-2 activity in the therapeutic effect of ghrelin in the course of ethanol-induced gastric ulcers in rats.

    PubMed

    Warzecha, Z; Ceranowicz, P; Dembinski, M; Cieszkowski, J; Ginter, G; Ptak-Belowska, A; Dembinski, A

    2014-02-01

    Previous studies have shown that treatment with ghrelin exhibits protective and therapeutic effects in the gut. Aim of our present investigation was to examine the influence of ghrelin administration on the healing of ethanol-induced gastric ulcers and determine the role of cyclooxygenase-1 and cyclooxygenase-2 in this effect. Our studies were performed on male Wistar rats. Gastric ulcers were induced by intragastric administration of 75% ethanol. Ghrelin alone or in combination with cyclooxygenase inhibitors was administered twice, 1 and 13 hours after ethanol application. Cyclooxygenase-1 (COX-1) inhibitor (SC-560, 10 mg/kg/dose) or COX-2 inhibitor (celecoxib, 10 mg/kg/dose) were given 30 min prior to ghrelin. Twelve or 24 hours after administration of ethanol, rats were anesthetized and experiments were terminated. The study revealed that administration of ethanol induced gastric ulcers in all animals and this effect was accompanied by the reduction in gastric blood flow and mucosal DNA synthesis. Moreover induction of gastric ulcer by ethanol significantly increased mucosal expression of mRNA for COX-2, IL-1β and TNF-α. Treatment with ghrelin significantly accelerated gastric ulcer healing. Therapeutic effect of ghrelin was associated with significant reversion of the ulcer-evoked decrease in mucosal blood flow and DNA synthesis. Ghrelin administration also caused the reduction in mucosal expression of mRNA for IL-1β and TNF-α. Addition of SC-560 slightly reduced the therapeutic effect of ghrelin in the healing of ethanol-induced ulcer and the ulcer area in rats treated SC-560 plus ghrelin was significantly smaller than that observed in rats treated with saline or SC-560 alone. Pretreatment with celecoxib, a COX-2 inhibitor, abolished therapeutic effect of ghrelin. We concluded that treatment with ghrelin increases healing rate of gastric ulcers evoked by ethanol and this effect is related to improvement in mucosal blood flow, an increase in mucosal cell

  17. Ghrelin, a natural GH secretagogue produced by the stomach, induces hyperglycemia and reduces insulin secretion in humans.

    PubMed

    Broglio, F; Arvat, E; Benso, A; Gottero, C; Muccioli, G; Papotti, M; van der Lely, A J; Deghenghi, R; Ghigo, E

    2001-10-01

    Ghrelin, a 28 amino acid gastric hormone is a natural ligand of the GH Secretagogue (GHS) receptor (GHS-R) and strongly stimulates GH secretion though, like synthetic GHS, it shows other endocrine and non-endocrine activities. Aim of the present study was to clarify whether ghrelin administration influences insulin and glucose levels in humans. To this goal, we compared the effects of ghrelin, hexarelin, a synthetic GHS, or placebo on insulin and glucose as well as on GH levels in 11 normal young volunteers (age [mean +/- SEM]: 28.5 +/- 3.1 yr; BMI: 22.2 +/- 0.9 Kg/m(2)). Ghrelin induced very marked increase in GH secretion (DeltaAUC(0-180): 5777.1 +/- 812.6 microg/l/h; p < 0.01) which was not modified by placebo. Placebo administration did not modify insulin and glucose levels. On the other hand, ghrelin administration induced a prompt increase in glucose levels (DeltaAUC(0-180): 1343.1 +/- 443.5 mg/dl/h; p < 0.01 vs. saline). Absolute glucose levels at +15' were already higher than those at baseline (93.9 +/- 7.1 mg/dl; p < 0.01) and persisted elevated up to 165' (90.3 +/- 5.8 mg/dl; p < 0.01 vs. 0'). Ghrelin administration was also followed by a decrease in serum insulin levels (DeltaAUC(0-180): -207.1 +/- 70.5 mU/l/h; p < 0.05 vs. saline). Absolute insulin levels were significantly reduced from 30' (11.4 +/- 0.9 mU/l, p < 0.1 vs. 0'), showed the nadir at +45' (10.0 +/- 0.6 mU/l, p < 0.01 vs. 0') and then persisted lower (p < 0.01) than baseline up to +105'. Hexarelin administration did not modify glucose and insulin levels despite its marked GH-releasing effect (DeltaAUC(0-180): 4156.8 +/- 1180.3 microg/l/h; p < 0.01 vs. saline) that was slightly lower (p < 0.05) than that of ghrelin. In conclusion, these findings show that, besides stimulating GH secretion, ghrelin is a gastric hormone possessing metabolic actions such as hyperglycemic effect and lowering effect on insulin secretion in humans, at least after acute administration.

  18. NMDA preconditioning and neuroprotection in vivo: delayed onset of kainic acid-induced neurodegeneration and c-Fos attenuation in CA3a neurons.

    PubMed

    Mohammadi, Shirin; Pavlik, Alfred; Krajci, Dimitrolos; Al-Sarraf, Hameed

    2009-02-23

    Intraventricular (i.c.v.) kainic acid (KA) causes an acute excitotoxic lesion to the CA3 region of rodent hippocampus. Recent evidence implicated c-fos gene in regulating neuron survival and death following an excitotoxic insult. In this study we attempted to prevent KA-induced damage in CA3 neurons with NMDA preconditioning, which produced a marked expression of c-fos in the hippocampus. NMDA (0.6-6 microg, i.c.v.) was injected to anesthetized rats alone or 1 h before KA (0.15 microg, i.c.v.). Following KA injection, vibratome sections were processed for immunohistochemistry/electron microscopy. c-Fos and Nissl staining were used to estimate the extent of neuronal excitation and damage, respectively. Quantitative evaluation of c-Fos-labeled cells showed significantly less c-Fos in CA3a than in neighboring CA3b and CA2 from 1 to 4 h after KA alone. Attenuation of expressed c-Fos in CA3a was accompanied by damage of neurons with more apoptotic than necrotic signs. NMDA preconditioning elevated CA3a c-Fos expression and at 1 and 2 h exceeded markedly that after KA alone. However, at 4 h after KA, NMDA-preconditioned c-Fos induction in CA3a diminished to the same level as that seen after KA alone. The onset of neuronal degeneration was delayed in similar way. While NMDA-induced c-Fos expression in CA3a could be blocked by MK-801 completely, MK-801 and CNQX were both without significant effect on KA-induced c-Fos expression and neuronal damage. In conclusion, inhibition of c-Fos expression and onset of neuronal damage in CA3a following icv KA injection might be transiently delayed by i.c.v. NMDA preconditioning.

  19. Ghrelin-Induced Orexigenic Effect in Rats Depends on the Metabolic Status and Is Counteracted by Peripheral CB1 Receptor Antagonism

    PubMed Central

    Alen, Francisco; Crespo, Inmaculada; Ramírez-López, María Teresa; Jagerovic, Nadine; Goya, Pilar; de Fonseca, Fernando Rodríguez; de Heras, Raquel Gómez; Orio, Laura

    2013-01-01

    Ghrelin is an endogenous regulator of energy homeostasis synthesized by the stomach to stimulate appetite and positive energy balance. Similarly, the endocannabinoid system is part of our internal machinery controlling food intake and energy expenditure. Both peripheral and central mechanisms regulate CB1-mediated control of food intake and a functional relationship between hypothalamic ghrelin and cannabinoid CB1 receptor has been proposed. First of all, we investigated brain ghrelin actions on food intake in rats with different metabolic status (negative or equilibrate energy balance). Secondly, we tested a sub-anxiogenic ultra-low dose of the CB1 antagonist SR141716A (Rimonabant) and the peripheral-acting CB1 antagonist LH-21 on ghrelin orexigenic actions. We found that: 1) central administration of ghrelin promotes food intake in free feeding animals but not in 24 h food-deprived or chronically food-restricted animals; 2) an ultra-low dose of SR141716A (a subthreshold dose 75 folds lower than the EC50 for induction of anxiety) completely counteracts the orexigenic actions of central ghrelin in free feeding animals; 3) the peripheral-restricted CB1 antagonist LH-21 blocks ghrelin-induced hyperphagia in free feeding animals. Our study highlights the importance of the animaĺs metabolic status for the effectiveness of ghrelin in promoting feeding, and suggests that the peripheral endocannabinoid system may interact with ghrelińs signal in the control of food intake under equilibrate energy balance conditions. PMID:23565287

  20. Ghrelin and the cardiovascular system.

    PubMed

    Tokudome, Takeshi; Kishimoto, Ichiro; Miyazato, Mikiya; Kangawa, Kenj

    2014-01-01

    Ghrelin is a peptide that was originally isolated from the stomach. It exerts potent growth hormone (GH)-releasing and orexigenic activities. Several studies have highlighted the therapeutic benefits of ghrelin for the treatment of cardiovascular disease. In animal models of chronic heart failure, the administration of ghrelin improved cardiac function and remodeling; these findings were replicated in human patients with heart failure. Moreover, in an animal study, ghrelin administration effectively reduced pulmonary hypertension induced by chronic hypoxia. In addition, repeated administration of ghrelin to cachectic patients with chronic obstructive pulmonary disease had positive effects on overall body function, including muscle wasting, functional capacity and sympathetic activity. The administration of ghrelin early after myocardial infarction (MI) reduced fatal arrhythmia and related mortality. In ghrelin-deficient mice, both exogenous and endogenous ghrelin were protective against fatal arrhythmia and promoted remodeling after MI. Although the mechanisms underlying the effects of ghrelin on the cardiovascular system remain unclear, there are indications that its beneficial effects are mediated through both direct physiological actions, including increased GH levels, improved energy balance and direct actions on cardiovascular cells, and regulation of autonomic nervous system activity. Therefore, ghrelin is a promising novel therapeutic agent for cardiovascular disease.

  1. Pattern of Fos expression in the brain induced by selective activation of somatostatin receptor 2 in rats

    PubMed Central

    Goebel, Miriam; Stengel, Andreas; Wang, Lixin; Coskun, Tamer; Alsina-Fernandez, Jorge; Rivier, Jean; Taché, Yvette

    2010-01-01

    Central activation of somatostatin (sst) receptors by oligosomatostatin analogs inhibits growth hormone and stress-related rise in catecholamine plasma levels while stimulating grooming, feeding behaviors, gastric transit and acid secretion, which can be mimicked by selective sst2 receptor agonist. To evaluate the pattern of neuronal activation induced by peptide sst receptor agonists, we assessed Fos-expression in rat brain after intracerebroventricular (icv) injection of a newly developed selective sst2 agonist compared to the oligosomatostatin agonist, ODT8-SST, a pan-sst1–5 agonist. Ninety min after injection of vehicle (10µl) or previously established maximal orexigenic dose of peptides (1µg=1nmol/rat), brains were assessed for Fos-immunohistochemistry and doublelabeling. Food and water were removed after injection. The sst2 agonist and ODT8-SST induced a similar Fos distribution pattern except in the arcuate nucleus where only the sst2 agonist increased Fos. Compared to ODT8-SST, the sst2 agonist induced higher Fos-expression by 3.7-fold in the basolateral amygdaloid nucleus, 1.2-fold in the supraoptic nucleus (SON), 1.6-fold in the magnocellular paraventricular hypothalamic nucleus (mPVN), 4.1-fold in the external lateral parabrachial nucleus, and 2.6-fold in both the inferior olivary nucleus and superficial layer of the caudal spinal trigeminal nucleus. Doublelabeling in the hypothalamus showed that ODT8-SST activates 36% of oxytocin, 63% of vasopressin and 79% of sst2 immunoreactive neurons in the mPVN and 28%, 55% and 25% in the SON, respectively. Selective activation of sst2 receptor results in a more robust neuronal activation than the pan-sst1–5 agonist in various brain regions that may have relevance in sst2 mediated alterations of behavioral, autonomic and endocrine functions. PMID:20637739

  2. Intravenous injection of urocortin 1 induces a CRF2 mediated increase in circulating ghrelin and glucose levels through distinct mechanisms in rats.

    PubMed

    Wang, Lixin; Stengel, Andreas; Goebel-Stengel, Miriam; Shaikh, Almaas; Yuan, Pu-Qing; Taché, Yvette

    2013-01-01

    Urocortins (Ucns) injected peripherally decrease food intake and gastric emptying through peripheral CRF(2) receptors in rodents. However, whether Ucns influence circulating levels of the orexigenic and prokinetic hormone, ghrelin has been little investigated. We examined plasma levels of ghrelin and blood glucose after intravenous (iv) injection of Ucn 1, the CRF receptor subtype involved and underlying mechanisms in ad libitum fed rats equipped with a chronic iv cannula. Ucn 1 (10 μg/kg, iv) induced a rapid onset and long lasting increase in ghrelin levels reaching 68% and 219% at 0.5 and 3h post injection respectively and a 5-h hyperglycemic response. The selective CRF(2) agonist, Ucn 2 (3 μg/kg, iv) increased fasting acyl (3h: 49%) and des-acyl ghrelin levels (3h: 30%) compared to vehicle while the preferential CRF(1) agonist, CRF (3 μg/kg, iv) had no effect. Ucn 1's stimulatory actions were blocked by the selective CRF(2) antagonist, astressin(2)-B (100 μg/kg, iv). Hexamethonium (10 mg/kg, sc) prevented Ucn 1-induced rise in total ghrelin levels while not altering the hyperglycemic response. These data indicate that systemic injection of Ucns induces a CRF(2)-mediated increase in circulating ghrelin levels likely via indirect actions on gastric ghrelin cells that involves a nicotinic pathway independently from the hyperglycemic response.

  3. Ghrelin-Induced Enhancement of Vasopressin and Oxytocin Secretion in Rat Neurohypophyseal Cell Cultures.

    PubMed

    Gálfi, M; Radács, M; Molnár, Zs; Budai, I; Tóth, G; Pósa, A; Kupai, K; Szalai, Z; Szabó, R; Molnár, H A; Gardi, J; László, Ferenc A; Varga, Cs

    2016-12-01

    The effects of ghrelin on vasopressin and oxytocin secretion were studied in 13-14-day cell cultures of isolated rat neurohypophyseal tissue. The vasopressin and oxytocin contents of the supernatant were determined by radioimmunoassay after a 1- or 2-h incubation. Significantly increased levels of vasopressin and oxytocin production were detected in the cell culture media following ghrelin administration, depending on the ghrelin doses. The oxytocin level proved to be more elevated than that of vasopressin. The increase of vasopressin and oxytocin secretion could be totally blocked by previous administration of the ghrelin receptor antagonist ([D-Lys(3)]-growth hormone-releasing peptide-6). Application of the ghrelin receptor antagonist after ghrelin administration proved ineffective. The results indicate that vasopressin and oxytocin release is influenced directly by the ghrelin system, and the effects of ghrelin on vasopressin and oxytocin secretion from the neurohypophyseal tissue in rats can occur at the level of the posterior pituitary. Our observations lend support to the view that neurohypophysis contains ghrelin receptors.

  4. Fos Expression in Rat Brain During Depletion-Induced Thirst and Salt Appetite

    NASA Technical Reports Server (NTRS)

    Thunhorst, R. L.; Xu, Z.; Cicha, M. Z.; Zardetto-Smith, A. M.; Johnson, A. K.

    1998-01-01

    The expression of Fos protein (Fos immunoreactivity, Fos-ir) was mapped in the brain of rats subjected to an angiotensin-dependent model of thirst and salt appetite. The physiological state associated with water and sodium ingestion was produced by the concurrent subcutaneous administration of the diuretic furosemide (10 mg/kg) and a low dose of the angiotensin-converting enzyme (ACE) inhibitor captopril (5 mg/kg; Furo/Cap treatment). The animals were killed 2 h posttreatment, and the brains were processed for Fos-ir to assess neural activation. Furo/Cap treatment significantly increased Fos-ir density above baseline levels both in structures of the lamina terminalis and hypothalamus known to mediate the actions of ANG 2 and in hindbrain regions associated with blood volume and pressure regulation. Furo/Cap treatment also typically increased Fos-ir density in these structures above levels observed after administration of furosemide or captopril separately. Fos-ir was reduced to a greater extent in forebrain than in hindbrain areas by a dose of captopril (100 mg/kg sc) known to block the actions of ACE in the brain. The present work provides further evidence that areas of lamina terminalis subserve angiotensin-dependent thirst and salt appetite.

  5. [Ghrelin: beyond hunger regulation].

    PubMed

    Milke García, Maria del Pilar

    2005-01-01

    Man ingests food to mitigate hunger (mediated by physiological and biochemical signals), satisfy appetite (subjective sensation) and because of psychosocial reasons. Satiation biomarkers (stop feeding) are gastric distention and hormones (CCK, GLP-1) and satiety biomarkers (induce feeding) are food-induced thermogenesis, body temperature, glycaemia and also hormones (insulin, leptin and ghrelin). Oxidative metabolism/body composition, tryptophan/serotonin and proinflammatory cytokines are also implicated on hunger physiology. At the present time, ghrelin is the only known circulating orexigenic with potential on hunger/body weight regulation. It is a neuropeptide (endogenous ligand for the GH secretagogue) recently isolated from the oxyntic mucosa and synthesized mainly in the stomach. Its blood concentration depends on diet, hyperglucemia and adiposity/leptin. It is secreted 1-2 hours preprandially and its concentration decreases drastically during the postprandium. Ghrelin acts on the lateral hypothalamus and theoretically inhibits proinflammatory cytokine secretion and antagonizes leptin. Ghrelin physiologically increases food intake and stimulates adipogenesis, gastrointestinal motility and gastric acid secretion, and has other hormonal and cardiovascular functions. Ghrelin blood concentration is reduced in massive obesity, non-alcoholic steatohepatitis, polycystic ovary syndrome, acromegaly, hypogonadism, ageing, short bowel syndrome and rheumatoid arthritis; and increased in primary or secondary anorexia, starvation, chronic liver disease and celiac disease. Cerebral and peritoneal ghrelin administration (rats) and systemic administration (rats and healthy volunteers, cancer patients or patients on peritoneal dialysis) promotes food consumption and increases adiposity, of utmost importance in the treatment of patients with anorexia.

  6. Exaggerated C-fiber activation prevents peripheral nerve injury-induced hyperinducibility of c-Fos in partially deafferented spinal dorsal horn.

    PubMed

    Sugimoto, T; Funahashi, M; Xiao, C; Adachi, A; Ichikawa, H

    1997-02-01

    Dorsal horn neurons chronically deafferented by peripheral nerve injuries acquire hypersensitivity to noxious input from outside the original receptive field. This study examines the effect of electrical nerve stimulation at the time of injury on such injury-induced hypersensitivity. The medial 3/8 of the dorsal horn laminae I/II around the junction of 4th and 5th lumbar segments (the tibial territory) was deafferented by transection of the ipsilateral tibial nerve in rats. At 2 days or 3 weeks postinjury, the hindpaw was injected with formalin to induce c-fos. At 2 days, neurons with induced c-Fos protein-like immunoreactivity (fos-neurons) were largely confined in the lateral 5/8 of laminae I/II (the peroneal and hip, thus P and H territory). At 3 weeks, fos-neurons significantly increased in the deafferented tibial territory. A similar increase was also noted in the P and H territory. Thus the dorsal horn neurons exhibited c-fos hyperinducibility, an indication of hypersensitivity. Electrical stimulation with a train of 150 shocks (10 V, 2 ms) of the proximal nerve stump immediately after transection prevented the c-fos hyperinducibility. The effect was greater with the stimulation frequency of 0.5 Hz than 0.1 Hz or 10 Hz. The stimulation had no effect on the c-fos inducibility at 2 days postinjury.

  7. Continuous administration of antisense oligonucleotides to c-fos reduced the development of seizure susceptibility after ethacrynic acid-induced seizure in mice.

    PubMed

    Suzukawa, Junko; Omori, Kyoko; Yang, Li; Inagaki, Chiyoko

    2003-09-25

    We previously demonstrated that seizure susceptibility developed by the 14th day post-ethacrynic acid (EA)-induced seizure in mice, with a prolonged increase in the expression of c-fos mRNA in the brain during days 10-14. To examine whether such c-fos increase contributes to the development of seizure susceptibility, we administered antisense oligodeoxynucleotide to c-fos by continuous infusion into the lateral ventricle of mice that had shown a moderate stage of EA seizure, and evaluated the seizure susceptibility to kainic acid (10 mg/kg) on the 14th day. Antisense-infused mice displayed significant reduction of the c-Fos level in the hippocampus and cerebral cortex on the 7th and 14th days, and a significant decrease in seizure severity. These findings suggest that the prolonged increase in c-fos expression after EA seizure may lead to the development of seizure susceptibility.

  8. Water deprivation increases Fos expression in hypothalamic corticotropin-releasing factor neurons induced by right atrial distension in awake rats.

    PubMed

    Benedetti, Mauricio; Rorato, Rodrigo; Castro, Margaret; Machado, Benedito H; Antunes-Rodrigues, Jose; Elias, Lucila L K

    2008-11-01

    Atrial mechanoreceptors, sensitive to stretch, contribute in regulating heart rate and intravascular volume. The information from those receptors reaches the nucleus tractus solitarius and then the paraventricular nucleus (PVN), known to have a crucial role in the regulation of cardiovascular function. Neurons in the PVN synthesize CRF, AVP, and oxytocin (OT). Stimulation of atrial mechanoreceptors was performed in awake rats implanted with a balloon at the junction of the superior vena cava and right atrium. Plasma ACTH, AVP, and OT concentrations and Fos, CRF, AVP, and OT immunolabeling in the PVN were determined after balloon inflation in hydrated and water-deprived rats. The distension of the balloon increased the plasma ACTH concentrations, which were higher in water-deprived than in hydrated rats (P < 0.05). In addition, the distension in the water-deprived group decreased plasma AVP concentrations (P < 0.05), compared with the respective control group. The distension increased the number of Fos- and double-labeled Fos/CRF neurons in the parvocellular PVN, which was higher in the water-deprived than in the hydrated group (P < 0.01). There was no difference in the Fos expression in magnocellular PVN neurons after distension in hydrated and water-deprived groups, compared with respective controls. In conclusion, parvocellular CRF neurons showed an increase of Fos expression induced by stimulation of right atrial mechanoreceptors, suggesting that CRF participates in the cardiovascular reflex adjustments elicited by volume loading. Activation of CRF neurons in the PVN by cardiovascular reflex is affected by osmotic stimulation.

  9. Papillomavirus-Associated Tumor Formation Critically Depends on c-Fos Expression Induced by Viral Protein E2 and Bromodomain Protein Brd4

    PubMed Central

    Schneider, Markus; Schuetz, Johanna; Leiprecht, Natalie; Hudjetz, Benjamin; Brodbeck, Stephan; Corall, Silke; Dreer, Marcel; Schwab, Roxana Michaela; Grimm, Martin; Wu, Shwu-Yuan; Stubenrauch, Frank; Chiang, Cheng-Ming; Iftner, Thomas

    2016-01-01

    We investigated the mechanism of how the papillomavirus E2 transcription factor can activate promoters through activator protein (AP)1 binding sites. Using an unbiased approach with an inducible cell line expressing the viral transcription factor E2 and transcriptome analysis, we found that E2 induces the expression of the two AP1 components c-Fos and FosB in a Brd4-dependent manner. In vitro RNA interference confirmed that c-Fos is one of the AP1 members driving the expression of viral oncogenes E6/E7. Mutation analysis and in vivo RNA interference identified an essential role for c-Fos/AP1 and also for the bromodomain protein Brd4 for papillomavirus-induced tumorigenesis. Lastly, chromatin immunoprecipitation analysis demonstrated that E2 binds together with Brd4 to a canonical E2 binding site (E2BS) in the promoter of c-Fos, thus activating c-Fos expression. Thus, we identified a novel way how E2 activates the viral oncogene promoter and show that E2 may act as a viral oncogene by direct activation of c-Fos involved in skin tumorigenesis. PMID:26727473

  10. Long-term suppression of methamphetamine-induced c-Fos expression in rat striatum by the injection of c-fos antisense oligodeoxynucleotides absorbed in water-absorbent polymer.

    PubMed

    Semba, Jun'ichi; Wakuta, Maki; Suhara, Tetsuya

    2004-10-01

    The use of water-absorbent polymer (WAP) as a hydrogel carrier for the slow delivery of antisense oligodeoxynucleotides (ODN) in the brain, was recently developed. In this experiment, 15-mer phosphorothioate ODN, complementary to c-fos gene absorbed in WAP, was injected in the rat striatum. The expression of c-Fos-immunoreactivity induced by methamphetamine (6 mg/kg, intraperitoneally) around the injection site was suppressed until 5 days after injection. Using this method, it was observed that unilateral injection with c-fos antisense ODN into the rat striatum caused robust ipsilateral rotations after methamphetamine challenge 4 days post injection. This method is simple, and the biological and behavioral effects of antisense ODN in WAP can be maintained for several days even after a single injection into the brain.

  11. Neutralizing circulating ghrelin by expressing a growth hormone secretagogue receptor-based protein protects against high-fat diet-induced obesity in mice.

    PubMed

    Gagnon, J; Zhu, L; Anini, Y; Wang, Q

    2015-09-01

    Ghrelin is a stomach-derived peptide hormone that stimulates appetite and promotes adiposity through binding to the growth hormone secretagogue receptor (GHS-R1a). Administration of ghrelin in rodents increases weight gain due to stimulating food intake and reducing fat utilization. Therefore, reducing circulating ghrelin levels holds the potential to reduce weight gain. We developed a GHS-R1a-fusion constructs of a decoy protein containing the ligand-binding domains of the ghrelin receptor. Intramuscular injection of the GHSR/Fc plasmid decreased circulating levels of acylated-ghrelin. When challenged with the high fat diet, treated mice displayed reduced weight gain compared with controls, which was associated with reduced fat accumulation in the peritoneum but not lean mass. Quantitative PCR with reverse transcription showed increased PPARγ and hormone sensitive lipase transcripts levels in adipose tissue of treated animals, illustrating a preference for increased fat utilization. Intra-peritoneal glucose tolerance and insulin tolerance tests showed improved glucose clearance and insulin sensitivity in GHSR/Fc treated animals. We suggest that in vivo expression of the GHSR-based fusion protein prevents diet-induced weight gain, altering adipose gene expression and improving glucose tolerance. These findings, while confirming the role of ghrelin in peripheral energy metabolism, suggest that a strategy involving neutralization of the circulation ghrelin by intramuscular injection of the GHSR1/Fc fusion construct may find clinical application in the treatment of obesity.

  12. Inhibition of carcinogen induced c-Ha-ras and c-fos proto-oncogenes expression by dietary curcumin

    PubMed Central

    Limtrakul, Porn-ngarm; Anuchapreeda, Songyot; Lipigorngoson, Suwiwek; Dunn, Floyd W

    2001-01-01

    Background We investigated the chemopreventive action of dietary curcumin on 7,12-dimethylbenz(a)anthracene (DMBA)-initiated and 12,0-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor formation in Swiss albino mice. Curcumin, a yellow coloring matter isolated from roots of Curcuma longa Linn, is a phenolic compound possessing antioxidant, free radical scavenger, and antiinflammatory properties. It has been shown by previously reported work that TPA-induced skin tumors were inhibited by topical application of curcumin, and curcumin has been shown to inhibit a variety of biological activities of TPA. Topical application of curcumin was reported to inhibit TPA-induced c-fos, c-jun and c-myc gene expression in mouse skin. This paper reports the effects of orally administered curcumin, which was consumed as a dietary component at concentrations of 0.2 % or 1 %, in ad libitum feeding. Results Animals in which tumors had been initiated with DMBA and promoted with TPA experienced significantly fewer tumors and less tumor volume if they ingested either 0.2% or 1% curcumin diets. Also, the dietary consumption of curcumin resulted in a significantly decreased expression of ras and fos proto-oncogenes in the tumorous skin, as measured by enhanced chemiluminesence Western blotting detection system (Amersham). Conclusions Whereas earlier work demonstrated that topical application of curcumin to mouse skin inhibited TPA-induced expression of c-fos, c-jun and c-myc oncogenes, our results are the first to show that orally consumed curcumin significantly inhibited DMBA- and TPA-induced ras and fos gene expression in mouse skin. PMID:11231886

  13. Ghrelin protects human umbilical vein endothelial cells against advanced glycation end products-induced apoptosis via NO/cGMP signaling

    PubMed Central

    Li, Pengjie; Liu, Ying; Xiang, Ying; Lin, Miao; Gao, Jinling

    2015-01-01

    Objectives: The aim of this study was to investigate the intracellular mechanism involved in the anti-apoptotic effect of ghrelin on human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were pretreated with ghrelin before exposure to 200 μg/ml advanced glycation end products (AGEs)-BSA for 48 h. Cell viability and apoptosis were determined by MTT assay and Annexin V/PI staining. Intracellular cGMP levels evaluation and cGMP analogs were employed to explore possible mechanisms. Results: The inhibitory effect on AGEs induced HUVECs apoptosis could be exerted by ghrelin and co-incubation with growth hormone secretagogue receptor (GHSR)-1a antagonist [D-Lys3]-GHRP-6 abolished this inhibition. Decreased cGMP level in AGEs induced HUVECs apoptosis was restored by ghrelin pretreatment and abolished by [D-Lys3]-GHRP-6 co-incubation. cGMP analogs (8 Br-cGMP and DB-cGMP) pretreatment also exhibited inhibitory effect on AGEs induced HUVECs apoptosis. Conclusions: Our results demonstrated that ghrelin produces a protective effect on HUVECs through GHS-R1a and cGMP/NO signaling pathway mediates the effect of ghrelin. These observations suggest a novel intracellular mechanism in the process of AGEs induced HUVECs apoptosis. PMID:26629013

  14. Ghrelin inhibits AngII -induced expression of TNF-α, IL-8, MCP-1 in human umbilical vein endothelial cells

    PubMed Central

    Deng, Bin; Fang, Fang; Yang, Tianlu; Yu, Zaixin; Zhang, Bin; Xie, Xiumei

    2015-01-01

    Aim: Ghrelin, a gastric peptide, is involved in several metabolic and cardiovascular processes. Emerging evidence indicates the potential involvement of ghrelin in low-grade inflammatory diseases such as atherosclerosis and hypertension. Cytokine-induced inflammation is critical in these pathological states. The growth hormone secretagogue receptor (GHSR) has been identified in blood vessels, so we predict that ghrelin might inhibit proinflammatory responses in human umbilical vein endothelial cells (HUVECs). The aim of this study is to examine the effect of ghrelin on angiotension II (AngII)-induced expression of TNF-α, MCP-1, IL-8 in HUVECs. Method: HUVECs were pretreated with ghrelin, with or without the specific antagonist of GHSR [D-Lys3]-GHRP-6, the selective inhibitor of nuclear factor-kappaB (NF-κB) PDTC, and the selective inhibitor of extracellular signal-regulated kinase (ERK1/2) PD98059. The cells were finally treated with AngII. The expression of TNF-α, MCP-1, IL-8 was examined by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The activity of ERK1/2 and NF-κB was analyzed by Western blot. Result: our study showed that ghrelin inhibited AngII -induced expression of IL-8, TNF-α and MCP-1 in the HUVECs via GHSR pathway in concentration- and time-dependent manners. We also found that ghrelin inhibited AngII -induced activation of ERK1/2 and NF-κB. Conclusions: these results suggest that Ghrelin may play novel antiinflammatory and immunoregulatory roles in HUVECs. PMID:25785032

  15. Shifting the Circadian Rhythm of Feeding in Mice Induces Gastrointestinal, Metabolic and Immune Alterations Which Are Influenced by Ghrelin and the Core Clock Gene Bmal1

    PubMed Central

    Laermans, Jorien; Broers, Charlotte; Beckers, Kelly; Vancleef, Laurien; Steensels, Sandra; Thijs, Theo; Tack, Jan; Depoortere, Inge

    2014-01-01

    Background In our 24-hour society, an increasing number of people are required to be awake and active at night. As a result, the circadian rhythm of feeding is seriously compromised. To mimic this, we subjected mice to restricted feeding (RF), a paradigm in which food availability is limited to short and unusual times of day. RF induces a food-anticipatory increase in the levels of the hunger hormone ghrelin. We aimed to investigate whether ghrelin triggers the changes in body weight and gastric emptying that occur during RF. Moreover, the effect of genetic deletion of the core clock gene Bmal1 on these physiological adaptations was studied. Methods Wild-type, ghrelin receptor knockout and Bmal1 knockout mice were fed ad libitum or put on RF with a normal or high-fat diet (HFD). Plasma ghrelin levels were measured by radioimmunoassay. Gastric contractility was studied in vitro in muscle strips and in vivo (13C breath test). Cytokine mRNA expression was quantified and infiltration of immune cells was assessed histologically. Results The food-anticipatory increase in plasma ghrelin levels induced by RF with normal chow was abolished in HFD-fed mice. During RF, body weight restoration was facilitated by ghrelin and Bmal1. RF altered cytokine mRNA expression levels and triggered contractility changes resulting in an accelerated gastric emptying, independent from ghrelin signaling. During RF with a HFD, Bmal1 enhanced neutrophil recruitment to the stomach, increased gastric IL-1α expression and promoted gastric contractility changes. Conclusions This is the first study demonstrating that ghrelin and Bmal1 regulate the extent of body weight restoration during RF, whereas Bmal1 controls the type of inflammatory infiltrate and contractility changes in the stomach. Disrupting the circadian rhythm of feeding induces a variety of diet-dependent metabolic, immune and gastrointestinal alterations, which may explain the higher prevalence of obesity and immune

  16. Exercise protects against obesity induced semen abnormalities via downregulating stem cell factor, upregulating Ghrelin and normalizing oxidative stress.

    PubMed

    Alhashem, Fahaid; Alkhateeb, Mahmoud; Sakr, Hussein; Alshahrani, Mesfer; Alsunaidi, Mohammad; Elrefaey, Hesham; Alessa, Riyad; Sarhan, Mohammad; Eleawa, Samy M; Khalil, Mohammad A

    2014-01-01

    Increased oxidative stress and hormonal imbalance have been hypothesized to underlie infertility in obese animals. However, recent evidence suggests that Ghrelin and Stem Cell Factor (SCF) play an important role in fertility, in lean individuals. Therefore, this study aimed at investigating whether changes in the levels of Ghrelin and SCF in rat testes underlie semen abnormal parameters observed in obese rats, and secondly, whether endurance exercise or Orlistat can protect against changes in Ghrelin, SCF, and/or semen parameters in diet induced obese rats. Obesity was modelled in male Wistar rats using High Fat Diet (HFD) 12-week protocol. Eight week-old rats (n=40) were divided into four groups, namely, Group I: fed with a standard diet (12 % of calories as fat); Group II: fed HFD (40 % of calories as fat); Group III: fed the HFD with a concomitant dose of Orlistat (200 mg/kg); and Group IV: fed the HFD and underwent 30 min daily swimming exercise. The model was validated by measuring the levels of testosterone, FSH, LH, estradiol, leptin, triglycerides, total, HDL, and LDL cholesterol, and final change in body weight. Levels were consistent with published obesity models (see Results). As predicted, the HFD group had a 76.8 % decrease in sperm count, 44.72 % decrease in sperm motility, as well as 47.09 % increase in abnormal sperm morphology. Unlike the control group, in the HFD group (i.e. obese rats) Ghrelin mRNA and protein were elevated, while SCF mRNA and protein were diminished in the testes. Furthermore, in the HFD group, SOD and GPx activities were significantly reduced, 48.5±5.8 % (P=0.0012) and 45.6±4.6 % (P=0.0019), respectively, while TBARS levels were significantly increased (112.7±8.9 %, P=0.0001). Finally, endurance exercise training and Orlistat administration individually and differentially protected semen parameters in obese rats. The mechanism includes, but is not limited to, normalizing the levels of Ghrelin, SCF, SOD, GPx and TBARS. In rat

  17. Retrieval of morphine-associated context induces cFos in dentate gyrus neurons.

    PubMed

    Rivera, Phillip D; Raghavan, Ramya K; Yun, Sanghee; Latchney, Sarah E; McGovern, Mary-Katherin; García, Emily F; Birnbaum, Shari G; Eisch, Amelia J

    2015-04-01

    Addiction has been proposed to emerge from associations between the drug and the reward-associated contexts. This associative learning has a cellular correlate, as there are more cFos+ neurons in the hippocampal dentate gyrus (DG) after psychostimulant conditioned place preference (CPP) versus saline controls. However, it is unknown whether morphine CPP leads to a similar DG activation, or whether DG activation is due to locomotion, handling, pharmacological effects, or-as data from contextual fear learning suggests-exposure to the drug-associated context. To explore this, we employed an unbiased, counterbalanced, and shortened CPP design that led to place preference and more DG cFos+ cells. Next, mice underwent morphine CPP but were then sequestered into the morphine-paired (conditioned stimulus+ [CS+]) or saline-paired (CS-) context on test day. Morphine-paired mice sequestered to CS+ had ∼30% more DG cFos+ cells than saline-paired mice. Furthermore, Bregma analysis revealed morphine-paired mice had more cFos+ cells in CS+ compared to CS- controls. Notably, there was no significant difference in DG cFos+ cell number after handling alone or after receiving morphine in home cage. Thus, retrieval of morphine-associated context is accompanied by activation of hippocampal DG granule cell neurons.

  18. TGF beta induces a sustained c-fos expression associated with stimulation or inhibition of cell growth in EL2 or NIH 3T3 fibroblasts.

    PubMed

    Liboi, E; Di Francesco, P; Gallinari, P; Testa, U; Rossi, G B; Peschle, C

    1988-02-29

    We have previously indicated that epidermal growth factor (EGF) plays a fundamental role in the proliferation control of EL2 rat fibroblast line. It is shown here that transforming growth factor beta (TGF beta) stimulates both DNA synthesis and proliferation of EL2 cells, while exerting an inhibitory effect on the growth of murine NIH-3T3 fibroblasts. We also report the effect of TGF beta and EGF on c-fos expression in EL2 cells, as compared to that of TGF beta in NIH-3T3 fibroblasts. In EL2 cells EGF induces a transient c-fos expression at both mRNA and protein level, as previously observed in NIH-3T3 fibroblasts treated with platelet-derived or fibroblast growth factor (PDGF, FGF). Conversely, TGF beta induces in EL2 cells a sustained expression of fos mRNA and protein, which are still detectable at least 24 and 7 hr after treatment respectively. In NIH-3T3 fibroblasts TGF beta causes a sustained fos RNA expression, which is not associated, however, with detectable fos protein. We conclude that in fibroblasts stimulated by mitogens c-fos expression may be differentially modulated, depending of the growth factor and the cell line. This is seemingly due to differential regulation of fos gene expression, not only at the transcriptional and/or post-transcriptional level (transient or sustained fos RNA induction by EGF or TGF beta in EL2 cells), but also at the translational level (fos protein(s) induction by TGF beta in EL2 but not NIH-3T3 fibroblasts, possibly related to the stimulatory vs inhibitory effect of this factor on the growth of the former vs the latter line).

  19. The atypical antipsychotic, olanzapine, potentiates ghrelin-induced receptor signaling: An in vitro study with cells expressing cloned human growth hormone secretagogue receptor.

    PubMed

    Tagami, Keita; Kashiwase, Yohei; Yokoyama, Akinobu; Nishimura, Hitomi; Miyano, Kanako; Suzuki, Masami; Shiraishi, Seiji; Matoba, Motohiro; Ohe, Yuichiro; Uezono, Yasuhito

    2016-08-01

    The growth hormone secretagogue receptor (GHS-R) belongs to Gαq-coupled G protein-coupled receptor (GPCR) that mediates growth hormone release, food intake, appetite, glucose metabolism and body composition. Ghrelin has been identified as an endogenous ligand for GHS-R, and it is the only orexigenic peptide found in the peripheral organs. Olanzapine, an atypical antipsychotic agent that binds to and inhibits the activation of GPCR for several neurotransmitters, has metabolic side effects such as excessive appetite and weight gain. Recently, studies have revealed that the orexigenic mechanism of olanzapine is mediated via GHS-R signaling, although the precise mechanisms have not been clarified. In this study, we investigated the effect of olanzapine on ghrelin-mediated GHS-R signaling by using an electrical impedance-based receptor biosensor assay system (CellKey™). Olanzapine at concentrations of 10(-7) and 10(-6)mol/L enhanced ghrelin-induced (10(-10)-10(-8)mol/L) GHS-R activation. A Ca(2+) imaging assay revealed that olanzapine (10(-7) and 10(-6)mol/L) enhanced ghrelin (10(-7) M)-induced GHS-R activity. In contrast, haloperidol (an antipsychotic agent) failed to enhance this ghrelin-mediated GHS-R activation, as demonstrated by both the CellKey™ and Ca(2+) imaging assays. Together, these results suggest that olanzapine, but not haloperidol, promotes appetite by enhancing ghrelin-mediated GHS-R signaling.

  20. Social experience induces sex-specific fos expression in the amygdala of the juvenile rat.

    PubMed

    Weathington, Jill M; Strahan, J Alex; Cooke, Bradley M

    2012-07-01

    To compare the response of the medial amygdala and central amygdala to juvenile social subjugation (JSS), we used unbiased stereology to quantify the immediate early gene product Fos in prepubertal rats after aggressive or benign social encounters or handling. We estimated the overall number of neurons and the proportion of Fos immunoreactive neurons in the posterodorsal (MePD) and posteroventral medial amygdala (MePV) and the central amygdala (CeA). Experience elicited Fos in a sex- and hemisphere-dependent manner in the MePD. The left MePD was selective for JSS in both sexes, but the right MePD showed a specific Fos response to JSS in males only. In the MePV, irrespective of hemisphere or sex, JSS elicited the greatest amount of Fos, benign social experience elicited an intermediate level, and handling the least. None of the experiential conditions elicited significant levels of Fos in the CeA. We found a previously unreported sex difference in the number of CeA neurons (M>F) that was highly significant and a strong trend toward a sex difference (M>F) in the MePD. These data show that the posterior MeA subnuclei are more responsive to JSS than to benign social interaction, that sex interacts with hemispheric laterality to determine the response of the MePD to JSS and that the MePV responds to social experience and JSS. Taken together, these findings support the hypothesis that juvenile rats process JSS in a sex-specific manner.

  1. AP-1/Fos-TGase2 Axis Mediates Wounding-induced Plasmodium falciparum Killing in Anopheles gambiae*

    PubMed Central

    Nsango, Sandrine E.; Pompon, Julien; Xie, Ting; Rademacher, Annika; Fraiture, Malou; Thoma, Martine; Awono-Ambene, Parfait H.; Moyou, Roger S.; Morlais, Isabelle; Levashina, Elena A.

    2013-01-01

    Anopheline mosquitoes are the only vectors of human malaria worldwide. It is now widely accepted that mosquito immune responses play a crucial role in restricting Plasmodium development within the vector; therefore, further dissection of the molecular mechanisms underlying these processes should inform new vector control strategies urgently needed to roll back the disease. Here, using genome-wide transcriptional profiling, bioinformatics, and functional gene analysis, we identify a new axis of mosquito resistance to monoclonal Plasmodium falciparum infections that includes the AP-1 transcription factor Fos and the transglutaminase 2 (TGase2), a cross-linking enzyme with known roles in wound responses. We demonstrate that Fos regulates induction of TGase2 expression after wounding but does not affect expression of the components of the well characterized complement-like system. Silencing of Fos or of TGase2 aborts the wounding-induced mosquito killing of P. falciparum. These results reveal multiple signaling pathways that are required for efficient Plasmodium killing in Anopheles gambiae. PMID:23592781

  2. The pregnancy-induced increase in baseline circulating growth hormone in rats is not induced by ghrelin.

    PubMed

    El-Kasti, M M; Christian, H C; Huerta-Ocampo, I; Stolbrink, M; Gill, S; Houston, P A; Davies, J S; Chilcott, J; Hill, N; Matthews, D R; Carter, D A; Wells, T

    2008-03-01

    The elevation in baseline circulating growth hormone (GH) that occurs in pregnant rats is thought to arise from increased pituitary GH secretion, but the underlying mechanism remains unclear. Distribution, Fourier and algorithmic analyses confirmed that the pregnancy-induced increase in circulating GH in 3-week pregnant rats was due to a 13-fold increase in baseline circulating GH (P < 0.01), without any significant alteration in the parameters of episodic secretion. Electron microscopy revealed that pregnancy resulted in a reduction in the proportion of mammosomatotrophs (P < 0.01) and an increase in type II lactotrophs (P < 0.05), without any significant change in the somatotroph population. However, the density of the secretory granules in somatotrophs from 3-week pregnant rats was reduced (P < 0.05), and their distribution markedly polarised; the granules being grouped nearest the vasculature. Pituitary GH content was not increased, but steady-state GH mRNA levels declined progressively during pregnancy (P < 0.05). In situ hybridisation revealed that pregnancy was accompanied by a suppression of GH-releasing hormone mRNA expression in the arcuate nuclei (P < 0.05) and enhanced somatostatin mRNA expression in the periventricular nuclei (P < 0.05), an expression pattern normally associated with increased GH feedback. Although gastric ghrelin mRNA expression was elevated by 50% in 3-week pregnant rats (P < 0.01), circulating ghrelin, GH-secretagogue receptor mRNA expression and the GH response to a bolus i.v. injection of exogenous ghrelin were all largely unaffected during pregnancy. Although trace amounts of 'pituitary' GH could be detected in the placenta with radioimmunoassay, significant GH-immunoreactivity could not be observed by immunohistochemistry, indicating that rat placenta itself does not produce 'pituitary' GH. Although not excluding the possibility that the pregnancy-associated elevation in baseline circulating GH could arise from alternative extra

  3. Treatment with either obestatin or ghrelin attenuates mesenteric ischemia-reperfusion-induced oxidative injury of the ileum and the remote organ lung.

    PubMed

    Şen, Leyla Semiha; Karakoyun, Berna; Yeğen, Cumhur; Akkiprik, Mustafa; Yüksel, Meral; Ercan, Feriha; Özer, Ayşe; Yeğen, Berrak Ç

    2015-09-01

    To evaluate the effects of exogenous ghrelin or obestatin on intestinal injury and accompanying pulmonary injury, intestinal ischemia-reperfusion (I/R) was induced in rats by obstructing the superior mesenteric artery for 60min, whereas laparotomy was performed in the sham group. At the beginning of the 90-min reperfusion period, the rats were injected with obestatin (100μg/kg), ghrelin (10ng/kg), or saline intravenously (iv). At the end of reperfusion, the blood, ileum, and lung samples were taken for the histological and biochemical assays. In the saline-treated I/R group, the increased serum interleukin (IL)-1β level, high damage scores, and elevated tissue malondialdehyde level and collagen content in both tissues were significantly reduced by obestatin or ghrelin. Increased ileal myeloperoxidase activity of the saline-treated I/R group was reduced by treatment with obestatin or ghrelin, whereas increased pulmonary myeloperoxidase activity was reduced with administration of obestatin. Increased DNA fragmentation in the ileum of the saline-treated I/R group was reduced by both peptides. Elevated luminol-lucigenin chemiluminescence levels and nuclear factor kappa B (NF-κB) messenger RNA (mRNA) expression in the ileum of the saline-treated-I/R group were significantly decreased by obestatin or ghrelin treatment. I/R-induced depletion of the antioxidant glutathione in both ileal and pulmonary tissues was prevented with either obestatin or ghrelin treatment. Administration of either obestatin or ghrelin exerts similar protective effects against I/R-induced ileal and pulmonary injury, thus warranting further investigation for their possible use against ischemic intestinal injury.

  4. DNA binding of Jun and Fos bZip domains: homodimers and heterodimers induce a DNA conformational change in solution.

    PubMed Central

    John, M; Leppik, R; Busch, S J; Granger-Schnarr, M; Schnarr, M

    1996-01-01

    We constructed plasmids encoding the sequences for the bZip modules of c-Jun and c-Fos which could then be expressed as soluble proteins in Escherichia coli. The purified bZip modules were tested for their binding capacities of synthetic oligonucleotides containing either TRE or CRE recognition sites in electrophoretic mobility shift assays and circular dichroism (CD). Electrophoretic mobility shift assays showed that bZip Jun homodimers and bZip Jun/Fos heterodimers bind a collagenase-like TRE (CTGACTCAT) with dissociation constants of respectively 1.4 x 10(-7) M and 5 x 10(-8) M. As reported earlier [Patel et al. (1990) Nature 347, 572-575], DNA binding induces a marked change of the protein structure. However, we found that the DNA also undergoes a conformational change. This is most clearly seen with small oligonucleotides of 13 or 14 bp harboring respectively a TRE (TGACTCA) or a CRE (TGACGTCA) sequence. In this case, the positive DNA CD signal at 280 nm increases almost two-fold with a concomitant blue-shift of 3-4 nm. Within experimental error the same spectral changes are observed for TRE and CRE containing DNA fragments. The spectral changes observed with a non-specific DNA fragment are weaker and the signal of free DNA is recovered upon addition of much smaller salt concentrations than required for a specific DNA fragment. Surprisingly the spectral changes induced by Jun/Jun homodimers are not identical to those induced by Jun/Fos heterodimers. However, in both cases the increase of the positive CD band and the concomitant blue shift would be compatible with a B to A-transition of part of the binding site or a DNA conformation intermediate between the canonical A and B structures. PMID:8948639

  5. Ghrelin and GHRP-6-induced ACTH and cortisol release in thyrotoxicosis.

    PubMed

    Nascif, Sergio Oliva; Molica, Patrícia; Correa-Silva, Silvia Regina; Silva, Marcos Roberto; Lengyel, Ana-Maria Judith

    2009-01-01

    Thyrotoxicosis might alter the hypothalamic-pituitary-adrenal (HPA) axis. We evaluated the effects of ghrelin and GHRP-6 on the HPA axis in 20 hyperthyroid patients and in 9 controls. Mean basal cortisol (microg/dl) and ACTH (pg/ml) levels were higher in hyperthyroidism (cortisol: 10.7 +/- 0.7; ACTH: 21.5 +/- 2.9) compared to controls (cortisol: 8.1 +/- 0.7; ACTH: 13.5 +/- 1.8). In thyrotoxicosis Delta AUC cortisol values (microg/dl.90 min) after ghrelin (484 +/- 80) and GHRP-6 (115 +/- 63) were similar to controls (ghrelin: 524 +/- 107; GHRP-6: 192 +/- 73). A significant increase in Delta AUC ACTH (pg/ml x 90 min) after ghrelin was observed in thyrotoxicosis (4,189 +/- 1,202) compared to controls (1,499 +/- 338). Delta AUC ACTH values after GHRP-6 were also higher, although not significantly (patients: 927 +/- 330; controls: 539 +/- 237). In summary, our results suggest that ghrelin-mediated pathways of ACTH release might be activated by thyroid hormone excess, but adrenocortical reserve is maintained.

  6. Caloric Restriction Protects against Lactacystin-Induced Degeneration of Dopamine Neurons Independent of the Ghrelin Receptor

    PubMed Central

    Coppens, Jessica; Bentea, Eduard; Bayliss, Jacqueline A.; Demuyser, Thomas; Walrave, Laura; Albertini, Giulia; Van Liefferinge, Joeri; Deneyer, Lauren; Aourz, Najat; Van Eeckhaut, Ann; Portelli, Jeanelle; Andrews, Zane B.; Massie, Ann; De Bundel, Dimitri; Smolders, Ilse

    2017-01-01

    Parkinson’s disease (PD) is a neurodegenerative disorder, characterized by a loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc). Caloric restriction (CR) has been shown to exert ghrelin-dependent neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-based animal model for PD. We here investigated whether CR is neuroprotective in the lactacystin (LAC) mouse model for PD, in which proteasome disruption leads to the destruction of the DA neurons of the SNc, and whether this effect is mediated via the ghrelin receptor. Adult male ghrelin receptor wildtype (WT) and knockout (KO) mice were maintained on an ad libitum (AL) diet or on a 30% CR regimen. After 3 weeks, LAC was injected unilaterally into the SNc, and the degree of DA neuron degeneration was evaluated 1 week later. In AL mice, LAC injection significanty reduced the number of DA neurons and striatal DA concentrations. CR protected against DA neuron degeneration following LAC injection. However, no differences were observed between ghrelin receptor WT and KO mice. These results indicate that CR can protect the nigral DA neurons from toxicity related to proteasome disruption; however, the ghrelin receptor is not involved in this effect. PMID:28273852

  7. Role of hormonal axis, growth hormone - IGF-1, in the therapeutic effect of ghrelin in the course of cerulein-induced acute pancreatitis.

    PubMed

    Ceranowicz, D; Warzecha, Z; Dembinski, A; Ceranowicz, P; Cieszkowski, J; Kusnierz-Cabala, B; Tomaszewska, R; Kuwahara, A; Kato, I

    2010-10-01

    Ghrelin is a ligand for growth hormone secretagogue receptor and stimulates release of growth hormone (GH). Recent studies have shown that treatment with ghrelin exhibits protective and therapeutic effect in the course of experimental pancreatitis. The aim of present study was to examine the role of GH and insulin-like growth factor-1 (IGF-1) in these effects. Acute pancreatitis was induced by cerulein. Study was performed on pituitary-intact hypophysectomized rats. Ghrelin was administered twice a day at the dose of 8 nmol/kg/dose. IGF-1 was given twice a day at the dose of 20 nmol/kg/dose. The severity of acute pancreatitis was assessed 0 h or 1, 2, 3, 5 and 10 days after the last dose of cerulein. Administration of cerulein led to the development of acute edematous pancreatitis. In pituitary-intact rats, treatment with ghrelin reduced biochemical indexes of the severity of acute pancreatitis and morphological signs of pancreatic damage, leading to faster regeneration of the pancreas reduction in serum concentration of pro-inflammatory interleukin-1β and decrease in serum activity of amylase and lipase. These effects were accompanied with an improvement of pancreatic blood flow and an increase in pancreatic DNA synthesis. Hypophysectomy delayed the healing of the pancreas and abolished the therapeutic effect of ghrelin. In hypophysectomized rats with pancreatitis, treatment with IGF-1 exhibits therapeutic effect similar to that observed in ghrelin-treated rats with the intact pituitary. We conclude that therapeutic effect of ghrelin in cerulein-induced pancreatitis is indirect and depends on the release of GH and IGF-1.

  8. Effect of blonanserin on methamphetamine-induced disruption of latent inhibition and c-Fos expression in rats.

    PubMed

    Kuramashi, Aki; Abe, Hiroshi; Koganemaru, Go; Matsuo, Hisae; Ikeda, Tetsuya; Ebihara, Kosuke; Funahashi, Hideki; Takeda, Ryuichiro; Nishimori, Toshikazu; Ishida, Yasushi

    2013-08-09

    To clarify the psychopharmacological profile of blonanserin, a novel antipsychotic, we examined its effect on the methamphetamine-induced disruption of latent inhibition (LI) and the neural activation related to this effect in rats. To evaluate the LI, we used a conditioned emotional response in which a tone (conditioned stimulus) was paired with a mild foot shock (unconditioned stimulus). This paradigm was presented to rats licking water. Methamphetamine-induced (1.0mg/kg, i.p.) disruption of LI was significantly improved by the administration of a higher dose (3.0mg/kg, i.p.) of blonanserin and tended to be improved by 1.0-mg/kg blonanserin and 0.2-mg/kg haloperidol but not by a lower dose (0.3mg/kg) of blonanserin. Immunohistochemical examination showed blonanserin (3.0mg/kg, i.p.) increased c-Fos expression in the shell area but not in the core area of the nucleus accumbens while methamphetamine (3.0mg/kg, i.p.) produced the opposite expression pattern. Blonanserin also increased the number of c-Fos expressions in the central amygdala nucleus but not in the basolateral amygdala nucleus or the prefrontal cortex. Blonanserin ameliorates the methamphetamine-induced disruption of LI, as other antipsychotics do, and a neuronal activation and/or modulation of neurotransmission in the nucleus accumbens is related to the disruption of LI by methamphetamine and to its amelioration by blonanserin.

  9. Receptor-Selective Agonists Induce Emesis and Fos Expression in the Brain and Enteric Nervous System of the Least Shrew (Cryptotis parva)

    PubMed Central

    Ray, Andrew P.; Chebolu, Seetha; Darmani, Nissar A.

    2009-01-01

    Research on the mechanisms of emesis has implicated multiple neurotransmitters via both central (dorsal vagal complex) and peripheral (enteric neurons and enterochromaffin cells) anatomical substrates. Taking advantage of advances in receptor-specific agonists, and utilizing Fos expression as a functional activity marker, this study demonstrates a strong, but incomplete, overlap in anatomical substrates for a variety of emetogens. We used cisplatin and specific agonists to 5-HT3 serotonergic, D2/D3 dopaminergic, and NK1 tachykininergic receptors to induce vomiting in the least shrew (Cryptotis parva), and quantified the resulting Fos expression. The least shrew is a small mammal whose responses to emetic challenges are very similar to its human counterparts. In all cases, the enteric nervous system, nucleus of the solitary tract, and dorsal motor nucleus of the vagus demonstrated significantly increased Fos immunoreactivity (Fos-IR). However, Fos-IR induction was notably absent from the area postrema following the dopaminergic and NK1 receptor-specific agents. Two brain nuclei not usually discussed regarding emesis, the dorsal raphe nucleus and paraventricular thalamic nucleus, also demonstrated increased emesis-related Fos-IR. Taken together, these data suggest the dorsal vagal complex is part of a common pathway for a variety of distinct emetogens, but there are central emetic substrates, both medullary and diencephalic, that can be accessed without directly stimulating the area postrema. PMID:19699757

  10. Neural Correlates of Birth: Labor Contractions Induce C-Fos Expression In Newborn Rat Brain

    NASA Technical Reports Server (NTRS)

    Ronca, A. E.; Daly, M. E.; Baer, L. A.; Hills, E. M.; Conway, G.; Dalton, Bonnie (Technical Monitor)

    2002-01-01

    At birth, the newborn mammal must make rapid adaptations to the extrauterine environment to survive. We have previously shown that labor contractions augment the appearance of adaptive responses at birth, viz., postpartum breathing and the onset of suckling. Since neuronal activity has been shown to upregulate the activity of immediate early genes (IEGs) in the brain, we analyzed the neural distribution of c-Fos protein expression in newborn rats using immunohistochemistry. Previous studies have reported a burst of c-Fos mRNA expression in mouse and rat brain at birth however relationships to labor and delivery have not been examined. In the present study, we exposed near-term rat fetuses to elements of the vaginal birth process: 1) Simulated labor contractions. 2) Postpartum cooling (22 deg C). 3) Umbilical cord occlusion. and 4) Stroking to mimic postpartum licking by the dam. Cardinally delivered newborns (VG) were compared with those delivered by cesarean section following either prenatal exposure to compressions (C) [simulated labor contractions], or no compressions (NC) [no labor contractions]. Similar patterns of c-fos activation were observed throughout hypothalamic and thalamic nuclei, hippocampus and cerebral cortex in VG and C newborns that were not apparent in NC newborns. Our results indicate that labor contractions play a role in the induction of widespread neural activation in the newborn brain.

  11. Differential involvement of 3', 5'-cyclic adenosine monophosphate-dependent protein kinase in regulation of Fos and tyrosine hydroxylase expression in the heart after naloxone induced morphine withdrawal.

    PubMed

    Almela, Pilar; Cerezo, Manuela; González-Cuello, A; Milanés, M Victoria; Laorden, M Luisa

    2007-01-01

    We previously demonstrated that morphine withdrawal induced hyperactivity of the heart by the activation of noradrenergic pathways innervating the left and right ventricle, as evaluated by noradrenaline (NA) turnover and Fos expression. We investigated whether cAMP-dependent protein kinase (PKA) plays a role in this process by estimating changes in PKA immunoreactivity and the influence of inhibitor of PKA on Fos protein expression, tyrosine hydroxylase (TH) immunoreactivity levels and NA turnover in the left and right ventricle. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. Morphine withdrawal was precipitated on day 8 by an injection of naloxone (5 mg/kg). When opioid withdrawal was precipitated, an increase in PKA immunoreactivity and phospho-CREB (cyclic AMP response element protein) levels were observed in the heart. Moreover, morphine withdrawal induces Fos expression, an enhancement of NA turnover and an increase in the total TH levels. When the selective PKA inhibitor HA-1004 was infused, concomitantly with morphine pellets, it diminished the increase in NA turnover and the total TH levels observed in morphine-withdrawn rats. However, this inhibitor neither modifies the morphine withdrawal induced Fos expression nor the increase of nonphosphorylated TH levels. The present findings indicate that an up-regulated PKA-dependent transduction pathway might contribute to the activation of the cardiac catecholaminergic neurons in response to morphine withdrawal and suggest that Fos is not a target of PKA at heart levels.

  12. Delta 9-tetrahydrocannabinol suppresses vomiting behavior and Fos expression in both acute and delayed phases of cisplatin-induced emesis in the least shrew.

    PubMed

    Ray, Andrew P; Griggs, Lisa; Darmani, Nissar A

    2009-01-03

    Cisplatin chemotherapy frequently causes severe vomiting in two temporally separated clusters of bouts dubbed the acute and delayed phases. Cannabinoids can inhibit the acute phase, albeit through a poorly understood mechanism. We examined the substrates of cannabinoid-mediated inhibition of both the emetic phases via immunolabeling for serotonin, Substance P, cannabinoid receptors 1 and 2 (CB(1), CB(2)), and the neuronal activation marker Fos in the least shrew (Cryptotis parva). Shrews were injected with cisplatin (10mg/kg i.p.), and one of vehicle, Delta(9)-THC, or both Delta(9)-THC and the CB(1) receptor antagonist SR141716A (2mg/kg i.p.), and monitored for vomiting. Delta(9)-THC-pretreatment caused concurrent decreases in the number of shrews expressing vomiting and Fos-immunoreactivity (Fos-IR), effects which were blocked by SR141716A-pretreatment. Acute phase vomiting induced Fos-IR in the solitary tract nucleus (NTS), dorsal motor nucleus of the vagus (DMNX), and area postrema (AP), whereas in the delayed phase Fos-IR was not induced in the AP at all, and was induced at lower levels in the other nuclei when compared to the acute phase. CB(1) receptor-IR in the NTS was dense, punctate labeling indicative of presynaptic elements, which surrounded Fos-expressing NTS neurons. CB(2) receptor-IR was not found in neuronal elements, but in vascular-appearing structures. All areas correlated with serotonin- and Substance P-IR. These results support published acute phase data in other species, and are the first describing Fos-IR following delayed phase emesis. The data suggest overlapping but separate mechanisms are invoked for each phase, which are sensitive to antiemetic effects of Delta(9)-THC mediated by CB(1) receptors.

  13. UV-induced DNA damage is an intermediate step in UV-induced expression of human immunodeficiency virus type 1, collagenase, c-fos, and metallothionein

    SciTech Connect

    Stein, B.; Rahmsdorf, H.J.; Steffen, A.; Litfin, M.; Herrlich, P. )

    1989-11-01

    UV irradiation of human and murine cells enhances the transcription of several genes. Here we report on the primary target of relevant UV absorption, on pathways leading to gene activation, and on the elements receiving the UV-induced signal in the human immunodeficiency virus type 1 (HIV-1) long terminal repeat, in the gene coding for collagenase, and in the cellular oncogene fos. In order to induce the expression of genes, UV radiation needs to be absorbed by DNA and to cause DNA damage of the kind that cannot be repaired by cells from patients with xeroderma pigmentosum group A. UV-induced activation of the three genes is mediated by the major enhancer elements (located between nucleotide positions -105 and -79 of HIV-1, between positions -72 and -65 of the collagenase gene, and between positions -320 and -299 of fos). These elements share no apparent sequence motif and bind different trans-acting proteins; a member of the NF kappa B family binds to the HIV-1 enhancer, the heterodimer of Jun and Fos (AP-1) binds to the collagenase enhancer, and the serum response factors p67 and p62 bind to fos. DNA-binding activities of the factors recognizing the HIV-1 and collagenase enhancers are augmented in extracts from UV-treated cells. The increase in activity is due to posttranslational modification. While AP-1 resides in the nucleus and must be modulated there, NF kappa B is activated in the cytoplasm, indicating the existence of a cytoplasmic signal transduction pathway triggered by UV-induced DNA damage. In addition to activation, new synthesis of AP-1 is induced by UV radiation.

  14. Effects of electroacupuncture on ethanol-induced impairments of spatial learning and memory and Fos expression in the hippocampus in rats.

    PubMed

    Lu, Bin; Ma, Zhao; Cheng, Fei; Zhao, Yan; Zhang, Xin; Mao, Huijuan; Shen, Xueyong; Liu, Sheng

    2014-07-25

    It is well established that alcohol impairs spatial learning and memory. Here, we investigated the effects of electroacupuncture (EA) at ST36 or nonacupoint on ethanol-induced learning and memory impairment and the expression of Fos in the hippocampus. Ethanol (5g/kg) was administered intragastrically once a day for 5 consecutive days; 2Hz EA was administered immediately after ethanol exposure. After a 2-day ethanol abstinence, for 6 consecutive days, the rats were submitted to Morris water maze training. Probe trials were performed on 1 day after the final training session. We also applied immunohistochemistry to detect Fos-positive nuclei in the hippocampus. We found that 5-day ethanol exposure markedly decreased spatial learning and memory abilities in the Morris water maze task as indicated by escape latency and time in the target quadrant. EA treatment shortened the time of reaching platform and increased times traveled in the target quadrant (P<0.05). Animals administered with ethanol emitted significantly fewer Fos expression in the hippocampal CA1 area. EA increased Fos expression in the hippocampal CA1 area. Significant correlations were obtained between Fos protein expression in CA1 and time in the target quadrant. Altogether, these results suggest that EA protects against ethanol-induced impairments of spatial learning and memory, which may be involved in the hippocampal CA1 area. EA treatment may provide a novel nonpharmacological strategy for ethanol-induced learning and memory impairment.

  15. Cytisine modulates chronic voluntary ethanol consumption and ethanol-induced striatal up-regulation of ΔFosB in mice.

    PubMed

    Sajja, Ravi Kiran; Rahman, Shafiqur

    2013-06-01

    Chronic administration of ethanol induces persistent accumulation of ΔFosB, an important transcription factor, in the midbrain dopamine system. This process underlies the progression to addiction. Previously, we have shown that cytisine, a neuronal nicotinic acetylcholine receptor (nAChR) partial agonist, reduces various ethanol-drinking behaviors and ethanol-induced striatal dopamine function. However, the effects of cytisine on chronic ethanol drinking and ethanol-induced up-regulation of striatal ΔFosB are not known. Therefore, we examined the effects of cytisine on chronic voluntary ethanol consumption and associated striatal ΔFosB up-regulation in C57BL/6J mice using behavioral and biochemical methods. Following the chronic voluntary consumption of 15% (v/v) ethanol under a 24-h two-bottle choice intermittent access (IA; 3 sessions/week) or continuous access (CA; 24 h/d and 7 d/week) paradigm, mice received repeated intraperitoneal injections of saline or cytisine (0.5 or 3.0 mg/kg). Ethanol and water intake were monitored for 24 h post-treatment. Pretreatment with cytisine (0.5 or 1.5 mg/kg) significantly reduced ethanol consumption and preference in both paradigms at 2 h and 24 h post-treatment. The ΔFosB levels in the ventral and dorsal striatum were determined by Western blotting 18-24 h after the last point of ethanol access. In addition, cytisine (0.5 mg/kg) significantly attenuated up-regulation of ΔFosB in the ventral and dorsal striatum following chronic ethanol consumption in IA and CA paradigms. The results indicate that cytisine modulates chronic voluntary ethanol consumption and reduces ethanol-induced up-regulation of striatal ΔFosB. Further, the data suggest a critical role of nAChRs in chronic ethanol-induced neurochemical adaptations associated with ethanol addiction.

  16. Oral ‘hydrogen water' induces neuroprotective ghrelin secretion in mice

    PubMed Central

    Matsumoto, Akio; Yamafuji, Megumi; Tachibana, Tomoko; Nakabeppu, Yusaku; Noda, Mami; Nakaya, Haruaki

    2013-01-01

    The therapeutic potential of molecular hydrogen (H2) is emerging in a number of human diseases and in their animal models, including in particular Parkinson's disease (PD). H2 supplementation of drinking water has been shown to exert disease-modifying effects in PD patients and neuroprotective effects in experimental PD model mice. However, H2 supplementation does not result in detectable changes in striatal H2 levels, indicating an indirect effect. Here we show that H2 supplementation increases gastric expression of mRNA encoding ghrelin, a growth hormone secretagogue, and ghrelin secretion, which are antagonized by the β1-adrenoceptor blocker, atenolol. Strikingly, the neuroprotective effect of H2 water was abolished by either administration of the ghrelin receptor-antagonist, D-Lys3 GHRP-6, or atenolol. Thus, the neuroprotective effect of H2 in PD is mediated by enhanced production of ghrelin. Our findings point to potential, novel strategies for ameliorating pathophysiology in which a protective effect of H2 supplementation has been demonstrated. PMID:24253616

  17. The hallucinogen d-lysergic acid diethylamide (d-LSD) induces the immediate-early gene c-Fos in rat forebrain.

    PubMed

    Frankel, Paul S; Cunningham, Kathryn A

    2002-12-27

    The hallucinogen d-lysergic acid diethylamide (d-LSD) evokes dramatic somatic and psychological effects. In order to analyze the neural activation induced by this unique psychoactive drug, we tested the hypothesis that expression of the immediate-early gene product c-Fos is induced in specific regions of the rat forebrain by a relatively low, behaviorally active, dose of d-LSD (0.16 mg/kg, i.p.); c-Fos protein expression was assessed at 30 min, and 1, 2 and 4 h following d-LSD injection. A time- and region-dependent expression of c-Fos was observed with a significant increase (P<0.05) in the number of c-Fos-positive cells detected in the anterior cingulate cortex at 1 h, the shell of the nucleus accumbens at 1 and 2 h, the bed nucleus of stria terminalis lateral at 2 h and the paraventricular hypothalamic nucleus at 1, 2 and 4 h following systemic d-LSD administration. These data demonstrate a unique pattern of c-Fos expression in the rat forebrain following a relatively low dose of d-LSD and suggest that activation of these forebrain regions contributes to the unique behavioral effects of d-LSD.

  18. Medial prefrontal cortex neuronal activation and synaptic alterations after stress-induced reinstatement of palatable food seeking: a study using c-fos-GFP transgenic female rats.

    PubMed

    Cifani, Carlo; Koya, Eisuke; Navarre, Brittany M; Calu, Donna J; Baumann, Michael H; Marchant, Nathan J; Liu, Qing-Rong; Khuc, Thi; Pickel, James; Lupica, Carl R; Shaham, Yavin; Hope, Bruce T

    2012-06-20

    Relapse to maladaptive eating habits during dieting is often provoked by stress and there is evidence for a role of ovarian hormones in stress responses and feeding. We studied the role of these hormones in stress-induced reinstatement of food seeking and medial prefrontal cortex (mPFC) neuronal activation in c-fos-GFP transgenic female rats, which express GFP in strongly activated neurons. Food-restricted ovariectomized or sham-operated c-fos-GFP rats were trained to lever-press for palatable food pellets. Subsequently, lever-pressing was extinguished and reinstatement of food seeking and mPFC neuronal activation was assessed after injections of the pharmacological stressor yohimbine (0.5-2 mg/kg) or pellet priming (1-4 noncontingent pellets). Estrous cycle effects on reinstatement were also assessed in wild-type rats. Yohimbine- and pellet-priming-induced reinstatement was associated with Fos and GFP induction in mPFC; both reinstatement and neuronal activation were minimally affected by ovarian hormones in both c-fos-GFP and wild-type rats. c-fos-GFP transgenic rats were then used to assess glutamatergic synaptic alterations within activated GFP-positive and nonactivated GFP-negative mPFC neurons following yohimbine-induced reinstatement of food seeking. This reinstatement was associated with reduced AMPA receptor/NMDA receptor current ratios and increased paired-pulse facilitation in activated GFP-positive but not GFP-negative neurons. While ovarian hormones do not appear to play a role in stress-induced relapse of food seeking in our rat model, this reinstatement was associated with unique synaptic alterations in strongly activated mPFC neurons. Our paper introduces the c-fos-GFP transgenic rat as a new tool to study unique synaptic changes in activated neurons during behavior.

  19. Unacylated ghrelin promotes adipogenesis in rodent bone marrow via ghrelin O-acyl transferase and GHS-R1a activity: evidence for target cell-induced acylation

    PubMed Central

    Hopkins, Anna L.; Nelson, Timothy A. S.; Guschina, Irina A.; Parsons, Lydia C.; Lewis, Charlotte L.; Brown, Richard C.; Christian, Helen C.; Davies, Jeffrey S.; Wells, Timothy

    2017-01-01

    Despite being unable to activate the cognate ghrelin receptor (GHS-R), unacylated ghrelin (UAG) possesses a unique activity spectrum that includes promoting bone marrow adipogenesis. Since a receptor mediating this action has not been identified, we re-appraised the potential interaction of UAG with GHS-R in the regulation of bone marrow adiposity. Surprisingly, the adipogenic effects of intra-bone marrow (ibm)-infused acylated ghrelin (AG) and UAG were abolished in male GHS-R-null mice. Gas chromatography showed that isolated tibial marrow adipocytes contain the medium-chain fatty acids utilised in the acylation of UAG, including octanoic acid. Additionally, immunohistochemistry and immunogold electron microscopy revealed that tibial marrow adipocytes show prominent expression of the UAG-activating enzyme ghrelin O-acyl transferase (GOAT), which is located in the membranes of lipid trafficking vesicles and in the plasma membrane. Finally, the adipogenic effect of ibm-infused UAG was completely abolished in GOAT-KO mice. Thus, the adipogenic action of exogenous UAG in tibial marrow is dependent upon acylation by GOAT and activation of GHS-R. This suggests that UAG is subject to target cell-mediated activation – a novel mechanism for manipulating hormone activity. PMID:28361877

  20. Chronic ghrelin treatment reduced photophobia and anxiety-like behaviors in nitroglycerin- induced migraine: role of pituitary adenylate cyclase-activating polypeptide.

    PubMed

    Farajdokht, Fereshteh; Babri, Shirin; Karimi, Pouran; Alipour, Mohammad Reza; Bughchechi, Ramin; Mohaddes, Gisou

    2017-03-01

    Chronic migraine is a debilitating disorder that has a significant impact on patients and society. Nearly all migraineurs frequently reported light sensitivity during a headache attack. Pituitary adenylate cyclase-activating polypeptide (PACAP) plays an important role in the activation of trigeminal system and migraine pain. To identify the effect of chronic ghrelin treatment on endogenous PACAP and associated symptoms of migraine, an experimental chronic migraine model was induced by intermittent intraperitoneal (i.p) injection of nitroglycerin (NTG). Photophobia and anxiety-like behaviors were determined in the modified elevated plus maze on days 2, 4, 6, 8, and 10 and in the light/dark box on days 3, 5, 7, 9, and 11. Blood levels of PACAP and cortisol were assessed by enzyme-linked immunosorbent (ELISA) kits. Chronic injection of NTG evoked photophobia and anxiety-like behaviors and treatment with ghrelin (150 μg/kg) for 11 days effectively attenuated photophobia and anxiety-like behaviors in the both paradigms. We further found that NTG increased the blood levels of PACAP and cortisol, which was significantly reduced by ghrelin treatment. Additionally, staining with Hematoxylin and Eosin (H&E) revealed that ghrelin reduced NTG-induced increase in the number of satellite glial cells in the trigeminal ganglion. Furthermore, for the first time we showed that repeated administrations of NTG increased white blood cell (WBC) counts and mean platelet volume (MPV), and decreased platelet counts. These results indicated that ghrelin decreased migraine associated symptoms possibly through attenuating endogenous PACAP and cortisol levels. Therefore, ghrelin may hold therapeutic potentialities in managing the chronic migraine.

  1. Prostaglandin E2-induced up-regulation of c-fos messenger ribonucleic acid is primarily mediated by 3',5'-cyclic adenosine monophosphate in MC3T3-E1 osteoblasts

    NASA Technical Reports Server (NTRS)

    Fitzgerald, J.; Dietz, T. J.; Hughes-Fulford, M.

    2000-01-01

    The mechanism by which the proto-oncogene, c-fos, is up-regulated in response to PGE2 in the mouse osteoblastic (MC3T3-E1) cell line was investigated using RT-PCR. c-fos messenger RNA up-regulation by dmPGE2 is rapid, starting 10 min post stimulation, and transient. The specific protein kinase A (PKA) inhibitor, H89, inhibited c-fos induction. Moreover, down-regulation of protein kinase C (PKC) activity by chronic TPA treatment had no effect on the induction of c-fos by dmPGE2. We conclude that up-regulation of c-fos by dmPGE2 is primarily dependent on PKA in MC3T3-E1 osteoblasts. In S49 lymphoma wild-type but not S49 cyc- cells, which are deficient in cAMP signaling, dmPGE2 up-regulates c-fos and increases cell growth compared with unstimulated cells. Thus in S49 lymphoma cells, c-fos induction by PGE2 is also dependent on cAMP signaling. The minimal c-fos promoter region required for dmPGE2-induced expression was identified by transfecting c-fos promoter deletion constructs coupled to the chloramphenicol acetyltransferase (CAT) reporter gene into Vero cells. Transfection of a plasmid containing 99 bp c-fos proximal promoter was sufficient to direct c-fos/CAT expression following stimulation with dmPGE2. Because induction of c-fos is mediated by cAMP, these data are consistent with activation of c-fos via the CRE/ATF cis element.

  2. Stress-Induced Locomotor Sensitization to Amphetamine in Adult, but not in Adolescent Rats, Is Associated with Increased Expression of ΔFosB in the Nucleus Accumbens

    PubMed Central

    Carneiro de Oliveira, Paulo E.; Leão, Rodrigo M.; Bianchi, Paula C.; Marin, Marcelo T.; Planeta, Cleopatra da Silva; Cruz, Fábio C.

    2016-01-01

    While clinical and pre-clinical evidence suggests that adolescence is a risk period for the development of addiction, the underlying neural mechanisms are largely unknown. Stress during adolescence has a huge influence on drug addiction. However, little is known about the mechanisms related to the interaction among stress, adolescence and addiction. Studies point to ΔFosB as a possible target for this phenomenon. In the present study, adolescent and adult rats (postnatal day 28 and 60, respectively) were restrained for 2 h once a day for 7 days. Three days after their last exposure to stress, the animals were challenged with saline or amphetamine (1.0 mg/kg i.p.) and amphetamine-induced locomotion was recorded. Immediately after the behavioral tests, rats were decapitated and the nucleus accumbens was dissected to measure ΔFosB protein levels. We found that repeated restraint stress increased amphetamine-induced locomotion in both the adult and adolescent rats. Furthermore, in adult rats, stress-induced locomotor sensitization was associated with increased expression of ΔFosB in the nucleus accumbens. Our data suggest that ΔFosB may be involved in some of the neuronal plasticity changes associated with stress induced-cross sensitization with amphetamine in adult rats. PMID:27672362

  3. TMJ inflammation increases Fos expression in the nucleus raphe magnus induced by subsequent formalin injection of the masseter or hindpaw of rats.

    PubMed

    Oh, Sang-Hoon; Imbe, Hiroki; Iwai-Liao, Yasutomo

    2006-08-01

    The study was designed to examine the effect of persistent temporomandibular joint (TMJ) inflammation on neuronal activation in the descending pain modulatory system in response to noxious stimulus. Formalin was injected into the left masseter muscle or hindpaw of rats 10 days after injection of the left TMJ with saline or complete Freund's adjuvant (CFA). The results showed that 10-day persistent TMJ inflammation (induced by CFA) alone did not induce a significant increase in Fos-like immunoreactive (Fos-LI) neurons in the rostral ventromedial medulla (RVM) or locus coeruleus (LC), but that formalin injection of the masseter muscle or hindpaw induced a significant increase in Fos-LI neurons in the RVM and LC of rats with and without TMJ inflammation (P < 0.05). However, persistent TMJ inflammation significantly increased Fos-LI neurons in the nucleus raphe magnus (NRM) induced by subsequent formalin injection of the masseter muscle and hindpaw (70.2% increase and 53.8% increase, respectively, over the control TMJ-saline-injected rats; P < 0.05). The results suggest that persistent TMJ inflammation increases neuronal activity, in particularly in the NRM, by the plastic change of the descending pain modulatory system after ipsilateral application of a noxious stimulus to either orofacial area or a spatially remote body area.

  4. TGF alpha and v-fos cooperation in transgenic mouse epidermis induces aberrant keratinocyte differentiation and stable, autonomous papillomas.

    PubMed

    Wang, X J; Greenhalgh, D A; Lu, X R; Bickenbach, J R; Roop, D R

    1995-01-19

    To assess the synergistic effect of growth and transcription factor deregulation on carcinogenesis in vivo, mating experiments were performed between transgenic mice expressing human TGF alpha or v-fos exclusively in the epidermis by means of a human keratin K1-based targeting vector (HK1.fos, HK1.TGF alpha and HK1.fos/alpha). While HK1.TGF alpha mice exhibited mild epidermal hyperplasia resulting in a wrinkled appearance, this hyperplasia was significantly increased in HK1.fos/alpha mice which also exhibited a novel opalescent and peeling skin phenotype. HK1.fos/alpha keratinocyte differentiation was considerably deregulated with cornified cells appearing in the granular layer, granular cells in the spinous layer and a sixfold increase in BrdU labeling over normal. In addition, hyperplastic HK1.fos/alpha epidermis exhibited aberrant loricrin, filaggrin and novel K13 expression associated with v-fos expression. Unlike adult HK1.TGF alpha controls, hyperplasia persisted in HK1.fos/alpha adults which also rapidly developed autonomous squamous cell papillomas. These results demonstrate that v-fos and TGF alpha over-expression can cooperate to reprogram keratinocyte differentiation and elicit the early stages of neoplasia. Moreover, TGF alpha over-expression appeared to play an early, initiating role in HK1.fos/alpha papilloma etiology, and a promotion role in the accelerated appearance of v-fos wound-associated preneoplastic phenotypes. However, the stable persistence of HK1.fos/alpha papillomas for up to 12 months, suggests that additional events are required for malignant conversion.

  5. Effects of ghrelin and des-acyl ghrelin on neurogenesis of the rat fetal spinal cord

    SciTech Connect

    Sato, Miho; Nakahara, Keiko; Goto, Shintaro; Kaiya, Hiroyuki; Miyazato, Mikiya . E-mail: a0d201u@cc.miyazaki-u.ac.jp; Date, Yukari; Nakazato, Masamitsu; Kangawa, Kenji; Murakami, Noboru

    2006-11-24

    Expressions of the growth hormone secretagogue receptor (GHS-R) mRNA and its protein were confirmed in rat fetal spinal cord tissues by RT-PCR and immunohistochemistry. In vitro, over 3 nM ghrelin and des-acyl ghrelin induced significant proliferation of primary cultured cells from the fetal spinal cord. The proliferating cells were then double-stained using antibodies against the neuronal precursor marker, nestin, and the cell proliferation marker, 5-bromo-2'-deoxyuridine (BrdU), and the nestin-positive cells were also found to be co-stained with antibody against GHS-R. Furthermore, binding studies using [{sup 125}I]des-acyl ghrelin indicated the presence of a specific binding site for des-acyl ghrelin, and confirmed that the binding was displaced with unlabeled des-acyl ghrelin or ghrelin. These results indicate that ghrelin and des-acyl ghrelin induce proliferation of neuronal precursor cells that is both dependent and independent of GHS-R, suggesting that both ghrelin and des-acyl ghrelin are involved in neurogenesis of the fetal spinal cord.

  6. Characterization of the transduction pathway involved in c-fos and c-jun expression induced by Aggregatibacter actinomycetemcomitans lipopolysaccharides in human gingival fibroblasts.

    PubMed

    Gutiérrez-Venegas, Gloria; Castillo-Alemán, Ramiro

    2008-11-01

    Periodontal disease is an inflammatory disease caused by infection with oral bacteria that results in tooth exfoliation. Lipopolysaccharides (LPS) are a major component of the outer membrane of Gram-negative microorganisms and are involved in the inflammatory response. c-fos and c-jun are involved in pathological conditions such as inflammatory disorders. Inflammatory signaling cascades leading to c-fos activation in human gingival fibroblasts (HGFs) are not well characterized. Thus, we have investigated the kinase pathways involved in c-fos and c-jun activation induced by LPS in human gingival fibroblasts. LPS promoted a dose- and time-dependent increase in c-fos transcription. Phosphoinositide-phospholipase C inhibitor (U-73122), protein kinase A inhibitor (H89), MEK1 inhibitor (PD 98,059), p38 inhibitor (SB203580), and tyrosine kinase inhibitors (genistein and herbimycin) attenuated the LPS effect, while the PI-3 K inhibitor (Wortmannin) had no effect on LPS-induced c-fos transcription. Protein kinase C inhibitors (Ro 31-8220, calphostin C, staurosporine, and chelerythrine chloride) also inhibited LPS-induced c-fos transcription. However, long-term treatment (24 -h) with the PKC activator tetradecanoyl phorbol-13-acetate (PMA) had no significant effect on LPS-induced transcription in HGFs. We also found an increase in c-jun expression in HGF stimulated with LPS. In addition, experiments using pharmacological inhibitors of individual mitogen-activated protein kinases (MAPK) and of protein kinase C (PKC) revealed that p38, ERK 1/2, and PKC are involved in LPS-induced c-jun expression. Our results indicate that LPS-induced c-fos and c-jun expressions are mediated by two different signaling pathways: one through phosphoinositide-phospholipase C via an upstream protein tyrosine kinase, which activates PKC isoforms that are insensitive to phorbol stress, and the second through activation of protein kinase A (PKA). Both kinases regulate the phosphorylation of the

  7. Myeloid-Specific Fos-Related Antigen-1 Regulates Cigarette Smoke–Induced Lung Inflammation, Not Emphysema, in Mice

    PubMed Central

    Vaz, Michelle; Rajasekaran, Subbiah; Potteti, Haranatha R.

    2015-01-01

    Heightened lung inflammation is a cardinal feature of chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS)-induced macrophage recruitment and activation, accompanied by abnormal secretion of a number of inflammatory cytokines and matrix metalloproteinases, play a major role in the pathophysiology of COPD. The Fos-related antigen-1 (Fra-1) transcription factor differentially regulates several cellular processes that are implicated in COPD, such as inflammation and immune responses, cell proliferation and death, and extracellular remodeling. Although CS stimulates Fra-1 expression in the lung, the precise role of this transcription factor in the regulation of CS-induced lung inflammation in vivo is poorly understood. Here, we report that myeloid-specific Fra-1 signaling is important for CS-induced lung macrophagic inflammatory response. In response to chronic CS exposure, mice with Fra-1 specifically deleted in myeloid cells showed reduced levels of CS-induced lung macrophagic inflammation, accompanied by decreased expression levels of proinflammatory cytokines compared with their wild-type counterparts. Consistent with this result, bone marrow–derived Fra-1–null macrophages treated with CS showed decreased levels of proinflammatory mediators and matrix metalloproteinases. Interestingly, deletion of Fra-1 in myeloid cells did not affect the severity of emphysema. We propose that Fra-1 plays a key role in promoting chronic CS-induced lung macrophagic inflammation in vivo, and that targeting this transcription factor may be useful in dampening persistent lung inflammation in patients with COPD. PMID:25489966

  8. Ghrelin and motilin in the gastrointestinal system.

    PubMed

    Chen, Chih-Yen; Tsai, Chang-Youh

    2012-01-01

    Human ghrelin and human motilin, belonging to the ghrelin/motilin-related peptide family, share 36% amino acid sequence identity, while the human ghrelin receptor exhibits a remarkable 50% overall identity with the human motilin receptor. In addition to their structural resemblance, ghrelin and motilin are the only two mammalian hormones known to decrease in the postprandial period. Ghrelin and motilin participate in initiating the migrating motor complex in the stomach, and stimulate gastrointestinal motility, accelerate gastric emptying, and induce "gastric hunger". In addition to modulating the release of growth hormone and gut motility, ghrelin plays a crucial role in the secretion and protection of the stomach and colon. Ghrelin mimetics and motilin agonists are currently being developed to reverse gastrointestinal hypomotility disorders. With additional appetite-enhancing, adiposity-promoting, and anti-inflammatory effects, ghrelin and rikkunshito (a traditional Japanese herb enhancing acyl ghrelin signaling) are superior to motilin in the treatment of cancer-related anorexia and cachexia, post-chemotherapy symptoms, rheumatological diseases, age-related frailty, as well as post-operative, septic, and post-burn gut ileus.

  9. Ghrelin and obestatin: different role in fetal lung development?

    PubMed

    Nunes, Susana; Nogueira-Silva, Cristina; Dias, Emanuel; Moura, Rute S; Correia-Pinto, Jorge

    2008-12-01

    Ghrelin and obestatin are two proteins that originate from post-translational processing of the preproghrelin peptide. Various authors claim an opposed role of ghrelin and obestatin in several systems. Preproghrelin mRNA is significantly expressed in airway epithelium throughout lung development, predominantly during the earliest stages. The aim of this study was to evaluate the role of ghrelin and obestatin in fetal lung development in vitro. Immunohistochemistry studies were performed at different gestational ages in order to clarify the expression pattern of ghrelin, GHS-R1a, obestatin and GPR39 during fetal lung development. Fetal rat lung explants were harvested at 13.5 days post-conception (dpc) and cultured during 4 days with increasing doses of total ghrelin, acylated ghrelin, desacyl-ghrelin, ghrelin antagonist (D-Lys(3)-GHRP-6) or obestatin. Immunohistochemistry studies demonstrated that ghrelin, GHS-R1a, obestatin and GPR39 proteins were expressed in primitive rat lung epithelium throughout all studied gestational ages. Total and acylated ghrelin supplementation significantly increased the total number of peripheral airway buds, whereas desacyl-ghrelin induced no effect. Moreover, GHS-R1a antagonist significantly decreased lung branching. Finally, obestatin supplementation induced no significant effect in the measured parameters. The present study showed that ghrelin has a positive effect in fetal lung development through its GHS-R1a receptor, whereas obestatin has no effect on lung branching.

  10. Novel analogs of ghrelin: physiological and clinical implications.

    PubMed

    Halem, Heather A; Taylor, John E; Dong, Jesse Z; Shen, Yeelana; Datta, Rakesh; Abizaid, Alfonso; Diano, Sabrina; Horvath, Tamas; Zizzari, Philippe; Bluet-Pajot, Marie-Thèrèse; Epelbaum, Jacques; Culler, Michael D

    2004-08-01

    Ghrelin, the 28 amino acid peptide recently identified as the natural ligand for the growth hormone (GH) secretagogue (GHS) receptor, has multiple activities in addition to stimulation of GH secretion, including stimulation of feeding and weight gain. To utilize these actions for potential therapeutic benefit, we have produced analogs of human ghrelin with enhanced metabolic stability, affinity for the GHS receptor, and efficacy in stimulating weight gain. We have also discovered an analog of ghrelin, BIM-28163, that is an antagonist at the GHS receptor and that fully inhibits GHS receptor activation induced by native ghrelin. In vivo, BIM-28163 does not increase GH secretion but fully blocks ghrelin-induced GH secretion. In contrast, BIM-28163 acts as a full agonist with regard to the ghrelin actions of stimulating weight gain and food intake. These results suggest that a receptor other than the GHS receptor mediates the actions of ghrelin on feeding and weight gain. This concept is strengthened by our observation that at certain hypothalamic sites, BIM-28163 acts as an antagonist of ghrelin-induced neuronal activation, while at other sites, both ghrelin and BIM-28163 induce neuronal activation via the same receptor. Collectively, these results indicate the existence of a novel ghrelin receptor that may regulate the feeding activity of ghrelin. Using BIM-28163 as a tool to define the endogenous role of ghrelin in normal GH secretion, we have demonstrated that antagonism of the GHS receptor in normal rats does not impair the pulsatility of GH secretion but lowers the pulse amplitude and mean GH level. These results demonstrate that endogenous ghrelin acts to amplify the basic pattern of GH secretion established by the interplay of hypothalamic GH-releasing hormone and somatostatin. These studies demonstrate the feasibility of creating ghrelin analogs that are selective for specific activities, as well as their utility in dissecting the role of ghrelin in both

  11. Amphetamine and cocaine induce drug-specific activation of the c-fos gene in striosome-matrix compartments and limbic subdivisions of the striatum.

    PubMed Central

    Graybiel, A M; Moratalla, R; Robertson, H A

    1990-01-01

    Amphetamine and cocaine are stimulant drugs that act on central monoaminergic neurons to produce both acute psychomotor activation and long-lasting behavioral effects including addiction and psychosis. Here we report that single doses of these drugs induce rapid expression of the nuclear proto-oncogene c-fos in the forebrain and particularly in the striatum, an extrapyramidal structure implicated in addiction and in long-term drug-induced changes in motor function. The two drugs induce strikingly different patterns of c-fos expression in the striosome-matrix compartments and limbic subdivisions of the striatum, and their effects are pharmacologically distinct, although both are sensitive to dopamine receptor blockade. We propose that differential activation of immediate-early genes by psychostimulants may be an early step in drug-specific molecular cascades contributing to acute and long-lasting psychostimulant-induced changes in behavior. Images PMID:2118661

  12. Androgen receptors and estrogen receptors are colocalized in male rat hypothalamic and limbic neurons that express Fos immunoreactivity induced by mating.

    PubMed

    Gréco, B; Edwards, D A; Michael, R P; Clancy, A N

    1998-01-01

    Conversion of testosterone into estradiol is important for male rat sexual behavior, and both steroids probably contribute to mating. The distributions of neurons containing androgen receptors (AR) and estrogen receptors (ER) overlap, and many AR-immunoreactive (AR-ir) neurons express Fos immunoreactivity (Fos-ir) induced by mating. Because mating-induced Fos-ir in the male rat occurs mainly in AR-ir neurons, and because both steroids are important for mating, we hypothesized that (i) AR-ir and ER-ir are colocalized and that (ii) some of these neurons are activated during mating. We examined, in adjacent sections from the medial preoptic area (MPN) through the central tegmental field (CTF), the expression of ER-ir in: (i) AR-ir-containing neurons, and (ii) Fos-ir-expressive neurons. PG21 anti-AR, OA-11-824 anti-c-fos, H222 or 1D5 anti-ER primary antibodies were visualized, respectively, with cyanine-conjugated, fluorescein- or cyanine-conjugated, and fluorescein-conjugated secondary antibodies in male rats which were killed 1 h after ejaculating with a receptive female. In MPN, bed nucleus of the stria terminalis (BNST), and medial amygdala (MEA), 80-90% of ER-ir labeling occurred in AR-ir-positive neurons but only about 30% of AR-ir neurons were ER-ir-positive. No ER-ir was found in the CTF. This suggests the presence of three types of brain neurons sensitive to gonadal steroid hormones: neurons sensitive to androgens only, neurons sensitive to both androgens and estrogens, and neurons sensitive to estrogens only. About 50% of ER-ir labeling occurred in cells expressing mating-induced Fos-ir but only about 30% of Fos-ir neurons were ER-ir-positive. These findings suggest that, in the MPN, at least two different neuronal populations are activated during mating: the first contains AR-ir only and the second contains AR-ir and ER-ir. In the BNST and MEA, at least three hormonally sensitive populations are activated during mating: the two described above plus a third

  13. Neurogenic Effects of Ghrelin on the Hippocampus

    PubMed Central

    Kim, Chanyang; Kim, Sehee; Park, Seungjoon

    2017-01-01

    Mammalian neurogenesis continues throughout adulthood in the subventricular zone of the lateral ventricle and in the subgranular zone of the dentate gyrus in the hippocampus. It is well known that hippocampal neurogenesis is essential in mediating hippocampus-dependent learning and memory. Ghrelin, a peptide hormone mainly synthesized in the stomach, has been shown to play a major role in the regulation of energy metabolism. A plethora of evidence indicates that ghrelin can also exert important effects on neurogenesis in the hippocampus of the adult brain. The aim of this review is to discuss the current role of ghrelin on the in vivo and in vitro regulation of neurogenesis in the adult hippocampus. We will also discuss the possible role of ghrelin in dietary restriction-induced hippocampal neurogenesis and the link between ghrelin-induced hippocampal neurogenesis and cognitive functions. PMID:28282857

  14. Neurogenic Effects of Ghrelin on the Hippocampus.

    PubMed

    Kim, Chanyang; Kim, Sehee; Park, Seungjoon

    2017-03-08

    Mammalian neurogenesis continues throughout adulthood in the subventricular zone of the lateral ventricle and in the subgranular zone of the dentate gyrus in the hippocampus. It is well known that hippocampal neurogenesis is essential in mediating hippocampus-dependent learning and memory. Ghrelin, a peptide hormone mainly synthesized in the stomach, has been shown to play a major role in the regulation of energy metabolism. A plethora of evidence indicates that ghrelin can also exert important effects on neurogenesis in the hippocampus of the adult brain. The aim of this review is to discuss the current role of ghrelin on the in vivo and in vitro regulation of neurogenesis in the adult hippocampus. We will also discuss the possible role of ghrelin in dietary restriction-induced hippocampal neurogenesis and the link between ghrelin-induced hippocampal neurogenesis and cognitive functions.

  15. Role of thalamic nuclei in the modulation of Fos expression within the cerebral cortex during hypertonic saline-induced muscle nociception.

    PubMed

    Xiao, Y; Lei, J; Ye, G; Xu, H; You, H-J

    2015-09-24

    It has been proposed that thalamic mediodorsal (MD) and ventromedial (VM) nuclei form thalamic 'nociceptive discriminators' in discrimination of nociceptive afferents, and specifically govern endogenous descending facilitation and inhibition. The present study conducted in rats was to explore the role of thalamic MD and VM nuclei in modulation of cerebral neuronal activities by means of detection of spatiotemporal variations of Fos expression within the cerebral cortex. Following a unilateral intramuscular injection of 5.8% saline into the gastrocnemius muscle, Fos expression within the bilateral, different areas of the cerebral cortex except S2 was significantly increased (P<0.05). Particularly, the increases in Fos expression within the cingulate cortex and the insular cortex occurred at 0.5h, 4h and reached the peak level at 4h, 16h, respectively. Electrolytic lesion of the contralateral thalamic MD and VM nuclei significantly blocked the 5.8% saline intramuscularly induced increases in Fos expression within the bilateral cingulate and insular cortices, respectively. Additionally, the 5.8% saline-induced Fos expression in the cingulate cortex and the insular cortex were dose-dependently attenuated by microinjection of μ-opioid antagonist β-funaltrexamine hydrochloride into the thalamic MD and VM nuclei. It is suggested that (1) the neural circuits of 'thalamic MD nucleus - cingulate cortex' and 'thalamic VM nucleus - insular cortex' form two distinct pathways in the endogenous control of nociception, (2) mirror or contralateral pain is hypothesized to be related to cross-talk of neuronal activities within the bilateral cerebral cortices modulated by μ-opioid receptors within the thalamic MD and VM nuclei.

  16. Nalfurafine prevents 5'-guanidinonaltrindole- and compound 48/80-induced spinal c-fos expression and attenuates 5'-guanidinonaltrindole-elicited scratching behavior in mice.

    PubMed

    Inan, S; Dun, N J; Cowan, A

    2009-09-29

    The aims of the present study were to establish if nalfurafine, a kappa opioid agonist, inhibits compulsive scratching in mice elicited by the s.c. administration (behind the neck) of 5'-guanidinonaltrindole (GNTI), a kappa opioid antagonist; to assess if nalfurafine prevents c-fos expression provoked by GNTI or compound 48/80, two chemically diverse pruritogens; and to distinguish on the basis of neuroanatomy, those neurons in the brainstem activated by either GNTI-induced itch or formalin-induced pain (both compounds given s.c. to the right cheek). Pretreatment of mice with nalfurafine (0.001-0.03 mg/kg s.c.) attenuated GNTI (0.3 mg/kg)-evoked scratching dose-dependently. A standard antiscratch dose of nalfurafine (0.02 mg/kg) had no marked effect on the spontaneous locomotion of mice. Tolerance did not develop to the antiscratch activity of nalfurafine. Both GNTI and compound 48/80 provoked c-fos expression on the lateral side of the superficial layer of the dorsal horn of the cervical spinal cord and pretreating mice with nalfurafine inhibited c-fos expression induced by both pruritogens. In contrast to formalin, GNTI did not induce c-fos expression in the trigeminal nucleus suggesting that pain and itch sensations are projected differently along the sensory trigeminal pathway. Our data indicate that the kappa opioid system is involved, at least in part, in the pathogenesis of itch; and that nalfurafine attenuates excessive scratching and prevents scratch-induced neuronal activity at the spinal level. On the basis of our results, nalfurafine holds promise as a potentially useful antipruritic in human conditions involving itch.

  17. Chronic light deprivation inhibits appetitive associative learning induced by ethanol and its respective c-Fos and pCREB expression.

    PubMed

    Varela, Patrícia; Escosteguy-Neto, João Carlos; Coelho, Carolina Tesone; Mello, Luiz Eugênio; da Silveira, Dartiu Xavier; Santos-Junior, Jair Guilherme

    2014-11-01

    To address the role of mixed anxiety/mood disorder on appetitive associative learning, we verify whether previous chronic light deprivation changes ethanol-induced conditioned place preference and its respective expression of c-Fos and pCREB, markers of neuronal activity and plasticity. The experimental group was maintained in light deprivation for 24 h for a period of 4 wk. Subsequently, it was adapted to a standard light-dark cycle for 1 wk. As a control, some mice were maintained in standard cycle for a period of 4 wk (Naïve group). Then, all animals were submitted to behavioral tests to assess emotionality: elevated plus maze; open field; and forced swim. After that, they were submitted to ethanol-induced conditioned place preference. Ninety minutes after the place preference test, they were perfused, and their brains processed for c-Fos and pCREB immunohistochemistry. Light deprivation induced anxiety-like trait (elevated plus maze), despair (forced swim), and hyperlocomotion (open field), common features seen in other animal models of depression. Ethanol-induced conditioned place preference was accompanied by increases on c-Fos and pCREB in the hippocampus, prefrontal cortex and striatum. Interestingly, mice previously submitted to light deprivation did not develop either acquisition and/or expression of ethanol-induced conditioned place preference or increases in c-Fos and pCREB. Therefore, chronic light deprivation mimics several behavioral aspects of other animal models of depression. Furthermore, it could be useful to study the neurochemical mechanisms involved in the dual diagnosis. However, given its likely deleterious effects on appetitive associative memory, it should be used with caution to investigate the cognitive aspects related to the dual diagnosis.

  18. Effect of NMDA receptor antagonist MK-801 on light-induced Fos expression in the suprachiasmatic nuclei and on melatonin production in the Syrian hamster.

    PubMed

    Vuillez, P; Jacob, N; Teclemariam-Mesbah, R; Van Rossum, A; Vivien-Roels, B; Pévet, P

    1998-09-01

    In mammals, circadian rhythms generated by the suprachiasmatic nuclei (SCN) are daily synchronized by a light-dark cycle. Photic information is transmitted to the SCN mainly through the direct retinohypothalamic tract, the neurotransmitters involved being excitatory amino acids. It is also commonly accepted that photoperiodic information coming from the retina via the SCN is transduced by the pineal into a nocturnal signal, i.e. melatonin production. Light exposure at night induces (1) an inhibition of melatonin synthesis and (2) an expression of c-fos in numerous cells of SCN. To determine the role of the NMDA receptor in these effects, we treated Syrian hamsters with ip injections of MK-801, a noncompetitive NMDA receptor antagonist. Several subpopulations of light-sensitive cells in the SCN are affected by MK-801. According to previous studies, MK-801 inhibits light-induced Fos immunoreactivity mainly in the most ventral part of the SCN. However, we observed that numerous other cells are still activated by light. When light is applied in the middle of the night, MK-801 pretreatment does not reduce Fos-ir in the dorsal SCN. At the beginning of the night, labeled cells in this part of the nucleus appear even more numerous after MK-801. We also found that MK-801 fails to reduce the light-induced inhibition of melatonin synthesis. Moreover, in control animals, which received no light stimulation, ip injection of MK-801 induces by itself a dose-dependent inhibition of melatonin production.

  19. Long-term ethanol self-administration induces ΔFosB in male and female adolescent, but not in adult, Wistar rats.

    PubMed

    Wille-Bille, Aranza; de Olmos, Soledad; Marengo, Leonardo; Chiner, Florencia; Pautassi, Ricardo Marcos

    2017-03-06

    Early-onset ethanol consumption predicts later development of alcohol use disorders. Age-related differences in reactivity to ethanol's effects may underlie this effect. Adolescent rats are more sensitive and less sensitive than adults to the appetitive and aversive behavioral effects of ethanol, respectively, and more sensitive to the neurotoxic effects of experimenter-administered binge doses of ethanol. However, less is known about age-related differences in the neural consequences of self-administered ethanol. ΔFosB is a transcription factor that accumulates after chronic drug exposure and serves as a molecular marker of neural plasticity associated with the transition to addiction. We analyzed the impact of chronic (18 two-bottle choice intake sessions spread across 42days, session length: 18h) ethanol [or only vehicle (control group)] self-administration during adolescence or adulthood on the induction of ΔFosB in several brain areas, anxiety-like behavior, and ethanol-induced locomotor activity and conditioned place preference (CPP) in Wistar rats. Adolescent rats exhibited a progressive escalation of ethanol intake and preference, whereas adult rats exhibited a stable pattern of ingestion. Few behavioral differences in the open field or light-dark test were observed after the intake test. Furthermore, ethanol self-administration did not promote the expression of ethanol-induced CPP. There were, however, large age-related differences in the neural consequences of ethanol drinking: a significantly greater number of ethanol-induced ΔFosB-positive cells was found in adolescents vs. adults in the prelimbic cortex, dorsolateral striatum, nucleus accumbens core and shell, and central amygdala nucleus capsular and basolateral amygdala, with sex-related differences found at central amygdala. This greater ethanol-induced ΔFosB induction may represent yet another age-related difference in the sensitivity to ethanol that may put adolescents at higher risk for

  20. The role of the vagus nerve in the migrating motor complex and ghrelin- and motilin-induced gastric contraction in suncus.

    PubMed

    Miyano, Yuki; Sakata, Ichiro; Kuroda, Kayuri; Aizawa, Sayaka; Tanaka, Toru; Jogahara, Takamichi; Kurotani, Reiko; Sakai, Takafumi

    2013-01-01

    The upper gastrointestinal (GI) tract undergoes a temporally coordinated cyclic motor pattern known as the migrating motor complex (MMC) in both dogs and humans during the fasted state. Feeding results in replacement of the MMC by a pattern of noncyclic, intermittent contractile activity termed as postprandial contractions. Although the MMC is known to be stimulated by motilin, recent studies have shown that ghrelin, which is from the same peptide family as motilin, is also involved in the regulation of the MMC. In the present study, we investigated the role of the vagus nerve on gastric motility using conscious suncus-a motilin- and ghrelin-producing small animal. During the fasted state, cyclic MMC comprising phases I, II, and III was observed in both sham-operated and vagotomized suncus; however, the duration and motility index (MI) of phase II was significantly decreased in vagotomized animals. Motilin infusion (50 ng·kg(-1)·min(-1) for 10 min) during phase I had induced phase III-like contractions in both sham-operated and vagotomized animals. Ghrelin infusion (0.1, 0.3, 1, 3, or 10 µg·kg(-1)·min(-1) for 10 min) enhanced the amplitude of phase II MMC in sham-operated animals, but not in vagotomized animals. After feeding, phase I was replaced by postprandial contractions, and motilin infusion (50 ng·kg(-1)·min(-1) for 10 min) did not induce phase III-like contractions in sham-operated suncus. However, in vagotomized suncus, feeding did not evoke postprandial contractions, but exogenous motilin injection strongly induced phase III-like contractions, as noted during the phase I period. Thus, the results indicate that ghrelin stimulates phase II of the MMC via the vagus nerve in suncus. Furthermore, the vagus nerve is essential for initiating postprandial contractions, and inhibition of the phase III-like contractions induced by motilin is highly dependent on the vagus nerve.

  1. Thapsigargin induces rapid, transient growth inhibition and c-fos expression followed by sustained growth stimulation in mouse keratinocyte cultures.

    PubMed

    Harmon, C S; Ducote, J; Xiong, Y

    1996-08-01

    Although the sesquiterpene lactone thapsigargin has been shown to possess hyperplastic and tumor-promoting activities when applied topically to mouse skin in vivo, the cellular mechanism(s) which underlie these effects are unclear. We show here that thapsigargin treatment of Primary mouse epidermal keratinocytes increased intracellular free Ca2+ concentration (Cai) in a concentration-dependent manner. Thapsigargin induced a rapid, transient elevation in keratinocyte Cai, in part due to the release of Ca2+ from intracellular stores. This response was followed by a sustained elevation in Ca2+, resulting entirely from calcium influx. Thapsigargin elicited a biphasic effect on keratinocyte DNA synthesis: a rapid inhibitory effect (50-60% inhibition at 4-8 h), followed by a very marked and sustained elevation. Prolonged treatment of keratinocytes with thapsigargin at relatively high concentrations resulted in cytotoxicity (inhibition of neutral red uptake). The rapid antiproliferative effect of thapsigargin was not associated with cytotoxicity, as determined by either neutral red uptake or by trypan blue exclusion, and was not blocked by pretreatment with Ro 31-7349, a selective inhibitor of protein kinase C. The rapid antiproliferative effect of thapsigargin was associated with rapid, transient activation of keratinocyte c-fos expression and rapid inhibition of total protein synthesis. Taken together, these findings raise the possibility that the hyperplastic and tumor-promoting activities of thapsigargin on epidermis in vivo result from direct keratinocyte growth stimulation as a consequence of a prolonged elevation in levels of Cai.

  2. Current and potential roles of ghrelin in clinical practice.

    PubMed

    Angelidis, G; Valotassiou, V; Georgoulias, P

    2010-12-01

    Ghrelin is a novel GH-releasing peptide, which has been identified as an endogenous ligand for GH-secretagogue receptor. Ghrelin is mainly secreted by the stomach and plays a critical role in a variety of physiological processes including endocrine, metabolic, cardiovascular, immunological, and other actions. Ghrelin stimulates food intake via hypothalamic neurons and causes a positive energy balance and body weight gain by decreasing fat utilization and promoting adiposity. Given the multiple effects of ghrelin, its potential clinical applications have been evaluated in various conditions. Preliminary trials have shown that it may prove valuable in the management of disease-induced cachexia. Ghrelin may improve the wasting syndrome through GH-dependent or GH-independent effects. Moreover, ghrelin may play a role in the management of disorders of gut motility and obesity. Finally, other potential clinical applications of ghrelin include the treatment of patients with diabetes mellitus, infections, rheumatological diseases or GH deficiency and the diagnosis of this hormonal disorder.

  3. Obesity Impairs the Action of the Neuroendocrine Ghrelin System.

    PubMed

    Zigman, Jeffrey M; Bouret, Sebastien G; Andrews, Zane B

    2016-01-01

    Ghrelin is a metabolic hormone that promotes energy conservation by regulating appetite and energy expenditure. Although some studies suggest that antagonizing ghrelin function attenuates body weight gain and glucose intolerance on a high calorie diet, there is little information about the metabolic actions of ghrelin in the obese state. In this review, we discuss the novel concept of obesity-induced central ghrelin resistance in neural circuits regulating behavior, and impaired ghrelin secretion from the stomach. Interestingly, weight loss restores ghrelin secretion and function, and we hypothesize that ghrelin resistance is a mechanism designed to protect a higher body weight set-point established during times of food availability, to maximize energy reserves during a time of food scarcity.

  4. IP{sub 3}-dependent intracellular Ca{sup 2+} release is required for cAMP-induced c-fos expression in hippocampal neurons

    SciTech Connect

    Zhang, Wenting; Tingare, Asmita; Ng, David Chi-Heng; Johnson, Hong W.; Schell, Michael J.; Lord, Rebecca L.; Chawla, Sangeeta

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer cAMP-induced c-fos expression in hippocampal neurons requires a submembraneous Ca{sup 2+} pool. Black-Right-Pointing-Pointer The submembraneous Ca{sup 2+} pool derives from intracellular ER stores. Black-Right-Pointing-Pointer Expression of IP{sub 3}-metabolizing enzymes inhibits cAMP-induced c-fos expression. Black-Right-Pointing-Pointer SRE-mediated and CRE-mediated gene expression is sensitive to IP{sub 3}-metabolizing enzymes. Black-Right-Pointing-Pointer Intracellular Ca{sup 2+} release is required for cAMP-induced nuclear translocation of TORC1. -- Abstract: Ca{sup 2+} and cAMP are widely used in concert by neurons to relay signals from the synapse to the nucleus, where synaptic activity modulates gene expression required for synaptic plasticity. Neurons utilize different transcriptional regulators to integrate information encoded in the spatiotemporal dynamics and magnitude of Ca{sup 2+} and cAMP signals, including some that are Ca{sup 2+}-responsive, some that are cAMP-responsive and some that detect coincident Ca{sup 2+} and cAMP signals. Because Ca{sup 2+} and cAMP can influence each other's amplitude and spatiotemporal characteristics, we investigated how cAMP acts to regulate gene expression when increases in intracellular Ca{sup 2+} are buffered. We show here that cAMP-mobilizing stimuli are unable to induce expression of the immediate early gene c-fos in hippocampal neurons in the presence of the intracellular Ca{sup 2+} buffer BAPTA-AM. Expression of enzymes that attenuate intracellular IP{sub 3} levels also inhibited cAMP-dependent c-fos induction. Synaptic activity induces c-fos transcription through two cis regulatory DNA elements - the CRE and the SRE. We show here that in response to cAMP both CRE-mediated and SRE-mediated induction of a luciferase reporter gene is attenuated by IP{sub 3} metabolizing enzymes. Furthermore, cAMP-induced nuclear translocation of the CREB coactivator TORC1 was inhibited by

  5. Hyperglycemia abolishes meal-induced satiety by a dysregulation of ghrelin and peptide YY3-36 in healthy overweight/obese humans.

    PubMed

    Knudsen, Sine H; Karstoft, Kristian; Solomon, Thomas P J

    2014-01-15

    Satiety and satiety-regulating gut hormone levels are abnormal in hyperglycemic individuals. We aimed to determine whether these abnormalities are secondary to hyperglycemia. Ten healthy overweight/obese subjects (age: 56 ± 3 yr; BMI: 30.3 ± 1.2 kg/m(2)) received three equicaloric meals at t = 0, 4, and 8 h in the absence (control trial) and presence of experimental hyperglycemia (hyperglycemia trial; 5.4 mM above basal). Circulating levels of glucose, insulin, ghrelin, and peptide YY (PYY)3-36 and visual analog scale ratings of satiety were measured throughout each trial. In the control trial, glucose, insulin, PYY3-36, and the feeling of fullness were increased in the postprandial periods, whereas ghrelin was decreased. In the hyperglycemia trial, in which plasma glucose was increased to 11.2 ± 0.1 mmol/l, postprandial meal responses (AUC: 0-2, 4-6, and 8-10 h) of PYY3-36 were lower (meal 1, P < 0.0001; meal 2, P < 0.001; meal 3, P < 0.05), whereas insulin (meal 1, P < 0.01; meal 2, P < 0.001; meal 3, P < 0.05) and ghrelin (meal 1, P < 0.05; meal 2, P > 0.05; meal 3, P > 0.05) were higher compared with the control trial. Furthermore, the incremental (Δ0-0.5, 4-4.5, and 8-8.5 h) ghrelin response to the first and third meals was higher in the hyperglycemia trial in contrast to control (Δ: 2.3 ± 8.0, P = 0.05; Δ: 14.4 ± 2.5, P < 0.05). Also, meal-induced fullness was prevented (meal 1, P = 0.06; meal 2, P = 0.01; meal 3, P = 0.08) by experimental hyperglycemia. Furthermore, trends in ghrelin, PYY3-36, and fullness were described by different polynomial functions between the trials. In conclusion, hyperglycemia abolishes meal-induced satiety and dysregulates postprandial responses of the gut hormones PYY3-36 and ghrelin in overweight/obese healthy humans.

  6. Methyl supplementation attenuates cocaine-seeking behaviors and cocaine-induced c-Fos activation in a DNA methylation-dependent manner.

    PubMed

    Wright, Katherine N; Hollis, Fiona; Duclot, Florian; Dossat, Amanda M; Strong, Caroline E; Francis, T Chase; Mercer, Roger; Feng, Jian; Dietz, David M; Lobo, Mary Kay; Nestler, Eric J; Kabbaj, Mohamed

    2015-06-10

    Epigenetic mechanisms, such as histone modifications, regulate responsiveness to drugs of abuse, such as cocaine, but relatively little is known about the regulation of addictive-like behaviors by DNA methylation. To investigate the influence of DNA methylation on the locomotor-activating effects of cocaine and on drug-seeking behavior, rats receiving methyl supplementation via chronic l-methionine (MET) underwent either a sensitization regimen of intermittent cocaine injections or intravenous self-administration of cocaine, followed by cue-induced and drug-primed reinstatement. MET blocked sensitization to the locomotor-activating effects of cocaine and attenuated drug-primed reinstatement, with no effect on cue-induced reinstatement or sucrose self-administration and reinstatement. Furthermore, upregulation of DNA methyltransferase 3a and 3b and global DNA hypomethylation were observed in the nucleus accumbens core (NAc), but not in the medial prefrontal cortex (mPFC), of cocaine-pretreated rats. Glutamatergic projections from the mPFC to the NAc are critically involved in the regulation of cocaine-primed reinstatement, and activation of both brain regions is seen in human addicts when reexposed to the drug. When compared with vehicle-pretreated rats, the immediate early gene c-Fos (a marker of neuronal activation) was upregulated in the NAc and mPFC of cocaine-pretreated rats after cocaine-primed reinstatement, and chronic MET treatment blocked its induction in both regions. Cocaine-induced c-Fos expression in the NAc was associated with reduced methylation at CpG dinucleotides in the c-Fos gene promoter, effects reversed by MET treatment. Overall, these data suggest that drug-seeking behaviors are, in part, attributable to a DNA methylation-dependent process, likely occurring at specific gene loci (e.g., c-Fos) in the reward pathway.

  7. Methyl Supplementation Attenuates Cocaine-Seeking Behaviors and Cocaine-Induced c-Fos Activation in a DNA Methylation-Dependent Manner

    PubMed Central

    Wright, Katherine N.; Hollis, Fiona; Duclot, Florian; Dossat, Amanda M.; Strong, Caroline E.; Francis, T. Chase; Mercer, Roger; Feng, Jian; Dietz, David M.; Lobo, Mary Kay; Nestler, Eric J.

    2015-01-01

    Epigenetic mechanisms, such as histone modifications, regulate responsiveness to drugs of abuse, such as cocaine, but relatively little is known about the regulation of addictive-like behaviors by DNA methylation. To investigate the influence of DNA methylation on the locomotor-activating effects of cocaine and on drug-seeking behavior, rats receiving methyl supplementation via chronic l-methionine (MET) underwent either a sensitization regimen of intermittent cocaine injections or intravenous self-administration of cocaine, followed by cue-induced and drug-primed reinstatement. MET blocked sensitization to the locomotor-activating effects of cocaine and attenuated drug-primed reinstatement, with no effect on cue-induced reinstatement or sucrose self-administration and reinstatement. Furthermore, upregulation of DNA methyltransferase 3a and 3b and global DNA hypomethylation were observed in the nucleus accumbens core (NAc), but not in the medial prefrontal cortex (mPFC), of cocaine-pretreated rats. Glutamatergic projections from the mPFC to the NAc are critically involved in the regulation of cocaine-primed reinstatement, and activation of both brain regions is seen in human addicts when reexposed to the drug. When compared with vehicle-pretreated rats, the immediate early gene c-Fos (a marker of neuronal activation) was upregulated in the NAc and mPFC of cocaine-pretreated rats after cocaine-primed reinstatement, and chronic MET treatment blocked its induction in both regions. Cocaine-induced c-Fos expression in the NAc was associated with reduced methylation at CpG dinucleotides in the c-Fos gene promoter, effects reversed by MET treatment. Overall, these data suggest that drug-seeking behaviors are, in part, attributable to a DNA methylation-dependent process, likely occurring at specific gene loci (e.g., c-Fos) in the reward pathway. PMID:26063926

  8. Expression and colocalization of NMDA receptor and FosB/ΔFosB in sensitive brain regions in rats after chronic morphine exposure.

    PubMed

    Zhang, Qiang; Liu, Qi; Li, Tongzhou; Liu, You; Wang, Lei; Zhang, Zhonghai; Liu, Hongzhi; Hu, Min; Qiao, Yuehua; Niu, Haichen

    2016-02-12

    Research in the last decade demonstrated that the NMDA receptor (NMDAR) has an important role in opiate-induced neural and behavioral plasticity. In addition, increased levels of FosB-like proteins (FosB/ΔFosB) were found to be related to morphine withdrawal behaviors. However, the relationship between NMDAR and FosB/ΔFosB in sensitive brain regions during morphine withdrawal is largely unknown. In this study, we aimed to investigate NMDAR dynamics and FosB/ΔFosB levels in multiple brain regions and whether they are related in sensitive brain regions during morphine abstinence. Quantitative immunohistochemistry was adopted to test NMDAR and FosB/ΔfosB levels during morphine withdrawal in rats. Increased NMDAR and FosB/ΔFosB levels were found in the nucleus accumbens core (AcbC), nucleus accumbens shell (AcbSh), central amygdaloid nucleuscapsular part (CeC), ventral tegmental area (VTA) and cingulate cortex (Cg). Double-immunofluorescence labeling indicated that NMDAR colocalized with Fos/ΔFosB in these five regions. These results suggest that multiple phenotypic regions are mediated by NMDAR and Fos/ΔFosB during morphine withdrawal, such as the motivational (AcbC, AcbSh), limbic (CeC, VTA) and executive (Cg) system pathways, and may be the primary targets of NMDAR and Fos/ΔfosB that impact morphine withdrawal behaviors.

  9. Inhibitory Effect of Oleic Acid on Octanoylated Ghrelin Production.

    PubMed

    Oiso, Shigeru; Nobe, Miyuki; Iwasaki, Syuhei; Nii, Wakana; Goto, Natsumi; Seki, Yukari; Nakajima, Kensuke; Nakamura, Kazuo; Kariyazono, Hiroko

    2015-01-01

    Ghrelin is a growth hormone-releasing peptide that also displays orexigenic activity. Since serine-3 acylation with octanoylate (octanoylation) is essential for the orexigenic activity of ghrelin, suppression of octanoylation could lead to amelioration or prevention of obesity. To enable the exploration of inhibitors of octanoylated ghrelin production, we developed a cell-based assay system using AGS-GHRL8 cells, in which octanoylated ghrelin concentration increases in the presence of octanoic acid. Using this assay system, we investigated whether fatty acids contained in foods or oils, such as acetic acid, stearic acid, oleic acid, linoleic acid, and α-linolenic acid, have inhibitory effects on octanoylated ghrelin production. Acetic acid did not suppress the increase in octanoylated ghrelin production in AGS-GHRL8 cells, which was induced by the addition of octanoic acid. However, stearic acid, oleic acid, linoleic acid, and α-linolenic acid significantly suppressed octanoylated ghrelin production, with the effect of oleic acid being the strongest. Additionally, oleic acid decreased the serum concentration of octanoylated ghrelin in mice. The serum concentration of des-acyl ghrelin (without acyl modification) was also decreased, but the decrease was smaller than that of octanoylated ghrelin. Decreased octanoylated ghrelin production likely resulted from post-translational ghrelin processing, as there were no significant differences in gene expression in the stomach between oleic acid-treated mice and controls. These results suggest that oleic acid is a potential inhibitor of octanoylated ghrelin production and that our assay system is a valuable tool for screening compounds with suppressive effects on octanoylated ghrelin production.

  10. A novel human ghrelin variant (In1-ghrelin) and ghrelin-O-acyltransferase are overexpressed in breast cancer: potential pathophysiological relevance.

    PubMed

    Gahete, Manuel D; Córdoba-Chacón, José; Hergueta-Redondo, Marta; Martínez-Fuentes, Antonio J; Kineman, Rhonda D; Moreno-Bueno, Gema; Luque, Raúl M; Castaño, Justo P

    2011-01-01

    The human ghrelin gene, which encodes the ghrelin and obestatin peptides, contains 5 exons (Ex), with Ex1-Ex4 encoding a 117 amino-acid (aa) preproprotein that is known to be processed to yield a 28-aa (ghrelin) and/or a 23-aa (obestatin) mature peptides, which possess biological activities in multiple tissues. However, the ghrelin gene also encodes additional peptides through alternative splicing or post-translational modifications. Indeed, we previously identified a spliced mRNA ghrelin variant in mouse (In2-ghrelin-variant), which is regulated in a tissue-dependent manner by metabolic status and may thus be of biological relevance. Here, we have characterized a new human ghrelin variant that contains Ex0-1, intron (In) 1, and Ex2 and lacks Ex3-4. This human In1-ghrelin variant would encode a new prepropeptide that conserves the first 12aa of native-ghrelin (including the Ser3-potential octanoylation site) but has a different C-terminal tail. Expression of In1-variant was detected in 22 human tissues and its levels were positively correlated with those of ghrelin-O-acyltransferase (GOAT; p = 0.0001) but not with native-ghrelin expression, suggesting that In1-ghrelin could be a primary substrate for GOAT in human tissues. Interestingly, levels of In1-ghrelin variant expression in breast cancer samples were 8-times higher than those of normal mammary tissue, and showed a strong correlation in breast tumors with GOAT (p = 0.0001), ghrelin receptor-type 1b (GHSR1b; p = 0.049) and cyclin-D3 (a cell-cycle inducer/proliferation marker; p = 0.009), but not with native-ghrelin or GHSR1a expression. Interestingly, In1-ghrelin variant overexpression increased basal proliferation of MDA-MB-231 breast cancer cells. Taken together, our results provide evidence that In1-ghrelin is a novel element of the ghrelin family with a potential pathophysiological role in breast cancer.

  11. Effect of ghrelin receptor antagonist on meal patterns in cholecystokinin type 1 receptor null mice.

    PubMed

    Lee, Jennifer; Martin, Elizabeth; Paulino, Gabriel; de Lartigue, Guillaume; Raybould, Helen E

    2011-05-03

    Vagal afferent neurons (VAN) express the cholecystokinin (CCK) type 1 receptor (CCK₁R) and, as predicted by the role of CCK in inducing satiation, CCK₁R⁻/⁻ mice ingest larger and longer meals. However, after a short fast, CCK₁R⁻/⁻ mice ingesting high fat (HF) diets initiate feeding earlier than wild-type mice. We hypothesized that the increased drive to eat in CCK₁R⁻/⁻ mice eating HF diet is mediated by ghrelin, a gut peptide that stimulates food intake. The decrease in time to first meal, and the increase in meal size and duration in CCK₁R⁻/⁻ compared to wild-type mice ingesting high fat (HF) diet were reversed by administration of GHSR1a antagonist D-(Lys3)-GHRP-6 (p<0.05). Administration of the GHSR1a antagonist significantly increased expression of the neuropeptide cocaine and amphetamine-regulated transcript (CART) in VAN of HF-fed CCK₁R⁻/⁻ but not wild-type mice. Administration of the GHSR1a antagonist decreased neuronal activity measured by immunoreactivity for fos protein in the nucleus of the solitary tract (NTS) and the arcuate nucleus of both HF-fed wild-type and CCK₁R⁻/⁻ mice. The data show that hyperphagia in CCK₁R⁻/⁻ mice ingesting HF diet is reversed by blockade of the ghrelin receptor, suggesting that in the absence of the CCK₁R, there is an increased ghrelin-dependent drive to feed. The site of action of ghrelin receptors is unclear, but may involve an increase in expression of CART peptide in VAN in HF-fed CCK₁R⁻/⁻ mice.

  12. Ghrelin Attenuates Intestinal Barrier Dysfunction Following Intracerebral Hemorrhage in Mice

    PubMed Central

    Cheng, Yijun; Wei, Yongxu; Yang, Wenlei; Cai, Yu; Chen, Bin; Yang, Guoyuan; Shang, Hanbing; Zhao, Weiguo

    2016-01-01

    Intestinal barrier dysfunction remains a critical problem in patients with intracerebral hemorrhage (ICH) and is associated with poor prognosis. Ghrelin, a brain-gut peptide, has been shown to exert protection in animal models of gastrointestinal injury. However, the effect of ghrelin on intestinal barrier dysfunction post-ICH and its possible underlying mechanisms are still unknown. This study was designed to investigate whether ghrelin administration attenuates intestinal barrier dysfunction in experimental ICH using an intrastriatal autologous blood infusion mouse model. Our data showed that treatment with ghrelin markedly attenuated intestinal mucosal injury at both histomorphometric and ultrastructural levels post-ICH. Ghrelin reduced ICH-induced intestinal permeability according to fluorescein isothiocyanate conjugated-dextran (FITC-D) and Evans blue extravasation assays. Concomitantly, the intestinal tight junction-related protein markers, Zonula occludens-1 (ZO-1) and claudin-5 were upregulated by ghrelin post-ICH. Additionally, ghrelin reduced intestinal intercellular adhesion molecule-1 (ICAM-1) expression at the mRNA and protein levels following ICH. Furthermore, ghrelin suppressed the translocation of intestinal endotoxin post-ICH. These changes were accompanied by improved survival rates and an attenuation of body weight loss post-ICH. In conclusion, our results suggest that ghrelin reduced intestinal barrier dysfunction, thereby reducing mortality and weight loss, indicating that ghrelin is a potential therapeutic agent in ICH-induced intestinal barrier dysfunction therapy. PMID:27929421

  13. Ghrelin in the regulation of body weight and metabolism.

    PubMed

    Castañeda, T R; Tong, J; Datta, R; Culler, M; Tschöp, M H

    2010-01-01

    Ghrelin, a peptide hormone predominantly produced by the stomach, was isolated as the endogenous ligand for the growth hormone secretagogue receptor. Ghrelin is a potent stimulator of growth hormone (GH) secretion and is the only circulatory hormone known to potently enhance feeding and weight gain and to regulate energy homeostasis following central and systemic administration. Therapeutic intervention with ghrelin in catabolic situations may induce a combination of enhanced food intake, increased gastric emptying and nutrient storage, coupled with an increase in GH thereby linking nutrient partitioning with growth and repair processes. These qualities have fostered the idea that ghrelin-based compounds may have therapeutic utility in treating malnutrition and wasting induced by various sub-acute and chronic disorders. Conversely, compounds that inhibit ghrelin action may be useful for the prevention or treatment of metabolic syndrome components such as obesity, impaired lipid metabolism or insulin resistance. In recent years, the effects of ghrelin on glucose homeostasis, memory function and gastrointestinal motility have attracted considerable amount of attention and revealed novel therapeutic targets in treating a wide range of pathologic conditions. Furthermore, discovery of ghrelin O-acyltransferase has also opened new research opportunities that could lead to major understanding of ghrelin physiology. This review summarizes the current knowledge on ghrelin synthesis, secretion, mechanism of action and biological functions with an additional focus on potential for ghrelin-based pharmacotherapies.

  14. Hypovolemic hemorrhage induces Fos expression in the rat hypothalamus: Evidence for involvement of the lateral hypothalamus in the decompensatory phase of hemorrhage.

    PubMed

    Göktalay, G; Millington, W R

    2016-05-13

    This study tested the hypothesis that the hypothalamus participates in the decompensatory phase of hemorrhage by measuring Fos immunoreactivity and by inhibiting neuronal activity in selected hypothalamic nuclei with lidocaine or cobalt chloride. Previously, we reported that inactivation of the arcuate nucleus inhibited, but did not fully prevent, the fall in arterial pressure evoked by hypotensive hemorrhage. Here, we report that hemorrhage (2.2 ml/100g body weight over 20 min) induced Fos expression in a high percentage of cells in the paraventricular, supraoptic and arcuate nuclei of the hypothalamus as shown previously. Lower densities of Fos immunoreactive cells were also found in the medial preoptic area (mPOA), anterior hypothalamus, lateral hypothalamus (LH), dorsomedial hypothalamus, ventromedial hypothalamus (VMH) and posterior hypothalamus. Bilateral injection of lidocaine (2%; 0.1 μl or 0.3 μl) or cobalt chloride (5mM; 0.3 μl) into the tuberal portion of the LH immediately before hemorrhage was initiated reduced the magnitude of hemorrhagic hypotension and bradycardia significantly. Lidocaine injection into the VMH also attenuated the fall in arterial pressure and heart rate evoked by hemorrhage although inactivation of the mPOA or rostral LH was ineffective. These findings indicate that hemorrhage activates neurons throughout much of the hypothalamus and that a relatively broad area of the hypothalamus, extending from the arcuate nucleus laterally through the caudal VMH and tuberal LH, plays an important role in the decompensatory phase of hemorrhage.

  15. Ifenprodil Attenuates Methamphetamine-Induced Behavioral Sensitization and Activation of Ras-ERK-∆FosB Pathway in the Caudate Putamen.

    PubMed

    Li, Lu; Liu, Xinshe; Qiao, Chuchu; Chen, Gang; Li, Tao

    2016-10-01

    Addiction is a debilitating, chronic psychiatric disorder that is difficult to cure completely owing to the high rate of relapse. Behavioral sensitization is considered to may underlie behavioral changes, such as relapse, caused by chronic abuse of psychomotor stimulants. Thus, its animal models have been widely used to explore the etiology of addiction. Recently, increasing evidence has demonstrated that N-methyl-D-aspartate receptors (NMDARs) play an important role in addiction to psychomotor stimulants. However, the role of GluN2B-containing receptors and their downstream signaling pathway(s) in behavioral sensitization induced by methamphetamine (METH) have not been investigated yet. In this study, we used different doses of ifenprodil (2.5, 5, 10 mg/kg), a selective antagonist of the GluN2B subunit, to investigate the role of GluN2B-containing NMDARs in METH-induced behavioral sensitization. We then examined changes in the levels of Ras, phosphorylated extracellular signal-regulated kinase (pERK)/ERK, and ∆FosB in the caudate putamen (CPu) by western blot. We found that 2.5 or 10 mg/kg ifenprodil significantly attenuated METH-induced behavioral sensitization, whereas the mice treated with a moderate dose of ifenprodil (5 mg/kg) displayed no significant changes. Further results of western blot experiments showed that repeated administration of METH caused the increases in the levels of Ras, pERK/ERK and ∆FosB in the CPu, and these changes were inhibited by only the 2.5 mg/kg dose of ifenprodil. In conclusion, these results demonstrated that 2.5 mg/kg ifenprodil could attenuate METH-induced behavioral sensitization. Moreover, GluN2B-containing NMDARs and their downstream Ras-ERK-∆FosB signaling pathway in the CPu might be involved in METH-induced behavioral sensitization.

  16. Cue-Induced Food Seeking After Punishment Is Associated With Increased Fos Expression in the Lateral Hypothalamus and Basolateral and Medial Amygdala.

    PubMed

    Campbell, Erin J; Barker, David J; Nasser, Helen M; Kaganovsky, Konstantin; Dayas, Christopher V; Marchant, Nathan J

    2017-02-20

    In humans, relapse to unhealthy eating habits following dieting is a significant impediment to obesity treatment. Food-associated cues are one of the main triggers of relapse to unhealthy eating during self-imposed abstinence. Here we report a behavioral method examining cue-induced relapse to food seeking following punishment-induced suppression of food taking. We trained male rats to lever press for food pellets that were delivered after a 10-s conditional stimulus (CS) (appetitive). Following training, 25% of reinforced lever presses resulted in the presentation of a compound stimulus consisting of a novel CS (aversive) and the appetitive CS followed by a pellet and footshock. After punishment-imposed abstinence, we tested the rats in an extinction test where lever pressing resulted in the presentation of either the appetitive or aversive CS. We then compared activity of lateral hypothalamus (LH) and associated extrahypothalamic regions following this test. We also assessed Fos expression in LH orexin and GABA neurons. We found that cue-induced relapse of food seeking on test was higher in rats tested with the appetitive CS compared to the aversive CS. Relapse induced by the appetitive CS was associated with increased Fos expression in LH, caudal basolateral amygdala (BLA), and medial amygdala (MeA). This relapse was also associated with increased Fos expression in LH orexin and VGAT-expressing neurons. These data show that relapse to food seeking can be induced by food-associated cues after punishment-imposed abstinence, and this relapse is associated with increased activity in LH, caudal BLA, and MeA. (PsycINFO Database Record

  17. Beta-adrenoceptor Activation by Norepinephrine Enhances Lipopolysaccharide-induced Matrix Metalloproteinase-9 Expression Through the ERK/JNK-c-Fos Pathway in Human THP-1 Cells

    PubMed Central

    Yin, Xiang; Zhou, Linli; Han, Fei; Han, Jie; Zhang, Yuanyuan; Sun, Zewei; Zhao, Wenting; Wang, Zhen

    2017-01-01

    Aim: Atherosclerosis is a chronic inflammatory disease, which leads to thrombosis and acute coronary syndrome. Matrix metalloproteinase-9 (MMP-9) is involved in the stability of the extracellular matrix (ECM) and atherosclerosis plaque. Until now, it is established that lipopolysaccharide (LPS) and norepinephrine (NE) are associated with the pathological process of atherosclerosis. However, the combined effect of LPS and NE on MMP-9 is unclear. We investigated the combined effect of LPS and NE on MMP-9 expression in human monocytes and the mechanism involved in the process. Methods: THP-1 cells were cultured and treated with LPS and/or NE. MMP-9 and TIMP-1 gene and protein expression were detected by real time PCR and ELISA, respectively. MMP-9 activity was detected by gelatin zymography. Adrenoceptor antagonists and MAPKs inhibitors were used to clarify the mechanism. Pathway-related proteins were detected by Western blot. Results: We found that NE enhances LPS-induced MMP-9 and TIMP-1 expression as well as MMP-9 activity in THP-1 cells. This effect is reversed by the beta (β)-adrenoceptor antagonist propranolol, extracellular signal-regulated kinases (ERK) inhibitor U0126, and c-Jun N-terminal kinase (JNK) inhibitor SP600125. NE enhances LPS-induced ERK/JNK phosphorylation. NE up-regulates LPS-induced c-Fos expression, which is counteracted by propranolol, U0126, and SP600125. Furthermore, c-Fos silence reverses the effect of NE on MMP-9 activity. Conclusions: Our results suggest that NE enhances LPS-induced MMP-9 expression through β-adrenergic receptor and downstream ERK/JNK-c-Fos pathway. This study may help us to understand the combined effect and mechanism of NE/LPS on MMP-9 expression. PMID:27237101

  18. Food restriction, ghrelin, its antagonist and obestatin control expression of ghrelin and its receptor in chicken hypothalamus and ovary.

    PubMed

    Sirotkin, Alexander V; Pavlova, Silvia; Tena-Sempere, Manuel; Grossmann, Roland; Jiménez, Magdalena Romero; Rodriguez, Juan Manuel Castellano; Valenzuela, Francisco

    2013-01-01

    The purpose of the present study was to identify the role of age, nutritional state and some metabolic hormones in control of avian hypothalamic and ovarian ghrelin/ghrelin receptor system. We examined the effect of food restriction, administration of ghrelin 1-18, ghrelin antagonistic analogue (D-Lys-3)-GHRP-6, obestatin and combinations of them on the expression of ghrelin and ghrelin receptor (GHS-R1a) in hypothalamus and ovary of old (23months of age) and young (7months of age) chickens. Expression of mRNAs for ghrelin and GHS-R1a in both hypothalamus and largest ovarian follicle was measured by RT-PCR. It was observed that food restriction could promote the expression of ghrelin and GHS-R1a in hypothalamus and ovary of the old chickens, but in the young chickens it reduced expression of ghrelin and did not affect expression of GHS-R1a in the ovary. Administration of ghrelin 1-18 did not affect hypothalamic or ovarian ghrelin mRNA, but significantly increased the expression of GHS-R1a in hypothalamus, but not in ovary. (D-Lys-3)-GHRP-6, significantly stimulated accumulation of ghrelin, but not GHS-R1a mRNA in hypothalamus or ghrelin or GHS-R1a in the ovary. Ghrelin 1-18 and (D-Lys-3)-GHRP-6, when given together, were able either to prevent or to induce effect of these hormones. Obestatin administration increased expression of ghrelin gene in the hypothalamus, but not expression of hypothalamic GHS-R1a, ovarian ghrelin and GHS-R1a. Furthermore, obestatin was able to modify effect of both ghrelin and fasting on hypothalamic and ovarian mRNA for ghrelin GHS-R1a. Our results (1) confirm the existence of ghrelin and its functional receptors GHS-R1a in the chicken hypothalamus and ovary (2) confirm the age-dependent control of ovarian ghrelin by feeding, (3) demonstrate, that nutritional status can influence the expression of both ghrelin and GHS-R1a in hypothalamus and in the ovary (3) demonstrates for the first time, that ghrelin can promote generation of its

  19. Administration of exogenous acylated ghrelin or rikkunshito, an endogenous ghrelin enhancer, improves the decrease in postprandial gastric motility in an acute restraint stress mouse model

    PubMed Central

    Nahata, M; Saegusa, Y; Sadakane, C; Yamada, C; Nakagawa, K; Okubo, N; Ohnishi, S; Hattori, T; Sakamoto, N; Takeda, H

    2014-01-01

    Background Physical or psychological stress causes functional disorders in the upper gastrointestinal tract. This study aims to elucidate the ameliorating effect of exogenous acylated ghrelin or rikkunshito, a Kampo medicine which acts as a ghrelin enhancer, on gastric dysfunction during acute restraint stress in mice. Methods Fasted and postprandial motor function of the gastric antrum was wirelessly measured using a strain gauge force transducer and solid gastric emptying was detected in mice exposed to restraint stress. Plasma corticosterone and ghrelin levels were also measured. To clarify the role of ghrelin on gastrointestinal dysfunction in mice exposed to stress, exogenous acylated ghrelin or rikkunshito was administered, then the mice were subjected to restraint stress. Key Results Mice exposed to restraint stress for 60 min exhibited delayed gastric emptying and increased plasma corticosterone levels. Gastric motility was decreased in mice exposed to restraint stress in both fasting and postprandial states. Restraint stress did not cause any change in plasma acylated ghrelin levels, but it significantly increased the plasma des-acyl ghrelin levels. Administration of acylated ghrelin or rikkunshito improved the restraint stress-induced delayed gastric emptying and decreased antral motility. Ameliorating effects of rikkunshito on stress-induced gastric dysfunction were abolished by simultaneous administration of a ghrelin receptor antagonist. Conclusions & Inferences Plasma acylated/des-acyl ghrelin imbalance was observed in acute restraint stress. Supplementation of exogenous acylated ghrelin or enhancement of endogenous ghrelin signaling may be useful in the treatment of decreased gastric function caused by stress. PMID:24684160

  20. Autoregulation of fos: the dyad symmetry element as the major target of repression.

    PubMed Central

    König, H; Ponta, H; Rahmsdorf, U; Büscher, M; Schönthal, A; Rahmsdorf, H J; Herrlich, P

    1989-01-01

    Fos and Jun co-operatively repress the fos promoter. Removal of all putative Fos/Jun binding sites from the fos promoter neither obliterates the repression by Fos/Jun in transient cotransfection experiments in NIH3T3 cells nor the turn-off kinetics of serum-induced fos expression in stably transfected NIH3T3 cells. The dyad symmetry element (DSE) suffices to subject a promoter to this type of repression. However, one of the putative Fos/Jun binding sites (-292 to -299 and thus located immediately adjacent to the DSE), determines the very low level of basal expression. Images PMID:2511006

  1. Ghrelin in Central Neurons

    PubMed Central

    Ferrini, F; Salio, C; Lossi, L; Merighi, A

    2009-01-01

    Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, is released in the bloodstream in response to a negative energetic status. Since discovery, the hypothalamus was identified as the main source of ghrelin in the CNS, and effects of the peptide have been mainly observed in this area of the brain. In recent years, an increasing number of studies have reported ghrelin synthesis and effects in specific populations of neurons also outside the hypothalamus. Thus, ghrelin activity has been described in midbrain, hindbrain, hippocampus, and spinal cord. The spectrum of functions and biological effects produced by the peptide on central neurons is remarkably wide and complex. It ranges from modulation of membrane excitability, to control of neurotransmitter release, neuronal gene expression, and neuronal survival and proliferation. There is not at present a general consensus concerning the source of ghrelin acting on central neurons. Whereas it is widely accepted that the hypothalamus represents the most important endogenous source of the hormone in CNS, the existence of extra-hypothalamic ghrelin-synthesizing neurons is still controversial. In addition, circulating ghrelin can theoretically be another natural ligand for central ghrelin receptors. This paper gives an overview on the distribution of ghrelin and its receptor across the CNS and critically analyses the data available so far as regarding the effects of ghrelin on central neurotransmission. PMID:19721816

  2. Ghrelin in central neurons.

    PubMed

    Ferrini, F; Salio, C; Lossi, L; Merighi, A

    2009-03-01

    Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, is released in the bloodstream in response to a negative energetic status. Since discovery, the hypothalamus was identified as the main source of ghrelin in the CNS, and effects of the peptide have been mainly observed in this area of the brain. In recent years, an increasing number of studies have reported ghrelin synthesis and effects in specific populations of neurons also outside the hypothalamus. Thus, ghrelin activity has been described in midbrain, hindbrain, hippocampus, and spinal cord. The spectrum of functions and biological effects produced by the peptide on central neurons is remarkably wide and complex. It ranges from modulation of membrane excitability, to control of neurotransmitter release, neuronal gene expression, and neuronal survival and proliferation. There is not at present a general consensus concerning the source of ghrelin acting on central neurons. Whereas it is widely accepted that the hypothalamus represents the most important endogenous source of the hormone in CNS, the existence of extra-hypothalamic ghrelin-synthesizing neurons is still controversial. In addition, circulating ghrelin can theoretically be another natural ligand for central ghrelin receptors. This paper gives an overview on the distribution of ghrelin and its receptor across the CNS and critically analyses the data available so far as regarding the effects of ghrelin on central neurotransmission.

  3. Inhibition of osteoclast differentiation and bone resorption by rotenone, through down-regulation of RANKL-induced c-Fos and NFATc1 expression.

    PubMed

    Kwak, Han Bok; Lee, Byeong Ki; Oh, Jaemin; Yeon, Jeong-Tae; Choi, Sik-Won; Cho, Hae Joong; Lee, Myeung Su; Kim, Jeong-Joong; Bae, Ji-Myung; Kim, Seong Hwan; Kim, Hun Soo

    2010-03-01

    Osteoclasts are responsible for bone erosion in diseases as diverse as osteoporosis, periodontitis, and rheumatoid arthritis. Natural plant-derived products have received recent attention as potential therapeutic and preventative drugs in human disease. The effect of rotenone in RANKL-induced osteoclast differentiation was examined in this study. Rotenone inhibited RANKL-mediated osteoclast differentiation in bone marrow macrophages (BMMs) in a dose-dependent manner without any evidence of cytotoxicity. The mRNA expression of c-Fos, NFATc1, TRAP, and OSCAR in RANKL-treated BMMs was inhibited by rotenone treatment. Rotenone strongly inhibited p38 and ERK phosphorylation and I-kappaB degradation in RANKL-stimulated BMMs, and did not inhibit JNK phosphorylation. Further, RANKL-induced c-Fos and NFATc1 protein expression was suppressed by rotenone. Rotenone additionally inhibited the bone resorptive activity of differentiated osteoclasts. A lipopolysaccharide (LPS)-induced bone erosion study was also performed to assess the effects of rotenone in vivo. Mice treated with rotenone demonstrated marked attenuation of bone erosion based on Micro CT and histologic analysis of femurs. These results collectively suggested that rotenone demonstrated inhibitory effects on osteoclast differentiation in vitro and suppressed inflammatory bone loss in vivo. Rotenone may therefore serve as a useful drug in the prevention of bone loss.

  4. Imipramine-induced c-Fos expression in the medial prefrontal cortex is decreased in the ACTH-treated rats.

    PubMed

    Li, Bingjin; Suemaru, Katsuya; Kitamura, Yoshihisa; Gomita, Yutaka; Araki, Hiroaki; Cui, Ranji

    2013-11-01

    Previous studies have shown that the antidepressive-like effect of tricyclic antidepressants is blocked by repeated treatments with adrenocorticotropic hormone (ACTH). However, little is known about the neuroanatomy underlying the mechanism of the imipramine treatment-resistant depression model. In the present study, first experimental evidence showed no significant difference of the serum imipramine concentrations between the saline and ACTH-treated rats. In further study, imipramine produced significant increases in the c-Fos expression in the medial prefrontal cortex (mPFC), the dentate gyrus of the hippocampus (DGH), and the central nucleus of the amygdala (CeA), in rats repeatedly treated with saline. The imipramine-increased c-Fos immunoreactivity was suppressed in the mPFC of rats repeatedly treated with ACTH. However, there was no significant difference in c-Fos expression in the DGH and CeA between ACTH- and saline-treated rats. These results suggest that the mPFC is maybe involved in effects of the imipramine in the ACTH-treated rats.

  5. Expression of c-fos mRNA in the Basal Ganglia Associated with Contingent Tolerance to Amphetamine-Induced Hypophagia

    PubMed Central

    Bachand, Kimberlee D.; Guthrie, Kathleen M.; Wolgin, David L.

    2009-01-01

    Tolerance to the hypophagic effect of psychostimulants is contingent on having access to food while intoxicated. Rats given chronic injections of such drugs with access to food learn to suppress stereotyped movements, which interfere with feeding. In contrast, controls given the drug after food access do not learn to suppress stereotypy and, therefore, do not become tolerant. To determine the role of the basal ganglia in this phenomenon, we used in situ hybridization to measure the expression of c-fos mRNA, a marker for neural activation, in the brains of tolerant and nontolerant rats. Rats given chronic amphetamine injections prior to food access learned to suppress stereotyped movements, whereas yoked controls given the drug after feeding did not. Following an acute injection of amphetamine, both of these groups had higher levels of c-fos mRNA than saline-treated controls throughout the striatum, in the nucleus accumbens core, the ventral pallidum and layers V–VI of the motor cortex. In contrast, tolerant rats, which had learned to suppress stereotypy, had higher levels of c-fos mRNA than both amphetamine- and saline-treated controls in the entopeduncular nucleus, globus pallidus, subthalamic nucleus, pedunculopontine nucleus, nucleus accumbens shell, olfactory tubercle, somatosensory cortex, and layers II–IV of motor cortex. These data suggest that the learned suppression of amphetamine-induced stereotypy involves the activation of dorsal striatal pathways previously implicated in response selection as well as the ventral striatum, long implicated in appetitive motivation and reinforcement. PMID:19084559

  6. Ghrelin and appetite control in humans--potential application in the treatment of obesity.

    PubMed

    Patterson, Michael; Bloom, Stephen R; Gardiner, James V

    2011-11-01

    Ghrelin is a peptide hormone secreted into circulation from the stomach. It has been postulated to act as a signal of hunger. Ghrelin administration acutely increases energy intake in lean and obese humans and chronically induces weight gain and adiposity in rodents. Circulating ghrelin levels are elevated by fasting and suppressed following a meal. Inhibiting ghrelin signaling therefore appears an attractive target for anti-obesity therapies. A number of different approaches to inhibiting the ghrelin system to treat obesity have been explored. Despite this, over a decade after its discovery, no ghrelin based anti-obesity therapies are close to reaching the market. This article discusses the role of ghrelin in appetite control in humans, examines different approaches to inhibiting the ghrelin system and assesses their potential as anti-obesity therapies.

  7. Characterization of adult ghrelin and ghrelin receptor knockout mice under positive and negative energy balance.

    PubMed

    Sun, Yuxiang; Butte, Nancy F; Garcia, Jose M; Smith, Roy G

    2008-02-01

    Ghrelin and the ghrelin receptor (GH secretagogue receptor, GHS-R), are believed to have important roles in energy homeostasis. We describe results from the first studies to be conducted in congenic (N10) adult ghrelin(-/-) and Ghsr(-/-) mice under conditions of both positive (high-fat diet) and negative (caloric restriction) energy balance. In contrast to results from young N2 mutant mice, changes in body weight and energy expenditure are not clearly distinguishable across genotypes. Although respiratory quotient was lower in mice fed a high-fat diet, no differences were evident between littermate wild-type and null genotypes. With normal chow, a modest decrease trend in respiratory quotient was detected in ghrelin(-/-) mice but not in Ghsr(-/-) mice. Under caloric restriction, the weight loss of ghrelin(-/-) and Ghsr(-/-) mice was identical to wild-type littermates, but blood glucose levels were significantly lower. We conclude that adult congenic ghrelin(-/-) and Ghsr(-/-) mice are not resistant to diet-induced obesity but under conditions of negative energy balance show impairment in maintaining glucose homeostasis. These results support our hypothesis that the primary metabolic function of ghrelin in adult mice is to modulate glucose sensing and insulin sensitivity, rather than directly regulate energy intake and energy expenditure.

  8. Regional Fos-expression induced by γ-hydroxybutyrate (GHB): comparison with γ-butyrolactone (GBL) and effects of co-administration of the GABAB antagonist SCH 50911 and putative GHB antagonist NCS-382.

    PubMed

    van Nieuwenhuijzen, P S; McGregor, I S; Chebib, M; Hunt, G E

    2014-09-26

    γ-Hydroxybutyrate (GHB) has a complex array of neural actions that include effects on its own high-affinity GHB receptor, the release of neuroactive steroids, and agonist actions at GABAA and GABAB receptors. We previously reported partial overlap in the c-Fos expression patterns produced by GHB and the GABAB agonist, baclofen in rats. The present study extends these earlier findings by examining the extent to which GHB Fos expression and behavioral sedation are prevented by (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), a GABAB antagonist, and NCS-382, a putative antagonist at the high-affinity GHB receptor. We also compare Fos expression caused by GHB and its precursor γ-butyrolactone (GBL), which is a pro-drug for GHB but lacks the high sodium content of the parent GHB molecule. Both GHB (1,000 mg/kg) and GBL (600 mg/kg) induced rapid sedation in rats that lasted over 90 min and caused similar Fos expression patterns, albeit with GBL causing greater activation of the nucleus accumbens (core and shell) and dentate gyrus (granular layer). Pretreatment with SCH 50911 (100mg/kg) partly reversed the sedative effects of GHB and significantly reduced GHB-induced Fos expression in only four regions: the tenia tecta, lateral habenula, dorsal raphe and laterodorsal tegmental nucleus. NCS-382 (50mg/kg) had no effect on GHB-induced sedation or Fos expression. When given alone, both NCS-382 and SCH 50911 increased Fos expression in the bed nucleus of the stria terminalis, central amygdala, parasubthalamic nucleus and nucleus of the solitary tract. SCH 50911 alone affected the Islands of Calleja and the medial, central and paraventricular thalamic nuclei. Overall, this study shows a surprising lack of reversal of GHB-induced Fos expression by two relevant antagonists, both of which have marked intrinsic actions. This may reflect the limited doses tested but also suggests that GHB Fos expression reflects mechanisms independent of GHB and GABAB receptors.

  9. Novel cues reinstate cocaine-seeking behavior and induce Fos protein expression as effectively as conditioned cues.

    PubMed

    Bastle, Ryan M; Kufahl, Peter R; Turk, Mari N; Weber, Suzanne M; Pentkowski, Nathan S; Thiel, Kenneth J; Neisewander, Janet L

    2012-08-01

    Cue reinstatement of extinguished cocaine-seeking behavior is a widely used model of cue-elicited craving in abstinent human addicts. This study examined Fos protein expression in response to cocaine cues or to novel cues as a control for activation produced by test novelty. Rats were trained to self-administer cocaine paired with either a light or a tone cue, or received yoked saline and cue presentations, and then underwent daily extinction training. They were then tested for reinstatement of extinguished cocaine-seeking behavior elicited by response-contingent presentations of either the cocaine-paired cue or a novel cue (that is, tone for those trained with a light or vice versa). Surprisingly, conditioned and novel cues both reinstated responding and increased Fos similarly in most brain regions. Exceptions included the anterior cingulate, which was sensitive to test cue modality in saline controls and the dorsomedial caudate-putamen, where Fos was correlated with responding in the novel, but not conditioned, cue groups. In subsequent experiments, we observed a similar pattern of reinstatement in rats trained and tested for sucrose-seeking behavior, whereas rats trained and tested with the cues only reinstated to a novel, and not a familiar, light or tone. The results suggest that novel cues reinstate responding to a similar extent as conditioned cues regardless of whether animals have a reinforcement history with cocaine or sucrose, and that both types of cues activate similar brain circuits. Several explanations as to why converging processes may drive drug and novel cue reinforcement and seeking behavior are discussed.

  10. Do Lactation-Induced Changes in Ghrelin, Glucagon-Like Peptide-1, and Peptide YY Influence Appetite and Body Weight Regulation during the First Postpartum Year?

    PubMed

    Larson-Meyer, D Enette; Schueler, Jessica; Kyle, Erin; Austin, Kathleen J; Hart, Ann Marie; Alexander, Brenda M

    2016-01-01

    To determine whether fasting and meal-induced appetite-regulating hormones are altered during lactation and associated with body weight retention after childbearing, we studied 24 exclusively breastfeeding women (BMI = 25.2 ± 3.6 kg/m(2)) at 4-5 weeks postpartum and 20 never-pregnant controls (BMI = 24.0 ± 3.1 kg/m(2)). Ghrelin, PYY, GLP-1, and appetite ratings were measured before/and 150 minutes after a standardized breakfast and 60 minutes after an ad libitum lunch. Body weight/composition were measured at 6 and 12 months. Fasting and area under-the-curve responses for appetite-regulating hormones did not differ between lactating and control groups; ghrelinacyl, however, tended to track higher after the standardized breakfast in lactating women and was higher (p < 0.05) after the ad libitum lunch despite a 24% higher energy intake (p < 0.05). By 12 months, lactating women lost 5.3 ± 2.2 kg (n = 18), whereas control women (n = 15) remained weight stable (p = 0.019); fifteen of the lactating women returned to within ±2.0 kg of prepregnancy weight but three retained >6.0 kg. The retainers had greater (p < 0.05) postmeal ghrelin rebound responses following breakfast. Overall these studies do not support the hypothesis that appetite-regulating hormones are altered during lactation and associated with postpartum weight retention. Altered ghrelin responses, however, deserve further exploration.

  11. Do Lactation-Induced Changes in Ghrelin, Glucagon-Like Peptide-1, and Peptide YY Influence Appetite and Body Weight Regulation during the First Postpartum Year?

    PubMed Central

    Larson-Meyer, D. Enette; Schueler, Jessica; Kyle, Erin; Austin, Kathleen J.; Hart, Ann Marie; Alexander, Brenda M.

    2016-01-01

    To determine whether fasting and meal-induced appetite-regulating hormones are altered during lactation and associated with body weight retention after childbearing, we studied 24 exclusively breastfeeding women (BMI = 25.2 ± 3.6 kg/m2) at 4-5 weeks postpartum and 20 never-pregnant controls (BMI = 24.0 ± 3.1 kg/m2). Ghrelin, PYY, GLP-1, and appetite ratings were measured before/and 150 minutes after a standardized breakfast and 60 minutes after an ad libitum lunch. Body weight/composition were measured at 6 and 12 months. Fasting and area under-the-curve responses for appetite-regulating hormones did not differ between lactating and control groups; ghrelinacyl, however, tended to track higher after the standardized breakfast in lactating women and was higher (p < 0.05) after the ad libitum lunch despite a 24% higher energy intake (p < 0.05). By 12 months, lactating women lost 5.3 ± 2.2 kg (n = 18), whereas control women (n = 15) remained weight stable (p = 0.019); fifteen of the lactating women returned to within ±2.0 kg of prepregnancy weight but three retained >6.0 kg. The retainers had greater (p < 0.05) postmeal ghrelin rebound responses following breakfast. Overall these studies do not support the hypothesis that appetite-regulating hormones are altered during lactation and associated with postpartum weight retention. Altered ghrelin responses, however, deserve further exploration. PMID:27313876

  12. β1-Adrenergic receptor deficiency in ghrelin-expressing cells causes hypoglycemia in susceptible individuals

    PubMed Central

    Mani, Bharath K.; Osborne-Lawrence, Sherri; Vijayaraghavan, Prasanna; Hepler, Chelsea; Zigman, Jeffrey M.

    2016-01-01

    Ghrelin is an orexigenic gastric peptide hormone secreted when caloric intake is limited. Ghrelin also regulates blood glucose, as emphasized by the hypoglycemia that is induced by caloric restriction in mouse models of deficient ghrelin signaling. Here, we hypothesized that activation of β1-adrenergic receptors (β1ARs) localized to ghrelin cells is required for caloric restriction–associated ghrelin release and the ensuing protective glucoregulatory response. In mice lacking the β1AR specifically in ghrelin-expressing cells, ghrelin secretion was markedly blunted, resulting in profound hypoglycemia and prevalent mortality upon severe caloric restriction. Replacement of ghrelin blocked the effects of caloric restriction in β1AR-deficient mice. We also determined that treating calorically restricted juvenile WT mice with beta blockers led to reduced plasma ghrelin and hypoglycemia, the latter of which is similar to the life-threatening, fasting-induced hypoglycemia observed in infants treated with beta blockers. These findings highlight the critical functions of ghrelin in preventing hypoglycemia and promoting survival during severe caloric restriction and the requirement for ghrelin cell–expressed β1ARs in these processes. Moreover, these results indicate a potential role for ghrelin in mediating beta blocker–associated hypoglycemia in susceptible individuals, such as young children. PMID:27548523

  13. Taste aversion learning induced c-fos expression in the nucleus of the solitary tract after spontaneous flavor intake: role of the inter-stimulus interval.

    PubMed

    Mediavilla, Cristina; Bernal, Antonio; Puerto, Amadeo

    2007-09-01

    Taste aversion learning (TAL) can be induced by associating a flavor intake with the immediate or delayed (30 min) intragastric administration of a noxious substance, e.g., hypertonic NaCl. The objective of this study was to analyze the induction of c-Fos immunoreactivity in the intermediate nucleus of the solitary nucleus (iNST) after acquisition of a contiguous or delayed TAL, offering the flavor for voluntary consumption in both cases. The behavioral results obtained indicate that, although the learning was established under both experimental conditions, an increase in c-Fos induction was only produced in the group that learned by means of a non-delayed TAL. Immunohistochemical analyses revealed the participation of different brain structures in these two TAL modalities. Thus, the nucleus of the solitary tract may be involved in the TAL procedure in which voluntary flavor intake and intragastric administration of the noxious visceral stimulus are contiguous but not in delayed TAL, which would depend on other anatomical circuits that do not include the iNST.

  14. Clinical application of ghrelin.

    PubMed

    Strasser, Florian

    2012-01-01

    Ghrelin as a human natural hormone is involved in fundamental regulatory processes of eating and energy balance. Ghrelin signals the nutrient availability from the gastrointestinal tract to the central nervous system, up-regulates food intake and lowers energy expenditure mainly through hypothalamic mediators acting both centrally and peripherally including the gastrointestinal tract (motility, epithelium), promotes both neuro-endocrine and inflammatory signals to increase skeletal muscle growth and decrease protein breakdown, and increases lipolysis while body fat utilization is reduced. Ghrelin does more to exert its probably sentinel role around "human energy": it influences through mainly extra-hypothalamic actions the hedonic and incentive value of food, mood and anxiety, sleep-wake regulation, learning and memory, and neurogenesis. Recently numerous ghrelin gene-derived peptides were discovered, demonstrating the complexity within the ghrelin/ghrelin receptor axis. For clinical applications, not only the natural ghrelin and its slice variants, but also several modified or artificial molecules acting at ghrelin-associated receptors were and are developed. Current clinical applications are limited to clinical studies, focusing mainly on cachexia in chronic heart failure, COPD, cancer, endstage- renal-disease or cystic fibrosis, but also on frailty in elderly, gastrointestinal motility (e.g., gastroparesis, functional dyspepsia, postoperative ileus), after curative gastrectomy, anorexia nervosa, growth hormone deficient patients, alcohol craving, sleep-wake regulation (e.g. major depression), or sympathetic nervous activity in obesity. The results of completed, preliminary studies support the clinical potential of ghrelin, ghrelin gene-derived peptides, and artificial analogues, suggesting that larger clinical trials are demanded to move ghrelin towards an available and reimbursed pharmaceutical intervention.

  15. Ghrelin and the short- and long-term regulation of appetite and body weight.

    PubMed

    Cummings, David E

    2006-08-30

    Ghrelin, an acylated upper gastrointestinal peptide, is the only known orexigenic hormone. Considerable evidence implicates ghrelin in mealtime hunger and meal initiation. Circulating levels decrease with feeding and increase before meals, achieving concentrations sufficient to stimulate hunger and food intake. Preprandial ghrelin surges occur before every meal on various fixed feeding schedules and also among individuals initiating meals voluntarily without time- or food-related cues. Ghrelin injections stimulate food intake rapidly and transiently, primarily by increasing appetitive feeding behaviors and the number of meals. Preprandial ghrelin surges are probably triggered by sympathetic nervous output. Postprandial suppression is not mediated by nutrients in the stomach or duodenum, where most ghrelin is produced. Rather, it results from post-ingestive increases in lower intestinal osmolarity (information probably relayed to the foregut via enteric nervous signaling), as well as from insulin surges. Consequently, ingested lipids suppress ghrelin poorly compared with other macronutrients. Beyond a probable role in meal initiation, ghrelin also fulfills established criteria for an adiposity-related hormone involved in long-term body-weight regulation. Ghrelin levels circulate in relation to energy stores and manifest compensatory changes in response to body-weight alterations. Ghrelin crosses the blood-brain barrier and stimulates food intake by acting on several classical body-weight regulatory centers, including the hypothalamus, hindbrain, and mesolimbic reward system. Chronic ghrelin administration increases body weight via diverse, concerted actions on food intake, energy expenditure, and fuel utilization. Congenital ablation of the ghrelin or ghrelin-receptor gene causes resistance to diet-induced obesity, and pharmacologic ghrelin blockade reduces food intake and body weight. Ghrelin levels are high in Prader-Willi syndrome and low after gastric bypass

  16. Reduction in circulating ghrelin concentration after maturation does not affect food intake.

    PubMed

    Ariyasu, Hiroyuki; Yamada, Go; Iwakura, Hiroshi; Matsumura, Sigenobu; Inoue, Kazuo; Kangawa, Kenji; Nakao, Kazuwa; Akamizu, Takashi

    2014-01-01

    Ghrelin has a potent orexigenic effect and induces adiposity when administered exogenously. Since plasma ghrelin levels rise before meals, ghrelin was thought to play a crucial role in the regulation of appetite. In contrast, mice deficient in the production of ghrelin or the corresponding receptor, GHS-R, do not eat less, throwing the role of ghrelin in the regulation of energy homeostasis into question. Since these mice lack ghrelin or GHS-R from the time of conception, the possibility that compensatory mechanisms may have arisen during development cannot be ruled out. In this study, we used a transgenic mouse model that expresses human diphtheria toxin (DT) receptor cDNA under the control of the ghrelin promoter (GPDTR-Tg mice). As previously reported, an injection of DT into this mouse model ablates ghrelin-secreting cells in the stomach but not in the hypothalamus, resulting in a reduction in circulating ghrelin levels. We used this model system to evaluate the physiological roles of circulating ghrelin in the regulation of food intake. Meal patterns, diurnal and nocturnal meal sizes, and cumulative food intake of DT-treated GPDTR-Tg mice were not affected, although circulating ghrelin levels markedly decreased even after fasting. These mice also displayed normal responses to starvation; however, the use of fat increased and slower weight gain when maintained on a high fat diet was observed. Together, these data suggest that circulating ghrelin does not play a crucial role in feeding behavior, but rather is involved in maintaining body weight.

  17. Impact of bread making on fructan chain integrity and effect of fructan enriched breads on breath hydrogen, satiety, energy intake, PYY and ghrelin.

    PubMed

    Morris, C; Lynn, A; Neveux, C; Hall, A C; Morris, G A

    2015-08-01

    Recently, there has been considerable interest in the satiety inducing properties of inulin type fructans (ITF) as a tool for weight management. As a staple food, breads provide an excellent vehicle for ITF supplementation however the integrity of the ITF chains and properties upon bread making need to be assessed. Breads enriched with 12% fructooligosaccharides (FOS) and 12% inulin were baked and the degree of polymerisation of fructans extracted from the breads were compared to those of pure compounds. An acute feeding study with a single blind cross-over design was conducted with 11 participants to investigate the effect of ITF enriched breads on breath hydrogen, self-reported satiety levels, active ghrelin, total PYY and energy intake. Size exclusion chromatography indicated that little or no depolymerisation of inulin occurred during bread making, however, there was evidence of modest FOS depolymerisation. Additionally, ITF enriched breads resulted in increased concentrations of exhaled hydrogen although statistical significance was reached only for the inulin enriched bread (p = 0.001). There were no significant differences between bread types in reported satiety (p = 0.129), plasma active ghrelin (p = 0.684), plasma PYY (p = 0.793) and energy intake (p = 0.240). These preliminary results indicate that inulin enriched bread may be a suitable staple food to increase ITF intake. Longer intervention trials are required to assess the impact of inulin enriched breads on energy intake and body weight.

  18. Continuous antagonism of the ghrelin receptor results in early induction of salt-sensitive hypertension.

    PubMed

    Sato, Takahiro; Nakashima, Yoshiki; Nakamura, Yuki; Ida, Takanori; Kojima, Masayasu

    2011-02-01

    Ghrelin is a hormone that mediates a variety of physiological roles, such as stimulating appetite, initiating food intake, and modulating energy metabolism. Although it has been reported that a bolus injection of ghrelin decreases blood pressure, the effect of continuous ghrelin administration on vasoregulation has yet to be determined. We examined the longitudinal effect of ghrelin on vasoregulation using Dahl-Iwai salt-sensitive rats. In this model, a high-salt diet induced high blood pressure and increased ghrelin levels but reduced food intake. In salt-sensitive hypertension, cumulative food intake decreased, while both ghrelin messenger RNA levels and plasma ghrelin content increased. Continuous administration of a ghrelin receptor agonist, growth hormone releasing peptide-6 (GHRP-6), for 2 weeks by mini-osmotic pump did not change blood pressure values although the cumulative food intake recovered. In contrast, continuous administration of a ghrelin receptor antagonist, [D-Lys³]-GHRP-6, induced early elevations in blood pressure without changes in heart rate. Quantitative RT-PCR revealed high expression levels of genes involved in the catecholamine biosynthetic pathway, tyrosine hydroxylase and dopamine-β-hydroxylase, after continuous [D-Lys³]-GHRP-6 administration. These results indicate that continuous antagonism of the ghrelin receptor results in early induction of salt-sensitive hypertension in this animal model and suggests that increases in autonomic nervous activity induced by ghrelin receptor antagonism are responsible, as indicated by the high expression levels of genes in the catecholamine biosynthetic pathway.

  19. Effects of ghrelin on anorexia in tumor-bearing mice with eicosanoid-related cachexia.

    PubMed

    Wang, Wenhua; Andersson, Marianne; Iresjö, Britt-Marie; Lönnroth, Christina; Lundholm, Kent

    2006-06-01

    Ghrelin is a novel brain-gut peptide that stimulates food intake and may secondarily increase body weight via a growth hormone secretagogue receptor (GHS-R). Tumor-bearing mice (MCG101), characterized by anorexia, fat loss and muscle wasting due to increased concentration of PGE2 and proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha), were provided ghrelin i.p. at a low (20 microg/day) and high dose (40 microg/day) to examine the ability of ghrelin to counteract tumor-induced anorexia. Immunohistochemical staining and Western blot analyses were used to identify GHS-R expression in the brain as well as its relationship to NPY expression in hypothalamic neurons. GHS-R mRNA in hypothalamus and ghrelin mRNA in gastric fundus were quantified by RT-PCR. Body composition was determined by carcass extractions. GHS-R expression in hypothalamus and plasma ghrelin levels were significantly increased in freely-fed tumor-bearing mice, while gastric fundus expression of ghrelin was unaltered compared to non-tumor-bearing mice (controls). Ghrelin treatment increased food intake, body weight and whole body fat at both low and high doses of ghrelin in normal controls, while tumor-bearing mice showed improved intake and body composition at the high dose of ghrelin only. Exogenous ghrelin normalized the GHS-R expression in hypothalamus from tumor-bearing mice without alterations in the gastric fundus expression of ghrelin. Tumor growth was not altered by exogenous ghrelin. Our results indicate that MCG 101-bearing mice became ghrelin resistant despite upregulation of hypothalamic GHS-R expression, which confirms similar indirect observations in cancer patients. Thus, other factors downstream of the ghrelin-GHS-R system appear to be more important than ghrelin to explain cancer-induced anorexia.

  20. Anxiolytic-Like Effects of Increased Ghrelin Receptor Signaling in the Amygdala

    PubMed Central

    Jensen, Morten; Ratner, Cecilia; Rudenko, Olga; Christiansen, Søren H.; Skov, Louise J.; Hundahl, Cecilie; Woldbye, David P.D.

    2016-01-01

    Background: Besides the well-known effects of ghrelin on adiposity and food intake regulation, the ghrelin system has been shown to regulate aspects of behavior including anxiety and stress. However, the effect of virus-mediated overexpression of the ghrelin receptor in the amygdala has not previously been addressed directly. Methods: First, we examined the acute effect of peripheral ghrelin administration on anxiety- and depression-like behavior using the open field, elevated plus maze, forced swim, and tail suspension tests. Next, we examined the effect of peripheral ghrelin administration and ghrelin receptor deficiency on stress in a familiar and social environment using the Intellicage system. Importantly, we also used a novel approach to study ghrelin receptor signaling in the brain by overexpressing the ghrelin receptor in the amygdala. We examined the effect of ghrelin receptor overexpression on anxiety-related behavior before and after acute stress and measured the modulation of serotonin receptor expression. Results: We found that ghrelin caused an anxiolytic-like effect in both the open field and elevated plus maze tests. Additionally, it attenuated air-puff–induced stress in the social environment, while the opposite was shown in ghrelin receptor deficient mice. Finally, we found that overexpression of the ghrelin receptor in the basolateral division of the amygdala caused an anxiolytic-like effect and decreased the 5HT1a receptor expression. Conclusions: Ghrelin administration and overexpression of the ghrelin receptor in the amygdala induces anxiolytic-like behavior. Since the ghrelin receptor has high constitutive activity, ligand-independent signaling in vivo may be important for the observed anxiolytic-like effects. The anxiolytic effects seem to be mediated independently from the HPA axis, potentially engaging the central serotonin system. PMID:26578081

  1. Effect of rhynchophylline on the expression of p-CREB and sc-Fos in triatum and hippocampal CA1 area of methamphetamine-induced conditioned place preference rats.

    PubMed

    Liu, Wei; Peng, Qiu-Xian; Lin, Xiao-Liang; Luo, Chao-Hua; Jiang, Ming-Jin; Mo, Zhi-Xian; Yung, Ken Kin-Lam

    2014-01-01

    To explore the effect of rhynchophylline (Rhy) on the expression of p-CREB and c-Fos in the striatum and hippocampal CA1 area of methamphetamine-induced conditioned place preference (CPP) rat, methamphetamine (2 mg/kg) was injected to rats and the conditioned place preference was observed in these rats treated with or without Rhy. An immunohistochemistry assay was used to determine the expression of p-CREB and c-Fos in the striatum and hippocampal CA1 area. Methamphetamine induced significant behavior alteration in CPP, while after pretreatment with rhynchophylline or ketamine, the time of staying in methamphetamine-paired compartment of rats was significantly reduced. Methamphetamine also increased the number of p-CREB positive cells in the striatum and hippocampal CA1 zone, as well as p-Fos positive cells. However, the compound Rhy could attenuate the effect. These findings show that Rhy can suppress the acquisition of CPP in rats induced by methamphetamine and the action may be related with the reduced expression of p-CREB and p-Fos in the striatum and hippocampus.

  2. An Integrative Review on Role and Mechanisms of Ghrelin in Stress, Anxiety and Depression.

    PubMed

    Bali, Anjana; Jaggi, Amteshwar Singh

    2016-01-01

    Ghrelin is orexigenic hormone primarily synthesized by endocrine X/A-like cells of gastric oxyntic mucosa to stimulate appetite and food intake along with regulation of growth hormone and insulin secretion; glucose and lipid metabolism; gastrointestinal motility; blood pressure, heart rate and neurogenesis. Furthermore, peripherally (after crossing the blood brain barrier) as well as centrally synthesized ghrelin (in the hypothalamus) regulates diverse functions of central nervous system including stress-associated behavioral functions. Exposure to stress alters the ghrelin levels and alteration in ghrelin levels significantly affects neuro-endocrinological parameters; metabolism-related physiology, behavior and mood. Studies have shown both anxiolytic and anxiogenic role of ghrelin suggesting its dual role in modulating anxiety-related behavior. However, it is proposed that increase in ghrelin levels during stress condition is an endogenous stress coping behavior and increased ghrelin levels may be required to prevent excessive anxiety. In preclinical and clinical studies, an elevation in ghrelin levels during depression has been correlated with their antidepressant activities. Ghrelin-induced modulation of stress and associated conditions has been linked to alteration in hypothalamic-pituitary-adrenal (HPA) axis; autonomic nervous system (mainly sympathetic nervous system and serotonergic neurotransmission. A reciprocal relationship has been reported between corticotropin-releasing hormone (CRH) and ghrelin as ghrelin increases the release of CRH, ACTH and corticosteroids; while CRH decreases the expression of ghrelin. Similarly, ghrelin increases the serotonin turnover and in turn, serotonin controls ghrelin signaling to modulate anxiety-related behavior. The present review discusses the dual role of ghrelin in stress and related behavioral disorders along with possible mechanisms.

  3. Ghrelin and cancer.

    PubMed

    Chopin, Lisa; Walpole, Carina; Seim, Inge; Cunningham, Peter; Murray, Rachael; Whiteside, Eliza; Josh, Peter; Herington, Adrian

    2011-06-20

    Ghrelin is a peptide hormone that was originally isolated from the stomach as the endogenous ligand for the growth hormone secretagogue receptor (GHSR). Ghrelin has many functions, including the regulation of appetite and gut motility, growth hormone release from the anterior pituitary and roles in the cardiovascular and immune systems. Ghrelin and its receptor are expressed in a number of cancers and cancer cell lines and may play a role in processes associated with cancer progression, including cell proliferation, apoptosis, and cell invasion and migration.

  4. New ghrelin agonist, HM01 alleviates constipation and L-dopa-delayed gastric emptying in 6-hydroxydopamine rat model of Parkinson’s disease

    PubMed Central

    Karasawa, H.; Pietra, C.; Giuliano, C.; Garcia-Rubio, S.; Xu, X.; Yakabi, S.; Taché, Y.; Wang, L.

    2015-01-01

    Background Constipation and L-dopa-induced gastric dysmotility are common gastrointestinal (GI) symptoms in Parkinson’s disease (PD). We investigate the novel ghrelin agonist, HM01 influence on GI motor dysfunctions in 6-hydroxydopamine (6-OHDA) rats. Methods HM01 pharmacological profiles were determined in vitro and in vivo in rats. We assessed changes in fecal output and water content, and gastric emptying (GE) in 6-OHDA rats treated or not with orogastric (og) HM01 and L-dopa/carbidopa (LD/CD, 20/2 mg kg−1). Fos immunoreactivity (ir) cells in specific brain and lumbosacral spinal cord were quantified. Key results HM01 displayed a high binding affinity to ghrelin receptor (Ki: 1.42 ± 0.36 nM), 4.3±1.0 h half-life and high brain/plasma ratio. 6-OHDA rats had reduced daily fecal output (22%) and water intake (23%) compared to controls. HM01 (3 and 10 mg kg−1) similarly reversed the decreased 4-h fecal weight and water content in 6-OHDA rats. Basal GE was not modified in 6-OHDA rats, however, LD/CD (once or daily for 8 days) delayed GE in 6-OHDA and control rats that was prevented by HM01 (3 mg kg−1 acute or daily before LD/CD). HM01 increased Fos-ir cell number in the area postrema, arcuate nucleus, nucleus tractus solitarius and lumbosacral intermediolateral column of 6-OHDA rats where 6-OHDA had a lowering effect compared to controls. Conclusions & Inferences 6-OHDA rats display constipation- and adipsia-like features of PD and L-dopa-inhibited GE. The new orally active ghrelin agonist, HM01 crosses the blood brain barrier and alleviates these alterations suggesting a potential benefit for PD with GI disorders. PMID:25327342

  5. L-DOPA-induced dyskinesia in adult rats with a unilateral 6-OHDA lesion of dopamine neurons is paralleled by increased c-fos gene expression in the subthalamic nucleus.

    PubMed

    Soghomonian, Jean-Jacques

    2006-05-01

    Levodopa (L-DOPA), the metabolic precursor of dopamine, is widely used as a pharmacological agent for the symptomatic treatment of Parkinson's disease. However, long-term L-DOPA use results in abnormal involuntary movements such as dyskinesias. There is evidence that abnormal cell signaling in the basal ganglia is involved in L-DOPA-induced dyskinesia. The subthalamic nucleus (STN) plays a key role in the circuitry of the basal ganglia and in the pathophysiology of Parkinson's disease. However, the contribution of the STN to L-DOPA-induced dyskinesias remains unclear. The objective of this work was to study the effects of acute or chronic systemic administration of L-DOPA to adult rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion of dopamine neurons on c-fos expression in the STN and test the hypothesis that these effects correlate with L-DOPA-induced dyskinesias. c-fos mRNA expression was measured in the STN by in situ hybridization histochemistry at the single cell level. Our results confirm earlier evidence that the chronic administration of L-DOPA to rats with a unilateral 6-OHDA lesion increases c-fos expression in the STN. We also report that c-fos expression can be increased following an acute injection of L-DOPA to 6-OHDA-lesioned rats but not following a chronic injection of L-DOPA to sham-operated, unlesioned rats. Finally, we provide evidence that the occurrence and severity of dyskinesia is correlated with c-fos mRNA levels in the ipsilateral STN. These results suggest that altered cell signaling in the STN is involved in some of the behavioral effects induced by systemic L-DOPA administration.

  6. Regulatory neuropeptides (ghrelin, obestatin and nesfatin-1) levels in serum and reproductive tissues of female and male rats with fructose-induced metabolic syndrome.

    PubMed

    Catak, Zekiye; Aydin, Suleyman; Sahin, Ibrahim; Kuloglu, Tuncay; Aksoy, Aziz; Dagli, Adile Ferda

    2014-06-01

    Although, the exact mechanisms underlying the development of the metabolic syndrome (MetS) are not still completely understood, obesity, circulated peptide hormone levels and their interaction with genetic factors are considered largely responsible. The purpose of this study is to explore how the levels of ghrelin, obestatin (OBS) and NUCB2/nesfatin-1 (NES)/NUCB2 change in serum and the reproductive tissues of female and male rats with fructose-induced metabolic syndrome, and whether the levels of each hormone is correlated with the hormones involved with fertility. Experiments were conducted on 5-week-old Sprague-Dawley male and female rats assigned to either a control group or a MetS group. Controls were fed standard rat food and water ad libitum, while the MetS group was fed standard food with 10% (v/v) fructose solution added to their drinking water for 12 weeks with a 12/12h photoperiod circle. Then, all animals were sacrificed after a one night fast. Peptides levels in the serum and reproductive tissues of rats were studied using the ELISA method while the immunoreactivity of reproductive system peptide hormones were shown by immunohistochemical staining method. Furthermore, the other biochemical parameters were measured using Konelab-60 equipment and infertility hormones were measured with Immulite2000. Fasting serum insulin, glucose, triglyceride, alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) levels were statistically significantly higher, and the amount of high density lipoprotein cholesterol (HDL-C) was significantly lower, in the MetS groups. Serum and tissue supernatant NES levels were significantly higher in the rats with MetS than the control group. Ghrelin, OBS and NES were expressed in the cytoplasm, concentrated around the apical parts of the epithelial cells in the reproductive tissues of the rats. The amounts of ghrelin were lower in the reproductive

  7. CRF Type 2 Receptors Mediate the Metabolic Effects of Ghrelin in C2C12 cells

    PubMed Central

    Gershon, Eran; Vale, Wylie W

    2014-01-01

    Objective Ghrelin is known to regulate appetite control and cellular metabolism. The Corticotropin-Releasing Factor (CRF) family is also known to regulate energy balance. In this study, we investigated the links between ghrelin and the CRF family in C2C12 cells, a mouse myoblast cell line. Design and methods C2C12 cells were treated with ghrelin in the presence or absence of CRF receptor antagonists and then subjected to different metabolic analyses. Results Ghrelin enhanced glucose uptake by C2C12 cells, induced GLUT4 translocation to the cell surface and decreased RBP4 expression. A CRF-R2 selective antagonist, anti-sauvagine-30, blocked ghrelin-induced glucose uptake, Ghrelin upregulated CRF-R2 but not CRF-R1 levels. Moreover, ghrelin-treated C2C12 cells displayed a cAMP and pERK activation in response to Ucn3, a CRF-R2 specific ligand, but not in response to CRF or stressin, CRF-R1 specific ligands. Ghrelin also induced UCP2 and UCP3 expression, which were blocked by anti-sauvagine-30. Ghrelin did not induce fatty acids uptake by C2C12 cells or ACC expression. Even though C2C12 cells clearly exhibited responses to ghrelin, the known ghrelin receptor, GHSR1a, was not detectable in C2C12 cells. Conclusion Our results suggest that, ghrelin plays a role in regulating muscle glucose and, raise the possibility that suppression of the CRF-R2 pathway might provide benefits in high ghrelin states. PMID:23804489

  8. Intracerebroventricular injection of ghrelin decreases wheel running activity in rats.

    PubMed

    Miyatake, Yumiko; Shiuchi, Tetsuya; Mawatari, Kazuaki; Toda, Satomi; Taniguchi, Yasuko; Futami, Akari; Sato, Fukiko; Kuroda, Masashi; Sebe, Mayu; Tsutsumi, Rie; Harada, Nagakatsu; Minokoshi, Yasuhiko; Kitamura, Tadahiro; Gotoh, Koro; Ueno, Masaki; Nakaya, Yutaka; Sakaue, Hiroshi

    2017-01-01

    There is an increasing interest in elucidating the molecular mechanisms by which voluntary exercise is regulated. In this study, we examined how the central nervous system regulates exercise. We used SPORTS rats, which were established in our laboratory as a highly voluntary murine exercise model. SPORTS rats showed lower levels of serum ghrelin compared with those of the parental line of Wistar rats. Intracerebroventricular and intraperitoneal injection of ghrelin decreased wheel-running activity in SPORTS rats. In addition, daily injection of the ghrelin inhibitor JMV3002 into the lateral ventricles of Wistar rats increased wheel-running activity. Co-administration of obestatin inhibited ghrelin-induced increases in food intake but did not inhibit ghrelin-induced suppression of voluntary exercise in rats. Growth hormone secretagogue receptor (GHSR) in the hypothalamus and hippocampus of SPORTS rats was not difference that in control rats. We created an arcuate nucleus destruction model by administering monosodium glutamate (MSG) to neonatal SPORTS rats. Injection of ghrelin into MSG-treated rats decreased voluntary exercise but did not increase food intake, suggesting that wheel-running activity is not controlled by the arcuate nucleus neurons that regulate feeding. These results provide new insights into the mechanism by which ghrelin regulates voluntary activity independent of arcuate nucleus neurons.

  9. Reduced Anticipatory Locomotor Responses to Scheduled Meals in Ghrelin Receptor Deficient Mice

    PubMed Central

    Blum, Ian D.; Patterson, Zack; Khazall, Rim; Lamont, Elaine Waddington; Sleeman, Mark W.; Horvath, Tamas L.; Abizaid, Alfonso

    2009-01-01

    Ghrelin, an orexigenic hormone produced by the stomach, is secreted in anticipation of scheduled meals and in correlation with anticipatory locomotor activity. We hypothesized that ghrelin is directly implicated in stimulating locomotor activity in anticipation of scheduled meals. To test this hypothesis, we observed 24 hr patterns of locomotor activity in mice with targeted mutations of the ghrelin receptor gene (GHSR KO) and wild-type littermates, all given access to food for four hours daily for 14 days. While WT and GHSR KO mice produced increases in anticipatory locomotor activity, anticipatory locomotor activity in GHSR KO mice was attenuated (p.< 0.05). These behavioral measures correlated with attenuated levels of Fos immunoreactivity in a number of hypothalamic nuclei from GHSR KO placed on the same restricted feeding schedule for seven days and sacrificed at ZT4. Interestingly, seven daily intraperitoeneal ghrelin injections mimicked hypothalamic Fos expression patterns to those seen in mice under restricted feeding schedules. These data suggest that ghrelin acts in the hypothalamus to augment locomotor activity in anticipation of scheduled meals. PMID:19666088

  10. Morphine-induced conditioned place preference and the alterations of p-ERK, p-CREB and c-fos levels in hypothalamus and hippocampus: the effects of physical stress.

    PubMed

    Pahlevani, P; Fatahi, Z; Moradi, M; Haghparast, A

    2014-12-08

    The hypothalamus and hippocampus are important areas involved in stress responses and reward processing. In addition, ERK/CREB pathway plays a critical role in the control of cellular responses to stress and reward. In the current study, effects of acute and subchronic stress on the alteration of p-ERK, p-CREB and c-fos levels in the hypothalamus and hippocampus of saline- or morphine-treated animals during morphine-induced conditioned place preference (CPP) procedure were investigated. Male Wistar rats were divided into two saline- and morphine-treated supergroups. Each supergroup includes of control, acute stress and subchronic stress groups. In all of groups, the CPP procedure was done, afterward the alternation of p-ERK/ERK ratio, p-CREB/CREB ratio and c-fos level in the hypothalamus and hippocampus were estimated by Western blot analysis. The results indicated that in saline- or morphine-treated animals, p-ERK/ERK ratio, p-CREB/CREB ratio and c-fos level increased after application of acute and subchronic stress (except for p-ERK/ERK ratio in morphine-control group). Our findings revealed that in saline- or morphine-treated animals, acute and subcronic stress increased the p-ERK/ERK ratio, p-CREB/CREB ratio and c-fos level in the hypothalamus and hippocampus and this enhancement in morphine-treated animals, was more considerable than that in saline-treated animals.

  11. CB1 Cannabinoid Agonist (WIN55,212-2) Within the Basolateral Amygdala Induced Sensitization to Morphine and Increased the Level of μ-Opioid Receptor and c-fos in the Nucleus Accumbens.

    PubMed

    Molaei, Marzieh; Fatahi, Zahra; Zaringhalam, Jalal; Haghparast, Abbas

    2016-04-01

    The basolateral amygdala (BLA) is rich of CB1 cannabinoid receptors (CB1R) and has reciprocal connections with the nucleus accumbens (NAc) which is involved in opioid sensitization. In this study, effects of intra-BLA administration of CB1R agonist on sensitization to antinociceptive effect of morphine and changes in the levels of μ-opioid receptor (MOR), p-CREB, and c-fos in the NAc were investigated. Animals received intra-BLA microinjection of CB1R agonist (WIN55,212-2) once daily for 3 days consecutively (sensitization period). After 5 days free of drug, tail-flick test was performed before and after the administration of an ineffective dose of morphine. Afterward, the levels of MOR, p-CREB, and c-fos proteins were measured in the NAc by Western blot analysis. The results indicated that intra-BLA injection of WIN55,212-2 during sensitization period resulted in the induction of antinociceptive responses by ineffective dose of morphine and caused a significant increase in the MOR and c-fos levels but not p-CREB/CREB ratio in the NAc. These finding revealed that CB1 receptor agonist in the BLA induces development of morphine sensitization and increases expression of MOR in the NAc. It seems that c-fos is one of the important factors involved in the induction of sensitization to antinociceptive effect of morphine.

  12. FosB Null Mutant Mice Show Enhanced Methamphetamine Neurotoxicity: Potential Involvement of FosB in Intracellular Feedback Signaling and Astroglial Function

    PubMed Central

    Kuroda, Kumi O; Ornthanalai, Veravej G; Kato, Tadafumi; Murphy, Niall P

    2010-01-01

    Previous studies show that (1) two members of fos family transcription factors, c-Fos and FosB, are induced in frontal brain regions by methamphetamine; (2) null mutation of c-Fos exacerbates methamphetamine-induced neurotoxicity; and (3) null mutation of FosB enhances behavioral responses to cocaine. Here we sought a role of FosB in responses to methamphetamine by studying FosB null mutant (−/−) mice. After a 10 mg/kg methamphetamine injection, FosB(−/−) mice were more prone to self-injury. Concomitantly, the intracellular feedback regulators of Sprouty and Rad-Gem-Kir (RGK) family transcripts had lower expression profiles in the frontoparietal cortex and striatum of the FosB(−/−) mice. Three days after administration of four 10 mg/kg methamphetamine injections, the frontoparietal cortex and striatum of FosB(−/−) mice contained more degenerated neurons as determined by Fluoro-Jade B staining. The abundance of the small neutral amino acids, serine, alanine, and glycine, was lower and/or was poorly induced after methamphetamine administration in the frontoparietal cortex and striatum of FosB(−/−) mice. In addition, methamphetamine-treated FosB(−/−) frontoparietal and piriform cortices showed more extravasation of immunoglobulin, which is indicative of blood–brain barrier dysfunction. Methamphetamine-induced hyperthermia, brain dopamine content, and loss of tyrosine hydroxylase immunoreactivity in the striatum, however, were not different between genotypes. These data indicate that FosB is involved in thermoregulation-independent protective functions against methamphetamine neurotoxicity in postsynaptic neurons. Our findings suggest two possible mechanisms of FosB-mediated neuroprotection: one is induction of negative feedback regulation within postsynaptic neurons through Sprouty and RGK. Another is supporting astroglial function such as maintenance of the blood–brain barrier, and metabolism of serine and glycine, which are important

  13. FosB null mutant mice show enhanced methamphetamine neurotoxicity: potential involvement of FosB in intracellular feedback signaling and astroglial function.

    PubMed

    Kuroda, Kumi O; Ornthanalai, Veravej G; Kato, Tadafumi; Murphy, Niall P

    2010-02-01

    Previous studies show that (1) two members of fos family transcription factors, c-Fos and FosB, are induced in frontal brain regions by methamphetamine; (2) null mutation of c-Fos exacerbates methamphetamine-induced neurotoxicity; and (3) null mutation of FosB enhances behavioral responses to cocaine. Here we sought a role of FosB in responses to methamphetamine by studying FosB null mutant (-/-) mice. After a 10 mg/kg methamphetamine injection, FosB(-/-) mice were more prone to self-injury. Concomitantly, the intracellular feedback regulators of Sprouty and Rad-Gem-Kir (RGK) family transcripts had lower expression profiles in the frontoparietal cortex and striatum of the FosB(-/-) mice. Three days after administration of four 10 mg/kg methamphetamine injections, the frontoparietal cortex and striatum of FosB(-/-) mice contained more degenerated neurons as determined by Fluoro-Jade B staining. The abundance of the small neutral amino acids, serine, alanine, and glycine, was lower and/or was poorly induced after methamphetamine administration in the frontoparietal cortex and striatum of FosB(-/-) mice. In addition, methamphetamine-treated FosB(-/-) frontoparietal and piriform cortices showed more extravasation of immunoglobulin, which is indicative of blood-brain barrier dysfunction. Methamphetamine-induced hyperthermia, brain dopamine content, and loss of tyrosine hydroxylase immunoreactivity in the striatum, however, were not different between genotypes. These data indicate that FosB is involved in thermoregulation-independent protective functions against methamphetamine neurotoxicity in postsynaptic neurons. Our findings suggest two possible mechanisms of FosB-mediated neuroprotection: one is induction of negative feedback regulation within postsynaptic neurons through Sprouty and RGK. Another is supporting astroglial function such as maintenance of the blood-brain barrier, and metabolism of serine and glycine, which are important glial modulators of nerve cells.

  14. Ghrelin-Reactive Immunoglobulins in Conditions of Altered Appetite and Energy Balance

    PubMed Central

    Fetissov, Sergueï O.; Lucas, Nicolas; Legrand, Romain

    2017-01-01

    Part of circulating ghrelin is bound to immunoglobulins (Ig) protecting it from degradation and preserving its functional activity. This review summarizes the data on ghrelin- and desacyl-ghrelin-reactive IgG in conditions of altered appetite and energy balance. Plasma levels and affinity kinetics of such IgG were compared in patients with obesity and anorexia nervosa (AN) and in animal models of obesity including ob/ob mice, high-fat diet-induced obese mice, and obese Zucker rats as well as in mice after chronic food restriction and activity-based anorexia and in rats with methotrexate-induced anorexia. We show that plasmatic IgG in both obese humans and animals are characterized by increased affinity for ghrelin. In contrast, patients with AN and anorectic rodents all show lower affinity of ghrelin- and desacyl-ghrelin-reactive IgG, respectively, the changes which were not observed in non-anorectic, chronically starved mice. We also show that affinity of ghrelin-reactive IgG correlate with plasma levels of ghrelin. These data point to common mechanisms underlying modifications of affinity kinetics properties of ghrelin-reactive IgG during chronic alterations of energy balance in humans and rodents and support a functional role of such autoantibodies in ghrelin-mediated regulation of appetite. PMID:28191004

  15. Serotonin2C receptor stimulation inhibits cocaine-induced Fos expression and DARPP-32 phosphorylation in the rat striatum independently of dopamine outflow.

    PubMed

    Devroye, Céline; Cathala, Adeline; Maitre, Marlène; Piazza, Pier Vincenzo; Abrous, Djoher Nora; Revest, Jean-Michel; Spampinato, Umberto

    2015-02-01

    The serotonin(2C) receptor (5-HT(2C)R) is known to control dopamine (DA) neuron function by modulating DA neuronal firing and DA exocytosis at terminals. Recent studies assessing the influence of 5-HT(2C)Rs on cocaine-induced neurochemical and behavioral responses have shown that 5-HT2CRs can also modulate mesoaccumbens DA pathway activity at post-synaptic level, by controlling DA transmission in the nucleus accumbens (NAc), independently of DA release itself. A similar mechanism has been proposed to occur at the level of the nigrostriatal DA system. Here, using in vivo microdialysis in freely moving rats and molecular approaches, we assessed this hypothesis by studying the influence of the 5-HT(2C)R agonist Ro 60-0175 on cocaine-induced responses in the striatum. The intraperitoneal (i.p.) administration of 1 mg/kg Ro 60-0175 had no effect on the increase in striatal DA outflow induced by cocaine (15 mg/kg, i.p.). Conversely, Ro 60-0175 inhibited cocaine-induced Fos immunoreactivity and phosphorylation of the DA and c-AMP regulated phosphoprotein of Mr 32 kDa (DARPP-32) at threonine 75 residue in the striatum. Finally, the suppressant effect of Ro 60-0175 on cocaine-induced DARPP-32 phosphorylation was reversed by the selective 5-HT(2C)R antagonist SB 242084 (0.5 mg/kg, i.p.). In keeping with the key role of DARPP-32 in DA neurotransmission, our results demonstrate that 5-HT(2C)Rs are capable of modulating nigrostriatal DA pathway activity at post-synaptic level, by specifically controlling DA signaling in the striatum.

  16. Neonatal overfeeding disrupts pituitary ghrelin signalling in female rats long-term; Implications for the stress response

    PubMed Central

    Ziko, Ilvana; Spencer, Sarah J.

    2017-01-01

    The hypothalamic-pituitary-adrenal (HPA) axis responses to psychological stress are exacerbated in adult female but not male rats made obese due to overfeeding in early life. Ghrelin, traditionally known for its role in energy homeostasis, has been recently recognised for its role in coordinating the HPA responses to stress, particularly by acting directly at the anterior pituitary where the growth hormone secretagogue receptor (GHSR), the receptor for acyl ghrelin, is abundantly expressed. We therefore hypothesised that neonatal overfeeding in female rats would compromise pituitary responsiveness to ghrelin, contributing to a hyperactive central stress responsiveness. Unlike in males where hypothalamic ghrelin signalling is compromised by neonatal overfeeding, there was no effect of early life diet on circulating ghrelin or hypothalamic ghrelin signalling in females, indicating hypothalamic feeding and metabolic ghrelin circuitry remains intact. However, neonatal overfeeding did lead to long-term alterations in the pituitary ghrelin system. The neonatally overfed females had increased neonatal and reduced adult expression of GHSR and ghrelin-O-acyl transferase (GOAT) in the pituitary as well as reduced pituitary responsiveness to exogenous acyl ghrelin-induced adrenocorticotropic hormone (ACTH) release in vitro. These data suggest that neonatal overfeeding dysregulates pituitary ghrelin signalling long-term in females, potentially accounting for the hyper-responsive HPA axis in these animals. These findings have implications for how females may respond to stress throughout life, suggesting the way ghrelin modifies the stress response at the level of the pituitary may be less efficient in the neonatally overfed. PMID:28282447

  17. Mediation of oxidative stress in hypothalamic ghrelin-associated appetite control in rats treated with phenylpropanolamine.

    PubMed

    Yu, C-H; Chu, S-C; Chen, P-N; Hsieh, Y-S; Kuo, D-Y

    2017-04-01

    Phenylpropanolamine (PPA)-induced appetite control is associated with oxidative stress in the hypothalamus. This study explored whether hypothalamic antioxidants participated in hypothalamic ghrelin system-associated appetite control in PPA-treated rats. Rats were given PPA daily for 4 days, and changes in food intake and the expression of neuropeptide Y (NPY), the cocaine- and amphetamine-regulated transcript (CART), superoxide dismutase, catalase, ghrelin, acyl ghrelin (AG), ghrelin O-acyltransferase (GOAT) and the ghrelin receptor (GHSR1a) were examined and compared. Results showed that both food intake and the expression of NPY and ghrelin/AG/GOAT/GHSR1a decreased in response to PPA treatment with maximum decrease on Day 2 of the treatment. In contrast, the expression of antioxidants and CART increased, with the maximum increase on Day 2, with the expression opposite to that of NPY and ghrelin. A cerebral infusion of either a GHSR1a antagonist or reactive oxygen species scavenger modulated feeding behavior and NPY, CART, antioxidants and ghrelin system expression, showing the involvement of ghrelin signaling and oxidative stress in regulating PPA-mediated appetite control. We suggest that hypothalamic ghrelin signaling system, with the help of antioxidants, may participate in NPY/CART-mediated appetite control in PPA-treated rats.

  18. Ghrelin stimulates angiogenesis in human microvascular endothelial cells: Implications beyond GH release

    SciTech Connect

    Li Aihua; Cheng Guangli; Zhu Genghui; Tarnawski, Andrzej S. . E-mail: atarnawski@yahoo.com

    2007-02-09

    Ghrelin, a peptide hormone isolated from the stomach, releases growth hormone and stimulates appetite. Ghrelin is also expressed in pancreas, kidneys, cardiovascular system and in endothelial cells. The precise role of ghrelin in endothelial cell functions remains unknown. We examined the expression of ghrelin and its receptor (GHSR1) mRNAs and proteins in human microvascular endothelial cells (HMVEC) and determined whether ghrelin affects in these cells proliferation, migration and in vitro angiogenesis; and whether MAPK/ERK2 signaling is important for the latter action. We found that ghrelin and GHSR1 are constitutively expressed in HMVEC. Treatment of HMVEC with exogenous ghrelin significantly increased in these cells proliferation, migration, in vitro angiogenesis and ERK2 phosphorylation. MEK/ERK2 inhibitor, PD 98059 abolished ghrelin-induced in vitro angiogenesis. This is First demonstration that ghrelin and its receptor are expressed in human microvascular endothelial cells and that ghrelin stimulates HMVEC proliferation, migration, and angiogenesis through activation of ERK2 signaling.

  19. Expression and Possible Immune-regulatory Function of Ghrelin in Oral Epithelium

    PubMed Central

    Ohta, K.; Laborde, N.J.; Kajiya, M.; Shin, J.; Zhu, T.; Thondukolam, A.K.; Min, C.; Kamata, N.; Karimbux, N.Y.; Stashenko, P.; Kawai, T.

    2011-01-01

    Originally found in stomach mucosa, ghrelin is a peptide appetite hormone that has been implicated as an immuno-modulatory factor. Ghrelin has also been found in salivary glands and saliva; however, its expression patterns and biological properties in the oral cavity remain unclear. Therefore, we investigated the expression patterns of ghrelin in saliva, gingival crevicular fluid (GCF), and gingival tissue, as well as its in vitro effects on IL-8 production by TNF-α or LPS-stimulated oral epithelial cells. In the clinical samples obtained from 12 healthy volunteers, the concentration of ghrelin in GCF remarkably exceeded that detected in saliva. The expression of ghrelin mRNAs and growth hormone secretagogue (GHS) receptors could be detected in human oral epithelial cells. Immunohistochemical analysis revealed the expression of ghrelin in gingival epithelium, as well as in fibroblasts in the lamina propria. Ghrelin increased intracellular calcium mobilization and cAMP levels in oral epithelial cells, suggesting that ghrelin acts on epithelial cells to induce cell signaling. Furthermore, synthetic ghrelin inhibited the production of IL-8 from TNF-α or LPS-stimulated oral epithelial cells. These results indicate that ghrelin produced in the oral cavity appears to play a regulatory role in innate immune responses to inflammatory infection. PMID:21865591

  20. Regional c-Fos and FosB/ΔFosB expression associated with chronic methamphetamine self-administration and methamphetamine-seeking behavior in rats.

    PubMed

    Cornish, J L; Hunt, G E; Robins, L; McGregor, I S

    2012-03-29

    The regional expression of the transcription factors c-Fos and FosB/ΔFosB was examined in rats given acute exposure to intravenous methamphetamine (METH) or repeated intravenous METH self-administration. One group of rats self-administered METH via lever pressing in 2 h sessions every day for 3 weeks and on a final test day received self-administered METH as usual. A second group with the same METH self-administration history received saline infusions on the test day, to induce drug-seeking behavior. Other rats were trained with infusions of intravenous saline that were yoked to the passive delivery of METH in the other two groups. On test day, half of these yoked rats received passive METH infusions for the first time, whereas the others received saline as usual. The results showed that acute METH produced a characteristic signature of Fos expression with elevations in striatal, cortical, and extended amygdala regions. Importantly, rats with a 3-week history of METH self-administration displayed similar regional Fos expression to rats receiving METH for the first time. Rats seeking, but not receiving, METH on the test day had augmented Fos in the lateral hypothalamus, septum, and vertical limb of the diagonal band of Broca, suggesting a primary role for these regions in METH-seeking behavior. Both acute and chronic METH activated orexin-positive cells in the perifornical area of the hypothalamus. FosB/ΔFosB was elevated in the lateral hypothalamus, posterior ventral tegmental area, central amygdala, and dorsal raphe of all the rats with a history of METH self-administration. This occurred regardless of whether they received METH on test day, suggesting presence of the long-lived FosB isoform, ΔFosB. Overall, these results show persistent upregulated regional brain Fos and FosB/ΔFosB expression with chronic METH self-administration and indicate a role for the lateral hypothalamus and lateral septum in METH-seeking behavior.

  1. Transitional change in rat fetal cell proliferation in response to ghrelin and des-acyl ghrelin during the last stage of pregnancy

    SciTech Connect

    Inoue, Yoshiyuki; Nakahara, Keiko; Kangawa, Kenji; Murakami, Noboru

    2010-03-12

    Expression of mRNA for the ghrelin receptor, GHS-R1a, was detected in various peripheral and central tissues of fetal rats, including skin, bone, heart, liver, gut, brain and spinal cord, on embryonic day (ED)15 and ED17. However, its expression in skin, bone, heart and liver, but not in gut, brain and spinal cord, became relatively weak on ED19 and disappeared after birth (ND2). Ghrelin and des-acyl ghrelin facilitated the proliferation of cultured fetal (ED17, 19), but not neonatal (ND2), skin cells. On the other hand, with regard to cells from the spinal cord and hypothalamus, the proliferative effect of ghrelin continued after birth, whereas the effect of des-acyl ghrelin on neurogenesis in these tissues was lost at the ED19 fetal and ND2 neonatal stages. Immunohistochemistry revealed that the cells in the hypothalamus induced to proliferate by ghrelin at the ND2 stage were positive for nestin and glial fibrillary acidic protein. These results suggest that in the period immediately prior to, and after birth, rat fetal cells showing proliferation in response to ghrelin and des-acyl ghrelin are at a transitional stage characterized by alteration of the expression of GHS-R1a and an undefined des-acyl ghrelin receptor, their responsiveness varying among different tissues.

  2. Calcium signals activated by ghrelin and D-Lys(3)-GHRP-6 ghrelin antagonist in developing dorsal root ganglion glial cells.

    PubMed

    Erriquez, Jessica; Bernascone, Silvia; Ciarletta, Monica; Filigheddu, Nicoletta; Graziani, Andrea; Distasi, Carla

    2009-09-01

    Ghrelin is a hormone regulating energy homeostasis via interaction with its receptor, GHSR-1a. Ghrelin activities in dorsal root ganglia (DRG) cells are unknown. Herein we show that ghrelin induces a change of cytosolic calcium concentration in both glia and neurons of embryonic chick DRG. Both RT-PCR and binding studies performed with fluorescent ghrelin in the presence of either unlabeled ghrelin or GHSR-1a antagonist D-Lys(3)-GHRP-6, indicate that DRG cells express GHSR-1a. In glial cells the response is characterized by a rapid transient rise in [Ca(2+)](i) followed by a long lasting rise. The calcium elevation is dependent on calcium release from thapsigargin-sensitive intracellular stores and on activation of two distinct Ca(2+) entry pathways, a receptor activated calcium entry and a store operated calcium entry. Surprisingly, D-Lys(3)-GHRP-6 exerts several activities in the absence of exogenous ghrelin: (i) it activates calcium release from thapsigargin-sensitive intracellular stores and calcium entry via voltage-operated channels in non-neuronal cells; (ii) it inhibits calcium oscillations in non-neuronal cells exhibiting spontaneous Ca(2+) activity and iii) it promotes apoptosis of DRG cells, both neurons and glia. In summary, we provide the first evidence for ghrelin activity in DRG, and we also demonstrate that the widely used D-Lys(3)-GHRP-6 ghrelin antagonist features ghrelin independent activities.

  3. Obestatin, a peptide encoded by the ghrelin gene, opposes ghrelin's effects on food intake.

    PubMed

    Zhang, Jian V; Ren, Pei-Gen; Avsian-Kretchmer, Orna; Luo, Ching-Wei; Rauch, Rami; Klein, Cynthia; Hsueh, Aaron J W

    2005-11-11

    Ghrelin, a circulating appetite-inducing hormone, is derived from a prohormone by posttranslational processing. On the basis of the bioinformatic prediction that another peptide also derived from proghrelin exists, we isolated a hormone from rat stomach and named it obestatin-a contraction of obese, from the Latin "obedere," meaning to devour, and "statin," denoting suppression. Contrary to the appetite-stimulating effects of ghrelin, treatment of rats with obestatin suppressed food intake, inhibited jejunal contraction, and decreased body-weight gain. Obestatin bound to the orphan G protein-coupled receptor GPR39. Thus, two peptide hormones with opposing action in weight regulation are derived from the same ghrelin gene. After differential modification, these hormones activate distinct receptors.

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

    PubMed

    Nahata, Miwa; Muto, Shuichi; Oridate, Nobuhiko; Ohnishi, Shunsuke; Nakagawa, Koji; Sadakane, Chiharu; Saegusa, Yayoi; Hattori, Tomohisa; Asaka, Masahiro; Takeda, Hiroshi

    2012-07-01

    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.

  5. Ghrelin Attenuates cAMP-PKA Signaling to Evoke Insulinostatic Cascade in Islet β-Cells

    PubMed Central

    Dezaki, Katsuya; Damdindorj, Boldbaatar; Sone, Hideyuki; Dyachok, Oleg; Tengholm, Anders; Gylfe, Erik; Kurashina, Tomoyuki; Yoshida, Masashi; Kakei, Masafumi; Yada, Toshihiko

    2011-01-01

    OBJECTIVE Ghrelin reportedly restricts insulin release in islet β-cells via the Gαi2 subtype of G-proteins and thereby regulates glucose homeostasis. This study explored whether ghrelin regulates cAMP signaling and whether this regulation induces insulinostatic cascade in islet β-cells. RESEARCH DESIGN AND METHODS Insulin release was measured in rat perfused pancreas and isolated islets and cAMP production in isolated islets. Cytosolic cAMP concentrations ([cAMP]i) were monitored in mouse MIN6 cells using evanescent-wave fluorescence imaging. In rat single β-cells, cytosolic protein kinase-A activity ([PKA]i) and Ca2+ concentration ([Ca2+]i) were measured by DR-II and fura-2 microfluorometry, respectively, and whole cell currents by patch-clamp technique. RESULTS Ghrelin suppressed glucose (8.3 mmol/L)-induced insulin release in rat perfused pancreas and isolated islets, and these effects of ghrelin were blunted in the presence of cAMP analogs or adenylate cyclase inhibitor. Glucose-induced cAMP production in isolated islets was attenuated by ghrelin and enhanced by ghrelin receptor antagonist and anti-ghrelin antiserum, which counteract endogenous islet-derived ghrelin. Ghrelin inhibited the glucose-induced [cAMP]i elevation and [PKA]i activation in MIN6 and rat β-cells, respectively. Furthermore, ghrelin potentiated voltage-dependent K+ (Kv) channel currents without altering Ca2+ channel currents and attenuated glucose-induced [Ca2+]i increases in rat β-cells in a PKA-dependent manner. CONCLUSIONS Ghrelin directly interacts with islet β-cells to attenuate glucose-induced cAMP production and PKA activation, which lead to activation of Kv channels and suppression of glucose-induced [Ca2+]i increase and insulin release. PMID:21788571

  6. Upregulation and nuclear translocation of testicular ghrelin protects differentiating spermatogonia from ionizing radiation injury

    PubMed Central

    Li, W; Zeng, Y; Zhao, J; Zhu, C-J; Hou, W-G; Zhang, S

    2014-01-01

    Proper control of apoptotic signaling is important for maintenance of testicular homeostasis after ionizing radiation (IR). Herein, we challenged the hypothesis that ghrelin, a pleiotropic modulator, is potentially involved in IR-induced germ cell injury. Lower body exposure to 2 Gy of IR induced a notable increase of ghrelin expression in the nuclear of differentiating spermatogonia at defined stages, with an impairment in the Leydig cells (LCs)-expressing ghrelin. Unexpectedly, inhibition of the ghrelin pathway by intraperitoneal injection of a specific GHS-R1α antagonist enhanced spermatogonia elimination by apoptosis during the early recovery following IR, and thereafter resulted in impaired male fertility, suggesting that the anti-apoptotic effects of evoked ghrelin, although transient along testicular IR injury, have a profound influence on the post-injury recovery. In addition, inhibition of ghrelin signaling resulted in a significant increase in the intratesticular testosterone (T) level at the end of 21 days after IR, which should stimulate the spermatogenic recovery from surviving spermatogonia to a certain extent during the late stage. We further demonstrated that the upregulation and nuclear trafficking of ghrelin, elaborately regulated by IR-elicited antioxidant system in spermatogonia, may act through a p53-dependent mechanism. The elicitation of ghrelin expression by IR stress, the regulation of ghrelin expression by IR-induced oxidative stress and the interaction between p53 and ghrelin signaling during IR injury were confirmed in cultured spermatogonia. Hence, our results represent the first evidence in support of a radioprotective role of ghrelin in the differentiating spermatogonia. The acutely, delicate regulation of local-produced ghrelin appears to be a fine-tune mechanism modulating the balance between testicular homeostasis and early IR injury. PMID:24853426

  7. Upregulation and nuclear translocation of testicular ghrelin protects differentiating spermatogonia from ionizing radiation injury.

    PubMed

    Li, W; Zeng, Y; Zhao, J; Zhu, C-J; Hou, W-G; Zhang, S

    2014-05-22

    Proper control of apoptotic signaling is important for maintenance of testicular homeostasis after ionizing radiation (IR). Herein, we challenged the hypothesis that ghrelin, a pleiotropic modulator, is potentially involved in IR-induced germ cell injury. Lower body exposure to 2 Gy of IR induced a notable increase of ghrelin expression in the nuclear of differentiating spermatogonia at defined stages, with an impairment in the Leydig cells (LCs)-expressing ghrelin. Unexpectedly, inhibition of the ghrelin pathway by intraperitoneal injection of a specific GHS-R1α antagonist enhanced spermatogonia elimination by apoptosis during the early recovery following IR, and thereafter resulted in impaired male fertility, suggesting that the anti-apoptotic effects of evoked ghrelin, although transient along testicular IR injury, have a profound influence on the post-injury recovery. In addition, inhibition of ghrelin signaling resulted in a significant increase in the intratesticular testosterone (T) level at the end of 21 days after IR, which should stimulate the spermatogenic recovery from surviving spermatogonia to a certain extent during the late stage. We further demonstrated that the upregulation and nuclear trafficking of ghrelin, elaborately regulated by IR-elicited antioxidant system in spermatogonia, may act through a p53-dependent mechanism. The elicitation of ghrelin expression by IR stress, the regulation of ghrelin expression by IR-induced oxidative stress and the interaction between p53 and ghrelin signaling during IR injury were confirmed in cultured spermatogonia. Hence, our results represent the first evidence in support of a radioprotective role of ghrelin in the differentiating spermatogonia. The acutely, delicate regulation of local-produced ghrelin appears to be a fine-tune mechanism modulating the balance between testicular homeostasis and early IR injury.

  8. Ghrelin and PYY levels in adolescents with severe obesity: effects of weight loss induced by long-term exercise training and modified food habits.

    PubMed

    Gueugnon, Carine; Mougin, Fabienne; Nguyen, Nhu Uyen; Bouhaddi, Malika; Nicolet-Guénat, Marie; Dumoulin, Gilles

    2012-05-01

    This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

  9. Gabaergic control of anxiety-like behavior, but not food intake, induced by ghrelin in the intermediate medial mesopallium of the neonatal chick.

    PubMed

    Gastón, M S; Schiöth, H B; De Barioglio, S R; Salvatierra, N A

    2015-01-01

    Ghrelin (Grh) is an endogenous ligand of the growth hormone secretagogue receptor. In neonatal chicks, central Ghr induces anxiogenic-like behavior but strongly inhibits food intake. The intermediate medial mesopallium (IMM) of the chick forebrain has been identified to be a site of the memory formation, and the modulation of the GABAA receptors that are present here modifies the expression of behavior. Thus, the GABAergic system may constitute a central pathway for Ghr action in regulating the processes of food intake and stress-related behaviors. Therefore, we investigated if the effect of systemic administration of bicuculline (GABAA receptor antagonist) and diazepam (benzodiazepine receptor agonist) on the anxiety in an Open Field test and inhibition in food intake induced by Grh (30pmol) when injected into IMM, were mediated by GABAergic transmission. In Open Field test, bicuculline was able to block the anxiogenic-like behavior induced by Ghr, whereas diazepam did not produce it. However, the co-administration of bicuculline or diazepam plus Ghr did not show any change in food intake at 30, 60 and 120min after injection compared to Ghr alone. Our results indicate for the first time that Ghr, injected into the forebrain IMM area, induces an anxiogenic-like behavior, which was blocked by bicuculline but not diazepam, thus suggesting that Ghr plays an important role in the response pattern to acute stressor, involving the possible participation of the GABAergic system. Nevertheless, as neither drug affected the hypophagia induced by intra-IMM Ghr, this suggests that it may be mediated by different mechanisms.

  10. Obestatin partially suppresses ghrelin stimulation of appetite in "high-responders" grass carp, Ctenopharyngodon idellus.

    PubMed

    Yuan, Xiaochen; Cai, Wenjing; Liang, Xu-Fang; Su, Hang; Yuan, Yongchao; Li, Aixuan; Tao, Ya-Xiong

    2015-06-01

    Ghrelin and obestatin are two gastrointestinal peptides obtained by post-translational processing of a common precursor, preproghrelin. The effect of obestatin on food intake is still controversial. The aim of the present study was to investigate the effects of ghrelin and obestatin on food intake in grass carp, Ctenopharyngodon idellus. Fish received intraperitoneal (IP) injection of saline, ghrelin (100 ng g(-1)BW), obestatin-like (25 ng g(-1)BW) and ghrelin in combination with obestatin-like. Ghrelin stimulation of food intake varied considerably among individual fish with 70.8% eliciting a robust response. In these high-responders, food intake was significantly increased by IP ghrelin within 2 h. Co-administration of ghrelin and obestatin-like resulted in a decrease in food intake, indicating that obestatin was able to antagonize the effect of ghrelin. However, IP obestatin-like alone could not regulate food intake in grass carp. RT-PCR analysis demonstrated that IP ghrelin peptide led to a significant increase in mRNA abundance of NPY, Y8a and Y8b genes compared to saline injected fish, while in combination with obestatin-like peptide decreased ghrelin-induced gene expressions of these three genes. IP sole obestatin-like peptide did not modify the expression levels of NPY, Y8a, Y8b, CART and POMC compared to the control group. Therefore, IP administration of obestatin-like peptide, partially blocking the ghrelin-induced appetite, investigated the possible involvement of obestatin as a mediator of the ghrelin stimulatory action on food intake, at least in "high-responders" grass carp.

  11. Motilin Stimulates Gastric Acid Secretion in Coordination with Ghrelin in Suncus murinus

    PubMed Central

    Goswami, Chayon; Shimada, Yoshiaki; Yoshimura, Makoto; Mondal, Anupom; Oda, Sen-ichi; Tanaka, Toru; Sakai, Takafumi; Sakata, Ichiro

    2015-01-01

    Motilin and ghrelin constitute a peptide family, and these hormones are important for the regulation of gastrointestinal motility. In this study, we examined the effect of motilin and ghrelin on gastric acid secretion in anesthetized suncus (house musk shrew, Suncus murinus), a ghrelin- and motilin-producing mammal. We first established a gastric lumen-perfusion system in the suncus and confirmed that intravenous (i.v.) administration of histamine (1 mg/kg body weight) stimulated acid secretion. Motilin (0.1, 1.0, and 10 μg/kg BW) stimulated the acid output in a dose-dependent manner in suncus, whereas ghrelin (0.1, 1.0, and 10 μg/kg BW) alone did not induce acid output. Furthermore, in comparison with the vehicle administration, the co-administration of low-dose (1 μg/kg BW) motilin and ghrelin significantly stimulated gastric acid secretion, whereas either motilin (1 μg/kg BW) or ghrelin (1 μg/kg BW) alone did not significantly induce gastric acid secretion. This indicates an additive role of ghrelin in motilin-induced gastric acid secretion. We then investigated the pathways of motilin/motilin and ghrelin-stimulated acid secretion using receptor antagonists. Treatment with YM 022 (a CCK-B receptor antagonist) and atropine (a muscarinic acetylcholine receptor antagonist) had no effect on motilin or motilin-ghrelin co-administration-induced acid output. In contrast, famotidine (a histamine H2 receptor antagonist) completely inhibited motilin-stimulated acid secretion and co-administration of motilin and ghrelin induced gastric acid output. This is the first report demonstrating that motilin stimulates gastric secretion in mammals. Our results also suggest that motilin and co-administration of motilin and ghrelin stimulate gastric acid secretion via the histamine-mediated pathway in suncus. PMID:26115342

  12. Systemic 5-Bromo-2-Deoxyuridine Induces Conditioned Flavor Aversion and C-Fos in the Visceral Neuraxis

    ERIC Educational Resources Information Center

    Kimbrough, Adam; Kwon, Bumsup; Eckel, Lisa A.; Houpt, Thomas A.

    2011-01-01

    5-bromo-2-deoxyuridine (BrdU) is often used in studies of adult neurogenesis and olfactory learning, but it can also have toxic effects on highly proliferative tissue. We found that pairing Kool-Aid flavors with acute systemic injections of BrdU induced strong conditioned flavor aversions. Intermittent injections during Kool-Aid-glucose…

  13. Correlation of ghrelin concentration and ghrelin, ghrelin-O-acetyltransferase (GOAT) and growth hormone secretagogue receptor 1a mRNAs expression in the proventriculus and brain of the growing chicken.

    PubMed

    Kitazawa, Takio; Hiraga, Takeo; Teraoka, Hiroki; Yaosaka, Noriko; Kaiya, Hiroyuki

    2015-01-01

    To determine mechanisms for age-related decrease of GHS-R1a expression in the chicken proventriculus, changes in mRNA expression of ghrelin and ghrelin-O-acetyltransferase (GOAT) as well as ghrelin concentrations in the proventriculus and plasma were examined in growing chickens. Changes in expression levels of ghrelin, GOAT and GHS-R1a mRNAs were also examined in different brain regions (pituitary, hypothalamus, thalamus, cerebellum, cerebral cortex, olfactory bulb, midbrain and medulla oblongata). Ghrelin concentrations in the proventriculus and plasma increased with aging and reached plateaus at 30-50 days after hatching. High level of ghrelin mRNA decreased at 3 days after hatching, and it became stable at half of the initial level. Expression levels of GHS-R1a and GOAT decreased 3 or 5 days after hatching and became stable at low levels. Significant negative correlations were found between plasma ghrelin and mRNA levels of GOAT and GHS-R1a. Expression levels of ghrelin mRNA were different in the brain regions, but a significant change was not seen with aging. GHS-R1a expression was detected in all brain regions, and age-dependent changes were observed in the pituitary and cerebellum. Different from the proventriculus, the expression of GOAT in the brain increased or did not change with aging. These results suggest that decreased GHS-R1a and GOAT mRNA expression in the proventriculus is due to endogenous ghrelin-induced down-regulation. Expression levels of ghrelin, GOAT and GHS-R1a in the brain were independently regulated from that in the proventriculus, and age-related and region-dependent regulation pattern suggests a local effect of ghrelin system in chicken brain.

  14. Possible involvement of ghrelin on pain threshold in obesity.

    PubMed

    Guneli, Ensari; Gumustekin, Mukaddes; Ates, Mehmet

    2010-03-01

    hypothesis that the diminution of the susceptibility to pain in lean subjects/animals may be induced by the increase in endogenous ghrelin activity, or increased of the susceptibility to pain in obese subject/animals may be induced by the decrease in endogenous ghrelin activity.

  15. Topography of methylphenidate (ritalin)-induced gene regulation in the striatum: differential effects on c-fos, substance P and opioid peptides.

    PubMed

    Yano, Motoyo; Steiner, Heinz

    2005-05-01

    Dopamine action alters gene regulation in striatal neurons. Methylphenidate increases extracellular levels of dopamine. We investigated the effects of acute methylphenidate treatment on gene expression in the striatum of adult rats. Molecular changes were mapped in 23 striatal sectors mostly defined by their predominant cortical inputs in order to determine the functional domains affected. Acute administration of 5 and 10 mg/kg (i.p.) of methylphenidate produced robust increases in the expression of the transcription factor c-fos and the neuropeptide substance P. Borderline effects were found with 2 mg/kg, but not with 0.5 mg/kg. For 5 mg/kg, c-fos mRNA levels peaked at 40 min and returned to baseline by 3 h after injection, while substance P mRNA levels peaked at 40-60 min and were back near control levels by 24 h. These molecular changes occurred in most sectors of the caudate-putamen, but were maximal in dorsal sectors that receive sensorimotor and medial agranular cortical inputs, on middle to caudal levels. In rostral and ventral striatal sectors, changes in c-fos and substance P expression were weaker or absent. No effects were seen in the nucleus accumbens, with the exception of c-fos induction in the lateral part of the shell. In contrast to c-fos and substance P, acute methylphenidate treatment had minimal effects on the opioid peptides dynorphin and enkephalin. These results demonstrate that acute methylphenidate alters the expression of c-fos and substance P preferentially in the sensorimotor striatum. These molecular changes are similar, but not identical, to those produced by other psychostimulants.

  16. Vesicular acetylcholine transporter knock down-mice are more susceptible to inflammation, c-Fos expression and sickness behavior induced by lipopolysaccharide.

    PubMed

    Leite, Hércules Ribeiro; Oliveira-Lima, Onésia Cristina de; Pereira, Luciana de Melo; Oliveira, Vinícius Elias de Moura; Prado, Vania Ferreira; Prado, Marco Antônio Máximo; Pereira, Grace Schenatto; Massensini, André Ricardo

    2016-10-01

    In addition to the well-known functions as a neurotransmitter, acetylcholine (ACh) can modulate of the immune system. Nonetheless, how endogenous ACh release inflammatory responses is still not clear. To address this question, we took advantage of an animal model with a decreased ACh release due a reduction (knockdown) in vesicular acetylcholine transporter (VAChT) expression (VAChT-KD(HOM)). These animals were challenged with lipopolysaccharide (LPS). Afterwards, we evaluated sickness behavior and quantified systemic and cerebral inflammation as well as neuronal activation in the dorsal vagal complex (DVC). VAChT-KD(HOM) mice that were injected with LPS (10mg/kg) showed increased mortality rate as compared to control mice. In line with this result, a low dose of LPS (0.1mg/kg) increased the levels of pro-inflammatory (TNF-α, IL-1β, and IL-6) and anti-inflammatory (IL-10) cytokines in the spleen and brain of VAChT-KD(HOM) mice in comparison with controls. Similarly, serum levels of TNF-α and IL-6 were increased in VAChT-KD(HOM) mice. This excessive cytokine production was completely prevented by administration of a nicotinic receptor agonist (0.4mg/kg) prior to the LPS injection. Three hours after the LPS injection, c-Fos expression increased in the DVC region of VAChT-KD(HOM) mice compared to controls. In addition, VAChT-KD(HOM) mice showed behavioral changes such as lowered locomotor and exploratory activity and reduced social interaction after the LPS challenge, when compared to control mice. Taken together, our results show that the decreased ability to release ACh exacerbates systemic and cerebral inflammation and promotes neural activation and behavioral changes induced by LPS. In conclusion, our findings support the notion that activity of cholinergic pathways, which can be modulated by VAChT expression, controls inflammatory and neural responses to LPS challenge.

  17. Ghrelin Modulates Physiologic and Pathologic Retinal Angiogenesis through GHSR-1a

    PubMed Central

    Zaniolo, Karine; Sapieha, Przemyslaw; Shao, Zhuo; Stahl, Andreas; Zhu, Tang; Tremblay, Sophie; Picard, Emilie; Madaan, Ankush; Blais, Martine; Lachapelle, Pierre; Mancini, Joseph; Hardy, Pierre; Smith, Lois E. H.; Ong, Huy

    2011-01-01

    Purpose. Vascular degeneration and the ensuing abnormal vascular proliferation are central to proliferative retinopathies. Given the metabolic discordance associated with these diseases, the authors explored the role of ghrelin and its growth hormone secretagogue receptor 1a (GHSR-1a) in proliferative retinopathy. Methods. In a rat model of oxygen-induced retinopathy (OIR), the contribution of ghrelin and GHSR-1a was investigated using the stable ghrelin analogs [Dap3]-ghrelin and GHRP6 and the GSHR-1a antagonists JMV-2959 and [D-Lys3]-GHRP-6. Plasma and retinal levels of ghrelin were analyzed by ELISA, whereas retinal expression and localization of GHSR-1a were examined by immunohistochemistry and Western blot analysis. The angiogenic and vasoprotective properties of ghrelin and its receptor were further confirmed in aortic explants and in models of vaso-obliteration. Results. Ghrelin is produced locally in the retina, whereas GHSR-1a is abundantly expressed in retinal endothelial cells. Ghrelin levels decrease during the vaso-obliterative phase and rise during the proliferative phase of OIR. Intravitreal delivery of [Dap3]-ghrelin during OIR significantly reduces retinal vessel loss when administered during the hyperoxic phase. Conversely, during the neovascular phase, ghrelin promotes pathologic angiogenesis through the activation of GHSR-1a. These angiogenic effects were confirmed ex vivo in aortic explants. Conclusions. New roles were disclosed for the ghrelin-GHSR-1a pathway in the preservation of retinal vasculature during the vaso-obliterative phase of OIR and during the angiogenic phase of OIR. These findings suggest that the ghrelin-GHSR-1a pathway can exert opposing effects on retinal vasculature, depending on the phase of retinopathy, and thus holds therapeutic potential for proliferative retinopathies. PMID:21642627

  18. Emergence of ghrelin as a treatment for cachexia syndromes.

    PubMed

    DeBoer, Mark Daniel

    2008-09-01

    Cachexia is a constellation of symptoms that amount to body wasting in the setting of a variety of chronic illnesses, including cancer, heart failure, chronic kidney disease, and acquired immunodeficiency syndrome. Cachexia is particularly worrisome clinically because it is associated with a worsened prognosis of the underlying disease. Despite a large amount of study in this area, no single agent has been shown to have consistent efficacy in human trials. One promising class in this setting is ghrelin receptor agonists. Ghrelin binds to the growth hormone secretagogue-1a receptor in appetite-regulating centers in the brain, increasing expression of neuropeptide Y and agouti-related peptide during short-term treatment. Ghrelin has also been shown to have anti-inflammatory properties, which is significant, given that cachexia is thought to be produced at least partly by inflammation induced by the underlying disease. Animal studies have demonstrated efficacy using growth hormone secretagogue receptor agonists to treat cachexia caused by cancer, chemotherapy, and chronic kidney disease. Limited human trials using ghrelin or ghrelin receptor agonists in cancer and heart disease have shown improved appetite and body mass during treatment, although longer-term trials are needed to confirm sustained effects. Also uncertain--but an intriguing possibility--is whether the improved weight gain with ghrelin treatment might also lessen the severity of the underlying disease and improve outcomes.

  19. Intracoronary ghrelin infusion decreases coronary blood flow in anesthetized pigs.

    PubMed

    Grossini, Elena; Molinari, Claudio; Mary, David A S G; Ghigo, Ezio; Bona, Gianni; Vacca, Giovanni

    2007-02-01

    The peptide ghrelin has been linked to the atherosclerotic process and coronary artery disease. We planned to study, for the first time, the primary effects of ghrelin on the intact coronary circulation and determine the mechanisms involved. In 24 sodium pentobarbitone-anesthetized pigs, changes in anterior descending coronary blood flow caused by intracoronary infusion of ghrelin at constant heart rate and arterial pressure were assessed using electromagnetic flowmeters. In 20 pigs, intracoronary infusion of ghrelin decreased coronary blood flow without affecting left ventricular maximum rate of change of left ventricular systolic pressure (dP/dt(max)), filling pressures of the heart or plasma levels of GH. In four pigs, this decrease was graded by step increments of infused dose of the hormone. The mechanisms of the above response were studied in the 20 pigs by repeating the experiment after coronary flow had returned to the control values observed before infusion. The ghrelin-induced coronary vasoconstriction was not affected by iv atropine (five pigs) or phentolamine (five pigs). This response was abolished by iv butoxamine (five pigs) and intracoronary N(omega)-nitro-l-arginine methyl ester (five pigs), even after reversing the increase in arterial pressure and coronary vascular resistance caused by the two blocking agents with iv infusion of papaverine. The present study showed that intracoronary infusion of ghrelin primarily caused coronary vasoconstriction. The mechanisms of this response were shown to involve the inhibition of a vasodilatory beta(2)-adrenergic receptor-mediated effect related to the release of nitric oxide.

  20. Ghrelin attenuates the growth of HO-8910 ovarian cancer cells through the ERK pathway

    PubMed Central

    Bai, R.X.; Wang, W.P.; Zhao, P.W.; Li, C.B.

    2016-01-01

    Ovarian cancer is one of the most common causes of death from gynecologic tumors and is an important public health issue. Ghrelin is a recently discovered bioactive peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR). Several studies have identified the protective effects of ghrelin on the mammalian reproductive system. However, little research has been done on the effects of ghrelin on ovarian cancer cells, and the underlying mechanisms of these effects. We sought to understand the potential involvement of mitogen-activated protein kinases (MAPKs) in ghrelin-mediated inhibition of growth of the ovarian line HO-8910. We applied different concentrations of ghrelin and an inhibitor of the ghrelin receptor (D-Lys3-GHRP-6) to HO-8910 cells and observed the growth rate of cells and changes in phosphorylation of the MAPKs ERK1/2, JNK and p38. We discovered that ghrelin-induced apoptosis of HO-8910 cells was though phosphorylated ERK1/2, and that this phosphorylation (as well as p90rsk phosphorylation) was mediated by the GHSR. The ERK1/2 pathway is known to play an essential part in the ghrelin-mediated apoptosis of HO-8910 cells. Hence, our study suggests that ghrelin inhibits the growth of HO-8910 cells primarily through the GHSR/ERK pathway. PMID:26840702

  1. Ghrelin directly stimulates adult hippocampal neurogenesis: implications for learning and memory.

    PubMed

    Li, Endan; Chung, Hyunju; Kim, Yumi; Kim, Dong Hyun; Ryu, Jong Hoon; Sato, Takahiro; Kojima, Masayasu; Park, Seungjoon

    2013-01-01

    Adult hippocampal neurogenesis is important in mediating hippocampal-dependent learning and memory. Exogenous ghrelin is known to stimulate progenitor cell proliferation in the dentate gyrus of adult hippocampus. The aim of this study was to investigate the role of endogenous ghrelin in regulating the in vivo proliferation and differentiation of the newly generating cells in the adult hippocampus using ghrelin knockout (GKO) mice. Targeted deletion of ghrelin gene resulted in reduced numbers of progenitor cells in the subgranular zone (SGZ) of the hippocampus, while ghrelin treatment restored progenitor cell numbers to those of wild-type controls. We also found that not only the number of bromodeoxyuridine (BrdU)-positive cells but also the fraction of immature neurons and newly generated neurons were decreased in the GKO mice, which were increased by ghrelin replacement. Additionally, in the GKO mice, we observed impairment of memory performance in Y-maze task and novel object recognition test. However, these functional deficiencies were attenuated by ghrelin administration. These results suggest that ghrelin directly induces proliferation and differentiation of adult neural progenitor cells in the SGZ. Our data suggest ghrelin may be a plausible therapeutic potential to enhance learning and memory processes.

  2. Fos is an essential component of the mammalian UV response.

    PubMed Central

    Schreiber, M; Baumann, B; Cotten, M; Angel, P; Wagner, E F

    1995-01-01

    Mouse 3T3 fibroblasts lacking c-fos were employed to demonstrate an essential function of the UV-inducible transcription factor AP-1 (Fos/Jun) in the response to the cytotoxic effects of short-wavelength ultraviolet (UVC) radiation. Clonogenic survival and proliferation of cells lacking c-fos were drastically reduced following UV irradiation. This UV hypersensitivity manifests itself primarily in increased cell death, partly by apoptosis, and prolonged recovery time from UV-induced cell cycle arrest. Co-culture with wild-type cells did not ameliorate the hypersensitivity of mutant cells. Transcriptional induction of the c-Fos target genes collagenase I, stromelysin-1 and stromelysin-2 by UV is almost absent in cells lacking c-fos which correlates with a reduced UV induction of AP-1 DNA-binding and transactivation activity. The repair of UV-induced DNA lesions was not affected, as shown by unscheduled DNA synthesis and host cell reactivation assays. These data demonstrate that c-Fos is involved in a novel protective function other than DNA repair against the harmful consequences of UVC. Images PMID:7489723

  3. Colocalization of Mating-Induced Fos and D2-Like Dopamine Receptors in the Medial Preoptic Area: Influence of Sexual Experience

    PubMed Central

    Nutsch, Victoria L.; Will, Ryan G.; Robison, Christopher L.; Martz, Julia R.; Tobiansky, Daniel J.; Dominguez, Juan M.

    2016-01-01

    Dopamine in the medial preoptic area (mPOA) stimulates sexual activity in males. This is evidenced by microdialysis and microinjection experiments revealing that dopamine receptor antagonists in the mPOA inhibit sexual activity, whereas agonists facilitate behavior. Microdialysis experiments similarly show a facilitative role for dopamine, as levels of dopamine in the mPOA increase with mating. While the majority of evidence suggests an important role for dopamine receptors in the mPOA in the regulation of male sexual behaviors, whether sexual activity or sexual experience influence dopamine receptor function in the mPOA has not been previously shown. Here we used immunohistochemical assays to determine whether varying levels of sexual activity or experience influence the number of cells containing Fos or D2 receptor immunoreactivity. Results show that sexual experience facilitated subsequent behavior, namely experience decreased latencies. Moreover, the number of cells with immunoreactivity for Fos or D2 correlated with levels of sexual experience and sexual activity. Sexual activity increased Fos immunoreactivity. Sexually experienced animals also had significantly more D2-positive cells. Sexually inexperienced animals copulating for the first time had a larger percentage of D2-positive cells containing Fos, when compared to sexually experienced animals. Finally, regardless of experience, animals that had sex prior to sacrifice had significantly more D2-positive cells that contained Fos, vs. animals that did not copulate. These findings are noteworthy because sexually experienced animals display increased sexual efficiency. The differences in activation of D2 and changes in receptor density may play a role in this efficiency and other behavioral changes across sexual experience. PMID:27147996

  4. Prevention of diet-induced obesity by safflower oil: insights at the levels of PPARalpha, orexin, and ghrelin gene expression of adipocytes in mice.

    PubMed

    Zhang, Zhong; Li, Qiang; Liu, Fengchen; Sun, Yuqian; Zhang, Jinchao

    2010-03-15

    The aim of this study was to investigate the prevention of diet-induced obesity by a high safflower oil diet and adipocytic gene expression in mice. Forty 3-week-old C57BL/6 mice were randomly divided into three groups: control group (CON, 5% lard + 5% safflower oil), high lard group (LAR, 45% lard + 5% safflower oil), and high safflower oil group (SAF, 45% safflower oil + 5% lard). After 10 weeks, 10 mice of the LAR group were switched to high safflower oil diet (LAR-SAF). Ten weeks later, glucose tolerance tests were performed by intraperitoneal injection of glucose. Circulating levels of lipid and insulin were measured and white adipose tissues were taken for gene chip and reverse transcriptase-polymerase chain reaction analysis. The LAR group showed higher body weight, adiposity index, insulin, and lipids than the CON group (P<0.05). The body weight in the LAR-SAF group decreased after dietary reversal. The plasma biochemical profiles decreased in the LAR-SAF and SAF groups (P<0.05) compared with those of the LAR group. The blood glucose level of the LAR-SAF group was reduced during intraperitoneal glucose tolerance test compared with that of the LAR group. The LAR-SAF group had lower levels of Orexin and Ghrelin gene expression, whereas the level of PPARalpha gene expression was significantly enhanced compared with that of the LAR group. So, the SAF diet can alter adipocytic adiposity-related gene expression and result in effective amelioration of diet-induced obesity.

  5. cAMP and in vivo hypoxia induce tob, ifr1, and fos expression in erythroid cells of the chick embryo.

    PubMed

    Dragon, Stefanie; Offenhäuser, Nina; Baumann, Rosemarie

    2002-04-01

    During avian embryonic development, terminal erythroid differentiation occurs in the circulation. Some of the key events, such as the induction of erythroid 2,3-bisphosphoglycerate (2,3-BPG), carbonic anhydrase (CAII), and pyrimidine 5'-nucleotidase (P5N) synthesis are oxygen dependent (Baumann R, Haller EA, Schöning U, and Weber M, Dev Biol 116: 548-551, 1986; Dragon S and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 280: R870-R878, 2001; Dragon S, Carey C, Martin K, and Baumann R, J Exp Biol 202: 2787-2795, 1999; Dragon S, Glombitza S, Götz R, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon S, Hille R, Götz R, and Baumann R, Blood 91: 3052-3058, 1998; Million D, Zillner P, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 261: R1188-R1196, 1991) in an indirect way: hypoxia stimulates the release of norepinephrine (NE)/adenosine into the circulation (Dragon et al., J Exp Biol 202: 2787-2795, 1999; Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996). This leads via erythroid beta-adrenergic/adenosine A(2) receptor activation to a cAMP signal inducing several proteins in a transcription-dependent manner (Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon et al., Blood 91: 3052-3058, 1998; Glombitza S, Dragon S, Berghammer M, Pannermayr M, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R973-R981, 1996). To understand how the cAMP-dependent processes are initiated, we screened an erythroid cDNA library for cAMP-regulated genes. We detected three genes that were strongly upregulated (>5-fold) by cAMP in definitive and primitive red blood cells. They are homologous to the mammalian Tob, Ifr1, and Fos proteins. In addition, the genes are induced in the intact embryo during short-term hypoxia. Because the genes are regulators of proliferation and differentiation in other cell types, we suggest that c

  6. Impairment of FOS mRNA stabilization following translation arrest in granulocytes from myelodysplastic syndrome patients.

    PubMed

    Feng, Xiaomin; Shikama, Yayoi; Shichishima, Tsutomu; Noji, Hideyoshi; Ikeda, Kazuhiko; Ogawa, Kazuei; Kimura, Hideo; Takeishi, Yasuchika; Kimura, Junko

    2013-01-01

    Although quantitative and qualitative granulocyte defects have been described in myelodysplastic syndromes (MDS), the underlying molecular basis of granulocyte dysfunction in MDS is largely unknown. We recently found that FOS mRNA elevation under translation-inhibiting stimuli was significantly smaller in granulocytes from MDS patients than in healthy individuals. The aim of this study is to clarify the cause of the impaired FOS induction in MDS. We first examined the mechanisms of FOS mRNA elevation using granulocytes from healthy donors cultured with the translation inhibitor emetine. Emetine increased both transcription and mRNA stability of FOS. p38 MAPK inhibition abolished the emetine-induced increase of FOS transcription but did not affect FOS mRNA stabilization. The binding of an AU-rich element (ARE)-binding protein HuR to FOS mRNA containing an ARE in 3'UTR was increased by emetine, and the knockdown of HuR reduced the FOS mRNA stabilizing effect of emetine. We next compared the emetine-induced transcription and mRNA stabilization of FOS between MDS patients and healthy controls. Increased rates of FOS transcription by emetine were similar in MDS and controls. In the absence of emetine, FOS mRNA decayed to nearly 17% of initial levels in 45 min in both groups. In the presence of emetine, however, 76.7±19.8% of FOS mRNA remained after 45 min in healthy controls, versus 37.9±25.5% in MDS (P<0.01). To our knowledge, this is the first report demonstrating attenuation of stress-induced FOS mRNA stabilization in MDS granulocytes.

  7. Physiological roles revealed by ghrelin and ghrelin receptor deficient mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ghrelin is a hormone made in the stomach and known primarily for its growth hormone releasing and orexigenic properties. Nevertheless, ghrelin through its receptor, the GHS-R1a, has been shown to exert many roles including regulation of glucose homeostasis, memory & learning, food addiction and neur...

  8. Caloric restriction stimulates autophagy in rat cortical neurons through neuropeptide Y and ghrelin receptors activation

    PubMed Central

    Carmo-Silva, Sara; Botelho, Mariana; de Almeida, Luís Pereira; Cavadas, Cláudia

    2016-01-01

    Caloric restriction is an anti-aging intervention known to extend lifespan in several experimental models, at least in part, by stimulating autophagy. Caloric restriction increases neuropeptide Y (NPY) in the hypothalamus and plasma ghrelin, a peripheral gut hormone that acts in hypothalamus to modulate energy homeostasis. NPY and ghrelin have been shown to be neuroprotective in different brain areas and to induce several physiological modifications similar to those induced by caloric restriction. However, the effect of NPY and ghrelin in autophagy in cortical neurons is currently not known. Using a cell culture of rat cortical neurons we investigate the involvement of NPY and ghrelin in caloric restriction-induced autophagy. We observed that a caloric restriction mimetic cell culture medium stimulates autophagy in rat cortical neurons and NPY or ghrelin receptor antagonists blocked this effect. On the other hand, exogenous NPY or ghrelin stimulate autophagy in rat cortical neurons. Moreover, NPY mediates the stimulatory effect of ghrelin on autophagy in rat cortical neurons. Since autophagy impairment occurs in aging and age-related neurodegenerative diseases, NPY and ghrelin synergistic effect on autophagy stimulation may suggest a new strategy to delay aging process. PMID:27441412

  9. UCP2 mediates ghrelin's action on NPY/AgRP neurons by lowering free radicals

    PubMed Central

    Andrews, Zane B.; Liu, Zhong-Wu; Walllingford, Nicholas; Erion, Derek M.; Borok, Erzsebet; Friedman, Jeffery M.; Tschöp, Matthias H.; Shanabrough, Marya; Cline, Gary; Shulman, Gerald I.; Coppola, Anna; Gao, Xiao-Bing; Horvath, Tamas L.; Diano, Sabrina

    2014-01-01

    The gut-derived hormone ghrelin exerts its effect on the brain by regulating neuronal activity. Ghrelin-induced feeding behaviour is controlled by arcuate nucleus neurons that co-express neuropeptide Y and agouti-related protein (NPY/AgRP neurons). However, the intracellular mechanisms triggered by ghrelin to alter NPY/AgRP neuronal activity are poorly understood. Here we show that ghrelin initiates robust changes in hypothalamic mitochondrial respiration in mice that are dependent on uncoupling protein 2 (UCP2). Activation of this mitochondrial mechanism is critical for ghrelin-induced mitochondrial proliferation and electric activation of NPY/AgRP neurons, for ghrelin-triggered synaptic plasticity of pro-opiomelanocortin-expressing neurons, and for ghrelin-induced food intake. The UCP2-dependent action of ghrelin on NPY/AgRP neurons is driven by a hypothalamic fatty acid oxidation pathway involving AMPK, CPT1 and free radicals that are scavenged by UCP2. These results reveal a signalling modality connecting mitochondria-mediated effects of G-protein-coupled receptors on neuronal function and associated behaviour. PMID:18668043

  10. Peripheral ghrelin injections stimulate food intake, foraging, and food hoarding in Siberian hamsters.

    PubMed

    Keen-Rhinehart, Erin; Bartness, Timothy J

    2005-03-01

    Fasting triggers many effects, including increases in circulating concentrations of ghrelin, a primarily stomach-derived orexigenic hormone. Exogenous ghrelin treatment stimulates food intake, implicating it in fasting-induced increases in feeding, a consummatory ingestive behavior. In Siberian hamsters, fasting also stimulates appetitive ingestive behaviors such as foraging and food hoarding. Therefore, we tested whether systemic ghrelin injections (3, 30, and 200 mg/kg) would stimulate these appetitive behaviors using a running wheel-based food delivery system coupled with simulated burrow housing. We also measured active ghrelin plasma concentrations after exogenous ghrelin treatment and compared them to those associated with fasting. Hamsters had the following: 1) no running wheel access, free food; 2) running wheel access, free food; or 3) foraging requirement (10 revolutions/pellet), no free food. Ghrelin stimulated foraging at 0-1, 2-4, and 4-24 h postinjection but failed to affect wheel running activity not coupled to food. Ghrelin stimulated food intake initially (200-350%, first 4 h) across all groups; however, in hamsters with a foraging requirement, ghrelin also stimulated food intake 4-24 h postinjection (200-250%). Ghrelin stimulated food hoarding 2-72 h postinjection (100-300%), most markedly 2-4 h postinjection in animals lacking a foraging requirement (635%). Fasting increased plasma active ghrelin concentrations in a time-dependent fashion, with the 3- and 30-mg/kg dose creating concentrations of the peptide comparable to those induced by 24-48 h of fasting. Collectively, these data suggest that exogenous ghrelin, similar to fasting, increases appetitive behaviors (foraging, hoarding) by Siberian hamsters, but dissimilar to fasting in this species, stimulates food intake.

  11. Long-lasting c-fos and NGF mRNA expressions and loss of perikaryal parvalbumin immunoreactivity in the development of epileptogenesis after ethacrynic acid-induced seizure.

    PubMed

    Suzukawa, J; Omori, K; Okugawa, G; Fujiseki, Y; Heizmann, C W; Inagaki, C

    1999-07-10

    A single cerebroventricular injection of ethacrynic acid (EA), a Cl(-)-ATPase inhibitor, induces generalized tonic-clonic convulsions in mice. To clarify whether such convulsive stimulus triggers a long-lasting rearrangement of the neural circuitry culminating in seizure susceptibility, we examined molecular, cellular and behavioral changes following the EA-induced seizure. The expression of immediate early gene c-fos mRNA as an index for cellular activation increased biphasically, with an early transient increase at 60 min and a late prolonged increase on the 10th to 14th day post-EA administration, most remarkably in the hippocampus and pyriform cortex. On the 14th day post-EA seizure, subconvulsive dose of kainic acid (5-17.5 mg/kg) caused severe (stage 5) seizure in 77% of the mice, with 70% mortality. In addition, the expression of nerve growth factor (NGF) also showed biphasic increases with close spatiotemporal correlation with c-fos expression. Moreover, the number of cell somata and the density of axon fibers of parvalbumin (PARV)-positive cells, a subpopulation of GABAergic interneurons, decreased in area dentata, CA1 and CA3 on the 7th and 14th day post-EA seizure. In area dentata and CA1, the density of glutamic acid decarboxylase (GAD)-positive cells also decreased on the 14th day. Thus, the transient EA-induced seizures appear to develop seizure susceptibility by causing damage of a subpopulation of inhibitory interneurons along with increases in the expression of c-fos and NGF in limbic structures.

  12. Ghrelin and its interactions with growth hormone, leptin and orexins: implications for the sleep-wake cycle and metabolism.

    PubMed

    García-García, Fabio; Juárez-Aguilar, Enrique; Santiago-García, Juan; Cardinali, Daniel P

    2014-02-01

    Several studies have shown that ghrelin administration promotes wakefulness in rodents, while in human males it induces sleep but has no effect in women. Ghrelin also plays an important role in metabolism and appetite regulation, and as described in this review may participate in the energy balance during sleep. In this review, we summarize some of the effects induced by ghrelin administration on the sleep-wake cycle in relation to the effects of other hormones, such as growth hormone, leptin, and orexin. Finally we discuss the relationship between sleep deprivation, obesity and ghrelin secretion pattern.

  13. Ghrelin receptor agonist GHRP-2 prevents arthritis-induced increase in E3 ubiquitin-ligating enzymes MuRF1 and MAFbx gene expression in skeletal muscle.

    PubMed

    Granado, Miriam; Priego, Teresa; Martín, Ana I; Villanúa, Maria Angeles; López-Calderón, Asunción

    2005-12-01

    Chronic arthritis is a catabolic state associated with an inhibition of the IGF system and a decrease in body weight. Cachexia and muscular wasting is secondary to protein degradation by the ubiquitin-proteasome pathway. The aim of this work was to analyze the effect of adjuvant-induced arthritis on the muscle-specific ubiquitin ligases muscle ring finger 1 (MuRF1) and muscle atrophy F-box (MAFbx) as well as on IGF-I and IGF-binding protein-5 (IGFBP-5) gene expression in the skeletal muscle. We also studied whether the synthetic ghrelin receptor agonist, growth hormone releasing peptide-2 (GHRP-2), was able to prevent arthritis-induced changes in the skeletal muscle. Arthritis induced an increase in MuRF1, MAFbx (P < 0.01), and tumor necrosis factor (TNF)-alpha mRNA (P < 0.05) in the skeletal muscle. Arthritis decreased the serum IGF-I and its gene expression in the liver (P < 0.01), whereas it increased IGF-I and IGFBP-5 gene expression in the skeletal muscle (P < 0.01). Administration of GHRP-2 for 8 days prevented the arthritis-induced increase in muscular MuRF1, MAFbx, and TNF-alpha gene expression. GHRP-2 treatment increased the serum concentrations of IGF-I and the IGF-I mRNA in the liver and in the cardiac muscle and decreased muscular IGFBP-5 mRNA both in control and in arthritic rats (P < 0.05). GHRP-2 treatment increased muscular IGF-I mRNA in control rats (P < 0.01), but it did not modify the muscular IGF-I gene expression in arthritic rats. These data indicate that arthritis induces an increase in the activity of the ubiquitin-proteasome proteolytic pathway that is prevented by GHRP-2 administration. The parallel changes in muscular IGFBP-5 and TNF-alpha gene expression with the ubiquitin ligases suggest that they can participate in skeletal muscle alterations during chronic arthritis.

  14. Ghrelin-AMPK Signaling Mediates the Neuroprotective Effects of Calorie Restriction in Parkinson's Disease

    PubMed Central

    Bayliss, Jacqueline A.; Lemus, Moyra B.; Stark, Romana; Santos, Vanessa V.; Thompson, Aiysha; Rees, Daniel J.; Galic, Sandra; Elsworth, John D.; Kemp, Bruce E.; Davies, Jeffrey S.

    2016-01-01

    Calorie restriction (CR) is neuroprotective in Parkinson's disease (PD) although the mechanisms are unknown. In this study we hypothesized that elevated ghrelin, a gut hormone with neuroprotective properties, during CR prevents neurodegeneration in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. CR attenuated the MPTP-induced loss of substantia nigra (SN) dopamine neurons and striatal dopamine turnover in ghrelin WT but not KO mice, demonstrating that ghrelin mediates CR's neuroprotective effect. CR elevated phosphorylated AMPK and ACC levels in the striatum of WT but not KO mice suggesting that AMPK is a target for ghrelin-induced neuroprotection. Indeed, exogenous ghrelin significantly increased pAMPK in the SN. Genetic deletion of AMPKβ1 and 2 subunits only in dopamine neurons prevented ghrelin-induced AMPK phosphorylation and neuroprotection. Hence, ghrelin signaling through AMPK in SN dopamine neurons mediates CR's neuroprotective effects. We consider targeting AMPK in dopamine neurons may recapitulate neuroprotective effects of CR without requiring dietary intervention. SIGNIFICANCE STATEMENT The neuroprotective mechanisms of calorie restriction (CR) in Parkinson's disease are unknown. Indeed, the difficulty to adhere to CR necessitates an alternative method to recapitulate the neuroprotective benefits of CR while bypassing dietary constraints. Here we show that CR increases plasma ghrelin, which targets substantia nigra dopamine to maintain neuronal survival. Selective deletion on AMPK beta1 and beta2 subunits only in DAT cre-expressing neurons shows that the ghrelin-induced neuroprotection requires activation of AMPK in substantia nigra dopamine neurons. We have discovered ghrelin as a key metabolic signal, and AMPK in dopamine neurons as its target, which links calorie restriction with neuroprotection in Parkinson's disease. Thus, targeting AMPK in dopamine neurons may provide novel neuroprotective benefits in Parkinson's disease. PMID

  15. Novel molecular aspects of ghrelin and leptin in the control of adipobiology and the cardiovascular system.

    PubMed

    Rodríguez, Amaia

    2014-01-01

    Ghrelin and leptin show opposite effects on energy balance. Ghrelin constitutes a gut hormone that is secreted to the bloodstream in two major forms, acylated and desacyl ghrelin. The isoforms of ghrelin not only promote adiposity by the activation of hypothalamic orexigenic neurons but also directly stimulate the expression of several fat storage-related proteins in adipocytes, including ACC, FAS, LPL and perilipin, thereby stimulating intracytoplasmic lipid accumulation. Moreover, both acylated and desacyl ghrelin reduce TNF-α-induced apoptosis and autophagy in adipocytes, suggesting an anti-inflammatory role of ghrelin in human adipose tissue. On the other hand, leptin is an adipokine with lipolytic effects. In this sense, leptin modulates via PI3K/Akt/mTOR the expression of aquaglyceroporins such as AQP3 and AQP7 that facilitate glycerol efflux from adipocytes in response to the lipolytic stimuli via its translocation from the cytosolic fraction (AQP3) or lipid droplets (AQP7) to the plasma membrane. Ghrelin and leptin also participate in the homeostasis of the cardiovascular system. Ghrelin operates as a cardioprotective factor with increased circulating acylated ghrelin concentrations in patients with left ventricular hypertrophy (LVH) causally related to LV remodeling during the progression to LVH. Additionally, leptin induces vasodilation by inducible NO synthase expression (iNOS) in the vascular wall. In this sense, leptin inhibits the angiotensin II-induced Ca(2+) increase, contraction and proliferation of VSMC through NO-dependent mechanisms. Together, dysregulation of circulating ghrelin isoforms and leptin resistance associated to obesity, type 2 diabetes, or the metabolic syndrome contribute to cardiometabolic derangements observed in these pathologies.

  16. Regulation of oxidative stress and somatostatin, cholecystokinin, apelin gene expressions by ghrelin in stomach of newborn diabetic rats.

    PubMed

    Coskun, Zeynep Mine; Sacan, Ozlem; Karatug, Ayse; Turk, Neslihan; Yanardag, Refiye; Bolkent, Sehnaz; Bolkent, Sema

    2013-09-01

    The aim of the study was to determine whether ghrelin treatment has a protective effect on gene expression and biochemical changes in the stomach of newborn streptozotocin (STZ) induced diabetic rats. In this study, four groups of Wistar rats were used: control, ghrelin control, diabetic and diabetic+ghrelin. The rats were sacrificed after four weeks of treatment for diabetes. The gene expressions of: somatostatin, cholecystokinin, apelin and the altered active caspase-3, active caspase-8, proliferating cell nuclear antigen, were investigated in the pyloric region of the stomach and antioxidant parameters were measured in all the stomach. Although ghrelin treatment to diabetic rats lowered the stomach lipid peroxidation levels, the stomach glutathione levels were increased. Exogenous ghrelin caused an increased activities of stomach catalase, superoxide dismutase, glutathione reductase and glutathione peroxidase in diabetic rats. Numbers of somatostatin, cholecystokinin and proliferating cell nuclear antigen immunoreactive cells decreased in the diabetic+ghrelin group compared to the diabetic group. Apelin mRNA expressions were remarkably less in the diabetic+ghrelin rats than in diabetic rats. The results may indicate that ghrelin treatment has a protective effect to some extent on the diabetic rats. This protection is possibly accomplished through the antioxidant activity of ghrelin observed in type 2 diabetes. Consequently exogenous ghrelin may be a candidate for therapeutic treatment of diabetes.

  17. Expression of c-fos in auditory and non-auditory brain regions of the gerbil after manipulations that induce tinnitus.

    PubMed

    Wallhäusser-Franke, E; Mahlke, C; Oliva, R; Braun, S; Wenz, G; Langner, G

    2003-12-01

    Subjective tinnitus is a phantom sound sensation that does not result from acoustic stimulation and is audible to the affected subject only. Tinnitus-like sensations in animals can be evoked by procedures that also cause tinnitus in humans. In gerbils, we investigated brain activation after systemic application of sodium salicylate or exposure to loud noise, both known to be reliable tinnitus-inductors. Brains were screened for neurons containing the c-fos protein. After salicylate injections, auditory cortex was the only auditory area with consistently increased numbers of immunoreactive neurons compared to controls. Exposure to impulse noise led to prolonged c-fos expression in auditory cortex and dorsal cochlear nucleus. After both manipulations c-fos expression was increased in the amygdala, in thalamic midline, and intralaminar areas, in frontal cortex, as well as in hypothalamic and brainstem regions involved in behavioral and physiological defensive reactions. Activation of these non-auditory areas was attributed to acute stress, to aversive-affective components and autonomous reactions associated with the treatments and a resulting tinnitus. The present findings are in accordance with former results that provided evidence for suppressed activation in auditory midbrain but enhanced activation of the auditory cortex after injecting high doses of salicylate. In addition, our present results provide evidence that acute stress coinciding with a disruption of hearing may evoke activation of the auditory cortex. We interpret these results in favor of our model of central tinnitus generation.

  18. Brief pup exposure induces Fos expression in the lateral habenula and serotonergic caudal dorsal raphe nucleus of paternally experienced male California mice (Peromyscus californicus).

    PubMed

    de Jong, T R; Measor, K R; Chauke, M; Harris, B N; Saltzman, W

    2010-09-01

    Fathers play a substantial role in infant care in a small but significant number of mammalian species, including humans. However, the neural circuitry controlling paternal behavior is much less understood than its female counterpart. In order to characterize brain areas activated by paternal care, male California mice were separated from their female mate and litter for 3 h and then exposed to a pup or a control object (a glass pebble with the approximate size and oblong shape of a newborn pup) for 10 min. All males receiving a pup showed a strong paternal response towards it, whereas males receiving a pebble interacted with it only occasionally. Despite the clear behavioral differences, exposure to a pup did not increase Fos-like immunoreactivity (Fos-LIR) compared to a pebble in brain areas previously found to be associated with parental care, including the medial preoptic nucleus and medial bed nucleus of the stria terminalis. Pup exposure did, however, significantly increase Fos-LIR in the lateral habenula (LHb) and in predominantly serotonergic neurons in the caudal dorsal raphe nucleus (DRC), as compared to pebble exposure. Both the LHb and DRC are known to be involved in the behavioral responses to strong emotional stimuli; therefore, these areas might play a role in controlling parental behavior in male California mice.

  19. Overexpression of c-fos increases recombination frequency in human osteosarcoma cells.

    PubMed

    van den Berg, S; Rahmsdorf, H J; Herrlich, P; Kaina, B

    1993-05-01

    We have shown previously that overexpression of c-Ha-ras, v-mos or c-fos increases the spontaneous level of chromosomal aberrations and gene mutations in NIH 3T3 cells, and that reduction of the Fos protein level inhibits aberration induction by c-Ha-ras and v-mos and also by irradiation with ultraviolet light (van den Berg et al., Mol. Carcinogenesis, 4, 460-466). In order to examine whether fos is also involved in DNA recombination, thymidine kinase (tk) deficient human osteosarcoma cells containing two versions of the herpes simplex virus tk gene inactivated by base insertion were either transiently or stably transfected with various fos expression plasmids. The frequency of tk+ revertants was significantly enhanced both upon transient transfection with RSV-promoter-fos gene constructs and by stimulation of Fos synthesis in stably transfected cells harbouring an inducible metallothionein promoter-fos construct. No such increases were observed in cells transfected with plasmids containing a truncated version of c-fos. The data indicate that c-fos is involved in generating various types of genetic changes including homologous recombination; a role of c-fos in genetic instability may contribute to its action in tumor promotion and progression.

  20. Ghrelin O-acyltransferase (GOAT) and energy metabolism.

    PubMed

    Li, Ziru; Mulholland, Michael; Zhang, Weizhen

    2016-03-01

    Ghrelin O-acyltransferase (GOAT), a member of MBOATs family, is essential for octanoylation of ghrelin, which is required for active ghrelin to bind with and activate its receptor. GOAT is expressed mainly in the stomach, pancreas and hypothalamus. Levels of GOAT are altered by energy status. GOAT contains 11 transmembrane helices and one reentrant loop. Its invariant residue His-338 and conserved Asn-307 are located in the endoplasmic reticulum lumen and cytosol respectively. GOAT contributes to the regulation of food intake and energy expenditure, as well as glucose and lipids homeostasis. Deletion of GOAT blocks the acylation of ghrelin leading to subsequent impairment in energy homeostasis and survival when mice are challenged with high energy diet or severe caloric restriction. GO-CoA-Tat, a peptide GOAT inhibitor, attenuates acyl-ghrelin production and prevents weight gain induced by a medium-chain triglycerides-rich high fat diet. Further, GO-CoA-Tat increases glucose- induced insulin secretion. Overall, inhibition of GOAT is a novel strategy for treatment of obesity and related metabolic disorders.

  1. Is ghrelin a signal for the development of metabolic systems?

    PubMed Central

    Grove, Kevin L.; Cowley, Michael A.

    2005-01-01

    Ghrelin, produced in the stomach, acts on growth hormone secretagogue receptors (GHSRs) in hypothalamic neurons to potently increase food intake. However, male mice with deletions of ghrelin (Ghrl–/– mice) or GHSR (Ghsr–/– mice) display normal growth and regulation of food intake. Furthermore, adult Ghrl–/– mice display a normal sensitivity to high-fat diet–induced obesity. These findings from early studies raised the question as to whether the ghrelin system is an essential component for the regulation of food intake and body weight homeostasis. However, recent studies by Wortley et al. and Zigman et al. demonstrate that Ghrl–/– and Ghsr–/– mice are resistant to diet-induced obesity when fed a high-fat diet during the early post-weaning period. This commentary highlights 3 key issues raised by these 2 reports: (a) the impact of ghrelin on the development of metabolic systems; (b) the constitutive activity of GHSR; and (c) gender differences in the sensitivity to deletion of the ghrelin signaling system. PMID:16322785

  2. The ghrelin/obestatin balance in the physiological and pathological control of growth hormone secretion, body composition and food intake.

    PubMed

    Hassouna, R; Zizzari, P; Tolle, V

    2010-07-01

    Ghrelin and obestatin are two gastrointestinal peptides obtained by post-translational processing of a common precursor, preproghrelin. Ghrelin is an orexigenic and adipogenic peptide and a potent growth hormone secretagogue (GHS) modified by the enzyme ghrelin-O-acyl-transferase to bind and activate its receptor, the GHS-R. The ghrelin/GHS-R pathway is complex and the effects of ghrelin on GH secretion, adiposity and food intake appear to be relayed by distinct mechanisms involving different transduction signals and constitutive activity for the GH-R, different cofactors as modulators of endogenous ghrelin signalling and/or alternative ghrelin receptors. The discovery of obestatin in 2005 brought an additional level of complexity to this fascinating system. Obestatin was initially identified as an anorexigenic peptide and as the cognate ligand for GPR39, but its effect on food intake and its ability to activate GPR39 are still controversial. Although several teams failed to reproduce the anorexigenic actions of obestatin, this peptide has been shown to antagonise GH secretion and food intake induced by ghrelin and could be an interesting pharmacological tool to counteract the actions of ghrelin. Ghrelin and obestatin immunoreactivities are recovered in the blood with an ultradian pulsatility and their concentrations in plasma vary with the nutritional status of the body. It is still a matter of debate whether both hormones are regulated by independent mechanisms and whether obestatin is a physiologically relevant peptide. Nevertheless, a significant number of studies show that the ghrelin/obestatin ratio is modified in anorexia nervosa and obesity. This suggests that the ghrelin/obestatin balance could be essential to adapt the body's response to nutritional challenges. Although measuring ghrelin and obestatin in plasma is challenging because many forms of the peptides circulate, more sensitive and selective assays to detect the different preproghrelin

  3. Voluntary exercise contributed to an amelioration of abnormal feeding behavior, locomotor activity and ghrelin production concomitantly with a weight reduction in high fat diet-induced obese rats.

    PubMed

    Mifune, Hiroharu; Tajiri, Yuji; Nishi, Yoshihiro; Hara, Kento; Iwata, Shimpei; Tokubuchi, Ichiro; Mitsuzono, Ryouichi; Yamada, Kentaro; Kojima, Masayasu

    2015-09-01

    In the present study, effects of voluntary exercise in an obese animal model were investigated in relation to the rhythm of daily activity and ghrelin production. Male Sprague-Dawley rats were fed either a high fat diet (HFD) or a chow diet (CD) from four to 16 weeks old. They were further subdivided into either an exercise group (HFD-Ex, CD-Ex) with a running wheel for three days of every other week or sedentary group (HFD-Se, CD-Se). At 16 weeks old, marked increases in body weight and visceral fat were observed in the HFD-Se group, together with disrupted rhythms of feeding and locomotor activity. The induction of voluntary exercise brought about an effective reduction of weight and fat, and ameliorated abnormal rhythms of activity and feeding in the HFD-Ex rats. Wheel counts as voluntary exercise was greater in HFD-Ex rats than those in CD-Ex rats. The HFD-obese had exhibited a deterioration of ghrelin production, which was restored by the induction of voluntary exercise. These findings demonstrated that abnormal rhythms of feeding and locomotor activity in HFD-obese rats were restored by infrequent voluntary exercise with a concomitant amelioration of the ghrelin production and weight reduction. Because ghrelin is related to food anticipatory activity, it is plausible that ghrelin participates in the circadian rhythm of daily activity including eating behavior. A beneficial effect of voluntary exercise has now been confirmed in terms of the amelioration of the daily rhythms in eating behavior and physical activity in an animal model of obesity.

  4. C-Fos Regulation by the MAPK and PKC Pathways in Intervertebral Disc Cells

    PubMed Central

    Yokoyama, Katsuya; Hiyama, Akihiko; Arai, Fumiyuki; Nukaga, Tadashi; Sakai, Daisuke; Mochida, Joji

    2013-01-01

    Background The gene encoding c-fos is an important factor in the pathogenesis of joint disease in patients with osteoarthritis. However, it is unknown whether the signal mechanism of c-fos acts in intervertebral disc (IVD) cells. We investigated whether c-fos is activated in relation to mitogen-activated protein kinases (MAPKs) and the protein kinase C (PKC) pathway in nucleus pulposus (NP) cells. Methodology/Results Reverse transcription-polymerase chain reaction and western blotting analyses were used to measure the expression of c-fos in rat IVD cells. Transfections were performed to determine the effects of c-fos on target gene activity. The effect of c-fos protein expression was examined in transfection experiments and in a 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide cell viability assay. Phorbol 12-myristate 13-acetate (PMA), the most commonly used phorbol ester, binds to and activates protein kinase C (PKC), causing a wide range of effects in cells and tissues. PMA induced the expression of c-fos gene transcription and protein expression, and led to activation of the MAPK pathways in NP cells. The c-fos promoter was suppressed completely in the presence of the MAPK inhibitor PD98059, an inhibitor of the MEK/ERK kinase cascade, but not in the presence of SKF86002, SB202190, or SP600125. The effects of the PKC pathway on the transcriptional activity of the c-fos were evaluated. PKCγ and PKCδ suppressed the promoter activity of c-fos. Treatment with c-fos inhibited aggrecan and Col2 promoter activities and the expression of these genes in NP cells. Conclusions This study demonstrated, for the first time, that the MAPK and PKC pathways had opposing effects on the regulation of c-fos in NP cells. Thus, the expression of c-fos can be suppressed in the extracellular matrix of NP cells. PMID:24023832

  5. Osteoblasts are target cells for transformation in c-fos transgenic mice

    PubMed Central

    1993-01-01

    We have generated transgenic mice expressing the proto-oncogene c-fos from an H-2Kb class I MHC promoter as a tool to identify and isolate cell populations which are sensitive to altered levels of Fos protein. All homozygous H2-c-fosLTR mice develop osteosarcomas with a short latency period. This phenotype is specific for c-fos as transgenic mice expressing the fos- and jun-related genes, fosB and c-jun, from the same regulatory elements do not develop any pathology despite high expression in bone tissues. The c-fos transgene is not expressed during embryogenesis but is expressed after birth in bone tissues before the onset of tumor formation, specifically in putative preosteoblasts, bone- forming osteoblasts, osteocytes, as well as in osteoblastic cells present within the tumors. Primary and clonal cell lines established from c-fos-induced tumors expressed high levels of exogenous c-fos as well as the bone cell marker genes, type I collagen, alkaline phosphatase, and osteopontin/2ar. In contrast, osteocalcin/BGP expression was either low or absent. All cell lines were tumorigenic in vivo, some of which gave rise to osteosarcomas, expressing exogenous c- fos mRNA, and Fos protein in osteoblastic cells. Detailed analysis of one osteogenic cell line, P1, and several P1-derived clonal cell lines indicated that bone-forming osteoblastic cells were transformed by Fos. The regulation of osteocalcin/BGP and alkaline phosphatase gene expression by 1,25-dihydroxyvitamin D3 was abrogated in P1-derived clonal cells, whereas glucocorticoid responsiveness was unaltered. These results suggest that high levels of Fos perturb the normal growth control of osteoblastic cells and exert specific effects on the expression of the osteoblast phenotype. PMID:8335693

  6. Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis by inhibiting the activation of nuclear factor-kappa B

    SciTech Connect

    Cheng, Jian; Zhang, Lin; Dai, Weiqi; Mao, Yuqing; Li, Sainan; Wang, Jingjie; Li, Huanqing; Guo, Chuanyong; Fan, Xiaoming

    2015-02-27

    Aim: This study aimed to investigate the effect and underlying mechanism of ghrelin on intestinal barrier dysfunction in dextran sulfate sodium (DSS)-induced colitis. Methods and results: Acute colitis was induced in C57BL/6J mice by administering 2.5% DSS. Saline or 25, 125, 250 μg/kg ghrelin was administrated intraperitoneally (IP) to mice 1 day before colitis induction and on days 4, 5, and 6 after DSS administration. IP injection of a ghrelin receptor antagonist, [D-lys{sup 3}]-GHRP-6, was performed immediately prior to ghrelin injection. Ghrelin (125 or 250 μg/kg) could reduce the disease activity index, histological score, and myeloperoxidase activities in experimental colitis, and also prevented shortening of the colon. Ghrelin could prevent the reduction of transepithelial electrical resistance and tight junction expression, and bolstered tight junction structural integrity and regulated cytokine secretion. Ultimately, ghrelin inhibited nuclear factor kappa B (NF-κB), inhibitory κB-α, myosin light chain kinase, and phosphorylated myosin light chain 2 activation. Conclusions: Ghrelin prevented the breakdown of intestinal barrier function in DSS-induced colitis. The protective effects of ghrelin on intestinal barrier function were mediated by its receptor GHSR-1a. The inhibition of NF-κB activation might be part of the mechanism underlying the effects of ghrelin that protect against barrier dysfunction. - Highlights: • Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis. • The effect of ghrelin is mediated by GHSR-1a. • Inhibition of NF-κB activation.

  7. Ghrelin and obestatin modulate growth hormone-releasing hormone release and synaptic inputs onto growth hormone-releasing hormone neurons.

    PubMed

    Feng, Dan D; Yang, Seung-Kwon; Loudes, Catherine; Simon, Axelle; Al-Sarraf, Tamara; Culler, Michael; Alvear-Perez, Rodrigo; Llorens-Cortes, Catherine; Chen, Chen; Epelbaum, Jacques; Gardette, Robert

    2011-09-01

    Ghrelin, a natural ligand of the growth hormone secretagogue receptor (GHS-R), is synthesized in the stomach but may also be expressed in lesser quantity in the hypothalamus where the GHS-R is located on growth hormone-releasing hormone (GHRH) neurons. Obestatin, a peptide derived from the same precursor as ghrelin, is able to antagonize the ghrelin-induced increase of growth hormone (GH) secretion in vivo but not from pituitary explants in vitro. Thus, the blockade of ghrelin-induced GH release by obestatin could be mediated at the hypothalamic level by the neuronal network that controls pituitary GH secretion. Ghrelin increased GHRH and decreased somatostatin (somatotropin-releasing inhibitory factor) release from hypothalamic explants, whereas obestatin only reduced the ghrelin-induced increase of GHRH release, thus indicating that the effect of ghrelin and obestatin is targeted to GHRH neurons. Patch-clamp recordings on mouse GHRH-enhanced green fluorescent protein neurons indicated that ghrelin and obestatin had no significant effects on glutamatergic synaptic transmission. Ghrelin decreased GABAergic synaptic transmission in 44% of the recorded neurons, an effect blocked in the presence of the GHS-R antagonist BIM28163, and stimulated the firing rate of 78% of GHRH neurons. Obestatin blocked the effects of ghrelin by acting on a receptor different from the GHS-R. These data suggest that: (i) ghrelin increases GHRH neuron excitability by increasing their action potential firing rate and decreasing the strength of GABA inhibitory inputs, thereby leading to an enhanced GHRH release; and (ii) obestatin counteracts ghrelin actions. Such interactions on GHRH neurons probably participate in the control of GH secretion.

  8. Using c-fos to study neuronal ensembles in corticostriatal circuitry of addiction

    PubMed Central

    Cruz, Fabio C.; Rubio, F. Javier; Hope, Bruce T.

    2014-01-01

    Learned associations between drugs and environment play an important role in addiction and are thought to be encoded within specific patterns of sparsely distributed neurons called neuronal ensembles. This hypothesis is supported by correlational data from in vivo electrophysiology and cellular imaging studies in relapse models in rodents. In particular, cellular imaging with the immediate early gene c-fos and its protein product Fos has been used to identify sparsely distributed neurons that were strongly activated during conditioned drug behaviors such as drug self-administration and context- and cue-induced reinstatement of drug seeking. Here we review how Fos and the c-fos promoter have been employed to demonstrate causal roles for Fos-expressing neuronal ensembles in prefrontal cortex and nucleus accumbens in conditioned drug behaviors. This work has allowed identification of unique molecular and electrophysiological alterations within Fos-expressing neuronal ensembles that may contribute to the development and expression of learned associations in addiction. PMID:25446457

  9. Impaired wake-promoting mechanisms in ghrelin receptor-deficient mice.

    PubMed

    Esposito, Matthew; Pellinen, Jacob; Kapás, Levente; Szentirmai, Éva

    2012-01-01

    Ghrelin receptors are expressed by key components of the arousal system. Exogenous ghrelin induces behavioral activation, promotes wakefulness and stimulates eating. We hypothesized that ghrelin-sensitive mechanisms play a role in the arousal system. To test this, we investigated the responsiveness of ghrelin receptor knockout (KO) mice to two natural wake-promoting stimuli. Additionally, we assessed the integrity of their homeostatic sleep-promoting system using sleep deprivation. There was no significant difference in the spontaneous sleep-wake activity between ghrelin receptor KO and wild-type (WT) mice. WT mice mounted robust arousal responses to a novel environment and food deprivation. Wakefulness increased for 6 h after cage change accompanied by increases in body temperature and locomotor activity. Ghrelin receptor KO mice completely lacked the wake and body temperature responses to new environment. When subjected to 48 h food deprivation, WT mice showed marked increases in their waking time during the dark periods of both days. Ghrelin receptor KO mice failed to mount an arousal response on the first night and wake increases were attenuated on the second day. The responsiveness to sleep deprivation did not differ between the two genotypes. These results indicate that the ghrelin-receptive mechanisms play an essential role in the function of the arousal system but not in homeostatic sleep-promoting mechanisms.

  10. Ghrelin activates hypophysiotropic corticotropin-releasing factor neurons independently of the arcuate nucleus.

    PubMed

    Cabral, Agustina; Portiansky, Enrique; Sánchez-Jaramillo, Edith; Zigman, Jeffrey M; Perello, Mario

    2016-05-01

    Previous work has established that the hormone ghrelin engages the hypothalamic-pituitary-adrenal neuroendocrine axis via activation of corticotropin-releasing factor (CRF) neurons of the hypothalamic paraventricular nucleus (PVN). The neuronal circuitry that mediates this effect of ghrelin is currently unknown. Here, we show that ghrelin-induced activation of PVN CRF neurons involved inhibition of γ-aminobutyric acid (GABA) inputs, likely via ghrelin binding sites that were localized at GABAergic terminals within the PVN. While ghrelin activated PVN CRF neurons in the presence of neuropeptide Y (NPY) receptor antagonists or in arcuate nucleus (ARC)-ablated mice, it failed to do it so in mice with ghrelin receptor expression limited to ARC agouti gene related protein (AgRP)/NPY neurons. These data support the notion that ghrelin activates PVN CRF neurons via inhibition of local GABAergic tone, in an ARC-independent manner. Furthermore, these data suggest that the neuronal circuits mediating ghrelin's orexigenic action vs. its role as a stress signal are anatomically dissociated.

  11. Arcuate AgRP neurons mediate orexigenic and glucoregulatory actions of ghrelin.

    PubMed

    Wang, Qian; Liu, Chen; Uchida, Aki; Chuang, Jen-Chieh; Walker, Angela; Liu, Tiemin; Osborne-Lawrence, Sherri; Mason, Brittany L; Mosher, Christina; Berglund, Eric D; Elmquist, Joel K; Zigman, Jeffrey M

    2014-02-01

    The hormone ghrelin stimulates eating and helps maintain blood glucose upon caloric restriction. While previous studies have demonstrated that hypothalamic arcuate AgRP neurons are targets of ghrelin, the overall relevance of ghrelin signaling within intact AgRP neurons is unclear. Here, we tested the functional significance of ghrelin action on AgRP neurons using a new, tamoxifen-inducible AgRP-CreER(T2) transgenic mouse model that allows spatiotemporally-controlled re-expression of physiological levels of ghrelin receptors (GHSRs) specifically in AgRP neurons of adult GHSR-null mice that otherwise lack GHSR expression. AgRP neuron-selective GHSR re-expression partially restored the orexigenic response to administered ghrelin and fully restored the lowered blood glucose levels observed upon caloric restriction. The normalizing glucoregulatory effect of AgRP neuron-selective GHSR expression was linked to glucagon rises and hepatic gluconeogenesis induction. Thus, our data indicate that GHSR-containing AgRP neurons are not solely responsible for ghrelin's orexigenic effects but are sufficient to mediate ghrelin's effects on glycemia.

  12. Ghrelin increases vagally-mediated gastric activity by central sites of action

    PubMed Central

    Swartz, Emily M.; Browning, Kirsteen N.; Travagli, R. Alberto; Holmes, Gregory M.

    2014-01-01

    Background Vagally dependent gastric reflexes are mediated through vagal afferent fibers synapsing upon neurons of the nucleus tractus solitarius (NTS) which, in turn modulate the preganglionic parasympathetic dorsal motor nucleus of the vagus (DMV) neurons within the medullary dorsal vagal complex (DVC). The expression and transport of ghrelin receptors has been documented for the afferent vagus nerve, and functional studies have confirmed that vagal pathways are integral to ghrelin-induced stimulation of gastric motility. However, the central actions of ghrelin within the DVC have not been explored fully. Methods We assessed the responses to ghrelin in fasted rats using: 1) in vivo measurements of gastric tone and motility following IVth ventricle application or unilateral microinjection of ghrelin into the dorsal vagal complex (DVC); and, 2) whole cell recordings from gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV) Results 1) IVth ventricle application or unilateral microinjection of ghrelin into the DVC elicited contractions of the gastric corpus via excitation of a vagal cholinergic efferent pathway; 2) Ghrelin facilitates excitatory, but not inhibitory, presynaptic transmission to DMV neurons. Conclusions Our data indicate that ghrelin acts centrally by activating excitatory synaptic inputs onto DMV neurons, resulting in increased cholinergic drive by way of vagal motor innervation to the stomach. PMID:24261332

  13. The expression of ghrelin O-acyltransferase (GOAT) in human tissues.

    PubMed

    Lim, Chung Thong; Kola, Blerina; Grossman, Ashley; Korbonits, Márta

    2011-01-01

    Ghrelin is a circulating growth hormone-releasing and appetite-inducing brain-gut peptide. It needs to be acylated on its serine-3 with octanoate for its endocrine actions. The acyl-transferase that catalyses ghrelin octanoylation has recently been identified and named as GOAT (ghrelin O-acyltransferase); GOAT enzyme is coded by the MBOAT4 gene. This study aimed to investigate GOAT expression in the human. The distribution of GOAT mRNA expression was studied in various human tissues using classical and real-time reverse transcription and polymerase chain reaction. GOAT expression was found in all tissues studied (stomach, adrenal cortex, breast, right and left colon, duodenum, jejunum, ileum, fat, Fallopian tube, gallbladder, lymph node, lymphocyte cell line, kidney, liver, lung, muscle, myocardium, pituitary, oesophagus, pancreas, ovary, placenta, prostate, testis, spleen and thyroid). The widespread expression of GOAT corresponds to the widespread distribution of ghrelin expression. GOAT expression was high in stomach and gut, the major ghrelin-secreting tissues, and in the pituitary, in which ghrelin is known to show autocrine and paracrine effects. Identification of GOAT expression in various tissues support the concept that in addition to the important endocrine effect of acylated ghrelin, the paracrine effects of locally synthetised and acylated ghrelin may be important.

  14. Importance of melanin-concentrating hormone receptor for the acute effects of ghrelin.

    PubMed

    Bjursell, Mikael; Egecioglu, Emil; Gerdin, Anna-Karin; Svensson, Lennart; Oscarsson, Jan; Morgan, David; Snaith, Michael; Törnell, Jan; Bohlooly-Y, Mohammad

    2005-01-28

    The hypothalamic peptide melanin-concentrating hormone (MCH) and the gastric hormone ghrelin take part in the regulation of energy homeostasis and stimulate food intake. In the present study, ghrelin was administered centrally to MCH-receptor knockout (MCHr KO) mice. MCHr KO mice and wild type (WT) controls both consumed more food when treated with ghrelin. After ghrelin administration, the serum levels of insulin increased only in WT mice whereas the serum levels of corticosterone increased both in WT and MCHr KO mice. The level of growth hormone (GH) mRNA in the pituitary gland was markedly increased in response to ghrelin injection in the WT mice but was unaffected in the MCHr KO mice. The different ghrelin responses could not be explained by a difference in growth hormone secretagogue receptor expression between MCHr KO and WT mice in the pituitary or hypothalamus. In summary, the MCHr is not required for ghrelin induced feeding. However, the MCHr does play a role for the effect of ghrelin on GH expression in the pituitary and serum insulin levels.

  15. Des-acyl ghrelin prevents heatstroke-like symptoms in rats exposed to high temperature and high humidity.

    PubMed

    Inoue, Yoshiyuki; Hayashi, Yujiro; Kangawa, Kenji; Suzuki, Yoshihiro; Murakami, Noboru; Nakahara, Keiko

    2016-02-26

    We have shown previously that des-acyl ghrelin decreases body temperature in rats through activation of the parasympathetic nervous system. Here we investigated whether des-acyl ghrelin ameliorates heatstroke in rats exposed to high temperature. Peripheral administration of des-acyl ghrelin significantly attenuated hyperthermia induced by exposure to high-temperature (35°C) together with high humidity (70-80%). Although biochemical analysis revealed that exposure to high temperature significantly increased hematocrit and the serum levels of aspartate amino transferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), creatinine and electrolytes (Na(+), K(+), Cl(-)), most of these heatstroke-associated reactions were significantly reduced by treatment with des-acyl ghrelin. The level of des-acyl ghrelin in plasma was also found to be significantly increased under high-temperature conditions. These results suggest that des-acyl ghrelin could be useful for preventing heatstroke under high temperature condition.

  16. Ghrelin acylation and metabolic control.

    PubMed

    Al Massadi, O; Tschöp, M H; Tong, J

    2011-11-01

    Since its discovery, many physiologic functions have been ascribed to ghrelin, a gut derived hormone. The presence of a median fatty acid side chain on the ghrelin peptide is required for the binding and activation of the classical ghrelin receptor, the growth hormone secretagogue receptor (GHSR)-1a. Ghrelin O-acyl transferase (GOAT) was recently discovered as the enzyme responsible for this acylation process. GOAT is expressed in all tissues that have been found to express ghrelin and has demonstrated actions on several complex endocrine organ systems such as the hypothalamus-pituitary-gonadal, insular and adrenal axis as well as the gastrointestinal (GI) tract, bone and gustatory system. Ghrelin acylation is dependent on the function of GOAT and the availability of substrates such as proghrelin and short- to medium-chain fatty acids (MCFAs). This process is governed by GOAT activity and has been shown to be modified by dietary lipids. In this review, we provided evidence that support an important role of GOAT in the regulation of energy homeostasis and glucose metabolism by modulating acyl ghrelin (AG) production. The relevance of GOAT and AG during periods of starvation remains to be defined. In addition, we summarized the recent literature on the metabolic effects of GOAT specific inhibitors and shared our view on the potential of targeting GOAT for the treatment of metabolic disorders such as obesity and type 2 diabetes.

  17. Ghrelin and gastrointestinal stromal tumors

    PubMed Central

    Zhu, Chang-Zhen; Liu, Dong; Kang, Wei-Ming; Yu, Jian-Chun; Ma, Zhi-Qiang; Ye, Xin; Li, Kang

    2017-01-01

    Ghrelin, as a kind of multifunctional protein polypeptide, is mainly produced in the fundus of the stomach and can promote occurrence and development of many tumors, including gastrointestinal tumors, which has been proved by the relevant researches. Most gastrointestinal stromal tumors (GISTs, about 80%), as the most common mesenchymal tumor, also develop in the fundus. Scientific research has confirmed that ghrelin, its receptors and mRNA respectively can be found in GISTs, which demonstrated the existence of a ghrelin autocrine/paracrine loop in GIST tissues. However, no reports to date have specified the mechanism whether ghrelin can promote the occurrence and development of GISTs. Studies of pulmonary artery endothelial cells in a low-oxygen environment and cardiac muscle cells in an ischemic environment have shown that ghrelin can activate the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway. Moreover, some studies of GISTs have confirmed that activation of the PI3K/AKT/mTOR pathway can indeed promote the growth and progression of GISTs. Whether ghrelin is involved in the development or progression of GISTs through certain pathways remains unknown. Can we find a new target for the treatment of GISTs? This review explores and summaries the relationship among ghrelin, the PI3K/AKT/mTOR pathway and the development of GISTs. PMID:28348480

  18. Ghrelin and gastrointestinal stromal tumors.

    PubMed

    Zhu, Chang-Zhen; Liu, Dong; Kang, Wei-Ming; Yu, Jian-Chun; Ma, Zhi-Qiang; Ye, Xin; Li, Kang

    2017-03-14

    Ghrelin, as a kind of multifunctional protein polypeptide, is mainly produced in the fundus of the stomach and can promote occurrence and development of many tumors, including gastrointestinal tumors, which has been proved by the relevant researches. Most gastrointestinal stromal tumors (GISTs, about 80%), as the most common mesenchymal tumor, also develop in the fundus. Scientific research has confirmed that ghrelin, its receptors and mRNA respectively can be found in GISTs, which demonstrated the existence of a ghrelin autocrine/paracrine loop in GIST tissues. However, no reports to date have specified the mechanism whether ghrelin can promote the occurrence and development of GISTs. Studies of pulmonary artery endothelial cells in a low-oxygen environment and cardiac muscle cells in an ischemic environment have shown that ghrelin can activate the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway. Moreover, some studies of GISTs have confirmed that activation of the PI3K/AKT/mTOR pathway can indeed promote the growth and progression of GISTs. Whether ghrelin is involved in the development or progression of GISTs through certain pathways remains unknown. Can we find a new target for the treatment of GISTs? This review explores and summaries the relationship among ghrelin, the PI3K/AKT/mTOR pathway and the development of GISTs.

  19. DeltaFosB in the nucleus accumbens is critical for reinforcing effects of sexual reward

    PubMed Central

    Pitchers, Kyle K.; Frohmader, Karla S.; Vialou, Vincent; Mouzon, Ezekiell; Nestler, Eric J.; Lehman, Michael N.; Coolen, Lique M.

    2010-01-01

    Sexual behavior in male rats is rewarding and reinforcing. However, little is known about the specific cellular and molecular mechanisms mediating sexual reward or the reinforcing effects of reward on subsequent expression of sexual behavior. The current study tests the hypothesis that ΔFosB, the stably expressed truncated form of FosB, plays a critical role in the reinforcement of sexual behavior and experience-induced facilitation of sexual motivation and performance. Sexual experience was shown to cause ΔFosB accumulation in several limbic brain regions including the nucleus accumbens (NAc), medial prefrontal cortex, ventral tegmental area and caudate putamen, but not the medial preoptic nucleus. Next, the induction of c-Fos, a downstream (repressed) target of ΔFosB, was measured in sexually experienced and naïve animals. The number of mating-induced c-Fos-IR cells was significantly decreased in sexually experienced animals compared to sexually naïve controls. Finally, ΔFosB levels and its activity in the NAc were manipulated using viral-mediated gene transfer to study its potential role in mediating sexual experience and experience-induced facilitation of sexual performance. Animals with ΔFosB over-expression displayed enhanced facilitation of sexual performance with sexual experience relative to controls. In contrast, the expression of ΔJunD, a dominant-negative binding partner of ΔFosB, attenuated sexual experience-induced facilitation of sexual performance, and stunted long-term maintenance of facilitation compared to GFP and ΔFosB over-expressing groups. Together, these findings support a critical role for ΔFosB expression in the NAc for the reinforcing effects of sexual behavior and sexual experience-induced facilitation of sexual performance. PMID:20618447

  20. A Signaling Network Controlling Androgenic Repression of c-Fos Protein in Prostate Adenocarcinoma Cells*

    PubMed Central

    Shankar, Eswar; Song, Kyung; Corum, Sarah L.; Bane, Kara L.; Wang, Hui; Kao, Hung-Ying; Danielpour, David

    2016-01-01

    The transcription factor c-Fos controls many important cellular processes, including cell growth and apoptosis. c-Fos expression is rapidly elevated in the prostate upon castration-mediated androgen withdrawal through an undefined mechanism. Here we show that androgens (5α-dihydrotestosterone and R1881) suppress c-Fos protein and mRNA expression induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) or EGF in human prostate cancer (PCa) cell lines. Such suppression transpires through a transcriptional mechanism, predominantly at the proximal serum response element of the c-fos promoter. We show that androgen signaling suppresses TPA-induced c-Fos expression through repressing a PKC/MEK/ERK/ELK-1 signaling pathway. Moreover, our results support the hypothesis that p38MAPK, PI3K, and PKCδ are involved in the androgenic regulation of c-Fos through controlling MEK/ERK. Stable silencing of c-Fos and PKCδ with shRNAs suggests that R1881 promotes cell death induced by low-dose TPA through a mechanism that is dependent on both PKCδ and loss of c-Fos expression. Reciprocally, loss of either PKCδ or c-Fos activates p38MAPK while suppressing the activation of ERK1/2. We also provide the first demonstration that R1881 permits cell death induced by low-dose TPA in the LNCaP androgen-dependent PCa cell line and that TPA-induced cell death is independent of exogenous androgen in the castration-resistant variants of LNCaP, C4-2 and C4-2B. Acquisition of androgen-independent killing by TPA correlates with activation of p38MAPK, suppression of ERK1/2, and loss of c-Fos. These results provide new insights into androgenic control of c-Fos and use of PKC inhibitors in PCa therapy. PMID:26786102

  1. Ghrelin does not affect gastrointestinal contractility in rainbow trout and goldfish in vitro.

    PubMed

    Kitazawa, Takio; Itoh, Kentaro; Yaosaka, Noriko; Maruyama, Keisuke; Matsuda, Kouhei; Teraoka, Hiroki; Kaiya, Hiroyuki

    2012-09-15

    Ghrelin has been identified in rainbow trout and goldfish, and it has been shown to regulate growth hormone release and food intake in these species as seen in mammals. The aim of this study was to investigate the functional role of ghrelin in regulation of gastrointestinal contractility in both fishes. Neither rainbow trout ghrelin nor rat ghrelin affected the contractility of gastrointestinal strips of rainbow trout. Similarly, goldfish ghrelin-17 and rat ghrelin did not cause marked contraction in the goldfish intestinal bulb. Detail examinations using the goldfish intestine revealed that human neurotensin, substance-P, goldfish neuromedine-U and carbachol showed apparent contractile activities in the intestinal strips. Electrical field stimulation (EFS, 1-20 Hz) caused a frequency-dependent contraction of the intestinal bulb. Atropine partially inhibited and tetrodotoxin abolished the EFS-induced contraction. Pretreatments with goldfish ghrelin-17 and rat ghrelin did not modify the EFS-induced contraction. The mRNAs of two types of growth hormone secretagogue receptor (GHS-R), GHS-R1a-1 and GHS-R1a-2, were detected in the goldfish intestine, and the expression level of GHS-R1a-2 was 4-times higher than that of GHS-R1a-1. The expression levels of GHS-R1a-1 and GHS-R1a-2 in four regions of the goldfish intestine (intestinal bulb, intestine-1, intestine-2 and intestine-3) were almost the same. In conclusion, ghrelin does not affect gastrointestinal contractility of the rainbow trout and goldfish, although GHSR-like receptor/GHS-R1a is expressed entire intestine. These results suggest diversity of ghrelin function in vertebrates.

  2. Correlation of Fos expression and circling asymmetry during gerbil vestibular compensation

    NASA Technical Reports Server (NTRS)

    Kaufman, G. D.; Shinder, M. E.; Perachio, A. A.

    1999-01-01

    Vestibular compensation is a central nervous system process resulting in recovery of functional movement and control following a unilateral vestibular lesion. Small pressure injections of phosphorothioate 20mer oligonucleotides were used to probe the role of the Fos transcription protein during vestibular compensation in the gerbil brainstem. During isoflurane gas anesthesia, antisense probes against the c-fos mRNA sequence were injected into the medial vestibular and prepositus nuclei unilaterally prior to a unilateral surgical labyrinthectomy. Anionic dyes, which did not interact with the oligonucleotides, were used to mark the injection site and help determine the extent of diffusion. The antiFos oligonucleotide injections reduced Fos expression at the injection site in neurons which normally express Fos after the lesion, and also affected circling behavior induced by hemilabyrinthectomy. With both ipsilateral and contralateral medial vestibular and prepositus nuclei injections, less ipsilateral and more contralateral circling was noted in animals injected with antiFos injections as compared to non-injected controls. The degree of change in these behaviors was dependent upon the side of the injection. Histologically, antiFos injections reduced the number of Fos immunolabeled neurons around the injection site, and increased Fos expression contralaterally. The correlation of the number of neurons with Fos expression to turning behavior was stronger for contralateral versus ipsilateral turns, and for neurons in the caudal and ipsilateral sub-regions of the medial vestibular and prepositus nuclei. The results are discussed in terms of neuronal firing activity versus translational activity based on the asymmetrical expression of the Fos inducible transcription factor in the medial vestibular and prepositus nuclei. Although ubiquitous in the brain, transcription factors like Fos can serve localized and specific roles in sensory-specific adaptive stimuli. Antisense

  3. The Neurobiological Impact of Ghrelin Suppression after Oesophagectomy

    PubMed Central

    Murphy, Conor F.; le Roux, Carel W.

    2016-01-01

    Ghrelin, discovered in 1999, is a 28-amino-acid hormone, best recognized as a stimulator of growth hormone secretion, but with pleiotropic functions in the area of energy homeostasis, such as appetite stimulation and energy expenditure regulation. As the intrinsic ligand of the growth hormone secretagogue receptor (GHS-R), ghrelin appears to have a broad array of effects, but its primary role is still an area of debate. Produced mainly from oxyntic glands in the stomach, but with a multitude of extra-metabolic roles, ghrelin is implicated in complex neurobiological processes. Comprehensive studies within the areas of obesity and metabolic surgery have clarified the mechanism of these operations. As a stimulator of growth hormone (GH), and an apparent inducer of positive energy balance, other areas of interest include its impact on carcinogenesis and tumour proliferation and its role in the cancer cachexia syndrome. This has led several authors to study the hormone in the cancer setting. Ghrelin levels are acutely reduced following an oesophagectomy, a primary treatment modality for oesophageal cancer. We sought to investigate the nature of this postoperative ghrelin suppression, and its neurobiological implications. PMID:28035969

  4. TGF-β Effects on Prostate Cancer Cell Migration and Invasion Require FosB

    PubMed Central

    Barrett, Cachétne S.X.; Millena, Ana C.; Khan, Shafiq A.

    2017-01-01

    BACKGROUND Activator Protein-1 (AP-1) family (cJun, JunB, JunD, cFos, FosB, Fra1, and Fra2) plays a central role in the transcriptional regulation of many genes that are associated with cell proliferation, differentiation, migration, metastasis, and survival. Many oncogenic signaling pathways converge at the AP-1 transcription complex. Transforming growth factor beta (TGF-β) is a multifunctional regulatory cytokine that regulates many aspects of cellular function, including cellular proliferation, differentiation, migration, apoptosis, adhesion, angiogenesis, immune surveillance, and survival. METHODS This study investigated, the role of FOS proteins in TGF-β signaling in prostate cancer cell proliferation, migration, and invasion. Steady state expression levels of FOS mRNA and proteins were determined using RT-PCR and western blotting analyses. DU145 and PC3 prostate cancer cells were exposed to TGF-β1 at varying time and dosage, RT-PCR, western blot, and immunofluorescence analyses were used to determine TGF-β1 effect on FOS mRNA and protein expression levels as well as FosB subcellular localization. Transient silencing of FosB protein was used to determine its role in cell proliferation, migration, and invasion. RESULTS Our data show that FOS mRNA and proteins were differentially expressed in human prostate epithelial (RWPE-1) and prostate cancer cell lines (LNCaP, DU145, and PC3). TGF-β1 induced the expression of FosB at both the mRNA and protein levels in DU145 and PC3 cells, whereas cFos and Fra1 were unaffected. Immunofluorescence analysis showed an increase in the accumulation of FosB protein in the nucleus of PC3 cells after treatment with exogenous TGF-β1. Selective knockdown of endogenous FosB by specific siRNA did not have any effect on cell proliferation in PC3 and DU145 cells. However, basal and TGF-β1- and EGF-induced cell migration was significantly reduced in DU145 and PC3 cells lacking endogenous FosB. TGF-β1- and EGF-induced cell invasion

  5. Light-induced c-Fos expression in the SCN and behavioural phase shifts of Djungarian hamsters with a delayed activity onset.

    PubMed

    Schöttner, Konrad; Vuillez, Patrick; Challet, Etienne; Pévet, Paul; Weinert, Dietmar

    2015-06-01

    C-Fos expression in the suprachiasmatic nucleus (SCN) and phase shifts of the activity rhythm following photic stimulation were investigated in Djungarian hamsters (Phodopus sungorus) of two different circadian phenotypes. Wild-type (WT) hamsters display robust daily patterns of locomotor activity according to the light/dark conditions. Hamsters of the DAO (delayed activity onset) phenotype, however, progressively delay the activity onset, whereas activity offset remains coupled to "light-on". Although the exact reason for the delayed activity onset is not yet clarified, it is connected with a disturbed interaction between the light/dark cycle and the circadian clock. The aim was to test the link between photoreception and the behavioral output of the circadian system in hamsters of both phenotypes, to get further insight in the underlying mechanism of the DAO phenomenon. Animals were exposed to short light pulses at different times during the dark period to analyze phase shifts of the activity rhythm and expression of Fos protein in the SCN. The results indicate that the photosensitive phase in DAO hamsters is shifted like the activity onset. Also, phase shifts were significantly smaller in DAO hamsters. At the same time, levels of Fos expression did not differ between phenotypes regarding the circadian phase. The results provide evidence that the shifted photosensitivity of the circadian system in DAO hamsters does not differ from that of WT animals, and lead us to conclude that processes within the SCN that enable light information to reset the circadian pacemaker might offer an explanation for the DAO phenomenon.

  6. On the central mechanism underlying ghrelin's chronic pro-obesity effects in rats: new insights from studies exploiting a potent ghrelin receptor antagonist.

    PubMed

    Salomé, N; Hansson, C; Taube, M; Gustafsson-Ericson, L; Egecioglu, E; Karlsson-Lindahl, L; Fehrentz, J A; Martinez, J; Perrissoud, D; Dickson, S L

    2009-09-01

    In the present study, we explore the central nervous system mechanism underlying the chronic central effects of ghrelin with respect to increasing body weight and body fat. Specifically, using a recently developed ghrelin receptor antagonist, GHS-R1A (JMV2959), we investigate the role of GHS-R1A in mediating the effects of ghrelin on energy balance and on hypothalamic gene expression. As expected, in adult male rats, chronic central treatment with ghrelin for 14 days, when compared to vehicle-treated control rats, resulted in an increased body weight, lean mass and fat mass (assessed by dual X-ray absorptiometry), dissected white fat pad weight, cumulative food intake, food efficiency, respiratory exchange ratio and a decrease of energy expenditure. Co-administration of the ghrelin receptor antagonist JMV2959 suppressed/blocked the majority of these effects, with the notable exception of ghrelin-induced food intake and food efficiency. The hypothesis emerging from these data, namely that GHS-R1A mediates the chronic effects of ghrelin on fat accumulation, at least partly independent of food intake, is discussed in light of the accompanying data regarding the hypothalamic genes coding for peptides and receptors involved in energy balance regulation, which were found to have altered expression in these studies.

  7. Region-specific increases in FosB/ΔFosB immunoreactivity in the rat brain in response to chronic sleep restriction.

    PubMed

    Hall, Shannon; Deurveilher, Samüel; Ko, Kristin Robin; Burns, Joan; Semba, Kazue

    2017-03-30

    Using a rat model of chronic sleep restriction (CSR) featuring periodic sleep deprivation with slowly rotating wheels (3h on/1h off), we previously observed that 99h of this protocol induced both homeostatic and allostatic (adaptive) changes in physiological and behavioural measures. Notably, the initial changes in sleep intensity and attention performance gradually adapted during CSR despite accumulating sleep loss. To identify brain regions involved in these responses, we used FosB/ΔFosB immunohistochemistry as a marker of chronic neuronal activation. Adult male rats were housed in motorized activity wheels and underwent the 3/1 CSR protocol for 99h, or 99h followed by 6 or 12days of recovery. Control rats were housed in home cages, locked activity wheels, or unlocked activity wheels that the animals could turn freely. Immunohistochemistry was conducted using an antibody that recognized both FosB and ΔFosB, and 24 brain regions involved in sleep/wake, autonomic, and limbic functions were examined. The number of darkly-stained FosB/ΔFosB-immunoreactive cells was increased immediately following 99h of CSR in 8/24 brain regions, including the medial preoptic and perifornical lateral hypothalamic areas, dorsomedial and paraventricular hypothalamic nuclei, and paraventricular thalamic nucleus. FosB/ΔFosB labeling was at control levels in all 8 brain areas following 6 or 12 recovery days, suggesting that most of the immunoreactivity immediately after CSR reflected FosB, the more transient marker of chronic neuronal activation. This region-specific induction of FosB/ΔFosB following CSR may be involved in the mechanisms underlying the allostatic changes in behavioural and physiological responses to CSR.

  8. Ghrelin and obestatin promote the allergic action in rat peritoneal mast cells as basic secretagogues.

    PubMed

    Hirayama, Tatsuya; Kawabe, Tsutomu; Matsushima, Miyoko; Nishimura, Yuko; Kobe, Yuko; Ota, Yui; Baba, Kenji; Takagi, Kenzo

    2010-11-01

    Ghrelin is an endogenous ligand of the type 1a growth hormone secretagogue receptor (GHSR1a) that regulates energy balance. Ghrelin and obestatin, derived from the post-translational processing of preproghrelin, are involved in a diverse range of biological activities, yet their effect on the immune system is not fully understood. In the present study, we investigated the roles of ghrelin and obestatin on mast cell degranulation and found that both ghrelin and obestatin induce the release of histamine from rat peritoneal mast cells. This induced histamine release was inhibited by the pertussis toxin, an inhibitor of Gα(i) protein, and extracellular Ca(2+). Rat peritoneal mast cells and rat basophilic leukemia (RBL-2H3) cells did not express the ghrelin receptor GHSR1a, suggesting that histamine release induced by ghrelin occurs via a receptor-independent mechanism. We report here that ghrelin and obestatin, belonging to the family of basic secretagogues, stimulate mast cells independent of a receptor, and this may play a crucial role at the site of allergy or inflammation.

  9. What is the general action of ghrelin for vertebrates? - comparisons of ghrelin's effects across vertebrates.

    PubMed

    Kaiya, Hiroyuki; Kangawa, Kenji; Miyazato, Mikiya

    2013-01-15

    Ten years and more passed since ghrelin was discovered. Various physiological actions of ghrelin have been documented in both mammalian and nonmammalian vertebrates. Do these actions have any commonality? In this review, we focused on several effects of ghrelin, and compared the effect across vertebrates. We would like to discuss possible general function of ghrelin in vertebrates.

  10. Ghrelin and the cardiovascular system.

    PubMed

    Isgaard, Jörgen

    2013-01-01

    Although ghrelin was initially associated with regulation of appetite, the cardiovascular system has also been recognized as a potentially important target for its effects. Moreover, experimental and a limited number of clinical studies suggest a potential role for ghrelin in the treatment of congestive heart failure. So far, reported cardiovascular effects of growth hormone secretagogues and/or ghrelin include lowering of peripheral resistance, either direct at the vascular level and/or by modulating sympathetic nervous activity. Other observed effects indicate possible improvement of contractility and cardioprotective and anti-inflammatory effects both in vivo and in vitro. Taken together, these results offer an interesting perspective on the future where further studies aiming at evaluating a role of growth hormone secretagogues and ghrelin in the treatment of cardiovascular disease are warranted.

  11. Physiological roles of ghrelin on obesity.

    PubMed

    Sato, Takahiro; Ida, Takanori; Nakamura, Yuki; Shiimura, Yuki; Kangawa, Kenji; Kojima, Masayasu

    2014-01-01

    Ghrelin is a stomach hormone that acts as an endogenous ligand of orphan G-protein coupled receptor. Ghrelin has various physiological functions, such as the stimulation of growth hormone release and of appetite, and fat accumulation. Ghrelin is the only peripheral hormone to transmit satiety signal. Mature ghrelin peptide is consisted of 28 amino acid residues, and is unusual among peptide hormones in that Ser3 is n-octanoylated to obtain. Furthermore, this modification is essential for ghrelin's activity. In order to add this side chain to acyl ghrelin, it is necessary for the recently discovered enzyme, ghrelin-O-acyl transferase (GOAT). Therefore, to understand of ghrelin's functions, it is useful to obtain the knowledge on structures and functions of ghrelin, ghrelin receptor and GOAT. Here, we review our current understanding of the structures and functions of ghrelin, and the relation between obesity and ghrelin. Finally, we referred to the ghrelin and related substances as a drug design target for obesity.

  12. Catalytic antibody degradation of ghrelin increases whole-body metabolic rate and reduces refeeding in fasting mice.

    PubMed

    Mayorov, Alexander V; Amara, Neri; Chang, Jason Y; Moss, Jason A; Hixon, Mark S; Ruiz, Diana I; Meijler, Michael M; Zorrilla, Eric P; Janda, Kim D

    2008-11-11

    Obesity is a chronic, costly, and globally prevalent condition, with excess caloric intake a suspected etiologic factor. Nonsurgical treatments are modestly efficacious, and weight loss maintenance is hampered by anti-famine homeostatic mechanisms. Ghrelin, a gastric hormone linked to meal initiation, energy expenditure, and fuel partitioning, is hypothesized to facilitate weight gain and impede weight loss. Unique among known animal peptides, the serine-3 residue of ghrelin is posttranslationally acylated with an n-octanoic acid, a modification important for the peptide's active blood-brain transport and growth hormone secretagogue receptor-1 agonist activity. Pharmacological degradation of ghrelin would be hypothesized to reduce ghrelin's biological effects. To study endogenous ghrelin's role in appetite and energy expenditure, we generated antibodies that hydrolyze the octanoyl moiety of ghrelin to form des-acyl ghrelin. The most proficient antibody catalyst, GHR-11E11, was found to display a second-order rate constant of 18 M(-1) x s(-1) for the hydrolysis of ghrelin to des-acyl ghrelin. I.v. administration of GHR-11E11 (50 mg/kg) maintained a greater metabolic rate in fasting C57BL/6J mice as compared with mice receiving a control antibody and suppressed 6-h refeeding after 24 h of food deprivation. Indirect respiratory measures of metabolism after refeeding and relative fuel substrate utilization were unaffected. The results support the hypothesis that acylated ghrelin stimulates appetite and curbs energy expenditure during deficient energy intake, whereas des-acyl ghrelin does not potently share these functions. Catalytic anti-ghrelin antibodies might thereby adjunctively aid consolidation of caloric restriction-induced weight loss and might also be therapeutically relevant to Prader-Willi syndrome, characterized after infancy by hyperghrelinemia, hyperphagia, and obesity.

  13. Intraportal Infusion of Ghrelin Could Inhibit Glucose-Stimulated GLP-1 Secretion by Enteric Neural Net in Wistar Rat

    PubMed Central

    Zhang, Xiyao; Li, Wensong; Li, Ping; Chang, Manli; Huang, Xu; Li, Qiang; Cui, Can

    2014-01-01

    As a regulator of food intake and energy metabolism, the role of ghrelin in glucose metabolism is still not fully understood. In this study, we determined the in vivo effect of ghrelin on incretin effect. We demonstrated that ghrelin inhibited the glucose-stimulated release of glucagon-like peptide-1 (GLP-1) when infused into the portal vein of Wistar rat. Hepatic vagotomy diminished the inhibitory effect of ghrelin on glucose-stimulated GLP-1 secretion. In addition, phentolamine, a nonselective α receptor antagonist, could recover the decrease of GLP-1 release induced by ghrelin infusion. Pralmorelin (an artificial growth hormone release peptide) infusion into the portal vein could also inhibit the glucose-stimulated release of GLP-1. And growth hormone secretagogue receptor antagonist, [D-lys3]-GHRP-6, infusion showed comparable increases of glucose stimulated GLP-1 release compared to ghrelin infusion into the portal vein. The data showed that intraportal infusion of ghrelin exerted an inhibitory effect on GLP-1 secretion through growth hormone secretagogue receptor 1α (GHS1α receptor), which indicated that the downregulation of ghrelin secretion after food intake was necessary for incretin effect. Furthermore, our results suggested that the enteric neural net involved hepatic vagal nerve and sympathetic nerve mediated inhibition effect of ghrelin on incretin effect. PMID:25247193

  14. Augmenting Effect of DA-9601 on Ghrelin in an Acute Gastric Injury Model

    PubMed Central

    Baek, Yoo Hum; Lee, Kang Nyeong; Jun, Dae Won; Yoon, Byung Chul; Kim, Ju Mi; Oh, Tae Young

    2011-01-01

    Background/Aims Acute gastric injury by alcohol or indomethacin has been reported to be prevented by DA-9601, an extract of the herb Artemisia asiatica. Ghrelin, an endogenously produced gastrointestinal peptide hormone, has also been demonstrated to play a role in gastric mucosal defense. The aim of this study was to investigate the effects of DA-9601 on ghrelin in an acute gastric injury model induced by alcohol or indomethacin. Methods A total of 140 Sprague-Dawley rats were divided into two groups, a placebo group and a DA-9601-pretreated group. Thirty minutes later, half of the rats in each group received ethanol injury and the other half received indomethacin injury. Levels of serum ghrelin and gastric mucosal ghrelin mRNA were measured by ELISA and RT-PCR, respectively. Results Immediately after ethanol administration, ghrelin increased in both groups pretreated with DA-9601 and placebo. However, the increase occurred more rapidly and was higher in the DA-9601-pretreated rats than in the controls that did not receive DA-9601-pretreatment. Similarly, from 30 minutes to 2 hours after indomethacin administration, the DA-9601-pretreated rats showed a significant increase in serum and gastric mucosal ghrelin concentrations, whereas placebo-pretreated rats showed only a mild increase. Conclusions DA-9601 potentiates the endogenous production and secretion of ghrelin in acute gastric injury models induced by ethanol or indomethacin. PMID:21461072

  15. Stimulus-specific combinatorial functionality of neuronal c-fos enhancers

    PubMed Central

    Joo, Jae-Yeol; Schaukowitch, Katie; Farbiak, Lukas; Kilaru, Gokhul; Kim, Tae-Kyung

    2015-01-01

    The c-fos gene is induced by a broad range of stimuli, and has been commonly used as a reliable marker for neural activity. Its induction mechanism and available reporter mouse lines are exclusively based on the c-fos promoter activity. Here, we demonstrate that multiple enhancers surrounding the c-fos gene are critical for ensuring robust c-fos response to various stimuli. Membrane depolarization, brain-derived neurotrophic factor (BDNF), and Forskolin activate distinct subsets of the enhancers to induce c-fos transcription in neurons, suggesting that stimulus-specific combinatorial activation of multiple enhancers underlies the broad inducibility of the c-fos gene. Accordingly, the functional requirement of key transcription factors varies depending on the type of stimulation. Combinatorial enhancer activation also occurs in the brain. Providing a comprehensive picture of the c-fos induction mechanism beyond the minimal promoter, our study should help in understanding the physiological nature of c-fos induction in relation to neural activity and plasticity. PMID:26595656

  16. Ghrelin inhibits the apoptosis of MC3T3-E1 cells through ERK and AKT signaling pathway

    SciTech Connect

    Liang, Qiu-Hua; Liu, Yuan; Wu, Shan-Shan; Cui, Rong-Rong; Yuan, Ling-Qing Liao, Er-Yuan

    2013-11-01

    Ghrelin is a 28-amino-acid peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR) and strongly stimulates the release of growth hormone from the hypothalamus–pituitary axis. Previous studies have identified the important physiological effects of ghrelin on bone metabolism, such as regulating proliferation and differentiation of osteoblasts, independent of GH/IGF-1 axis. However, research on effects and mechanisms of ghrelin on osteoblast apoptosis is still rare. In this study, we identified expression of GHSR in MC3T3-E1 cells and determined the effects of ghrelin on the apoptosis of osteoblastic MC3T3-E1 cells and the mechanism involved. Our data demonstrated that ghrelin inhibited the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, as determined by terminal deoxynucleotidyl transferase-mediated deoxyribonucleotide triphosphate nick end-labeling (TUNEL) and ELISA assays. Moreover, ghrelin upregulated Bcl-2 expression and downregulated Bax expression in a dose-dependent manner. Our study also showed decreased activated caspase-3 activity under the treatment of ghrelin. Further study suggested that ghrelin stimulated the phosphorylation of ERK and AKT. Pretreatment of cells with the ERK inhibitor PD98059, PI3K inhibitor LY294002, and GHSR-siRNA blocked the ghrelin-induced activation of ERK and AKT, respectively; however, ghrelin did not stimulate the phosphorylation of p38 or JNK. PD90859, LY294002 and GHSR-siRNA attenuated the anti-apoptosis effect of ghrelin in MC3T3-E1 cells. In conclusion, ghrelin inhibits the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, which may be mediated by activating the GHSR/ERK and GHSR/PI3K/AKT signaling pathways. - Highlights: • We explored the effects of ghrelin on serum deprivation-induced MC3T3-E1 cells apoptosis. • Both ELISA and TUNEL were used to detect the apoptosis. • The receptor of ghrelin, GHSR, was expressed in MC3T3-E1

  17. Ghrelin: much more than a hunger hormone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ghrelin is a multifaceted gut hormone that activates its receptor, growth hormone secretagogue receptor (GHS-R). Ghrelin's hallmark functions are its stimulatory effects on growth hormone release, food intake and fat deposition. Ghrelin is famously known as the 'hunger hormone'. However, ample recen...

  18. Thermogenic characterization of ghrelin receptor null mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ghrelin is the only known circulating orexigenic hormone that increases food intake and promotes adiposity, and these physiological functions of ghrelin are mediated through its receptor growth hormone secretagogue receptor (GHS-R). Ghrelin/GHS-R signaling plays a crucial role in energy homeostasis....

  19. Ghrelin modulates sympathetic nervous system activity and stress response in lean and overweight men.

    PubMed

    Lambert, Elisabeth; Lambert, Gavin; Ika-Sari, Carolina; Dawood, Tye; Lee, Katie; Chopra, Reena; Straznicky, Nora; Eikelis, Nina; Drew, Sara; Tilbrook, Alan; Dixon, John; Esler, Murray; Schlaich, Markus P

    2011-07-01

    Ghrelin is a growth hormone-releasing peptide secreted by the stomach with potent effects on appetite. Experimental and clinical studies indicate that ghrelin also influences cardiovascular regulation and metabolic function and mediates behavioral responses to stress. We investigated the effects of ghrelin on blood pressure (BP), sympathetic nervous system activity, and mental stress responses in lean (n=13) and overweight or obese (n=13) individuals. Subjects received an intravenous infusion of human ghrelin (5 pmol/kg per minute for 1 hour) and saline in a randomized fashion. Ghrelin decreased systolic (-6 and -11 mm Hg) and diastolic BP (-8 mm Hg for both), increased muscle sympathetic nervous system activity (18±2 to 28±3 bursts per min, P<0.05 and from 21±2 to 32±3 bursts per min, P<0.001) in lean and overweight or obese subjects, respectively, without a significant change in heart rate, calf blood flow, or vascular resistance. Ghrelin induced a rise in plasma glucose concentration in lean individuals (P<0.05) and increased cortisol levels in both groups (P<0.05). Stress induced a significant change in mean BP (+22 and +27 mm Hg), heart rate (+36 and +29 bpm), and muscle sympathetic nervous system activity (+6.1±1.6 and +6.8±2.7 bursts per min) during saline infusion in lean and overweight or obese subjects, respectively. During ghrelin infusion, the changes in BP and muscle sympathetic nerve activity in response to stress were significantly reduced in both groups (P<0.05). In conclusion, ghrelin exerts unique effects in that it reduces BP and increases muscle sympathetic nervous system activity and blunts cardiovascular responses to mental stress. These responses may represent a combination of peripheral (baroreflex-mediated) and central effects of ghrelin.

  20. 5-HT1A receptor activation counteracts c-Fos immunoreactivity induced in serotonin neurons of the raphe nuclei after immobilization stress in the male rat.

    PubMed

    Rioja, José; Santín, Luis J; Doña, Alicia; de Pablos, Laura; Minano, Francisco J; Gonzalez-Baron, Salvador; Aguirre, Jose A

    2006-04-24

    The serotoninergic system and the 5-HT1A receptors have been involved in the brain response to acute stress. The aim of our study was evaluate the role of the 5-HT1A receptors in serotoninergic cells of rostral and caudal raphe nuclei under acute immobilization in rats. Double immunocytochemical staining of 5-hydroxy-tryptamine and c-Fos protein and stereology techniques were used to study the specific cell activation in the raphe nuclei neurons in five groups (control group, immobilization group (immobilization lasting 1 h), DPAT group (8-OH-DPAT 0.3 mg/kg, s.c.), DPAT+IMMO group (8-OH-DPAT 0.3 mg/kg, s.c., 30' prior acute immobilization) and WAY+DPAT+IMMO group (WAY-100635 0.3 mg/kg, s.c. and 8-OH-DPAT 0.3 mg/kg, s.c., 45' and 30', respectively, before immobilization). Our results showed an increase in the number of c-Fos immunoreactive nuclei in serotoninergic cells in both dorsal and median raphe nuclei in the immobilized group. The 8-OH-DPAT pretreatment counteracted the excitatory effects of the acute immobilization in these brain regions. In addition, WAY-100635 administration reduced the effect of 8-OH-DPAT injection, suggesting a selective 5-HT1A receptor role. Raphe pallidus and raphe obscurus did not show any differences among experimental groups. We suggest that somatodendritic 5-HT1A receptors in rostral raphe nuclei may play a crucial role in both mediating the consequences of uncontrollable stress and the possible beneficial effects of treatment with 5-HT1A receptor agonists.

  1. Alcohol consumption increases locomotion in an open field and induces Fos-immunoreactivity in reward and approach/withdrawal-related neurocircuitries.

    PubMed

    Wscieklica, Tatiana; de Barros Viana, Milena; Le Sueur Maluf, Luciana; Pouza, Kathlein Cristiny Peres; Spadari, Regina Célia; Céspedes, Isabel Cristina

    2016-02-01

    Drug addiction is a chronically relapsing disorder characterized by compulsion to seek and take the drug, loss of control in limiting intake and, eventually, the emergence of a negative emotional state when access to the drug is prevented. Both dopamine and corticotropin-releasing factor (CRF)-mediated systems seem to play important roles in the modulation of alcohol abuse and dependence. The present study investigated the effects of alcohol consumption on anxiety and locomotor parameters and on the activation of dopamine and CRF-innervated brain regions. Male Wistar rats were given a choice of two bottles for 31 days, one containing water and the other a solution of saccharin + alcohol. Control animals only received water and a solution of 0.2% saccharin. On the 31st day, animals were tested in the elevated plus-maze and open field, and euthanized immediately after the behavioral tests. An independent group of animals was treated with ethanol and used to measure blood ethanol concentration. Results showed that alcohol intake did not alter behavioral measurements in the plus-maze, but increased the number of crossings in the open field, an index of locomotor activity. Additionally, alcohol intake increased Fos-immunoreactivity (Fos-ir) in the prefrontal cortex, in the shell region of the nucleus accumbens, in the medial and central amygdala, in the bed nucleus of the stria terminalis, in the septal region, and in the paraventricular and dorsomedial hypothalamus, structures that have been linked to reward and to approach/withdrawal behavior. These observations might be relevant to a better understanding of the behavioral and physiological alterations that follow alcohol consumption.

  2. Effects of Endurance Running and Dietary Fat on Circulating Ghrelin and Peptide YY

    PubMed Central

    Russell, Ryan D.; Willis, Kentz S.; Ravussin, Eric; Larson-Meyer, Enette D.

    2009-01-01

    -suppressing peptide PYY are influenced by the fat content of the diet and/or by a bout of intense endurance running. The low-fat, high-carbohydrate pre-exercise regimen compared to moderate-fat, moderate-carbohydrate regimen did not influence circulating plasma ghrelin and PYY concentrations Most importantly, both gut peptides were elevated following two to two-and-a-half hours of strenuous running which lasted between two and two and a half hours. The noted disruption in the normal inverse relationship between ghrelin and PYY at rest suggests that the interaction of ghrelin and PYY may be at least partially responsible for exercise-induced anorexia which is commonly reported following vigorous endurance exercise. PMID:21927572

  3. Ghrelin and the growth hormone secretagogue receptor in growth and development.

    PubMed

    Chanoine, J-P; De Waele, K; Walia, P

    2009-04-01

    The pancreas is a major source of ghrelin in the perinatal period, whereas gastric production progressively increases after birth. Loss of function of the genes for ghrelin or for the constitutively activated growth hormone secretagogue receptor (GHSR) does not affect birth weight and early postnatal growth. However, ghrl(-/-) or ghsr(-/-) mice fed a high fat diet starting soon after weaning are resistant to diet-induced obesity, suggesting that ghrelin affects the maturation of the metabolic axes involved in energy balance. In addition, animal and human studies suggest that GHSR plays a physiological role in linear growth. In mice, absence of the GHSR gene is associated with lower insulin-like growth factor 1 concentrations and lower body mass in adult animals, independently of food intake. In humans, a mutation of the GHSR gene that impairs the constitutive activity of the receptor was found in two families with short stature. Administration of acylated ghrelin to rat pups directly does not affect weight gain. In contrast, administration of ghrelin to pregnant or lactating rats results in greater fetal weight and postnatal weight gain, respectively, suggesting that maternal ghrelin may stimulate perinatal growth. These data point toward a physiological role for ghrelin and GHSR in growth and/or in the maturation of hormonal systems involved in the regulation of energy balance.

  4. Ablation of Ghrelin O-Acyltransferase Does Not Improve Glucose Intolerance or Body Adiposity in Mice on a Leptin-Deficient ob/ob Background

    PubMed Central

    Kirchner, Henriette; Heppner, Kristy M.; Holland, Jenna; Kabra, Dhiraj; Tschöp, Matthias H.; Pfluger, Paul T.

    2013-01-01

    Type 2 Diabetes is a global health burden and based on current estimates will become an even larger problem in the future. Developing new strategies to prevent and treat diabetes is a scientific challenge of high priority. The stomach hormone ghrelin has been associated with playing a role in the regulation of glucose homeostasis. However, its precise mechanism and impact on whole glucose metabolism remains to be elucidated. This study aims to clarify the role of the two ghrelin isoforms acyl- and desacyl ghrelin in regulating glucose homeostasis. Therefore ghrelin activating enzyme Ghrelin-O-acyltransferase (GOAT) was ablated in leptin-deficient ob/ob mice to study whether specific acyl ghrelin deficiency or desacyl ghrelin abundance modifies glucose tolerance on a massively obese background. As targeted deletion of acyl ghrelin does not improve glucose homeostasis in our GOAT-ob/ob mouse model we conclude that neither acyl ghrelin nor the increased ratio of desacyl/acyl ghrelin is crucial for controlling glucose homeostasis in the here presented model of massive obesity induced by leptin deficiency. PMID:23630616

  5. c-fos-like immunoreactivity in the cat's neuraxis following moderate hypoxia or hypercapnia.

    PubMed

    Larnicol, N; Wallois, F; Berquin, P; Gros, F; Rose, D

    1994-01-01

    The overall pattern of c-fos immunoreactivity was studied in the brainstem and spinal cord of cats subjected to moderate hypoxia or hypercapnia. In control cats (normoxic, normocapnic), c-fos was expressed mainly in pontine and periaqueductal grey but not in brainstem structures engaged in respiratory control nor in the spinal cord. Both hypoxia and hypercapnia induced c-fos expression in the parabrachial area (pneumotaxic center). In the retrotrapezoid nucleus, a structure involved in respiratory rhythmogenesis and chemoreception, immunoreactivity was detected in hypoxic but not in hypercapnic cats. Neurons in the nucleus raphe pallidus preferentially expressed c-fos in response to hypercapnia. Labelled neurons were concentrated in the dorsal and gelatinosus subnuclei of the solitary tract following hypoxia and hypercapnia, respectively. Our data suggest that some neurons that express c-fos in hypoxic or hypercapnic cats may be involved in coordination of cardiovascular and respiratory function.

  6. Immunization against active ghrelin using virus-like particles for obesity treatment.

    PubMed

    Andrade, Sara; Pinho, Filipa; Ribeiro, Andreia M; Carreira, Marcos; Casanueva, Felipe F; Roy, Polly; Monteiro, Mariana P

    2013-01-01

    Ghrelin is a gut hormone that stimulates food intake. In physiological conditions, ghrelin plasma levels rise with fasting and decrease after meals. Obese individuals have low fasting ghrelin levels that rise after food restriction, which is pointed out as a reason for the difficulty in maintaining weight loss. Some bariatric surgery procedures prevent rise in ghrelin levels with weight loss and this has been hypothesised to contribute to the long-term success of the treatment. The main goal of this study was to develop a safe and effective anti-ghrelin vaccine for obesity, through the chemical conjugation of ghrelin with a virus like particle, namely NS1 protein tubules from the Bluetongue Virus (BTV) using a hetero-bifunctional cross linker. Male adult C57BL/6 mice, with a normal weight and with diet-induced obesity (DIO), were randomized into six weight matched groups (n=6/group) and each group of mice received three intra-peritoneal injections with two weeks intervals, containing either 75 μg of ghrelin- NS1 immunoconjugate, 75 μg of NS1 or PBS. Our data show that immunized animals present increasing titres of anti-ghrelin antibodies, while their cumulative food intake significantly decreased and energy expenditure was significantly enhanced, although there were no significative changes in body weight.Vaccinated DIO mice also displayed significant decrease of NPY gene expression in the basal hypothalamus reflecting a decrease in central orexigenic signals. This study suggests that this anti-ghrelin vaccine has a positive impact on energy homeostasis and may be an additional therapeutical tool to be used with diet and exercise for obesity treatment.

  7. Ghrelin increases the motivation to eat, but does not alter food palatability.

    PubMed

    Overduin, Joost; Figlewicz, Dianne P; Bennett-Jay, Jennifer; Kittleson, Sepideh; Cummings, David E

    2012-08-01

    Homeostatic eating cannot explain overconsumption of food and pathological weight gain. A more likely factor promoting excessive eating is food reward and its representation in the central nervous system (CNS). The anorectic hormones leptin and insulin reduce food reward and inhibit related CNS reward pathways. Conversely, the orexigenic gastrointestinal hormone ghrelin activates both homeostatic and reward-related neurocircuits. The current studies were conducted to identify in rats the effects of intracerebroventricular ghrelin infusions on two distinct aspects of food reward: hedonic valuation (i.e., "liking") and the motivation to self-administer (i.e., "wanting") food. To assess hedonic valuation of liquid food, lick motor patterns were recorded using lickometry. Although ghrelin administration increased energy intake, it did not alter the avidity of licking (initial lick rates or lick-cluster size). Several positive-control conditions ruled out lick-rate ceiling effects. Similarly, when the liquid diet was hedonically devalued with quinine supplementation, ghrelin failed to reverse the quinine-associated reduction of energy intake and avidity of licking. The effects of ghrelin on rats' motivation to eat were assessed using lever pressing to self-administer food in a progressive-ratio paradigm. Ghrelin markedly increased motivation to eat, to levels comparable to or greater than those seen following 24 h of food deprivation. Pretreatment with the dopamine D1 receptor antagonist SCH-23390 eliminated ghrelin-induced increases in lever pressing, without compromising generalized licking motor control, indicating a role for D1 signaling in ghrelin's motivational feeding effects. These results indicate that ghrelin increases the motivation to eat via D1 receptor-dependent mechanisms, without affecting perceived food palatability.

  8. Structure and Physiological Actions of Ghrelin

    PubMed Central

    2013-01-01

    Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin. PMID:24381790

  9. Ghrelin plasmatic levels in patients with fibromyalgia.

    PubMed

    Otero, Miguel; Nogueiras, Ruben; Lago, Francisca; Meijide, Juan; Amarelo, Juan; Mera, Antonio; Gomez-Reino, Juan; Gualillo, Oreste

    2005-01-01

    Ghrelin is a recently discovered 28 amino acid peptide that regulates GH secretion and energy homeostasis. In fibromyalgia (FM) there are alterations in the pituitary-hypothalamic axis, particularly in the growth hormone (GH) secretion pattern. Whether this anomalous secretion of GH pertains to abnormal levels of ghrelin is still unknown. The purpose of this study was to investigate plasma ghrelin levels in patients with fibromyalgia (FM) compared with healthy controls. Plasmatic ghrelin concentrations were determined by a double antibody radioimmunoassay in 19 patients with FM and 14 healthy controls. Compared with controls, patients with FM did not show any significant differences of ghrelin plasmatic levels. In conclusion, FM is not associated with deviation in ghrelin concentrations. Existing alterations in FM with respect to GH are unlikely due to circulating ghrelin.

  10. Role of endogenous cortistatin in the regulation of ghrelin system expression at pancreatic level under normal and obese conditions.

    PubMed

    Chanclón, Belén; Luque, Raúl M; Córdoba-Chacón, José; Gahete, Manuel D; Pozo-Salas, Ana I; Castaño, Justo P; Gracia-Navarro, Francisco; Martínez-Fuentes, Antonio J

    2013-01-01

    Ghrelin-system components [native ghrelin, In1-ghrelin, Ghrelin-O-acyltransferase enzyme (GOAT) and receptors (GHS-Rs)] are expressed in a wide variety of tissues, including the pancreas, where they exert different biological actions including regulation of neuroendocrine secretions, food intake and pancreatic function. The expression of ghrelin system is regulated by metabolic conditions (fasting/obesity) and is associated with the progression of obesity and insulin resistance. Cortistatin (CORT), a neuropeptide able to activate GHS-R, has emerged as an additional link in gut-brain interplay. Indeed, we recently reported that male CORT deficient mice (cort-/-) are insulin-resistant and present a clear dysregulation in the stomach ghrelin-system. The present work was focused at analyzing the expression pattern of ghrelin-system components at pancreas level in cort-/- mice and their control littermates (cort +/+) under low- or high-fat diet. Our data reveal that all the ghrelin-system components are expressed at the mouse pancreatic level, where, interestingly, In1-ghrelin was expressed at higher levels than native-ghrelin. Thus, GOAT mRNA levels were significantly lower in cort-/- mice compared with controls while native ghrelin, In1-ghrelin and GHS-R transcript levels remained unaltered under normal metabolic conditions. Moreover, under obese condition, a significant increase in pancreatic expression of native-ghrelin, In1-ghrelin and GHS-R was observed in obese cort+/+ but not in cort-/- mice. Interestingly, insulin expression and release was elevated in obese cort+/+, while these changes were not observed in obese cort-/- mice. Altogether, our results indicate that the ghrelin-system expression is clearly regulated in the pancreas of cort+/+ and cort -/- under normal and/or obesity conditions suggesting that this system may play relevant roles in the endocrine pancreas. Most importantly, our data demonstrate, for the first time, that endogenous CORT is essential

  11. Lean mean fat reducing "ghrelin" machine: hypothalamic ghrelin and ghrelin receptors as therapeutic targets in obesity.

    PubMed

    Schellekens, Harriët; Dinan, Timothy G; Cryan, John F

    2010-01-01

    Obesity has reached epidemic proportions not only in Western societies but also in the developing world. Current pharmacological treatments for obesity are either lacking in efficacy and/or are burdened with adverse side effects. Thus, novel strategies are required. A better understanding of the intricate molecular pathways controlling energy homeostasis may lead to novel therapeutic intervention. The circulating hormone, ghrelin represents a major target in the molecular signalling regulating food intake, appetite and energy expenditure and its circulating levels often display aberrant signalling in obesity. Ghrelin exerts its central orexigenic action mainly in the hypothalamus and in particular in the arcuate nucleus via activation of specific G-protein coupled receptors (GHS-R). In this review we describe current pharmacological models of how ghrelin regulates food intake and how manipulating ghrelin signalling may give novel insight into developing better and more selective anti-obesity drugs. Accumulating data suggests multiple ghrelin variants and additional receptors exist to play a role in energy metabolism and these may well play an important role in obesity. In addition, the recent findings of hypothalamic GHS-R crosstalk and heterodimerization may add to the understanding of the complexity of bodyweight regulation.

  12. Soft Coral-Derived Lemnalol Alleviates Monosodium Urate-Induced Gouty Arthritis in Rats by Inhibiting Leukocyte Infiltration and iNOS, COX-2 and c-Fos Protein Expression

    PubMed Central

    Lee, Hsin-Pai; Huang, Shi-Ying; Lin, Yen-You; Wang, Hui-Min; Jean, Yen-Hsuan; Wu, Shu-Fen; Duh, Chang-Yih; Wen, Zhi-Hong

    2013-01-01

    An acute gout attack manifests in the joint as dramatic inflammation. To date, the clinical use of medicinal agents has typically led to undesirable side effects. Numerous efforts have failed to create an effective and safe agent for the treatment of gout. Lemnalol—an extract from Formosan soft coral—has documented anti-inflammatory and anti-nociceptive properties. In the present study, we attempt to examine the therapeutic effects of lemnalol on intra-articular monosodium urate (MSU)-induced gouty arthritis in rats. In the present study, we found that treatment with lemnalol (intramuscular [im]), but not colchicine (oral [po]), significantly attenuated MUS-induced mechanical allodynia, paw edema and knee swelling. Histomorphometric and immunohistochemistry analysis revealed that MSU-induced inflammatory cell infiltration, as well as the elevated expression of c-Fos and pro-inflammatory proteins (inducible nitric oxide synthase and cyclooxygenase-2) observed in synovial tissue, were significantly inhibited by treatment with lemnalol. We conclude that lemnalol may be a promising candidate for the development of a new treatment for gout and other acute neutrophil-driven inflammatory diseases. PMID:23306170

  13. Soft coral-derived lemnalol alleviates monosodium urate-induced gouty arthritis in rats by inhibiting leukocyte infiltration and iNOS, COX-2 and c-Fos protein expression.

    PubMed

    Lee, Hsin-Pai; Huang, Shi-Ying; Lin, Yen-You; Wang, Hui-Min; Jean, Yen-Hsuan; Wu, Shu-Fen; Duh, Chang-Yih; Wen, Zhi-Hong

    2013-01-10

    An acute gout attack manifests in the joint as dramatic inflammation. To date, the clinical use of medicinal agents has typically led to undesirable side effects. Numerous efforts have failed to create an effective and safe agent for the treatment of gout. Lemnalol-an extract from Formosan soft coral-has documented anti-inflammatory and anti-nociceptive properties. In the present study, we attempt to examine the therapeutic effects of lemnalol on intra-articular monosodium urate (MSU)-induced gouty arthritis in rats. In the present study, we found that treatment with lemnalol (intramuscular [im]), but not colchicine (oral [po]), significantly attenuated MUS-induced mechanical allodynia, paw edema and knee swelling. Histomorphometric and immunohistochemistry analysis revealed that MSU-induced inflammatory cell infiltration, as well as the elevated expression of c-Fos and pro-inflammatory proteins (inducible nitric oxide synthase and cyclooxygenase-2) observed in synovial tissue, were significantly inhibited by treatment with lemnalol. We conclude that lemnalol may be a promising candidate for the development of a new treatment for gout and other acute neutrophil-driven inflammatory diseases.

  14. Differential activation of c-Fos in the paraventricular nuclei of the hypothalamus and thalamus following myocardial infarction in rats

    PubMed Central

    Tae, Hyun-Jin; Park, Seung Min; Cho, Jeong Hwi; Kim, In Hye; Ahn, Ji Hyeon; Park, Joon Ha; Won, Moo-Ho; Chen, Bai Hui; Shin, Bich-Na; Shin, Myoung Cheol; Lee, Choong Hyun; Hong, Seongkweon; Lee, Jae-Chul; Cho, Jun Hwi

    2016-01-01

    Proto-oncogene c-Fos (c-Fos) is frequently used to detect a pathogenesis in central nervous system disorders. The present study examined changes in the immunoreactivity of c-Fos in the paraventricular nucleus of the hypothalamus (PVNH) and paraventricular nucleus of the thalamus (PVNT) following myocardial infarction (MI) in rats. Infarction in the left ventricle was examined by Masson's trichrome staining. Neuronal degeneration was monitored for 56 days after MI using crystal violet and Fluoro-Jade B histofluorescence staining. Changes in the immunoreactivity of c-Fos were determined using immunohistochemistry for c-Fos. The average infarct size of the left ventricle circumference was ~44% subsequent to MI. Neuronal degeneration was not detected in PVNH and PVNT following MI. c-Fos immunoreactive (+) cells were infrequently observed in the nuclei of the sham-group. However, the number of c-Fos+ cells was increased in the nuclei following MI and peaked in the PVNH and PVNT at 3 and 14 days, respectively. The number of c-Fos+ cells were comparable with the sham group at 56 days after MI. Therefore, MI may induce c-Fos immunoreactivity in PVNH and PVNT, this increase of c-Fos expression levels may be associated with the stress that occurs in the brain following MI. PMID:27601012

  15. Effect of electrolytic lesions of the dorsal diencephalic conduction system on the distribution of Fos-like immunoreactivity induced by rewarding electrical stimulation.

    PubMed

    Fakhoury, Marc; Voyer, David; Lévesque, Daniel; Rompré, Pierre-Paul

    2016-10-15

    The dorsal diencephalic conduction system (DDC) is an important pathway of the brain reward circuitry, linking together forebrain and midbrain structures. The present work was aimed at describing the effect of a DDC lesion on the distribution of Fos-like immunoreactivity (FLIR) following intracranial self-stimulation (ICSS) of the lateral hypothalamus (LH). Rats were implanted with monopolar electrodes and divided into three groups; the first two groups were trained to self-stimulate at the LH, whereas the third group received no stimulation and served as a control. Among the two groups that were trained for ICSS, one of them received a lesion at the DDC and was tested for ICSS on the subsequent 5days. On the last day of testing, control rats were placed in operant chambers without receiving any stimulation, and the remaining rats were allowed to receive the stimulation for 1h. All rats were then processed for FLIR. As previously shown, a lesion at the DDC resulted in significant attenuations of the rewarding effectiveness of LH stimulation. Results also show a higher FLIR in several reward-related areas following LH stimulation, especially in the hemisphere ipsilateral to the stimulation electrode. Compared to non-lesioned rats, lesioned animals had lower FLIR in certain brain regions, suggesting that those regions that were activated by the rewarding stimulation may be functionally interconnected with the DDC.

  16. An Indirect Action Contributes to C-Fos Induction in Paraventricular Hypothalamic Nucleus by Neuropeptide Y

    PubMed Central

    Fan, Shengjie; Dakshinamoorthy, Janani; Kim, Eun Ran; Xu, Yong; Huang, Cheng; Tong, Qingchun

    2016-01-01

    Neuropeptide Y (NPY) is a well-established orexigenic peptide and hypothalamic paraventricular nucleus (PVH) is one major brain site that mediates the orexigenic action of NPY. NPY induces abundant expression of C-Fos, an indicator for neuronal activation, in the PVH, which has been used extensively to examine the underlying NPY orexigenic neural pathways. However, PVH C-Fos induction is in discordance with the abundant expression of NPY receptors, a group of inhibitory Gi protein coupled receptors in the PVH, and with the overall role of PVH neurons in feeding inhibition, suggesting a mechanism of indirect action. Here we showed that the ability of NPY on C-Fos induction in the PVH was blunted in conditions of insulin deficiency and fasting, a condition associated with a high level of NPY and a low level of insulin. Moreover, insulin insufficiency blunted C-Fos induction in the PVH by fasting-induced re-feeding, and insulin and NPY induced c-Fos induction in the same group of PVH neurons. Finally, NPY produced normal C-Fos induction in the PVH with disruption of GABA-A receptors. Thus, our results revealed that PVH C-Fos induction by NPY is mediated by an indirect action, which is at least partially mediated by insulin action, but not GABA-A receptors. PMID:26813148

  17. Fos family protein degradation by the proteasome.

    PubMed

    Gomard, Tiphanie; Jariel-Encontre, Isabelle; Basbous, Jihane; Bossis, Guillaume; Moquet-Torcy, Gabriel; Mocquet-Torcy, Gabriel; Piechaczyk, Marc

    2008-10-01

    c-Fos proto-oncoprotein defines a family of closely related transcription factors (Fos proteins) also comprising Fra-1, Fra-2, FosB and DeltaFosB, the latter two proteins being generated by alternative splicing. Through the regulation of many genes, most of them still unidentified, they regulate major functions from the cell level up to the whole organism. Thus they are involved in the control of proliferation, differentiation and apoptosis, as well as in the control of responses to stresses, and they play important roles in organogenesis, immune responses and control of cognitive functions, among others. Fos proteins are intrinsically unstable. We have studied how two of them, c-Fos and Fra-1, are degraded. Departing from the classical scenario where unstable key cell regulators are hydrolysed by the proteasome after polyubiquitination, we showed that the bulk of c-Fos and Fra-1 can be broken down independently of any prior ubiquitination. Certain conserved structural domains suggest that similar mechanisms may also apply to Fra-2 and FosB. Computer search indicates that certain motifs shared by the Fos proteins and putatively responsible for instability are found in no other protein, suggesting the existence of degradation mechanisms specific for this protein family. Under particular signalling conditions, others have shown that a part of cytoplasmic c-Fos requires ubiquitination for fast turnover. This poses the question of the multiplicity of degradation pathways that apply to proteins depending on their intracellular localization.

  18. Is there an effect of ghrelin/ghrelin analogs on cancer? A systematic review

    PubMed Central

    Sever, Sakine; White, Donna L

    2016-01-01

    Ghrelin is a hormone with multiple physiologic functions, including promotion of growth hormone release, stimulation of appetite and regulation of energy homeostasis. Treatment with ghrelin/ghrelin-receptor agonists is a prospective therapy for disease-related cachexia and malnutrition. In vitro studies have shown high expression of ghrelin in cancer tissue, although its role including its impact in cancer risk and progression has not been established. We performed a systematic literature review to identify peer-reviewed human or animal in vivo original research studies of ghrelin, ghrelin-receptor agonists, or ghrelin genetic variants and the risk, presence, or growth of cancer using structured searches in PubMed database as well as secondary searches of article reference lists, additional reviews and meta-analyses. Overall, 45 (73.8%) of the 61 studies reviewed, including all 11 involving exogenous ghrelin/ghrelin-receptor agonist treatment, reported either a null (no statistically significant difference) or inverse association of ghrelin/ghrelin-receptor agonists or ghrelin genetic variants with cancer risk, presence or growth; 10 (16.7%) studies reported positive associations; and 6 (10.0%) reported both negative or null and positive associations. Differences in serum ghrelin levels in cancer cases vs controls (typically lower) were reported for some but not all cancers. The majority of in vivo studies showed a null or inverse association of ghrelin with risk and progression of most cancers, suggesting that ghrelin/ghrelin-receptor agonist treatment may have a favorable safety profile to use for cancer cachexia. Additional large-scale prospective clinical trials as well as basic bioscientific research are warranted to further evaluate the safety and benefits of ghrelin treatment in patients with cancer. PMID:27552970

  19. Organ-specific activation of the gastric branch of the efferent vagus nerve by ghrelin in urethane-anesthetized rats.

    PubMed

    Habara, Hiromi; Hayashi, Yujiro; Inomata, Norio; Niijima, Akira; Kangawa, Kenji

    2014-01-01

    Ghrelin plays multiple physiological roles such as growth hormone secretion and exerting orexigenic actions; however, its physiological roles in the electrical activity of autonomic nerves remain unclear. Here, we investigated the effects of human ghrelin on several autonomic nerve activities in urethane-anesthetized rats using an electrophysiological method. Intravenous injection of ghrelin at 3 μg/kg significantly and transiently potentiated the efferent activity of the gastric vagus nerve; however, it did not affect the efferent activity of the hepatic vagus nerve. The activated response to ghrelin in the gastric efferent vagus nerve was not affected by the gastric afferent vagotomy, suggesting that this effect was not induced via the gastric afferent vagus nerve. Ghrelin did not affect the efferent activity of the brown adipose tissue, adrenal gland sympathetic nerve, and the renal sympathetic nerve. In addition, rectal temperature and the plasma concentrations of norepinephrine, corticosterone, and renin were also not changed by ghrelin. These findings demonstrate that ghrelin stimulates the gastric efferent vagus nerve in an organ-specific manner without affecting the gastric afferent vagus nerve and that ghrelin does not acutely affect the efferent basal activity of the sympathetic nerve in rats.

  20. Elevated circulating acylated and total ghrelin concentrations along with reduced appetite scores in infants with failure to thrive.

    PubMed

    Tannenbaum, Gloria Shaffer; Ramsay, Maria; Martel, Chantal; Samia, Marwan; Zygmuntowicz, Catherine; Porporino, Mafalda; Ghosh, Shuvo

    2009-05-01

    Failure to thrive (FTT) is a term used to describe inadequate growth in infants. The immediate cause is undernutrition. Ghrelin is a potent orexigenic hormone that induces a positive energy balance and enhances appetite. There is no information regarding the possible role of ghrelin in infants with FTT. The aim of this study was 2-fold: 1) to examine circulating ghrelin levels in FTT infants, compared with those of normally growing infants; and 2) to evaluate appetitive behaviors in the two groups. Plasma acylated and total ghrelin concentrations were measured in nine FTT and five normally growing infants (age range, 9-18 mo). Appetite was assessed using three novel appetite measures. Both acylated and total ghrelin levels were significantly elevated in FTT infants compared with controls (p = 0.03 or less). Infants with FTT scored significantly lower than control infants on all appetite measures (p = 0.002 or less). Ghrelin levels were inversely related to appetite, weight velocity, weight/length z-scores, and weight z-score. These findings provide the first evidence that infants with FTT have higher circulating ghrelin concentrations but paradoxically lower appetite scores. Increased ghrelin secretion may reflect an adaptive mechanism attempting to increase appetite and preserve energy balance in response to poor nutritional state.

  1. Hypothalamic Ceramide Levels Regulated by CPT1C Mediate the Orexigenic Effect of Ghrelin

    PubMed Central

    Ramírez, Sara; Martins, Luís; Jacas, Jordi; Carrasco, Patricia; Pozo, Macarena; Clotet, Josep; Serra, Dolors; Hegardt, Fausto G.; Diéguez, Carlos; López, Miguel; Casals, Núria

    2013-01-01

    Recent data suggest that ghrelin exerts its orexigenic action through regulation of hypothalamic AMP-activated protein kinase pathway, leading to a decline in malonyl-CoA levels and desinhibition of carnitine palmitoyltransferase 1A (CPT1A), which increases mitochondrial fatty acid oxidation and ultimately enhances the expression of the orexigenic neuropeptides agouti-related protein (AgRP) and neuropeptide Y (NPY). However, it is unclear whether the brain-specific isoform CPT1C, which is located in the endoplasmic reticulum of neurons, may play a role in this action. Here, we demonstrate that the orexigenic action of ghrelin is totally blunted in CPT1C knockout (KO) mice, despite having the canonical ghrelin signaling pathway activated. We also demonstrate that ghrelin elicits a marked upregulation of hypothalamic C18:0 ceramide levels mediated by CPT1C. Notably, central inhibition of ceramide synthesis with myriocin negated the orexigenic action of ghrelin and normalized the levels of AgRP and NPY, as well as their key transcription factors phosphorylated cAMP-response element–binding protein and forkhead box O1. Finally, central treatment with ceramide induced food intake and orexigenic neuropeptides expression in CPT1C KO mice. Overall, these data indicate that, in addition to formerly reported mechanisms, ghrelin also induces food intake through regulation of hypothalamic CPT1C and ceramide metabolism, a finding of potential importance for the understanding and treatment of obesity. PMID:23493572

  2. Hepatic changes in metabolic gene expression in old ghrelin and ghrelin receptor knockout mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ghrelin knockout (GKO) and ghrelin receptor (growth hormone secretagogue receptor) knockout (GHSRKO) mice exhibit enhanced insulin sensitivity, but the mechanism is unclear. Insulin sensitivity declines with age and is inversely associated with accumulation of lipid in liver, a key glucoregulatory ...

  3. Ghrelin restores the endothelin 1/nitric oxide balance in patients with obesity-related metabolic syndrome.

    PubMed

    Tesauro, Manfredi; Schinzari, Francesca; Rovella, Valentina; Di Daniele, Nicola; Lauro, Davide; Mores, Nadia; Veneziani, Augusto; Cardillo, Carmine

    2009-11-01

    Obesity is associated with endothelial dysfunction related to decreased NO bioavailability, increased endothelin 1 vasoconstrictor activity, and decreased circulating ghrelin. Therefore, we tested whether exogenous ghrelin may have benefits to improve the balance between endothelin 1 and NO in patients with obesity-related metabolic syndrome. Vasoactive actions of endothelin 1 and NO were assessed in 8 patients with metabolic syndrome and 8 matched controls by evaluating forearm blood flow responses (strain-gauge plethysmography) to intra-arterial infusion of BQ-123 (endothelin A receptor antagonist; 10 nmol/min), followed by NG-monomethyl-L-arginine (NO synthase inhibitor; 4 micromol/min), before and after infusion of ghrelin (200 ng/min). In the absence of ghrelin, the vasodilator response to BQ-123 was greater in patients than in controls (P<0.001), whereas infusion of NG-monomethyl-L-arginine induced smaller vasoconstriction in patients than in controls (P=0.006). Importantly, exogenous ghrelin decreased the vasodilator response to BQ-123 (P=0.007 versus saline) and enhanced the magnitude of changes in forearm blood flow induced by NG-monomethyl-L-arginine (P=0.003) in patients but not in controls (both P>0.05). The favorable effect of ghrelin on endothelin A-dependent vasoconstriction was likely related to the stimulation of NO production, because no change in the vascular effect of BQ-123 was observed after ghrelin (P=0.44) in 5 patients with metabolic syndrome during continuous infusion of the NO donor sodium nitroprusside (0.2 microg/min). In patients with metabolic syndrome, ghrelin has benefits to normalize the balance between vasoconstrictor (endothelin 1) and vasodilating (NO) mediators, thus suggesting that this peptide has important peripheral actions to preserve vascular homeostasis in humans.

  4. Participation of ghrelin signalling in the reciprocal regulation of hypothalamic NPY/POMC-mediated appetite control in amphetamine-treated rats.

    PubMed

    Yu, Ching-Han; Chu, Shu-Chen; Chen, Pei-Ni; Hsieh, Yih-Shou; Kuo, Dong-Yih

    2017-06-01

    Hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) have been documented to participate in amphetamine (AMPH)-induced appetite suppression. This study investigated whether ghrelin signalling is associated with changes in NPY/POMC-mediated appetite control. Rats were given AMPH daily for four days, and changes in food intake, body weight, plasma ghrelin, hypothalamic NPY, melanocortin 3 receptor (MC3R), ghrelin O-acyltransferase (GOAT), acyl ghrelin (AG) and ghrelin receptor (GHSR1a) were examined and compared. Food intake, body weight and NPY expression decreased, while MC3R expression increased and expressed reciprocally to NPY expression during AMPH treatment. Plasma ghrelin and hypothalamic AG/GOAT/GHSR1a expression decreased on Day 1 and Day 2, which was associated with the positive energy metabolism, and returned to normal levels on Day 3 and Day 4, which was associated with the negative energy metabolism; this expression pattern was similar to that of NPY. Infusion with a GHSR1a antagonist or an NPY antisense into the brain enhanced the decrease in NPY and AG/GOAT/GHSR1a expression and the increase in MC3R expression compared to the AMPH-treated group. Peripheral ghrelin and the central ghrelin system participated in the regulation in AMPH-induced appetite control. These results shed light on the involvement of ghrelin signalling in reciprocal regulation of NPY/POMC-mediated appetite control and may prove useful for the development of anti-obesity drugs.

  5. Delta-9-tetrahydrocannabinol differently affects striatal c-Fos expression following haloperidol or clozapine administration.

    PubMed

    Marchese, Giorgio; Sanna, Angela; Casu, Gianluca; Casti, Paola; Spada, Gabriele Pinna; Ruiu, Stefania; Pani, Luca

    2008-11-19

    It was previously shown that haloperidol, but not clozapine, induced intense rat catalepsy when co-administered with delta-9-tetrahydrocannabinol. The present study investigated whether similar alterations could be observed on striatal c-Fos immunoreactivity after administration of the same drug combinations. Western Blot and immunocytochemistry stereological analyses indicated that delta-9-tetrahydrocannabinol (0.5 mg/kg) increased striatal c-Fos immunoreactivity induced by haloperidol (0.1 mg/kg). Conversely, no significant alterations of striatal c-Fos immunoreactivity were observed after injections of clozapine (10 mg/kg)+vehicle, clozapine+delta-9-tetrahydrocannabinol or vehicle+delta-9-tetrahydrocannabinol. The present results indicate that the behavioral effects induced by delta-9-tetrahydrocannabinol in haloperidol- and clozapine-treated rats are associated with different striatal c-Fos expressions.

  6. A mechanism of AP-1 suppression through interaction of c-Fos with lamin A/C

    PubMed Central

    Ivorra, Carmen; Kubicek, Markus; González, José M.; Sanz-González, Silvia M.; Álvarez-Barrientos, Alberto; O'Connor, José-Enrique; Burke, Brian; Andrés, Vicente

    2006-01-01

    AP-1 (Activating Protein 1) transcription factor activity is tightly regulated at multiple levels, including dimer formation (i.e., Fos/Jun). Here we show that the intermediate filament protein lamin A/C suppresses AP-1 function through direct interaction with c-Fos, and that both proteins can interact and colocalize at the nuclear envelope (NE) in mammalian cells. Perinuclear localization of c-Fos is absent in Lmna-null cells but can be restored by lamin A overexpression. In vitro, preincubation of c-Fos with lamin A prior to the addition of c-Jun inhibits AP-1 DNA-binding activity. In vivo, overexpression of lamin A reduces the formation of c-Fos/c-Jun heterodimers, and suppresses AP-1 DNA-binding and transcriptional activity. Notably, c-Fos colocalizes with lamin A/C at the NE in starvation-synchronized quiescent cells lacking detectable AP-1 DNA binding. In contrast, serum-induced AP-1 DNA-binding activity coincides with abundant nucleoplasmic c-Fos expression without changes in lamin A/C localization. We also found that Lmna-null cells display enhanced proliferation. In contrast, lamin A overexpression causes growth arrest, and ectopic c-Fos partially overcomes lamin A/C-induced cell cycle alterations. We propose lamin A/C-mediated c-Fos sequestration at the NE as a novel mechanism of transcriptional and cell cycle control. PMID:16452503

  7. Sustained Fos expression is observed in the developing brainstem auditory circuits of kanamycin-treated rats.

    PubMed

    Lee, Jae Ho; Kim, Hee Jung; Suh, Myung-Whan; Ahn, Seung Cheol

    2011-11-14

    It has been demonstrated that kanamycin treatment during early developmental period induces partial cochlear destruction and enhanced glutamatergic transmission at the medial nucleus of the trapezoid body (MNTB) - the lateral superior olive (LSO) synapses in the superior olivary complex (SOC). As c-fos was expected to be expressed in the SOC by kanamycin-induced cochlear damage, the expression of c-fos protein (Fos) was investigated using immunohistochemistry in kanamycin-treated rat pups. In the control rat pups less than postnatal (P) day 9 in age, Fos-like immunoreactivity (Fos-IR) was transiently observed in the MNTB and LSO on P6, but disappeared on P9, which reflects a physiologic process. In contrast, in kanamycin-treated rats, Fos-IR was consistently observed through P9. Because a significant increase in terminal uridine deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick-end labeling (TUNEL) and glial fibrillary acidic protein (GFAP) IR was not demonstrated in the MNTB and LSO of kanamycin-treated rats, the increased Fos-IR does not appear to indicate an ongoing pathologic process, but may be related to the increased activity caused by the disturbance in excitatory and inhibitory balance between brainstem auditory circuits.

  8. Ghrelin Attenuates Liver Fibrosis through Regulation of TGF-β1 Expression and Autophagy.

    PubMed

    Mao, Yuqing; Zhang, Shaoren; Yu, Fujun; Li, Huanqing; Guo, Chuanyong; Fan, Xiaoming

    2015-09-10

    Ghrelin is a stomach-derived growth hormone secretagogue that promotes various physiological effects, including energy metabolism and amelioration of inflammation. The purpose of this study was to investigate the protective mechanism of ghrelin against liver fibrosis. Liver fibrosis was induced in C57BL/6 mice by intraperitoneal injection of CCl₄ (2.0 mL/kg of 10% CCl₄ v/v solution in peanut oil) two times per week for eight weeks. Ghrelin (10 μg/kg) was intraperitoneally injected two times per week for eight weeks. A second murine liver fibrosis model was induced by bile duct ligation (BDL) and concurrent ghrelin administration for four weeks. Hematoxylin eosin (H&E), and Masson's trichrome were used to detect pathological changes to liver tissue. Western blotting was used to detect protein levels of transforming growth factor (TGF)-β1, phosphorylated Smad3 (p-Smad3), I-collage, α-smooth muscle actin (α-SMA), matrix metalloproteinases (MMPs) 2, tissue inhibitor of matrix metalloproteinases (TIMPs) 1, phosphorylated NF-κB (p-NF-κB), and microtubule-associated protein light chain 3 (LC3). In addition, qRT-PCR was used to detect mRNA levels of TGF-β1, I-collage, α-SMA, MMP2, TIMP1 and LC3, while levels of TGF-β1, p-Smad3, I-collage, α-SMA, and LC3 were detected immunohistochemically. Levels of aspartate aminotransferase and alanine aminotransferase were significantly decreased by ghrelin treatment. Ghrelin administration also significantly reduced the extent of pathological changes in both murine liver fibrosis models. Expression levels of I-collage and α-SMA in both models were clearly reduced by ghrelin administration. Furthermore, ghrelin treatment decreased protein expression of TGF-β1 and p-Smad3. The protein levels of NF-κB and LC3 were increased in the CCl₄- and BDL-treatment groups but were significantly reduced following ghrelin treatment. In addition, ghrelin inhibited extracellular matrix formation by decreasing NF-κB expression and

  9. Ghrelin at the interface of obesity and reward.

    PubMed

    Schellekens, Harriët; Dinan, Timothy G; Cryan, John F

    2013-01-01

    The prevalence of obesity continues to increase and has reached epidemic proportions. Accumulating data over the past few decades have given us key insights and broadened our understanding of the peripheral and central regulation of energy homeostasis. Despite this, the currently available pharmacological treatments, reducing body weight, remain limited due to poor efficacy and side effects. The gastric peptide ghrelin has been identified as the only orexigenic hormone from the periphery to act in the hypothalamus to stimulate food intake. Recently, a role for ghrelin and its receptor at the interface between homeostatic control of appetite and reward circuitries modulating the hedonic aspects of food has also emerged. Nonhomeostatic factors such as the rewarding and motivational value of food, which increase with food palatability and caloric content, can override homeostatic control of food intake. This nonhomeostatic decision to eat leads to overconsumption beyond nutritional needs and is being recognized as a key component in the underlying causes for the increase in obesity incidence worldwide. In addition, the hedonic feeding behavior has been linked to food addiction and an important role for ghrelin in the development of addiction has been suggested. Moreover, plasma ghrelin levels are responsive to conditions of stress, and recent evidence has implicated ghrelin in stress-induced food-reward behavior. The prominent role of the ghrelinergic system in the regulation of feeding gives rise to it as an effective target for the development of successful antiobesity pharmacotherapies that not only affect satiety but also selectively modulate the rewarding properties of food and reduce the desire to eat.

  10. Harmful Algal Bloom Toxins: c-Fos Protein Expression in the Brain of Killifish, Fundulus heteroclitus

    DTIC Science & Technology

    2006-04-21

    California coast linked to a toxic diatom bloom. Nature 403, 80–84. Schreiberagus, N., Horner, J., Torres, R., Chiu, F.C., Depinho, R.A., 1993. Zebra fish myc...protein product c-Fos, are known to be induced in neurons of mammals and fish as a result of neuronal timulation. The purpose of this study was to...physical stress on c-Fos induction. Groups of fish were exposed to the different tress agents, brain sections were processed for c-Fos staining, and

  11. Increased analgesic tolerance to acute morphine in fosB knock-out mice: a gender study.

    PubMed

    Solecki, Wojciech; Krowka, Tomasz; Kubik, Jakub; Kaczmarek, Leszek; Przewlocki, Ryszard

    2008-10-01

    The proteins of Fos family are a potential candidate to link molecular mechanisms of morphine action with behavioural effects such as morphine-induced reward, dependence and tolerance. We used both male and female mice lacking fosB gene to study its contribution to morphine effects. Morphine analgesia (tail-flick test) and hypothermia were studied using morphine at cumulative doses in morphine-naive and morphine-tolerant (tolerance induced by 24 h prior 100 mg/kg morphine administration) mice. FosB -/- mice, as compared to fosB +/+ mice, developed enhanced tolerance to morphine-induced analgesia. No effects of genotype or gender on tolerance to morphine-induced hypothermia were observed. These results suggest that fosB may be involved in the development of tolerance to morphine analgesia but not hypothermia. The gender study implicates that lack of FosB proteins in female fosB -/- mice enhanced morphine analgesic potency. In conclusion, we show that fosB gene is important to analgesia but not hypothermia phenotype indicating its role in morphine effects.

  12. Ghrelin levels in chronic periodontitis patients.

    PubMed

    Yılmaz, Gülin; Kırzıoğlu, Fatma Yeşim; Doğuç, Duygu Kumbul; Koçak, Havva; Orhan, Hikmet

    2014-01-01

    Ghrelin is a peptide hormone that has modulatory effects on the immune system. This study was designed to evaluate plasma ghrelin levels in patients with chronic periodontitis and to investigate if a relationship exists between ghrelin and periodontal parameters, serum cytokines, and bone turnover markers. Thirty-five chronic periodontitis patients (CP) and periodontal healthy individuals (C) were included in this study. Periodontal parameters were recorded. Blood samples were obtained to determine the levels of total and acylated ghrelin, interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), the soluble receptor activator nuclear factor kappaB ligand (sRANKL), alkaline phosphatase (ALP), and osteocalcin (OSC). Plasma levels of total and acylated ghrelin were significantly elevated in the CP group compared with the C group (p < 0.05). The difference was significant only between males in the two groups (groups were compared with respect to gender) (p < 0.05). There was no difference between the groups regarding the levels of serum sRANKL, TNF-α, and ALP. A relative increase in the serum levels of IL-1β and a decrease in the serum levels of OSC of the CP group were observed (p < 0.05). In addition, positive correlations between total ghrelin/ALP and total ghrelin/acylated ghrelin were discovered. We found no direct correlation between ghrelin levels and periodontal parameters. Our results indicate an increase of total and acylated ghrelin levels in patients with chronic periodontitis. Further, studies in larger populations (which could include ghrelin levels in gingival tissue, gingival crevicular fluid, and saliva) are needed in order to confirm the role of ghrelin in periodontal disease.

  13. Differential effects of olanzapine and clozapine on plasma levels of adipocytokines and total ghrelin.

    PubMed

    Lu, Mong-Liang; Wang, Tsu-Nai; Lin, Tsang-Yaw; Shao, Wen-Chuan; Chang, Sheng-Huang; Chou, Jen-Yu; Ho, Yi-Feng; Liao, Yin-To; Chen, Vincent Chin-Hung

    2015-04-03

    Second-generation antipsychotics (SGAs) have been associated with an increased liability for weight gain and metabolic side effects. Among SGAs, clozapine and olanzapine had great liability to induce weight gain and metabolic adverse reactions. Leptin, adiponectin, and total ghrelin play important roles in energy homeostasis and are suggested to be biomarkers of metabolic disturbances. The purpose of the present study was to investigate the differential effects of antipsychotics (olanzapine and clozapine) on the levels of adipocytokines (leptin and adiponectin) and total ghrelin. Three hundred and thirty-three patients with schizophrenia under clozapine or olanzapine monotherapy were recruited. Control participants were recruited from a healthy community population based on a health investigation (N=119). Fasting blood samples for glucose, cholesterol, triglycerides, leptin, adiponectin, and total ghrelin were analyzed. There were significant differences in the levels of cholesterol, triglycerides, and glucose between these three groups. Post hoc comparisons showed that the olanzapine group had the highest levels of cholesterol and triglycerides. The levels of leptin, adiponectin, and total ghrelin were also significantly different between the three groups after controlling age and body mass index (BMI). Post hoc comparisons showed that the olanzapine group had the lowest levels of adiponectin and total ghrelin. The present study found that the uses of olanzapine and clozapine were associated with changes in adipocytokines and total ghrelin, even after adjusting potential confounding factors. Olanzapine had greater influences on adiponectin and total ghrelin than clozapine. The changes in adipocytokines and total ghrelin were a direct effect of antipsychotics on hormonal pathways of energy homeostasis, rather than the result of weight gain.

  14. Ghrelin regulates GLP-1 production through mTOR signaling in L cells.

    PubMed

    Xu, Geyang; Hong, Xiaosi; Tang, Hong; Jiang, Sushi; Liu, Fenting; Shen, Zhemin; Li, Ziru; Zhang, Weizhen

    2015-11-15

    Glucagon-like peptide (GLP-1), an intestinal incretin produced in L-cells and released in response to meal intake, functions to promote insulin secretion and to decrease plasma glucose. Ghrelin is an orexigenic hormone critical for glucose homeostasis. The molecular mechanism by which ghrelin alters GLP-1 production remains largely unknown. Here we showed that ghrelin attenuates GLP-1 production through mTOR signaling. In GHSR1a null mice, ileal mTOR signaling, proglucagon and circulating GLP-1 were significantly increased. Antagonism of the GHSR1a by D-Lys-3-GHRP-6 increased GLP-1 synthesis and release in STC-1 cells. Treatment of STC-1 cells with ghrelin decreased the production of GLP-1. This effect was associated with a significant inhibition of mTOR signaling. Overexpression of ghrelin inhibited proglucagon promoter activity and GLP-1 production. Inhibition of mTOR activity by mTOR siRNA blocked D-Lys-3-GHRP-6 induced GLP-1 production in STC-1 cells. Our results suggest that mTOR signaling mediates the inhibitory effect of ghrelin on GLP-1 production.

  15. Ghrelin and nicotine stimulate equally the dopamine release in the rat amygdala.

    PubMed

    Palotai, Miklós; Bagosi, Zsolt; Jászberényi, Miklós; Csabafi, Krisztina; Dochnal, Roberta; Manczinger, Máté; Telegdy, Gyula; Szabó, Gyula

    2013-10-01

    The orexigenic peptide ghrelin plays a prominent role in the regulation of energy balance and in the mediation of reward processes and reinforcement for addictive drugs, such as nicotine. Nicotine is the principal psychoactive component in tobacco, which is responsible for addiction and relapse of smokers. Ghrelin and nicotine activates the mesolimbicocortical dopaminergic pathways via growth hormone secretagogue receptors (GHS-R1A) and nicotinic acetylcholine receptors (nAchR), respectively, resulting in the release of dopamine in the nucleus accumbens, the amygdala and the prefrontal cortex. In the present study an in vitro superfusion of rat amygdalar slices was performed in order to investigate the direct action of ghrelin and nicotine on the amygdalar dopamine release. Ghrelin increased significantly the dopamine release from the rat amygdala following electrical stimulation. This effect was inhibited by both the selective GHS-R1A antagonist GHRP-6 and the selective nAchR antagonist mecamylamine. Under the same conditions, nicotine also increased significantly the dopamine release from the rat amygdala. This effect was antagonized by mecamylamine, but not by GHRP-6. Co-administration of ghrelin and nicotine induced a similar increase of amygdalar dopamine release. This stimulatory effect was partially reversed by both GHRP-6 and mecamylamine. The present results demonstrate that both ghrelin and nicotine stimulates directly the dopamine release in the amygdala, an important dopaminergic target area of the mesolimbicocortical pathway.

  16. The Human Experience With Ghrelin Administration

    PubMed Central

    Garin, Margaret C.; Burns, Carrie M.; Kaul, Shailja

    2013-01-01

    Context: Ghrelin is an endogenous stimulator of GH and is implicated in a number of physiological processes. Clinical trials have been performed in a variety of patient populations, but there is no comprehensive review of the beneficial and adverse consequences of ghrelin administration to humans. Evidence Acquisition: PubMed was utilized, and the reference list of each article was screened. We included 121 published articles in which ghrelin was administered to humans. Evidence Synthesis: Ghrelin has been administered as an infusion or a bolus in a variety of doses to 1850 study participants, including healthy participants and patients with obesity, prior gastrectomy, cancer, pituitary disease, diabetes mellitus, eating disorders, and other conditions. There is strong evidence that ghrelin stimulates appetite and increases circulating GH, ACTH, cortisol, prolactin, and glucose across varied patient populations. There is a paucity of evidence regarding the effects of ghrelin on LH, FSH, TSH, insulin, lipolysis, body composition, cardiac function, pulmonary function, the vasculature, and sleep. Adverse effects occurred in 20% of participants, with a predominance of flushing and gastric rumbles and a mild degree of severity. The few serious adverse events occurred in patients with advanced illness and were not clearly attributable to ghrelin. Route of administration may affect the pattern of adverse effects. Conclusions: Existing literature supports the short-term safety of ghrelin administration and its efficacy as an appetite stimulant in diverse patient populations. There is some evidence to suggest that ghrelin has wider ranging therapeutic effects, although these areas require further investigation. PMID:23533240

  17. Ghrelin Receptors in Non-Mammalian Vertebrates

    PubMed Central

    Kaiya, Hiroyuki; Kangawa, Kenji; Miyazato, Mikiya

    2012-01-01

    The growth hormone secretagogue-receptor (GHS-R) was discovered in humans and pigs in 1996. The endogenous ligand, ghrelin, was discovered 3 years later, in 1999, and our understanding of the physiological significance of the ghrelin system in vertebrates has grown steadily since then. Although the ghrelin system in non-mammalian vertebrates is a subject of great interest, protein sequence data for the receptor in non-mammalian vertebrates has been limited until recently, and related biological information has not been well organized. In this review, we summarize current information related to the ghrelin receptor in non-mammalian vertebrates. PMID:23882259

  18. Effects of ghrelin and motilin on smooth muscle contractility of the isolated gastrointestinal tract from the bullfrog and Japanese fire belly newt.

    PubMed

    Kitazawa, Takio; Shimazaki, Misato; Kikuta, Ayumi; Yaosaka, Noriko; Teraoka, Hiroki; Kaiya, Hiroyuki

    2016-06-01

    Ghrelin has been identified in some amphibians and is known to stimulate growth hormone release and food intake as seen in mammals. Ghrelin regulates gastrointestinal motility in mammals and birds. The aim of this study was to determine whether ghrelin affects gastrointestinal smooth muscle contractility in bullfrogs (anuran) and Japanese fire belly newts (urodelian) in vitro. Neither bullfrog ghrelin nor rat ghrelin affected longitudinal smooth muscle contractility of gastrointestinal strips from the bullfrog. Expression of growth hormone secretagogue receptor 1a (GHS-R1a) mRNA was confirmed in the bullfrog gastrointestinal tract, and the expression level in the gastric mucosa was lower than that in the intestinal mucosa. In contrast, some gastrointestinal peptides, including substance P, neurotensin and motilin, and the muscarinic receptor agonist carbachol showed marked contraction, indicating normality of the smooth muscle preparations. Similar results were obtained in another amphibian, the Japanese fire belly newt. Newt ghrelin and rat ghrelin did not cause any contraction in gastrointestinal longitudinal muscle, whereas substance P and carbachol were effective causing contraction. In conclusion, ghrelin does not affect contractility of the gastrointestinal smooth muscle in anuran and urodelian amphibians, similar to results for rainbow trout and goldfish (fish) but different from results for rats and chickens. The results suggest diversity of ghrelin actions on the gastrointestinal tract across animals. This study also showed for the first time that motilin induces gastrointestinal contraction in amphibians.

  19. Persistent induction of c-fos and c-jun expression by asbestos

    SciTech Connect

    Heintz, N.H.; Mossman, B.T. ); Janssen, Y.M. Univ. of Limburg, Maastricht )

    1993-04-15

    To investigate the mechanisms of asbestos-induced carcinogenesis, expression of c-fos and c-jun protooncogenes was examined in rat pleural mesothelial cells and hamster tracheal epithelial cells after exposure to crocidolite or chrysotile asbestos. In contrast to phorbol 12-myristate 13-acetate, which induces rapid and transient increases in c-fos and c-jun mRNA, asbestos causes 2- to 5-fold increases in c-fos and c-jun mRNA that persist for at least 24 hr in mesothelial cells. The induction of c-fos and c-jun mRNA by asbestos in mesothelial cells is dose-dependent and is most pronounced with crocidolite, the type of asbestos most pathogenic in the causation of pleural mesothelioma. Induction of c-jun gene expression by asbestos occurs in tracheal epithelial cells but is not accompanied by a corresponding induction of c-fos gene expression. In both cell types, asbestos induces increases in protein factors that bind specifically to the DNA sites that mediate gene expression by the AP-1 family of transcription factors. The persistent induction of AP-1 transcription factors by asbestos suggests a model of asbestos-induced carcinogenesis involving chronic stimulation of cell proliferation through activation of the early response gene pathway that includes c-jun and/or c-fos. 30 refs., 5 figs.

  20. Rational design of dual peptides targeting ghrelin and Y2 receptors to regulate food intake and body weight.

    PubMed

    Kilian, Tom-Marten; Klöting, Nora; Bergmann, Ralf; Els-Heindl, Sylvia; Babilon, Stefanie; Clément-Ziza, Mathieu; Zhang, Yixin; Beck-Sickinger, Annette G; Chollet, Constance

    2015-05-28

    Ghrelin and Y2 receptors play a central role in appetite regulation inducing opposite effects. The Y2 receptor induces satiety, while the ghrelin receptor promotes hunger and weight gain. However, the food regulating system is tightly controlled by interconnected pathways where redundancies can lead to poor efficacy and drug tolerance when addressing a single molecule. We developed a multitarget strategy to synthesize dual peptides simultaneously inhibiting the ghrelin receptor and stimulating the Y2 receptor. Dual peptides showed dual activity in vitro, and one compound induced a slight diminution of food intake in a rodent model of obesity. In addition, stability studies in rats revealed different behaviors between the dual peptide and its corresponding monomers. The Y2 receptor agonist was unstable in blood, while the dual peptide showed an intermediate stability compared to that of the highly stable ghrelin receptor inverse agonist.

  1. Acylated and desacyl ghrelin are associated with hepatic lipogenesis, β-oxidation and autophagy: role in NAFLD amelioration after sleeve gastrectomy in obese rats

    PubMed Central

    Ezquerro, Silvia; Méndez-Giménez, Leire; Becerril, Sara; Moncada, Rafael; Valentí, Víctor; Catalán, Victoria; Gómez-Ambrosi, Javier; Frühbeck, Gema; Rodríguez, Amaia

    2016-01-01

    Bariatric surgery improves non-alcoholic fatty liver disease (NAFLD). Our aim was to investigate the potential role of ghrelin isoforms in the resolution of hepatic steatosis after sleeve gastrectomy, a restrictive bariatric surgery procedure, in diet-induced obese rats. Male Wistar rats (n = 161) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions [fed ad libitum a normal (ND) or a high-fat (HFD) diet or pair-fed]. Obese rats developed hepatosteatosis and showed decreased circulating desacyl ghrelin without changes in acylated ghrelin. Sleeve gastrectomy induced a dramatic decrease of desacyl ghrelin, but increased the acylated/desacyl ghrelin ratio. Moreover, sleeve gastrectomy reduced hepatic triglyceride content and lipogenic enzymes Mogat2 and Dgat1, increased mitochondrial DNA amount and induced AMPK-activated mitochondrial FFA β-oxidation and autophagy to a higher extent than caloric restriction. In primary rat hepatocytes, the incubation with both acylated and desacyl ghrelin (10, 100 and 1,000 pmol/L) significantly increased TG content, triggered AMPK-activated mitochondrial FFA β-oxidation and autophagy. Our data suggest that the decrease in the most abundant isoform, desacyl ghrelin, after sleeve gastrectomy contributes to the reduction of lipogenesis, whereas the increased relative acylated ghrelin levels activate factors involved in mitochondrial FFA β-oxidation and autophagy in obese rats, thereby ameliorating NAFLD. PMID:28008992

  2. Acylated and desacyl ghrelin are associated with hepatic lipogenesis, β-oxidation and autophagy: role in NAFLD amelioration after sleeve gastrectomy in obese rats.

    PubMed

    Ezquerro, Silvia; Méndez-Giménez, Leire; Becerril, Sara; Moncada, Rafael; Valentí, Víctor; Catalán, Victoria; Gómez-Ambrosi, Javier; Frühbeck, Gema; Rodríguez, Amaia

    2016-12-23

    Bariatric surgery improves non-alcoholic fatty liver disease (NAFLD). Our aim was to investigate the potential role of ghrelin isoforms in the resolution of hepatic steatosis after sleeve gastrectomy, a restrictive bariatric surgery procedure, in diet-induced obese rats. Male Wistar rats (n = 161) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions [fed ad libitum a normal (ND) or a high-fat (HFD) diet or pair-fed]. Obese rats developed hepatosteatosis and showed decreased circulating desacyl ghrelin without changes in acylated ghrelin. Sleeve gastrectomy induced a dramatic decrease of desacyl ghrelin, but increased the acylated/desacyl ghrelin ratio. Moreover, sleeve gastrectomy reduced hepatic triglyceride content and lipogenic enzymes Mogat2 and Dgat1, increased mitochondrial DNA amount and induced AMPK-activated mitochondrial FFA β-oxidation and autophagy to a higher extent than caloric restriction. In primary rat hepatocytes, the incubation with both acylated and desacyl ghrelin (10, 100 and 1,000 pmol/L) significantly increased TG content, triggered AMPK-activated mitochondrial FFA β-oxidation and autophagy. Our data suggest that the decrease in the most abundant isoform, desacyl ghrelin, after sleeve gastrectomy contributes to the reduction of lipogenesis, whereas the increased relative acylated ghrelin levels activate factors involved in mitochondrial FFA β-oxidation and autophagy in obese rats, thereby ameliorating NAFLD.

  3. Fat digestion is required for suppression of ghrelin and stimulation of peptide YY and pancreatic polypeptide secretion by intraduodenal lipid.

    PubMed

    Feinle-Bisset, Christine; Patterson, Michael; Ghatei, Mohammad A; Bloom, Stephen R; Horowitz, Michael

    2005-12-01

    Stimulation of cholecystokinin and glucagon-like peptide-1 secretion by fat is mediated by the products of fat digestion. Ghrelin, peptide YY (PYY), and pancreatic polypeptide (PP) appear to play an important role in appetite regulation, and their release is modulated by food ingestion, including fat. It is unknown whether fat digestion is a prerequisite for their suppression (ghrelin) or release (PYY, PP). Moreover, it is not known whether small intestinal exposure to fat is sufficient to suppress ghrelin secretion. Our study aimed to resolve these issues. Sixteen healthy young males received, on two separate occasions, 120-min intraduodenal infusions of a long-chain triglyceride emulsion (2.8 kcal/min) 1) without (condition FAT) or 2) with (FAT-THL) 120 mg of tetrahydrolipstatin (THL, lipase inhibitor), followed by a standard buffet-style meal. Blood samples for ghrelin, PYY, and PP were taken throughout. FAT infusion was associated with a marked, and progressive, suppression of plasma ghrelin from t = 60 min (P < 0.001) and stimulation of PYY from t = 30 min (P < 0.01). FAT infusion also stimulated plasma PP (P < or = 0.01), and the release was immediate. FAT-THL completely abolished the FAT-induced changes in ghrelin, PYY, and PP. In response to the meal, plasma ghrelin was further suppressed, and PYY and PP stimulated, during both FAT and FAT-THL infusions. In conclusion, in healthy humans, 1) the presence of fat in the small intestine suppresses ghrelin secretion, and 2) fat-induced suppression of ghrelin and stimulation of PYY and PP is dependent on fat digestion.

  4. Decreased GH secretion and enhanced ACTH and cortisol release after ghrelin administration in Cushing's disease: comparison with GH-releasing peptide-6 (GHRP-6) and GHRH.

    PubMed

    Correa-Silva, Silvia Regina; Nascif, Sérgio Oliva; Lengyel, Ana-Maria Judith

    2006-01-01

    GH responsiveness to GH secretagogues (GHS) is blunted in Cushing's disease (CD), while ACTH/cortisol responses are enhanced, by mechanisms still unclear. Ghrelin, the endogenous ligand for GHS-receptors (GHS-R), increases GH, ACTH, cortisol and glucose levels in humans. This study evaluated the GH, ACTH, cortisol and glucose-releasing effects of ghrelin in CD in comparison with GHRP-6. GHRH-induced GH release was also studied. Ten patients with CD (BMI 26.9+/-1.0 kg/m(2)) and ten controls (BMI 24.4+/-1.1 kg/m(2)) received ghrelin (1 microg/kg), GHRP-6 (1 microg/kg) and GHRH (100 microg) separately. GH, ACTH, cortisol and glucose levels were measured. In CD ghrelin-induced GH (microg/L; mean +/- SE) release (peak: 7.2+/-3.0) was higher than seen with GHRP-6 (2.7+/-1.0) and GHRH (0.7+/-0.2), but lower than in controls (ghrelin: 58.3+/-12.1; GHRP-6: 22.9+/-4.8; GHRH: 11.3+/-3.7). In controls ACTH (pg/mL) release after ghrelin (79.2+/-26.8) was higher than after GHRP-6 (23.6+/-5.7). In CD these responses (ghrelin: 192+/-43; GHRP-6: 185+/-56) were similar, and enhanced compared to controls. The same was observed with cortisol. Glucose levels failed to increase after ghrelin in CD, differently than in controls. Our data suggests that hypothalamic and pituitary pathways of GH release activated by ghrelin, GHRP-6 and GHRH are deranged in chronic hypercortisolism. The increased ACTH/cortisol responses to ghrelin and GHRP-6 in CD could be mediated by overexpression of GHS-R in ACTH-secreting adenomas. Hypercortisolism apparently impairs the ability of ghrelin to increase glucose levels.

  5. Ghrelin decreases food intake in juvenile rainbow trout (Oncorhynchus mykiss) through the central anorexigenic corticotropin-releasing factor system.

    PubMed

    Jönsson, Elisabeth; Kaiya, Hiroyuki; Björnsson, Björn Thrandur

    2010-03-01

    Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of food intake and adiposity in vertebrates. To investigate the central effect of native rainbow trout ghrelin (rtghrelin) on food intake in rainbow trout, as well as its possible mode of action, four groups of fish received a single injection into the third brain ventricle (i.c.v. injection): (1) control group (physiological saline) (2) ghrelin-treated group (2.0 ng rtghrelin g bwt(-1)), (3) group given the corticotropin-releasing hormone receptor antagonist alpha-helical CRF 9-41 (ahCRF) (4.0 ng g bwt(-1)) and (4) group receiving the same dose of both ghrelin and ahCRF. Food intake was assessed 1h after treatment. In addition, the presence of the GHS-R (the ghrelin receptor) in the rainbow trout CNS was examined with Western blot. To investigate peripheral effects of ghrelin, rainbow trout received an intraperitoneal cholesterol-based implant with or without rtghrelin, and daily food intake was measured during 14 days. Weight and length were measured at the start and termination of the experiment and specific growth rates were calculated. Mesenteric fat stores, muscle and liver lipid content were analysed after the treatment period. Central ghrelin injections decreased food intake compared with controls, and treatment with ahCRF abolished the ghrelin-effect. Western blot analysis of the GHS-R revealed a single band at around 60 kDa in pituitary, hypothalamus, brain and stomach. Long-term peripheral ghrelin treatment decreased daily food intake compared with controls. This was reflected in a ghrelin-induced decrease in weight growth rate (p<0.06). There was no effect of ghrelin on plasma GH levels or tissue fat stores. The conclusion from this study is that the GHS-R is indicated in the CNS in rainbow trout and that ghrelin may act there as an anorexigenic hormone, through a CRF-mediated pathway. Elevated peripheral ghrelin levels also seem to lead to decreased feed

  6. Ghrelin augments murine T-cell proliferation by activation of the phosphatidylinositol-3-kinase, extracellular signal-regulated kinase and protein kinase C signaling pathways

    PubMed Central

    Lee, Jun Ho; Patel, Kalpesh; Tae, Hyun Jin; Lustig, Ana; Kim, Jie Wan; Mattson, Mark P.; Taub, Dennis D.

    2014-01-01

    Thymic atrophy occurs during normal aging, and is accelerated by exposure to chronic stressors that elevate glucocorticoid levelsand impair the naïve T cell output. The orexigenic hormone ghrelin was recently shown to attenuate age-associated thymic atrophy. Here, we report that ghrelin enhances the proliferation of murine CD4+ primary T cells and a CD4+ T-cell line. Ghrelin induced activation of the ERK1/2 and Akt signaling pathways, via upstream activation of phosphatidylinositol-3-kinase and protein kinase C, to enhance T-cell proliferation. Moreover, ghrelin induced expression of the cell cycle proteins cyclin D1, cyclin E, cyclin-dependent kinase 2 (CDK2) and retinoblastoma phosphorylation. Finally, ghrelin activated the above-mentioned signaling pathways and stimulated thymocyte proliferation in young and older mice in vivo. PMID:25447526

  7. Active immunization against ghrelin decreases weight gain and alters plasma concentrations of growth hormone in growing pigs.

    PubMed

    Vizcarra, J A; Kirby, J D; Kim, S K; Galyean, M L

    2007-08-01

    Ghrelin has been implicated in the control of food intake and in the long-term regulation of body weight. We theorize that preventing the ability of ghrelin to interact with its receptors, would eventually lead to decreased appetite and thereby decrease body weight gain. To test our hypothesis, pigs were actively immunized against ghrelin. Ghrelin((1-10)) was conjugated to BSA and emulsified in Freund's incomplete adjuvant and diethylaminoethyl-dextran. Primary immunization was given at 19 weeks of age (WOA), with booster immunizations given 20 and 40 days after primary immunization. Body weight (BW) and plasma samples were collected weekly beginning at 19 WOA, and feed intake was measured daily. Fourteen days after primary immunization, the percentage of bound (125)I-ghrelin in plasma from immunized pigs was increased compared with control animals (P<0.001). Voluntary feed intake was decreased more than 15% in animals that were actively immunized against ghrelin compared with controls. By the end of the experiment, immunized pigs weighed 10% less than control animals (P<0.1). Concentrations of GH were increased (P<0.05) in immunized pigs. Apoptosis was not observed in post-mortem samples obtained from the fundic region of the stomach. Our observations suggest that immunization against ghrelin induces mild anorexia. This procedure could potentially be used as a treatment to control caloric intake and obesity.

  8. Recent Advances in Potential Clinical Application of Ghrelin in Obesity

    PubMed Central

    Delporte, Christine

    2012-01-01

    Ghrelin is the natural ligand of the growth hormone secretagogue receptor (GHS-R1a). Ghrelin is a 28 amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by ghrelin O-acyltransferase (GOAT). Ghrelin stimulates growth hormone secretion, but also appetite, food intake, weight gain, and gastric emptying. Ghrelin is involved in weight regulation, obesity, type 2 diabetes, and metabolic syndrome. Furthermore, a better understanding of ghrelin biology led to the identification of molecular targets modulating ghrelin levels and/or its biological effects: GOAT, ghrelin, and GHS-R1a. Furthermore, a recent discovery, showing the involvement of bitter taste receptor T2R in ghrelin secretion and/or synthesis and food intake, suggested that T2R could represent an additional interesting molecular target. Several classes of ghrelin-related pharmacological tools for the treatment of obesity have been or could be developed to modulate the identified molecular targets. PMID:22523666

  9. Hindbrain ghrelin receptor signaling is sufficient to maintain fasting glucose.

    PubMed

    Scott, Michael M; Perello, Mario; Chuang, Jen-Chieh; Sakata, Ichiro; Gautron, Laurent; Lee, Charlotte E; Lauzon, Danielle; Elmquist, Joel K; Zigman, Jeffrey M

    2012-01-01

    The neuronal coordination of metabolic homeostasis requires the integration of hormonal signals with multiple interrelated central neuronal circuits to produce appropriate levels of food intake, energy expenditure and fuel availability. Ghrelin, a peripherally produced peptide hormone, circulates at high concentrations during nutrient scarcity. Ghrelin promotes food intake, an action lost in ghrelin receptor null mice and also helps maintain fasting blood glucose levels, ensuring an adequate supply of nutrients to the central nervous system. To better understand mechanisms of ghrelin action, we have examined the roles of ghrelin receptor (GHSR) expression in the mouse hindbrain. Notably, selective hindbrain ghrelin receptor expression was not sufficient to restore ghrelin-stimulated food intake. In contrast, the lowered fasting blood glucose levels observed in ghrelin receptor-deficient mice were returned to wild-type levels by selective re-expression of the ghrelin receptor in the hindbrain. Our results demonstrate the distributed nature of the neurons mediating ghrelin action.

  10. KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.

    PubMed

    Han, X-R; Zha, Z; Yuan, H-X; Feng, X; Xia, Y-K; Lei, Q-Y; Guan, K-L; Xiong, Y

    2016-08-11

    KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations.

  11. Ghrelin receptor controls obesity by fat burning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Emerging evidence show that brown fat in the body produces heat to burn energy, thus prompting weight loss. Ghrelin is the only known hormone which increases appetite and promotes weight gain. We have reported that mice that lack the receptor which mediates the functions of ghrelin are lean. Our fu...

  12. Ghrelin in obesity and endocrine diseases.

    PubMed

    Scerif, Miski; Goldstone, Anthony P; Korbonits, Márta

    2011-06-20

    Ghrelin shows orexigenic effect through its action on the hypothalamic appetite-regulating pathways, while in the periphery ghrelin increases adipose tissue accumulation and has a diabetogenic effect on the liver and pancreas. Adenosine monophosphate-activated protein kinase (AMPK) has been suggested as one of the mediators of ghrelin's effects. Plasma ghrelin levels are dependent on body mass index as well as food intake patterns. Ghrelin levels are in general reduced in obese individuals and in subjects with insulin resistance. In contrast to other forms of obesity, patients with Prader-Willi syndrome (PWS) display high levels of ghrelin, reduced visceral adiposity and relative hypoinsulinemia. Relationships between obesity and common genomic variants of GHRL and GHS-R genes have been studied. Ghrelin may have a role in the weight-reducing effect of bariatric surgery; however, this is a much debated issue. Altered ghrelin levels have also been observed in Cushing's syndrome and thyroid disease probably due to the secondary insulin resistance in these subjects.

  13. Voluntary exercise attenuates obesity-associated inflammation through ghrelin expressed in macrophages.

    PubMed

    Kizaki, Takako; Maegawa, Taketeru; Sakurai, Takuya; Ogasawara, Jun-etsu; Ookawara, Tomomi; Oh-ishi, Shuji; Izawa, Tetsuya; Haga, Shukoh; Ohno, Hideki

    2011-09-30

    Chronic low-level inflammation is associated with obesity and a sedentary lifestyle, causing metabolic disturbances such as insulin resistance. Exercise training has been shown to decrease chronic low-level systemic inflammation in high-fat diet (HFD)-induced obesity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Ghrelin is a peptide hormone predominantly produced in the stomach that stimulates appetite and induces growth hormone release. In addition to these well-known functions, recent studies suggest that ghrelin localizes to immune cells and exerts an anti-inflammatory effect. The purpose of the current study was to investigate the role of ghrelin expressed in macrophages in the anti-inflammatory effects of voluntary exercise training. Expression of tumor necrosis factor-α (TNF-α), monocyte chemotactic protein (MCP)-1 and F4/80 was increased in adipose tissue from mice fed a HFD (HFD mice) compared with mice fed a standard diet (SD mice), whereas the expression of these inflammatory cytokines was markedly decreased in mice performing voluntary wheel running during the feeding of a HFD (HFEx mice). The expression of TNF-α was also increased in peritoneal macrophages by a HFD and exercise training inhibited the increase of TNF-α expression. Interestingly, expression of ghrelin in peritoneal macrophages was decreased by a HFD and recovered by exercise training. Suppression of ghrelin expression by siRNA increased TNF-α expression and LPS-stimulated NF-κB activation in RAW264 cells, which is a macrophage cell line. TNF-α expression by stimulation with LPS was significantly suppressed in RAW264 cells cultured in the presence of ghrelin. These results suggest that ghrelin exerts potent anti-inflammatory effects in macrophages and functions as a mediator of the beneficial effects of exercise training.

  14. Effects of acute ethionine injection on plasma ghrelin and obestatin levels in trained male rats.

    PubMed

    Ghanbari-Niaki, Abbass; Soltani, Rahelah; Shemshaki, Afsaneh; Kraemer, Robert R

    2010-07-01

    Ghrelin and obestatin are orexigenic and anorexigenic peptides, respectively, that are secreted from the stomach mucosa into the circulation. These peptides have opposing actions on food intake, weight gain, and adiposity. It is thought that ghrelin is sensitive to a negative energy environment and also plays a considerable role in short- and long-term energy balance and glucose homeostasis. It has been suggested that the levels of ghrelin and obestatin are upregulated by fasting, hypoglycemic status, and a physical-exercise-induced energy deficit. Ethionine (ETH), the ethyl analogue of methionine, has been shown to increase food intake, decrease adenosine triphosphate (ATP) and glycogen levels, and inhibit protein synthesis in the liver. The purpose of this study was to examine the effect of a single dose of ETH (0.7 mg/g of body weight) injection on resting plasma total ghrelin and obestatin concentrations in male trained rats. Thirty-two adult Wistar male rats weighing 180 to 200 g were randomly assigned to control (n = 16) and training (n =16) groups. The training group was exercised for 10 weeks (25 m/min, 0% grade, 60 minutes, and 5 d/wk). Seventy-two hours after the last exercise session, rats were injected with either saline (NaCl) or ETH and then killed. Ethionine compared with a NaCl injection resulted in significant (P < .013) reductions in resting hepatic ATP and glycogen levels, and in a significant (P < .001) increase in concentrations of plasma total ghrelin but not obestatin. The results indicate that ETH-induced liver ATP and glycogen deficiency could exert a powerful regulatory influence on plasma total ghrelin, but this is not the case for obestatin. Findings demonstrate the short-term energy-regulating capacity of ghrelin.

  15. Central responsiveness to a ghrelin mimetic (GHRP-6) is rapidly altered by acute changes in nutritional status in rats.

    PubMed

    Tung, Y C L; Hewson, A K; Carter, R N; Dickson, S L

    2005-06-01

    The hypothalamus appears to be more responsive to ghrelin and growth hormone secretagogues (GHS) in fasting, as reflected by a two- to three-fold increase in the number of cells detected that express Fos protein in the arcuate nucleus, in 48-h fasted rats compared to fed controls. Moreover, this increased hypothalamic responsiveness to GHS in fasting is regulated by the central action of exogenous leptin and insulin, although it is unknown whether these hormones mediate the changes in hypothalamic responsiveness to GHS associated with the fasting/fed state. In the present study, we show that refeeding with normal rat chow for only 2 h at the end of a 48-h fast reversed the potentiation of the Fos response to GHRP-6 observed in fasted rats. Circulating leptin and insulin levels remained significantly lower in refed rats compared to ad lib-fed rats, suggesting that the change in the hypothalamic sensitivity brought about by refeeding was independent of these hormones. By contrast, 2 h of chow refeeding at the end of a fast restored plasma glucose levels to those of the fed state. Refeeding with sugar alone for 2 h at the end of a 48-h fast also reduced the potentiated Fos response in fasting, indicating that elevated blood glucose can influence the central responsiveness to ghrelin/GHS. By contrast, infusion of the ileal satiety factor, PYY(3-36) (known to increase postprandially) did not alter the central responsiveness to GHRP-6, although it suppressed feeding and body weight as expected. This study highlights the importance of nutritional status in regulating the action of exogenous GHS (and presumably endogenous ghrelin) on the hypothalamic circuits controlling food intake.

  16. Teaghrelins, unique acylated flavonoid tetraglycosides in Chin-shin oolong tea, are putative oral agonists of the ghrelin receptor.

    PubMed

    Lo, Yuan-Hao; Chen, Ying-Jie; Chang, Chi-I; Lin, Yi-Wen; Chen, Chung-Yu; Lee, Maw-Rong; Lee, Viola S Y; Tzen, Jason T C

    2014-06-04

    Chin-shin oolong tea, a popular tea in Taiwan, was empirically perceived to induce hunger and accelerate gastric emptying in a manner similar to the physiological effects of ghrelin, an endogenous acylated peptide known as the hunger hormone. Two unique acylated flavonoid tetraglycosides previously identified in Chin-shin oolong tea were demonstrated to induce hunger of rats in a food intake assay and, thus, named teaghrelin-1 and teaghrelin-2. Similar to GHRP-6, a synthetic analogue of ghrelin, teaghrelin-1 stimulated growth hormone secretion of rat primary anterior pituitary cells in a dose-dependent manner, and the stimulation was inhibited by [D-Arg(1),D-Phe(5),D-Trp(7,9),Leu(11)]-substance P, an antagonist of the ghrelin receptor. While teaghrelin-2 remained unmodified, a meta-O-methylated metabolite of teaghrelin-1 was detected in bile of rats after intravenous injection. Presumably, teaghrelins are promising oral agonists of the ghrelin receptor.

  17. c-fos mRNA in mouse brain after MPTP treatment.

    PubMed

    Duchemin, A M; Gudehithlu, K P; Neff, N H; Hadjiconstantinou, M

    1992-04-01

    The neurotoxin, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induces a transient increase of mRNA for the immediate-early gene c-fos in the mouse brain. The c-fos mRNA level is MPTP dose-dependent and is evident in all brain regions tested including striatum, hypothalamus, cortex, hippocampus, cerebellum and midbrain. There are regional differences in the time-course for the rise of c-fos mRNA. Pretreatment with deprenyl, a selective monoamine oxidase B inhibitor, pargyline, a nonselective monoamine oxidase inhibitor, or mazindol, a dopamine uptake transport inhibitor, does not prevent the c-fos mRNA increase, suggesting that the elevation is due to the action of MPTP and not its neurotoxic metabolite MPP+.

  18. Ghrelin signaling in heart remodeling of adult obese mice.

    PubMed

    Lacerda-Miranda, Glauciane; Soares, Vivian M; Vieira, Anatalia K G; Lessa, Juliana G; Rodrigues-Cunha, Alessandra C S; Cortez, Erika; Garcia-Souza, Erica P; Moura, Anibal S

    2012-05-01

    Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), has been suggested to be associated to obesity, insulin secretion, cardiovascular growth and homeostasis. GHS-R has been found in most of the tissues, and among the hormone action it is included the regulation of heart energy metabolism. Therefore, hypernutrition during early life leads to obesity, induces cardiac hypertrophy, compromises myocardial function, inducing heart failure in adulthood. We examined ghrelin signaling process in cardiac remodeling in these obese adult mice. The cardiomyocytes (cmy) of left ventricle were analyzed by light microscopy and stereology, content and phosphorilation of cardiac proteins: ghrelin receptor (growth hormone secretagogue receptor 1a, GHSR-1a), protein kinase B (AKT and pAKT), phosphatidil inositol 3 kinase (PI3K), AMP-activated protein kinase (AMPK and pAMPK) and actin were achieved by Western blotting. GHSR-1a gene expression was analyzed by Real Time-PCR. We observed hyperglycemia and higher liver and visceral fat weight in obese when compared to control group. Obese mice presented a marked increase in heart weight/tibia length, indicating an enlarged heart size or a remodeling process. Obese mice had increased GHSR-1a content and expression in the heart associated to PI3K content and increased AKT content and phosphorylation. In contrast, AMPK content and phosphorylation in heart was not different between experimental groups. Ghrelin plasma levels in obese group were decreased when compared to control group. Our data suggest that remodeled myocardial in adult obese mice overnourished in early life are associated with higher phosphorylation of GHSR-1a, PI3K and AKT but not with AMPK.

  19. Genetic variants of ghrelin in metabolic disorders.

    PubMed

    Ukkola, Olavi

    2011-11-01

    An increasing understanding of the role of genes in the development of obesity may reveal genetic variants that, in combination with conventional risk factors, may help to predict an individual's risk for developing metabolic disorders. Accumulating evidence indicates that ghrelin plays a role in regulating food intake and energy homeostasis and it is a reasonable candidate gene for obesity-related co-morbidities. In cross-sectional studies low total ghrelin concentrations and some genetic polymorphisms of ghrelin have been associated with obesity-associated diseases. The present review highlights many of the important problems in association studies of genetic variants and complex diseases. It is known that population-specific differences in reported associations exist. We therefore conclude that more studies on variants of ghrelin gene are needed to perform in different populations to get deeper understanding on the relationship of ghrelin gene and its variants to obesity.

  20. The acute ghrelin response to a psychological stress challenge does not predict the post-stress urge to eat.

    PubMed

    Rouach, V; Bloch, M; Rosenberg, N; Gilad, S; Limor, R; Stern, N; Greenman, Y

    2007-07-01

    Ghrelin is a growth hormone and cortisol secretagogue that plays an important role in appetite and weight regulation. It is not known whether ghrelin is involved in the eating response to stress in humans. In the present study we examined the effects of psychologically induced stress on plasma ghrelin levels in patients with binge-eating disorder (BED) (n=8) and in healthy subjects of normal (n=8) or increased (n=8) body mass index (BMI). Volunteers were subjected to the standardized trier social stress test (TSST). Heart rate, blood pressure, serum cortisol, serum prolactin, and plasma ghrelin levels were measured throughout the test. In addition, subjects were requested to rate their feelings of anxiety, tension, urge to eat uncontrollably and desire to eat sweets by means of a visual analog scale both before and after the TSST. There was a significant rise in the systolic blood pressure (p=0.003) in the study population, reflecting induction of physiological changes by the psychological challenge. Basal ghrelin levels were higher in healthy normal weight (385.4+/-79 pg/ml) than in obese (170.4+/-15.7 pg/ml) subjects (p<0.033). Basal ghrelin levels in patients with BED (240+/-40.8 pg/ml) were at an intermediate level between thin and healthy obese subjects, but this difference did not attain statistical significance. There were no differences in ghrelin levels throughout the test among the groups after correction for BMI, age and gender. A significant difference in the trend time of ghrelin was revealed when the three groups were analyzed according to their cortisol response to stress. Ghrelin levels increased in cortisol responders whereas no change or a decrease in ghrelin levels occurred in cortisol non-responders (p=0.038). Furthermore, a positive correlation was found between the change in ghrelin and the change in cortisol during TSST (r=0.444, p=0.029) but not between the change in ghrelin and the change in systolic blood pressure. The combined score of

  1. Elevated blood active ghrelin and normal total ghrelin and obestatin concentrations in uterine leiomyoma.

    PubMed

    Markowska, A; Ziolkowska, A; Nowinka, K; Malendowicz, L K

    2009-01-01

    Ghrelin and obestatin originate from the same peptide precursor, preproghrelin. Both peptides are secreted in the blood. We investigated serum active and total ghrelin and obestatin concentrations in women with uterine myomatosis. Serum concentrations of active ghrelin in uterine leiomyoma were significantly higher compared to women in the control group (86 +/- 3 vs 56 +/- 9 pg/ml, respectively; p < 0.02). On the other hand, serum concentrations of total ghrelin and obestatin in uterine leiomyoma did not differ from those in the control group. In the control group the ratio of active to total ghrelin concentrations amounted to 0.62, while in women with uterine myoma it was 0.95, pointing to a prevalence of the active form of ghrelin in women with uterine myoma. Also the ratio of active ghrelin concentration to obestatin concentration was higher in the latter group while the ratio of total circulating ghrelin to obestatin concentrations was similar in the two groups. The data may suggest a role of active ghrelin in the development of a myoma. Moreover, the results indicate that increased blood ratios of active to total ghrelin and to obestatin concentrations are not specific for cachexia.

  2. Ghrelin in obesity, physiological and pharmacological considerations.

    PubMed

    Álvarez-Castro, Paula; Pena, Lara; Cordido, Fernando

    2013-04-01

    The aim of this review is to summarize the physiological and pharmacological aspects of ghrelin. Obesity can be defined as an excess of body fat and is associated with significant disturbances in metabolic and endocrine function. Obesity has become a worldwide epidemic. In obesity there is a decreased growth hormone (GH) secretion, and the altered somatotroph secretion in obesity is functional. Ghrelin is a peptide that has a unique structure with 28 amino-acids and an n-octanoyl ester at its third serine residue, which is essential for its potent stimulatory activity on somatotroph secretion. The pathophysiological mechanism responsible for GH hyposecretion in obesity is probably multifactorial, and there is probably a defect in ghrelin secretion. Ghrelin is the only known circulating orexigenic factor, and has been found to be reduced in obese humans. Ghrelin levels in blood decrease during periods of feeding. Due to its orexigenic and metabolic effects, ghrelin has a potential benefit in antagonizing protein breakdown and weight loss in catabolic conditions such as cancer cachexia, renal and cardiac disease, and age-related frailty. Theoretically ghrelin receptor antagonists could be employed as anti-obesity drugs, blocking the orexigenic signal. By blocking the constitutive receptor activity, inverse agonists of the ghrelin receptor may lower the set-point for hunger, and could be used for the treatment of obesity. In summary, ghrelin secretion is reduced in obesity, and could be partly responsible for GH hyposecretion in obesity, ghrelin antagonist or partial inverse agonists should be considered for the treatment of obesity.

  3. The ghrelin signalling system is involved in the consumption of sweets.

    PubMed

    Landgren, Sara; Simms, Jeffrey A; Thelle, Dag S; Strandhagen, Elisabeth; Bartlett, Selena E; Engel, Jörgen A; Jerlhag, Elisabet

    2011-03-23

    The gastric-derived orexigenic peptide ghrelin affects brain circuits involved in energy balance as well as in reward. Indeed, ghrelin activates an important reward circuit involved in natural- as well as drug-induced reward, the cholinergic-dopaminergic reward link. It has been hypothesized that there is a common reward mechanism for alcohol and sweet substances in both animals and humans. Alcohol dependent individuals have higher craving for sweets than do healthy controls and the hedonic response to sweet taste may, at least in part, depend on genetic factors. Rat selectively bred for high sucrose intake have higher alcohol consumption than non-sucrose preferring rats and vice versa. In the present study a group of alcohol-consuming individuals selected from a population cohort was investigated for genetic variants of the ghrelin signalling system in relation to both their alcohol and sucrose consumption. Moreover, the effects of GHS-R1A antagonism on voluntary sucrose-intake and operant self-administration, as well as saccharin intake were investigated in preclinical studies using rodents. The effects of peripheral grelin administration on sucrose intake were also examined. Here we found associations with the ghrelin gene haplotypes and increased sucrose consumption, and a trend for the same association was seen in the high alcohol consumers. The preclinical data show that a GHS-R1A antagonist reduces the intake and self-administration of sucrose in rats as well as saccharin intake in mice. Further, ghrelin increases the intake of sucrose in rats. Collectively, our data provide a clear indication that the GHS-R1A antagonists reduces and ghrelin increases the intake of rewarding substances and hence, the central ghrelin signalling system provides a novel target for the development of drug strategies to treat addictive behaviours.

  4. The Ghrelin Signalling System Is Involved in the Consumption of Sweets

    PubMed Central

    Landgren, Sara; Simms, Jeffrey A.; Thelle, Dag S.; Strandhagen, Elisabeth; Bartlett, Selena E.; Engel, Jörgen A.; Jerlhag, Elisabet

    2011-01-01

    The gastric-derived orexigenic peptide ghrelin affects brain circuits involved in energy balance as well as in reward. Indeed, ghrelin activates an important reward circuit involved in natural- as well as drug-induced reward, the cholinergic-dopaminergic reward link. It has been hypothesized that there is a common reward mechanism for alcohol and sweet substances in both animals and humans. Alcohol dependent individuals have higher craving for sweets than do healthy controls and the hedonic response to sweet taste may, at least in part, depend on genetic factors. Rat selectively bred for high sucrose intake have higher alcohol consumption than non-sucrose preferring rats and vice versa. In the present study a group of alcohol-consuming individuals selected from a population cohort was investigated for genetic variants of the ghrelin signalling system in relation to both their alcohol and sucrose consumption. Moreover, the effects of GHS-R1A antagonism on voluntary sucrose- intake and operant self-administration, as well as saccharin intake were investigated in preclinical studies using rodents. The effects of peripheral grelin administration on sucrose intake were also examined. Here we found associations with the ghrelin gene haplotypes and increased sucrose consumption, and a trend for the same association was seen in the high alcohol consumers. The preclinical data show that a GHS-R1A antagonist reduces the intake and self-administration of sucrose in rats as well as saccharin intake in mice. Further, ghrelin increases the intake of sucrose in rats. Collectively, our data provide a clear indication that the GHS-R1A antagonists reduces and ghrelin increases the intake of rewarding substances and hence, the central ghrelin signalling system provides a novel target for the development of drug strategies to treat addictive behaviours. PMID:21448464

  5. Effect of enalapril maleate on ghrelin levels in metabolic syndrome in rats.

    PubMed

    Aygen, Bilge; Kucuksu, Mehmet; Aydin, Suleyman; Ozercan, Ibrahim Hanifi

    2015-05-01

    We have explored how enalapril affects ghrelin levels in serum and renal tissues of rats with fructose-induced MetS, using 5-week-old Wistar albino male rats weighing 220 ± 20 g. They divided into 5 groups: (i) control (CT), no fructose supplement fed on standard rat pellet and tap water for 60 days, (ii) metabolic syndrome (MetS) fed with 10% fructose for 60 days, (iii) rats after metabolic syndrome developed treated with enalapril over 30 days (MetS+E30), (iv) rats in which only enalapril was administered for 60 days (E60), and (v) MetS-treated with enalapril for 60 days (MetS+E60). Enalapril maleate was given at 20mg/kg per day by gavage. Fasting serum insulin, uric acid, triglyceride, low-density lipoprotein cholesterol and total cholesterol levels were significantly higher, and the amount of high density lipoprotein cholesterol, and acylated and desacyl ghrelin levels was significantly lower in the MetS groups. Ghrelins were significantly lower in all 3 groups, which were administered enalapril than that of MetS and the control group. Immunohistochemical staining showed that the density of ghrelin was parallel to the serum levels of the peptide. Ghrelin immunoreactivity in the kidneys was of moderate density in the distal and collecting tubules, mild density in the proximal tubule and glomeruli, whereas the density decreased in the MetS group and other enalapril-treated groups. In conclusion, ghrelin levels in MetS groups were significantly lower than control group, and thus Enalapril treatment improves components of MetS and has direct effects on serum ghrelin levels that are independent of MetS.

  6. Ghrelin receptor regulates adipose tissue inflammation in aging

    PubMed Central

    Buras, Eric D.; Yu, Kaijiang; Wang, Ruitao; Smith, C. Wayne; Wu, Huaizhu; Sheikh-Hamad, David; Sun, Yuxiang

    2016-01-01

    Aging is commonly associated with low-grade adipose inflammation, which is closely linked to insulin resistance. Ghrelin is the only circulating orexigenic hormone which is known to increase obesity and insulin resistance. We previously reported that the expression of the ghrelin receptor, growth hormone secretagogue receptor (GHS-R), increases in adipose tissues during aging, and old Ghsr−/− mice exhibit a lean and insulin-sensitive phenotype. Macrophages are major mediators of adipose tissue inflammation, which consist of pro-inflammatory M1 and anti-inflammatory M2 subtypes. Here, we show that in aged mice, GHS-R ablation promotes macrophage phenotypical shift toward anti-inflammatory M2. Old Ghsr−/− mice have reduced macrophage infiltration, M1/M2 ratio, and pro-inflammatory cytokine expression in white and brown adipose tissues. We also found that peritoneal macrophages of old Ghsr−/− mice produce higher norepinephrine, which is in line with increased alternatively-activated M2 macrophages. Our data further reveal that GHS-R has cell-autonomous effects in macrophages, and GHS-R antagonist suppresses lipopolysaccharide (LPS)-induced inflammatory responses in macrophages. Collectively, our studies demonstrate that ghrelin signaling has an important role in macrophage polarization and adipose tissue inflammation during aging. GHS-R antagonists may serve as a novel and effective therapeutic option for age-associated adipose tissue inflammation and insulin resistance. PMID:26837433

  7. Ghrelin receptor regulates adipose tissue inflammation in aging.

    PubMed

    Lin, Ligen; Lee, Jong Han; Buras, Eric D; Yu, Kaijiang; Wang, Ruitao; Smith, C Wayne; Wu, Huaizhu; Sheikh-Hamad, David; Sun, Yuxiang

    2016-01-01

    Aging is commonly associated with low-grade adipose inflammation, which is closely linked to insulin resistance. Ghrelin is the only circulating orexigenic hormone which is known to increase obesity and insulin resistance. We previously reported that the expression of the ghrelin receptor, growth hormone secretagogue receptor (GHS-R), increases in adipose tissues during aging, and old Ghsr(-/-) mice exhibit a lean and insulin-sensitive phenotype. Macrophages are major mediators of adipose tissue inflammation, which consist of pro-inflammatory M1 and anti-inflammatory M2 subtypes. Here, we show that in aged mice, GHS-R ablation promotes macrophage phenotypical shift toward anti-inflammatory M2. Old Ghsrp(-/-) mice have reduced macrophage infiltration, M1/M2 ratio, and pro-inflammatory cytokine expression in white and brown adipose tissues. We also found that peritoneal macrophages of old Ghsrp(-/-) mice produce higher norepinephrine, which is in line with increased alternatively-activated M2 macrophages. Our data further reveal that GHS-R has cell-autonomous effects in macrophages, and GHS-R antagonist suppresses lipopolysaccharide (LPS)-induced inflammatory responses in macrophages. Collectively, our studies demonstrate that ghrelin signaling has an important role in macrophage polarization and adipose tissue inflammation during aging. GHS-R antagonists may serve as a novel and effective therapeutic option for age-associated adipose tissue inflammation and insulin resistance.

  8. The Expression of Fos, Jun and AP-1 DNA Binding Activity in Rat Supraoptic Nucleus Neurons Following Acute Versus Repeated Osmotic Stimulation

    DTIC Science & Technology

    1995-06-22

    stimulation. This pattern has been observed previously in the hippocampus after treatment with the seizure-inducing drug , metrazole (Sonnenberg et al... fosB , and fra-1 and -2. fra refers to ~OS­ ~elated ~ntigen. Western blot experiments and employment of less stringent nucleic acid hybridization...fos, fra-l and fosB , only form heterodimeric complexes with Jun-related proteins (Nakabeppu et al., 1988; Rauscher et al., 1988b) The AP-l site of many

  9. Ghrelin: Central and Peripheral Implications in Anorexia Nervosa

    PubMed Central

    Méquinion, Mathieu; Langlet, Fanny; Zgheib, Sara; Dickson, Suzanne; Dehouck, Bénédicte; Chauveau, Christophe; Viltart, Odile

    2012-01-01

    Increasing clinical and therapeutic interest in the neurobiology of eating disorders reflects their dramatic impact on health. Chronic food restriction resulting in severe weight loss is a major symptom described in restrictive anorexia nervosa (AN) patients, and they also suffer from metabolic disturbances, infertility, osteopenia, and osteoporosis. Restrictive AN, mostly observed in young women, is the third largest cause of chronic illness in teenagers of industrialized countries. From a neurobiological perspective, AN-linked behaviors can be considered an adaptation that permits the endurance of reduced energy supply, involving central and/or peripheral reprograming. The severe weight loss observed in AN patients is accompanied by significant changes in hormones involved in energy balance, feeding behavior, and bone formation, all of which can be replicated in animals models. Increasing evidence suggests that AN could be an addictive behavior disorder, potentially linking defects in the reward mechanism with suppressed food intake, heightened physical activity, and mood disorder. Surprisingly, the plasma levels of ghrelin, an orexigenic hormone that drives food-motivated behavior, are increased. This increase in plasma ghrelin levels seems paradoxical in light of the restrained eating adopted by AN patients, and may rather result from an adaptation to the disease. The aim of this review is to describe the role played by ghrelin in AN focusing on its central vs. peripheral actions. In AN patients and in rodent AN models, chronic food restriction induces profound alterations in the « ghrelin » signaling that leads to the development of inappropriate behaviors like hyperactivity or addiction to food starvation and therefore a greater depletion in energy reserves. The question of a transient insensitivity to ghrelin and/or a potential metabolic reprograming is discussed in regard of new clinical treatments currently investigated. PMID:23549309

  10. Cardiovascular effects of ghrelin antagonist in conscious rats.

    PubMed

    Vlasova, Maria A; Järvinen, Kristiina; Herzig, Karl-Heinz

    2009-08-07

    Ghrelin, a 28 aa growth-hormone-releasing peptide, has been shown to increase food intake and decrease arterial pressure in animals and in humans. Recently, a ghrelin antagonist (GhA), [d-Lys-3]-GHRP-6, was demonstrated to decrease food intake in mice, but its cardiovascular actions have not been described. In the present study, the effects of the GhA on cardiovascular parameters in conscious rats were investigated and the involvement of the sympathetic nervous system evaluated. Mean arterial pressure (MAP) and heart rate (HR) measurements were assessed by radiotelemetry. GhA was administered in doses of 2, 4 and 6 mg/kg subcutaneously (s.c.). MAP as well as HR was dose-dependently elevated after sc application of GhA. Sympathetic blockade of alpha-adrenoreceptors with phentolamine (3 mg/kg, s.c.) and simultaneous antagonism of beta(1)-adrenoreceptors with atenolol (10 mg/kg, s.c.) abolished the increase in MAP and HR induced by GhA (4 mg/kg, s.c.). Administration of phentolamine alone inhibited the increase of MAP, but not HR; atenolol alone abolished the elevation of both MAP and HR evoked by GhA. These results suggest that the peripheral injection of ghrelin antagonist increases arterial pressure and heart rate, at least in part, through the activation of the sympathetic nervous system. Therefore, the use of the ghrelin antagonist system as a therapeutic target for reduction in food intake might lead to serious side effects like elevated blood pressure in humans mostly already having an elevated blood pressure as part of their metabolic syndrome.

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

    PubMed

    Fujimiya, Mineko; Ataka, Koji; Asakawa, Akihiro; Chen, Chih-Yen; Kato, Ikuo; Inui, Akio

    2011-11-01

    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.

  12. Selective uptake and degradation of c-Fos and v-Fos by rat liver lysosomes.

    PubMed

    Aniento, F; Papavassiliou, A G; Knecht, E; Roche, E

    1996-07-15

    The transcription factor c-Fos is a short-lived protein and calpains and ubiquitin-dependent systems have been proposed to be involved in its degradation. In this report, we consider a lysosomal degradation pathway for c-Fos. Using a cell-free assay, we have found that freshly isolated lysosomes can take up and degrade c-Fos with high efficiency. v-Fos, the oncogenic counterpart of c-Fos, can also be taken up by lysosomes, yet the amount of incorporated protein is much lower. c-Fos uptake is independent of its phosphorylation state but it appears to be regulated by dimerization with differentially phosphorylated forms of c-Jun, while v-Fos escapes this regulation. Moreover, we show that c-Fos is immunologically detected in lysosomes isolated from the liver of rats treated with the protease inhibitor leupeptin. Altogether, these results suggest that lysosomes can also participate in the selective degradation of c-Fos in rat liver.

  13. Impairment of ghrelin synthesis in Helicobacter pylori-colonized stomach: new clues for the pathogenesis of H. pylori-related gastric inflammation.

    PubMed

    Paoluzi, Omero Alessandro; Blanco, Del Vecchio Giovanna; Caruso, Roberta; Monteleone, Ivan; Monteleone, Giovanni; Pallone, Francesco

    2014-01-21

    Ghrelin, the ligand of growth hormone secretagogue receptor 1a, takes part in several functions of the digestive system, including regulation of appetite, energy homeostasis, gastric acid secretion and motility. Ghrelin has also immunoregulatory properties and is supposed to inhibit some inflammatory pathways that can mediate gastric damage. Interestingly, ghrelin synthesis is reduced in the gastric mucosa of patients with Helicobacter pylori (H. pylori) infection, a worldwide condition inducing a T helper (Th)1/Th17 cell response-driven gastritis, which may evolve towards gastric atrophy and cancer. In this article, we review the available data on the expression of ghrelin in H. pylori infection and discuss how the defective ghrelin synthesis may contribute to sustain the ongoing inflammatory response in this disease.

  14. Effects of mild traumatic brain injury on immunoreactivity for the inducible transcription factors c-Fos, c-Jun, JunB, and Krox-24 in cerebral regions associated with conditioned fear responding.

    PubMed

    Abrous, D N; Rodriguez, J; le Moal, M; Moser, P C; Barnéoud, P

    1999-05-01

    We have previously demonstrated that mild traumatic brain injury (TBI) of the right parietal cortex results in a relatively selective deficit in conditioned fear responding. However, this behavioural deficit is very consistent and unrelated to the extent of the cortical necrotic lesion. We were therefore interested in determining if other brain regions might show a consistent response to mild TBI, and therefore, more reliably relate to the behavioural change. Increased expression of inducible transcription factors (ITFs) has been used to study which brain regions respond to a variety of events. In the present study, we examined the expression patterns of immunoreactivity (IR) for four ITFs (c-Fos, c-Jun, JunB, and Krox-24) at 3 h after mild fluid percussion TBI. Changes in ITF expression were only observed ipsilateral to the side of TBI. The clearest changes were observed in brain regions known to be involved in conditioned fear responding, such as the amygdala complex and hippocampal formation and several cortical regions. In contrast, no changes in IR for any of the ITFs were observed in the striatum, nucleus accumbens, nucleus basalis magnocellularis, septum or periacqueductal grey. Unlike the extent of visible damage to the cortex at the site of impact, the overexpression of ITFs showed a notable consistency between animals subjected to TBI. This consistency in regions known to be involved in conditioned fear responding (i.e., amygdala complex and hippocampal formation) lead us to suggest that it is these changes, rather than the more variable cortical necrotic lesion, that is responsible for the behavioural deficits we observe following mild TBI. Importantly, our results demonstrate that like the hippocampus, the amygdala is a sub-cortical structure particularly sensitive to the effects of mild brain trauma and underline the fact that cerebral regions distant from the location of the fluid impact can be affected.

  15. c-Fos over-expression promotes radioresistance and predicts poor prognosis in malignant glioma

    PubMed Central

    Feng, Guokai; Chen, Furong; Tu, Ziwei; Liu, Guiyun; Zhao, Yu; Peng, Ming-Jing; He, Zheng-Wen; Chen, Xiao-Yan; Lindsay, Holly; Xia, Yun-Fei; Li, Xiao-Nan

    2016-01-01

    c-Fos is a major component of activator protein (AP)-1 complex. It has been implicated in cell differentiation, proliferation, angiogenesis, invasion, and metastasis. To investigate the role of c-Fos in glioma radiosensitivity and to understand the underlying molecular mechanisms, we downregulated c-Fos gene expression by lentivirus-mediated shRNA in glioma cell lines and subsequently analyzed the radiosensitivity, DNA damage repair capacity, and cell cycle distribution. Finally, we explored its prognostic value in 41 malignant glioma patients by immunohistochemistry. Our results showed that silencing c-Fos sensitized glioma cells to radiation by increasing radiation-induced DNA double strand breaks (DSBs), disturbing the DNA damage repair process, promoting G2/M cell cycle arrest, and enhancing apoptosis. c-Fos protein overexpression correlated with poor prognosis in malignant glioma patients treated with standard therapy. Our findings provide new insights into the mechanism of radioresistance in malignant glioma and identify c-Fos as a potentially novel therapeutic target for malignant glioma patients. PMID:27602752

  16. Spatial memory extinction: a c-Fos protein mapping study.

    PubMed

    Méndez-Couz, M; Conejo, N M; Vallejo, G; Arias, J L

    2014-03-01

    While the neuronal basis of spatial memory consolidation has been thoroughly studied, the substrates mediating the process of extinction remain largely unknown. This study aimed to evaluate the functional contribution of selected brain regions during the extinction of a previously acquired spatial memory task in the Morris water maze. For that purpose, we used adult male Wistar rats trained in a spatial reference memory task. Learning-related changes in c-Fos inmunoreactive cells after training were evaluated in cortical and subcortical regions. Results show that removal of the hidden platform in the water maze induced extinction of the previously reinforced escape behavior after 16 trials, without spontaneous recovery 24h later. Extinction was related with significantly higher numbers of c-Fos positive nuclei in amygdala nuclei and prefrontal cortex. On the other hand, the lateral mammillary bodies showed higher number of c-Fos positive cells than the control group. Therefore, in contrast with the results obtained in studies of classical conditioning, we show the involvement of diencephalic structures mediating this kind of learning. In summary, our findings suggest that medial prefrontal cortex, the amygdala complex and diencephalic structures like the lateral mammillary nuclei are relevant for the extinction of spatial memory.

  17. Detection of molecular alterations in methamphetamine-activated Fos-expressing neurons from a single rat dorsal striatum using fluorescence-activated cell sorting (FACS).

    PubMed

    Liu, Qing-Rong; Rubio, Francisco J; Bossert, Jennifer M; Marchant, Nathan J; Fanous, Sanya; Hou, Xingyu; Shaham, Yavin; Hope, Bruce T

    2014-01-01

    Methamphetamine and other drugs activate a small proportion of all neurons in the brain. We previously developed a fluorescence-activated cell sorting (FACS)-based method to characterize molecular alterations induced selectively in activated neurons that express the neural activity marker Fos. However, this method requires pooling samples from many rats. We now describe a modified FACS-based method to characterize molecular alterations in Fos-expressing dorsal striatal neurons from a single rat using a multiplex pre-amplification strategy. Fos and NeuN (a neuronal marker) immunohistochemistry indicate that 5-6% of dorsal striatum neurons were activated 90 min after acute methamphetamine injections (5 mg/kg, i.p.) while less than 0.5% of neurons were activated by saline injections. We used FACS to separate NeuN-labeled neurons into Fos-positive and Fos-negative neurons and assessed mRNA expression using RT-qPCR from as little as five Fos-positive neurons. Methamphetamine induced 3-20-fold increases of immediate early genes arc, homer-2, c-fos, fosB, and its isoforms (ΔfosB and a novel isoform ΔfosB-2) in Fos-positive but not Fos-negative neurons. Immediate early gene mRNA induction was 10-fold lower or absent when assessed in unsorted samples from single dorsal striatum homogenates. Our modified method makes it feasible to study unique molecular alterations in neurons activated by drugs or drug-associated cues in complex addiction models. Methamphetamine and other drugs activate a small proportion of all neurons in the brain. We here report an improved method to characterize molecular alterations induced selectively in activated neurons that express the neural activity marker Fos. We used FACS along with targeted PCR pre-amplification to assess acute methamphetamine-induced gene expression from as few as 5 Fos-expressing neurons from a single rat dorsal striatum. Methamphetamine induced 3-20-fold increases of immediate early genes (IEGs) in Fos-positive but not

  18. Long-Term Exercise Is a Potent Trigger for ΔFosB Induction in the Hippocampus along the dorso–ventral Axis

    PubMed Central

    Nishijima, Takeshi; Kawakami, Masashi; Kita, Ichiro

    2013-01-01

    Physical exercise improves multiple aspects of hippocampal function. In line with the notion that neuronal activity is key to promoting neuronal functions, previous literature has consistently demonstrated that acute bouts of exercise evoke neuronal activation in the hippocampus. Repeated activating stimuli lead to an accumulation of the transcription factor ΔFosB, which mediates long-term neural plasticity. In this study, we tested the hypothesis that long-term voluntary wheel running induces ΔFosB expression in the hippocampus, and examined any potential region-specific effects within the hippocampal subfields along the dorso–ventral axis. Male C57BL/6 mice were housed with or without a running wheel for 4 weeks. Long-term wheel running significantly increased FosB/ΔFosB immunoreactivity in all hippocampal regions measured (i.e., in the DG, CA1, and CA3 subfields of both the dorsal and ventral hippocampus). Results confirmed that wheel running induced region-specific expression of FosB/ΔFosB immunoreactivity in the cortex, suggesting that the uniform increase in FosB/ΔFosB within the hippocampus is not a non-specific consequence of running. Western blot data indicated that the increased hippocampal FosB/ΔFosB immunoreactivity was primarily due to increased ΔFosB. These results suggest that long-term physical exercise is a potent trigger for ΔFosB induction throughout the entire hippocampus, which would explain why exercise can improve both dorsal and ventral hippocampus-dependent functions. Interestingly, we found that FosB/ΔFosB expression in the DG was positively correlated with the number of doublecortin-immunoreactive (i.e., immature) neurons. Although the mechanisms by which ΔFosB mediates exercise-induced neurogenesis are still uncertain, these data imply that exercise-induced neurogenesis is at least activity dependent. Taken together, our current results suggest that ΔFosB is a new molecular target involved in regulating exercise-induced

  19. Protective but Not Anticonvulsant Effects of Ghrelin and JMV-1843 in the Pilocarpine Model of Status epilepticus

    PubMed Central

    Lucchi, Chiara; Curia, Giulia; Vinet, Jonathan; Gualtieri, Fabio; Bresciani, Elena; Locatelli, Vittorio; Torsello, Antonio; Biagini, Giuseppe

    2013-01-01

    In models of status epilepticus ghrelin displays neuroprotective effects mediated by the growth hormone secretagogue-receptor 1a (GHS-R1a). This activity may be explained by anticonvulsant properties that, however, are controversial. We further investigated neuroprotection and the effects on seizures by comparing ghrelin with a more effective GHS-R1a agonist, JMV-1843. Rats were treated either with ghrelin, JMV-1843 or saline 10 min before pilocarpine, which was used to induce status epilepticus. Status epilepticus, developed in all rats, was attenuated by diazepam. No differences were observed among the various groups in the characteristics of pilocarpine-induced seizures. In saline group the area of lesion, characterized by lack of glial fibrillary acidic protein immunoreactivity, was of 0.45±0.07 mm2 in the hippocampal stratum lacunosum-moleculare, and was accompanied by upregulation of laminin immunostaining, and by increased endothelin-1 expression. Both ghrelin (P<0.05) and JMV-1843 (P<0.01) were able to reduce the area of loss in glial fibrillary acidic protein immunostaining. In addition, JMV-1843 counteracted (P<0.05) the changes in laminin and endothelin-1 expression, both increased in ghrelin-treated rats. JMV-1843 was able to ameliorate neuronal survival in the hilus of dentate gyrus and medial entorhinal cortex layer III (P<0.05 vs saline and ghrelin groups). These results demonstrate diverse protective effects of growth hormone secretagogues in rats exposed to status epilepticus. PMID:24015271

  20. Obestatin and insulin in pancreas of newborn diabetic rats treated with exogenous ghrelin.

    PubMed

    Turk, Neslihan; Dağistanli, Fatma Kaya; Sacan, Ozlem; Yanardag, Refiye; Bolkent, Sema

    2012-07-01

    The aim of the study was to evaluate the effect of ghrelin treatment on obestatin, insulin gene expression and biochemical parameters in the pancreas of newborn-streptozocin (STZ) diabetic rats. Rats were divided into 4 groups. Group I: control rats treated with physiological saline; group II: control rats treated with 100 μg/kg/day ghrelin; group III: two days after birth rats that received 100mg/kg STZ injected as a single dose to induce neonatal diabetes; group IV: neonatal-STZ-diabetic rats treated with ghrelin for four weeks. Sections of the pancreas were examined with immunohistochemistry for the expression of obestatin and insulin and in situ hybridization for the expression of insulin mRNA. The blood glucose levels were measured. Tissue homogenates were used for protein, glutathione, lipid peroxidation and non-enzymatic glycosylation levels and antioxidant enzyme analysis. There was a significant difference in blood glucose levels in newborn-STZ-diabetic rats compared to ghrelin treated diabetic rats at weeks 1, 2 and 4. In group IV, pancreatic non-enzymatic glycosylation and lipid peroxidation levels were decreased, however, glutathione levels and enzymatic activities were increased. Insulin peptide and mRNA (+) signals in islets of Langerhans and obestatin immunopositive cell numbers showed an increase in group IV compared to group III. These results suggest that administration of ghrelin to newborn rats may prevent effects of diabetes.

  1. Forebrain patterns of c-Fos and FosB induction during cancer-associated anorexia-cachexia in rat.

    PubMed

    Konsman, Jan Pieter; Blomqvist, Anders

    2005-05-01

    Forebrain structures are necessary for the initiation of food intake and its coupling to energy expenditure. The cancer-related anorexia-cachexia syndrome is typified by a prolonged increase in metabolic rate resulting in body weight loss which, paradoxically, is accompanied by reduced food intake. The aim of the present work was to study the forebrain expression of Fos proteins as activation markers and thus to identify potential neurobiological mechanisms favouring catabolic processes or modulating food intake in rats suffering from cancer-related anorexia-cachexia. Neurons in forebrain structures showing most pronounced induction of Fos proteins were further identified neurochemically. To provoke anorexia-cachexia, cultured Morris hepatoma 7777 cells were injected subcutaneously in Buffalo rats. This resulted in a slowly growing tumour inducing approximately 7% body weight loss and a 20% reduction in food intake when the tumour represented 1-2% of body mass. Anorexia-cachexia in these animals was found to be accompanied by Fos induction in several hypothalamic nuclei including the paraventricular and ventromedial hypothalamus, in the parastrial nucleus, the amygdala, the bed nucleus of the stria terminalis, ventral striatal structures and the piriform and somatosensory cortices. Neurochemical identification revealed that the vast majority of FosB-positive neurons in the nucleus accumbens, ventral caudate-putamen and other ventral striatal structures contained prodynorphin or proenkephalin mRNA. These findings indicate that forebrain structures that are part of neuronal networks modulating catabolic pathways and food ingestion are activated during tumour-associated anorexia-cachexia and may contribute to the lack of compensatory eating in response to weight loss characterizing this syndrome.

  2. Expression patterns of c-Fos early gene and phosphorylated ERK in the rat brain following 1-h immobilization stress: concomitant changes induced in association with stress-related sleep rebound.

    PubMed

    Keshavarzy, Fatemeh; Bonnet, Chantal; Behzadi, Gila; Bezhadi, Gila; Cespuglio, Raymond

    2015-01-01

    An immobilization stress (IS) of 1 h applied at the beginning of the dark phase is followed by a sleep rebound. During the restraint, serotonin released by the dorsal raphe nucleus within the arcuate area stimulates the availability of corticotropin-like intermediate lobe peptide (CLIP or ACTH18-39). Three hours after the restraint, CLIP, through its hypnogenic properties, contributes to the sleep rebound that follows the IS. Here, we immunohistochemically evaluated protein expression of the immediate early gene, c-Fos and phosphorylated extracellular signal-regulated kinase (p-ERK) in hypothalamic (preoptic area [POA], paraventricular nucleus [PVN], arcuate nucleus [ARC]) and brain stem (dorsal raphe [DR], locus coeruleus [LC]) nuclei involved in the acute response to stress and the subsequent stress-related sleep rebound (recovery period). Immediately after the 1-h restraint, c-Fos and p-ERK expression increased in all structures studied, particularly in PVN and LC. Three hours later, the number of p-ERK- and c-Fos-positive neurons was reduced in PVN and LC (p < 0.001) as well as in DR (p < 0.01) compared to control animals. In contrast, both c-Fos and p-ERK expression in POA neurons (p < 0.01) and c-Fos expression in ARC neurons (p < 0.001) were increased 3 h after the IS. The marked activation observed in PVN and LC nucleus immediately after the IS confirms that these structures are clearly reactive to stress. However, the high activity observed in POA and ARC neurons during the recovery period, not described to date, highlights the particular part played by these structures in the stress-related sleep rebound. An unbalance in the above processes may contribute to pathological outcomes, such as anxiety and depression.

  3. Ghrelin in the CNS: From hunger to a rewarding and memorable meal?

    PubMed Central

    Olszewski, Pawel K.; Schiöth, Helgi B.; Levine, Allen S.

    2008-01-01

    Ghrelin, the endogenous agonist of the growth hormone secretagogue receptor, has been shown to induce robust feeding responses in numerous experimental models. Although ghrelin comes from both peripheral and central sources, its hyperphagic properties, to a large extent, arise from activity at the brain level. The current review focuses on describing central mechanisms through which this peptide affects consumption. We address the issue of whether ghrelin serves just as a signal of energy needs of the organism or – as suggested by the most recent findings -also affects food intake via other feeding-related mechanisms, including reward and memory. Complexity of ghrelin’s role in the regulation of ingestive behavior is discussed by characterizing its influence on consumption, reward and memory as well as by defining its function within the brain circuitry and interplay with other neuropeptides. PMID:18308399

  4. c-fos modulates brain-derived neurotrophic factor mRNA expression in mouse hippocampal CA3 and dentate gyrus neurons.

    PubMed

    Dong, Mei; Wu, Yongfei; Fan, Yunxia; Xu, Ming; Zhang, Jianhua

    2006-05-29

    Excess neuronal excitation by glutamate induces neuron cell death, which may contribute to the pathogenesis of acute brain injuries and neurodegenerative diseases. Our previous studies using a mouse with hippocampal c-fos gene deletion showed that c-fos regulates neuronal excitability and excitotoxicity. Moreover, a delayed induction of brain-derived neurotrophic factor (BDNF) protein expression in response to kainic acid (KA) treatment was found in c-fos mutant mice compared to wildtype controls, suggesting that c-fos is important in the temporal control of BDNF induction. To further investigate mechanisms of in vivo regulation of c-fos on BDNF expression, we studied the expression of BDNF mRNA and its colocalization with c-Fos protein in the hippocampal formation in the presence and absence of KA. By in situ hybridization, we observed that the c-fos mutant and wildtype mice exhibited similar basal expression of BDNF in the absence of KA. In contrast, the KA-induced BDNF mRNA levels were significantly different in wildtype and c-fos mutant mice in CA3 and dentate gyrus regions. Our findings indicate that c-fos regulates expression of BDNF in distinct neuron populations of the hippocampal formation in vivo.

  5. Expression of c-fos gene in central nervous system of adult medaka (Oryzias latipes) after hypergravity stimulation

    NASA Astrophysics Data System (ADS)

    Shimomura, S.; Ijiri, K.

    The immediate-early genes serve as useful neurobiological tools for mapping brain activity induced by a sensory stimulation. In this study, we have examined brain activity related to gravity perception of medaka (Oryzias latipes) by use of c-fos. The gene, which is homologous to the c-fos genes of other vertebrates, was identified in medaka. Functionally important domains are highly conserved among all the vertebrate species analyzed. Intraperitoneal administration of kainic acid transiently induced the c-fos mRNAs in medaka brain. The results indicate that the expression of c-fos can be utilized as a suitable anatomical marker for the increased neural activities in the central nervous system of medaka. Fish were continuously exposed to 3G hypergravity by centrifugation. Investigation of c-fos mRNA expression showed that c-fos mRNA significantly increased 30 minutes after a start of 3G exposure. The distribution of its transcripts within brains was analyzed by an in situ hybridization method. The 3G-treated medakas displayed c-fos positive cells in their brainstem regions, which are related to vestibular function, such as torus semicircularis, posterior octavu nucleus, nucleus tangentialis and inferior olive. Our results established the method to trace the activated area in the fish brain following gravity stimulation. The method will be a useful tool for understanding gravity perception in the brain.

  6. Involvement of FOS-mediated miR-181b/miR-21 signalling in the progression of malignant gliomas.

    PubMed

    Tao, Tao; Wang, Yingyi; Luo, Hui; Yao, Lei; Wang, Lin; Wang, Jiajia; Yan, Wei; Zhang, Junxia; Wang, Huibo; Shi, Yan; Yin, Yu; Jiang, Tao; Kang, Chunsheng; Liu, Ning; You, Yongping

    2013-09-01

    Recently, a group of microRNAs (miRNAs) were shown to be dysregulated in gliomas, and involved in glioma development. However, the effect of miRNA-miRNA functional networks on gliomas is poorly understood. In this study, we identified that FBJ murine osteosarcoma viral oncogene homolog (FOS)-mediated miR-181b/miR-21 signalling was critical for glioma progression. Using microarrays and quantitative RT-PCR (qRT-PCR), we found increased FOS in high grade gliomas. FOS depletion (via FOS-shRNA), inhibited invasion and promoted apoptosis in glioma cells. Using microarrays, combined with Pearson correlation analysis, we found FOS positively correlated with miR-21 expression. Reduction of FOS inhibited miR-21 expression by binding to the miR-21 promoter using luciferase reporter assays. Introduction of miR-21 abrogated FOS knockdown-induced cell invasion and apoptosis. Moreover, bioinformatics and luciferase reporter assays showed that miR-181b modulated FOS expression by directly targeting the binding site within the 3'UTR. Expression of FOS with a FOS cDNA lacking 3'UTR overrided miR-181b-induced miR-21 expression and cell function. Finally, immunohistochemistry (IHC) and in situ hybridisation (ISH) analysis revealed a significant correlation in miR-181b, FOS and miR-21 expression in nude mouse tumour xenograft and human glioma tissues. To our knowledge, it is the first time to demonstrate that miR-181b/FOS/miR-21 signalling plays a critical role in the progression of gliomas, providing important clues for understanding the key roles of transcription factor mediated miRNA-miRNA functional network in the regulation of gliomas.

  7. The contractile effect of the ghrelin receptor antagonist, D-Lys3-GHRP-6, in rat fundic strips is mediated through 5-HT receptors.

    PubMed

    Depoortere, Inge; Thijs, Theo; Peeters, Theo

    2006-05-10

    Ghrelin is an orexigenic peptide present in the stomach with gastroprokinetic properties. Previous in vivo studies have shown that the ghrelin receptor antagonist, D-Lys(3)-GHRP-6, reduced food intake and delayed gastric emptying in rodents but these effects are at variance with the normal phenotype of the ghrelin knockout mice. To verify the specificity of the effects observed with D-Lys(3)-GHRP-6 this study aimed to investigate the pharmacology of D-Lys(3)-GHRP-6 in vitro. Rat fundic strips were suspended in a tissue bath and the contraction of strips to 10(-5) M of ghrelin, GHRP-6 or D-Lys(3)-GHRP-6 was measured isometrically in the absence and presence of blockers. Neither ghrelin, nor GHRP-6, induced significant contractions in the absence of electrical field stimulation thereby excluding the presence of ghrelin receptors on smooth muscle cells. In contrast D-Lys(3)-GHRP-6, induced a pronounced biphasic contraction of 13.9+/-1.8% and 40.5+/-3.2% relative to the response to 60 mM KCl. The contraction was blocked by the 5-HT(1,2) receptor antagonist methysergide and was markedly reduced by the 5-HT(2B) receptor antagonist, yohimbine, which also profoundly affected 5-HT induced contractions in fundic strips. The existence of 5-HT(2B) receptors in the fundus was confirmed by use of the 5-HT(2B) receptor agonist, BW 723C86. In contrast to ghrelin and GHRP-6, the ghrelin receptor antagonist, D-Lys(3)-GHRP-6, induced pronounced smooth muscle contractions in the rat fundus by interacting with 5-HT(2B) receptors. This may question the role of endogenous ghrelin in the effects observed with D-Lys(3)-GHRP-6 on food intake and gastric emptying in vivo.

  8. Single-dose and chronic corticosterone treatment alters c-Fos or FosB immunoreactivity in the rat cerebral cortex.

    PubMed

    Szakács, Réka; Fazekas, Ildikó; Mihály, András; Krisztin-Péva, Beáta; Juhász, Anna; Janka, Zoltán

    2010-03-01

    The aim of this study was to examine the effects of single-dose and chronic corticosterone treatment on the inducible transcription factor c-Fos and FosB, and thereby to estimate the effects of high-doses of corticosterone on calcium-dependent neuronal responses in the rat cerebral cortex. At the same time we investigated the distribution of interneurons containing calretinin (CR), vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY) in chronically treated animals in order to collect data on the involvement of inhibitory neurons in this process. Adult male rats were injected subcutaneously with 10mg corticosterone, whereas controls received the vehicle (sesame oil). The animals were fixed by transcardial perfusion 12 and 24h following single corticosterone injection, and the brains were processed for c-Fos and FosB immunohistochemistry. To investigate the effects of repeated corticosterone administration, rats were daily treated with the same amount of corticosterone (10mg/animal, subcutaneously) for 21 days. Controls were injected with vehicle. At the end of the experiment, the rats were perfused and immunohistochemistry was used to detect the presence of the FosB protein, CR, VIP and NPY. Quantitative evaluation of immunolabelled cells was performed in the neocortex and the hippocampus. The number of immunoreactive nuclei per unit area was used as a quantitative measure of the effects of corticosterone. It was found that a single-dose administration of corticosterone resulted in a significant, time-dependent increase of c-Fos protein immunoreactivity in the granule cell layer of the dentate gyrus, as well as in regions CA1 and CA3 of the hippocampus 12 and 24h post-injection with respect to control animals. Significant enhancement of c-Fos immunoreactivity was also observed in the neocortex at 12 and 24h post-injection. Single-dose treatment did not significantly alter FosB immunolabelling. Repeated administration of corticosterone produced a complex

  9. Central ghrelin signaling mediates the metabolic response of C57BL/6 male mice to chronic social defeat stress.

    PubMed

    Patterson, Z R; Khazall, R; Mackay, H; Anisman, H; Abizaid, A

    2013-03-01

    Chronic stressors promote metabolic disturbances, including obesity and metabolic syndrome. Ghrelin, a peptide that promotes appetite and the accumulation of adipose tissue, is also secreted in response to stressors to protect the brain and peripheral tissues from the effects of these stressors. Here we demonstrate that elevated ghrelin levels produced by chronic exposure to social stress are associated with increased caloric intake and body weight gain in male C57BL mice. In contrast, stressed mice lacking ghrelin receptors (GHSR KO mice) or C57BL mice receiving chronic intracerebroventricular delivery of the ghrelin receptor antagonist [d-Lys(3)]-GHRP-6 show attenuated weight gain and feeding responses under the same social stress paradigm. Interestingly, stressed GHSR KO mice showed depleted sc and intrascapular brown fat depots, whereas stressed young wild-type mice did not. In old wild-type mice, chronic social defeat increased visceral and intrascapular brown fat depots in association with increases in obesity markers like hyperleptinemia and hyperinsulinemia along with increased hypothalamic expression of neuropeptide Y and Agouti related peptide. Importantly, the elevated expression of these peptides persisted least for 2 weeks after cessation of the stressor regimen. In contrast, old GHSR KO mice did not show these alterations after chronic social defeat. These results suggest that ghrelin plays an important role in the metabolic adaptations necessary to meet the energetic demands posed by stressors, but chronic exposure to stress-induced ghrelin elevations ultimately could lead to long lasting metabolic dysfunctions.

  10. Ghrelin-ghrelin O-acyltransferase system in the pathogenesis of nonalcoholic fatty liver disease.

    PubMed

    Zhang, Shao-Ren; Fan, Xiao-Ming

    2015-03-21

    Nonalcoholic fatty liver disease (NAFLD) is currently considered as the most common liver disease in Western countries, and is rapidly becoming a serious threat to public health worldwide. However, the underlying mechanisms leading to the development of NAFLD are still not fully understood. The ghrelin-ghrelin O-acyltransferase (GOAT) system has recently been found to play a crucial role in both the development of steatosis and its progression to nonalcoholic steatohepatitis. Ghrelin, the natural ligand of the growth hormone secretagogue receptor, is a 28-amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by GOAT. The ghrelin-GOAT system is involved in insulin resistance, lipid metabolism dysfunction, and inflammation, all of which play important roles in the pathogenesis of NAFLD. A better understanding of ghrelin-GOAT system biology led to the identification of its potential roles in NAFLD. Molecular targets modulating ghrelin-GOAT levels and the biologic effects are being studied, which provide a new insight into the pathogenesis of NAFLD. This review probes into the possible relationship between the ghrelin-GOAT system and NAFLD, and considers the potential mechanisms by which the ghrelin-GOAT system brings about insulin resistance and other aspects concerning NAFLD.

  11. Microgravity decreases c-fos induction and serum response element activity.

    PubMed

    de Groot, R P; Rijken, P J; den Hertog, J; Boonstra, J; Verkleij, A J; de Laat, S W; Kruijer, W

    1990-09-01

    Several studies have shown that altered gravity conditions influence mammalian cell growth and differentiation. The molecular mechanisms underlying these effects, however, remain relatively obscure. In this paper we show that microgravity reached in a sounding rocket strongly decreases epidermal growth factor (EGF)-induced expression of the proto-oncogenes c-fos and c-jun, which are both implicated in the regulation of proliferation and differentiation. Decreased activity of the serum response element (SRE), present in the c-fos promoter-enhancer region, is probably responsible for the decrease in EGF-induced c-fos expression. In addition, we show that gravity alterations differentially modulate distinctive signal transduction pathways, indicating that gravity-dependent modulations of mammalian cell proliferation are unlikely to be caused by a nonspecific stress response of the cell.

  12. Ghrelin binding to serum albumin and its biological impact.

    PubMed

    Lufrano, Daniela; Trejo, Sebastián A; Llovera, Ramiro E; Salgueiro, Mariano; Fernandez, Gimena; Martínez Damonte, Valentina; González Flecha, F Luis; Raingo, Jesica; Ermácora, Mario R; Perelló, Mario

    2016-11-15

    Ghrelin is an octanoylated peptide hormone that plays a key role in the regulation of the body weight and glucose homeostasis. In plasma, ghrelin circulates bound to larger proteins whose identities are partially established. Here, we used size exclusion chromatography, mass spectrometry and isothermal titration microcalorimetry to show that ghrelin interacts with serum albumin. Furthermore, we found that such interaction displays an estimated dissociation constant (KD) in the micromolar range and involves albumin fatty-acid binding sites as well as the octanoyl moiety of ghrelin. Notably, albumin-ghrelin interaction reduces the spontaneous deacylation of the hormone. Both in vitro experiments-assessing ghrelin ability to inhibit calcium channels-and in vivo studies-evaluating ghrelin orexigenic effects-indicate that the binding to albumin affects the bioactivity of the hormone. In conclusion, our results suggest that ghrelin binds to serum albumin and that this interaction impacts on the biological activity of the hormone.

  13. Characterization of E-cadherin-dependent and -independent events in a new model of c-Fos-mediated epithelial-mesenchymal transition

    SciTech Connect

    Mejlvang, Jakob; Kriajevska, Marina; Berditchevski, Fedor; Bronstein, Igor; Lukanidin, Eugene M.; Pringle, J. Howard; Mellon, J. Kilian; Tulchinsky, Eugene M. . E-mail: et32@le.ac.uk

    2007-01-15

    Fos proteins have been implicated in control of tumorigenesis-related genetic programs including invasion, angiogenesis, cell proliferation and apoptosis. In this study, we demonstrate that c-Fos is able to induce mesenchymal transition in murine tumorigenic epithelial cell lines. Expression of c-Fos in MT1TC1 cells led to prominent alterations in cell morphology, increased expression of mesenchymal markers, vimentin and S100A4, DNA methylation-dependent down-regulation of E-cadherin and abrogation of cell-cell adhesion. In addition, c-Fos induced a strong {beta}-catenin-independent proliferative response in MT1TC1 cells and stimulated cell motility, invasion and adhesion to different extracellular matrix proteins. To explore whether loss of E-cadherin plays a role in c-Fos-mediated mesenchymal transition, we expressed wild-type E-cadherin and two different E-cadherin mutants in MT1TC1/c-fos cells. Expression of wild-type E-cadherin restored epithelioid morphology and enhanced cellular levels of catenins. However, exogenous E-cadherin did not influence expression of c-Fos-dependent genes, only partly suppressed growth of MT1TC1/c-fos cells and produced no effect on c-Fos-stimulated cell motility and invasion in matrigel. On the other hand, re-expression of E-cadherin specifically negated c-Fos-induced adhesion to collagen type I, but not to laminin or fibronectin. Of interest, mutant E-cadherin which lacks the ability to form functional adhesive complexes had an opposite, potentiating effect on cell adhesion to collagen I. These data suggest that cell adhesion to collagen I is regulated by the functional state of E-cadherin. Overall, our data demonstrate that, with the exception of adhesion to collagen I, c-Fos is dominant over E-cadherin in relation to the aspects of mesenchymal transition assayed in this study.

  14. Ghrelin signalling and obesity: at the interface of stress, mood and food reward.

    PubMed

    Schellekens, Harriët; Finger, Beate C; Dinan, Timothy G; Cryan, John F

    2012-09-01

    The neuronal circuitry underlying the complex relationship between stress, mood and food intake are slowly being unravelled and several studies suggest a key role herein for the peripherally derived hormone, ghrelin. Evidence is accumulating linking obesity as an environmental risk factor to psychiatric disorders such as stress, anxiety and depression. Ghrelin is the only known orexigenic hormone from the periphery to stimulate food intake. Plasma ghrelin levels are enhanced under conditions of physiological stress and ghrelin has recently been suggested to play an important role in stress-induced food reward behaviour. In addition, chronic stress or atypical depression has often demonstrated to correlate with an increase in ingestion of caloric dense 'comfort foods' and have been implicated as one of the major contributor to the increased prevalence of obesity. Recent evidence suggests ghrelin as a critical factor at the interface of homeostatic control of appetite and reward circuitries, modulating the hedonic aspects of food intake. Therefore, the reward-related feeding of ghrelin may reveal itself as an important factor in the development of addiction to certain foods, similar to its involvement in the dependence to drugs of abuse, including alcohol. This review will highlight the accumulating evidence demonstrating the close interaction between food, mood and stress and the development of obesity. We consider the ghrelinergic system as an effective target for the development of successful anti-obesity pharmacotherapies, which not only affects appetite but also selectively modulates the rewarding properties of food and impact on psychological well-being in conditions of stress, anxiety and depression.

  15. Tissue distribution and effects of fasting and obesity on the ghrelin axis in mice.

    PubMed

    Morash, Michael G; Gagnon, Jeffrey; Nelson, Stephanie; Anini, Younes

    2010-08-09

    Ghrelin is a 28 amino acid peptide hormone derived from the 117 amino acid proghrelin, following cleavage by proprotein convertase 1 (PC1). In this study, we comprehensively assessed the tissue distribution and the effect of fasting and obesity on preproghrelin, Exon-4D, PC1 and GOAT expression and proghrelin-derived peptide (PGDP) secretion. The stomach was the major source of preproghrelin expression and PDGPs, followed by the small intestine. The remaining peripheral tissues (including the brain and pancreas) contained negligible expression levels. We detected obestatin in all stomach proghrelin cells, however, 22% of proghrelin cells in the small intestine did not express obestatin. There were strain differences in ghrelin secretion in response to fasting between CD1 and C57BL/6 mice. After a 24 hour-fast, CD1 mice had increased plasma levels of total ghrelin and obestatin with no change in preproghrelin mRNA or PGDP tissues levels. C57BL/6 mice showed a different response to a 24 hour-fast having increased proghrelin mRNA expression, stomach acylated ghrelin peptide and no change in plasma obestatin in C57BL/6 mice. In obese mice (ob/ob and diet-induced obesity (DIO)) there was a significant increase in preproghrelin mRNA levels while tissue and plasma PGDP levels were significantly reduced. Fasting did not affect PGDP in obese mice. Obese models displayed differences in GOAT expression, which was elevated in DIO mice, but reduced in ob/ob mice. We did not find co-localization of the leptin receptor in ghrelin expressing stomach cells, ruling out a direct effect of leptin on stomach ghrelin synthesis and secretion.

  16. Pharmacologic inhibition of ghrelin receptor signaling is insulin sparing and promotes insulin sensitivity.

    PubMed

    Longo, Kenneth A; Govek, Elizabeth K; Nolan, Anna; McDonagh, Thomas; Charoenthongtrakul, Soratree; Giuliana, Derek J; Morgan, Kristen; Hixon, Jeffrey; Zhou, Chaoseng; Kelder, Bruce; Kopchick, John J; Saunders, Jeffrey O; Navia, Manuel A; Curtis, Rory; DiStefano, Peter S; Geddes, Brad J

    2011-10-01

    Ghrelin influences a variety of metabolic functions through a direct action at its receptor, the GhrR (GhrR-1a). Ghrelin knockout (KO) and GhrR KO mice are resistant to the negative effects of high-fat diet (HFD) feeding. We have generated several classes of small-molecule GhrR antagonists and evaluated whether pharmacologic blockade of ghrelin signaling can recapitulate the phenotype of ghrelin/GhrR KO mice. Antagonist treatment blocked ghrelin-induced and spontaneous food intake; however, the effects on spontaneous feeding were absent in GhrR KO mice, suggesting target-specific effects of the antagonists. Oral administration of antagonists to HFD-fed mice improved insulin sensitivity in both glucose tolerance and glycemic clamp tests. The insulin sensitivity observed was characterized by improved glucose disposal with dramatically decreased insulin secretion. It is noteworthy that these results mimic those obtained in similar tests of HFD-fed GhrR KO mice. HFD-fed mice treated for 56 days with antagonist experienced a transient decrease in food intake but a sustained body weight decrease resulting from decreased white adipose, but not lean tissue. They also had improved glucose disposal and a striking reduction in the amount of insulin needed to achieve this. These mice had reduced hepatic steatosis, improved liver function, and no evidence of systemic toxicity relative to controls. Furthermore, GhrR KO mice placed on low- or high-fat diets had lifespans similar to the wild type, emphasizing the long-term safety of ghrelin receptor blockade. We have therefore demonstrated that chronic pharmacologic blockade of the GhrR is an effective and safe strategy for treating metabolic syndrome.

  17. Progress in Small Molecule and Biologic Therapeutics Targeting Ghrelin Signaling.

    PubMed

    McGovern, Kayleigh R; Darling, Joseph E; Hougland, James L

    2016-01-01

    Ghrelin is a circulating peptide hormone involved in regulation of a wide array of physiological processes. As an endogenous ligand for growth hormone secretagogue receptor (GHSR1a), ghrelin is responsible for signaling involved in energy homeostasis, including appetite stimulation, glucose metabolism, insulin signaling, and adiposity. Ghrelin has also been implicated in modulation of several neurological processes. Dysregulation of ghrelin signaling is implicated in diseases related to these pathways, including obesity, type II diabetes, and regulation of appetite and body weight in patients with Prader-Willi syndrome. Multiple steps in the ghrelin signaling pathway are available for targeting in the development of therapeutics for these diseases. Agonists and antagonists of GHS-R1a have been widely studied and have shown varying levels of effectiveness within ghrelin-related physiological pathways. Agents targeting ghrelin directly, either through depletion of ghrelin levels in circulation or inhibitors of ghrelin O-acyltransferase whose action is required for ghrelin to become biologically active, are receiving increasing attention as potential therapeutic options. We discuss the approaches utilized to target ghrelin signaling and highlight the current challenges toward developing small-molecule agents as potential therapeutics for ghrelin-related diseases.

  18. The Ghrelin Axis in Disease; Potential Therapeutic Indications

    PubMed Central

    Nass, Ralf; Gaylinn, Bruce D.; Thorner, Michael O.

    2011-01-01

    Ghrelin, the natural ligand for the growth hormone (GH)-secretagogue receptor (GHS-R), is produced predominantly in the stomach. It is present in the circulation in two major forms, an acylated and an unacylated form, both of which have reported activities. Some of the best understood main effects of acylated ghrelin administration include anorexic effects, increased appetite and the stimulation of GH secretion. Ghrelin also seems to plays a role in glucose homeostasis, lipid metabolism and immune function. Based on its orexigenic and metabolic effects, ghrelin and ghrelin mimetics have potential benefit in antagonizing protein breakdown and weight loss in catabolic conditions such as cancer cachexia, renal, cardiac and pulmonary disease, and age-related frailty. Ghrelin also has potentially useful positive effects on cardiac function and gastric motility. Ghrelin antagonists may be of benefit to increase insulin sensitivity and potentiate weight loss. The following chapter presents some background on ghrelin and ghrelin assays and discusses some of the potential therapeutic approaches for the use of ghrelin, ghrelin mimetic compounds and ghrelin antagonists in clinical disease. PMID:21356273

  19. Effects of ghrelin, growth hormone-releasing peptide-6, and growth hormone-releasing hormone on growth hormone, adrenocorticotropic hormone, and cortisol release in type 1 diabetes mellitus.

    PubMed

    de Sá, Larissa Bianca Paiva Cunha; Nascif, Sergio Oliva; Correa-Silva, Silvia Regina; Molica, Patricia; Vieira, José Gilberto Henriques; Dib, Sergio Atala; Lengyel, Ana-Maria Judith

    2010-10-01

    In type 1 diabetes mellitus (T1DM), growth hormone (GH) responses to provocative stimuli are normal or exaggerated, whereas the hypothalamic-pituitary-adrenal axis has been less studied. Ghrelin is a GH secretagogue that also increases adrenocorticotropic hormone (ACTH) and cortisol levels, similarly to GH-releasing peptide-6 (GHRP-6). Ghrelin's effects in patients with T1DM have not been evaluated. We therefore studied GH, ACTH, and cortisol responses to ghrelin and GHRP-6 in 9 patients with T1DM and 9 control subjects. The GH-releasing hormone (GHRH)-induced GH release was also evaluated. Mean fasting GH levels (micrograms per liter) were higher in T1DM (3.5 ± 1.2) than in controls (0.6 ± 0.3). In both groups, ghrelin-induced GH release was higher than that after GHRP-6 and GHRH. When analyzing Δ area under the curve (ΔAUC) GH values after ghrelin, GHRP-6, and GHRH, no significant differences were observed in T1DM compared with controls. There was a trend (P = .055) to higher mean basal cortisol values (micrograms per deciliter) in T1DM (11.7 ± 1.5) compared with controls (8.2 ± 0.8). No significant differences were seen in ΔAUC cortisol values in both groups after ghrelin and GHRP-6. Mean fasting ACTH values were similar in T1DM and controls. No differences were seen in ΔAUC ACTH levels in both groups after ghrelin and GHRP-6. In summary, patients with T1DM have normal GH responsiveness to ghrelin, GHRP-6, and GHRH. The ACTH and cortisol release after ghrelin and GHRP-6 is also similar to controls. Our results suggest that chronic hyperglycemia of T1DM does not interfere with GH-, ACTH-, and cortisol-releasing mechanisms stimulated by these peptides.

  20. Regulation of fos-lacZ fusion gene expression in primary mouse epidermal keratinocytes isolated from transgenic mice.

    PubMed Central

    Bollag, W B; Xiong, Y; Ducote, J; Harmon, C S

    1994-01-01

    The expression of a fos-lacZ fusion gene was studied in primary mouse epidermal keratinocytes obtained from transgenic mice. This gene construct contains the entire upstream regulatory sequence of c-fos, and expression of the endogenous and fusion gene was shown by Northern analysis to correlate upon induction with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Using a chromogenic substrate of beta-galactosidase, we also demonstrated that expression of the fusion gene product, like that of Fos, was localized to the cell nucleus. In addition, we showed that epidermal keratinocytes responded to dialysed fetal bovine serum (FBS), TPA and high-calcium medium with enhanced Fos-lacZ expression and an inhibition of proliferation. The time course of induction of Fos-lacZ expression was similar for dialysed FBS and TPA, with a peak approximately 2 h after exposure. Exposure for approximately 24 h to an elevated extracellular calcium concentration was required to elicit an increase in Fos-lacZ expression. The lack of an immediate effect of raising medium calcium levels on Fos-lacZ expression contrasted with the rapidity of its effect on DNA synthesis, which was significantly inhibited within 6-8 h. In addition, we found that the protein kinase C inhibitor Ro 31-7549 blocked Fos-lacZ expression induced by TPA but had little or no effect on that elicited by high calcium levels. Thus, although our results indicate that the fos gene product may be involved in mediating epidermal keratinocyte growth arrest in response to differentiative agents such as FBS, TPA and high medium calcium levels, the exact role of this gene product remains unclear. Images Figure 1 Figure 2 PMID:8198544

  1. Regulation of fos-lacZ fusion gene expression in primary mouse epidermal keratinocytes isolated from transgenic mice.

    PubMed

    Bollag, W B; Xiong, Y; Ducote, J; Harmon, C S

    1994-05-15

    The expression of a fos-lacZ fusion gene was studied in primary mouse epidermal keratinocytes obtained from transgenic mice. This gene construct contains the entire upstream regulatory sequence of c-fos, and expression of the endogenous and fusion gene was shown by Northern analysis to correlate upon induction with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Using a chromogenic substrate of beta-galactosidase, we also demonstrated that expression of the fusion gene product, like that of Fos, was localized to the cell nucleus. In addition, we showed that epidermal keratinocytes responded to dialysed fetal bovine serum (FBS), TPA and high-calcium medium with enhanced Fos-lacZ expression and an inhibition of proliferation. The time course of induction of Fos-lacZ expression was similar for dialysed FBS and TPA, with a peak approximately 2 h after exposure. Exposure for approximately 24 h to an elevated extracellular calcium concentration was required to elicit an increase in Fos-lacZ expression. The lack of an immediate effect of raising medium calcium levels on Fos-lacZ expression contrasted with the rapidity of its effect on DNA synthesis, which was significantly inhibited within 6-8 h. In addition, we found that the protein kinase C inhibitor Ro 31-7549 blocked Fos-lacZ expression induced by TPA but had little or no effect on that elicited by high calcium levels. Thus, although our results indicate that the fos gene product may be involved in mediating epidermal keratinocyte growth arrest in response to differentiative agents such as FBS, TPA and high medium calcium levels, the exact role of this gene product remains unclear.

  2. Effect of ghrelin receptor agonist and antagonist on the activity of arcuate nucleus tyrosine hydroxylase containing neurons in C57BL/6 male mice exposed to normal or high fat diet.

    PubMed

    Pirnik, Z; Majercikova, Z; Holubova, M; Pirnik, R; Zelezna, B; Maletinska, L; Kiss, A

    2014-08-01

    Catecholamines participate in the food intake regulation, however, there are no literature data available, dealing with the activity of tyrosine hydroxylase (TH) neurons in response to stimulation or inhibition of GHS-R (growth hormone secretagogue receptor) in the hypothalamic arcuate nucleus (ARC). The present study was focused to reveal whether [Dpr(N-octanoyl) 3ghrelin], a stable GHS-R agonist, itself in doses of 5 or 10 mg/kg (s.c.) or in combination with GHS-R receptor antagonist ([DLys3]GHRP-6) in dose of 10 mg/kg (s.c.), may affect the activity of ARC TH-containing neurons in C57BL/6 male mice fed either with standard (SD) or high fat diet (HFD) that developed a diet-induced obesity (DIO). The data of the present study clearly indicate that both doses of GHS-R agonist stimulated food intake in SD mice and GHS-R antagonist significantly reduced GHS-R agonist orexinergic effect in SD mice and suppressed the voluntary food intake in HFD mice. Both doses of the GHS-R agonist stimulated Fos expression in ARC neurons in both diet groups of mice which was not abolished by GHS-R antagonist pretreatment. Moreover, both doses of the GHS-R agonist significantly influenced the activation of TH neurons in the ARC of SD mice. The GHS-R antagonist also significantly increased TH neurons activation after GHS-R agonist although this effect was less powerful in HFD mice. This is the first study demonstrating response of local ARC TH neurons to peripherally applied GHS-R agonist and antagonist. The present data point out that the response of TH neurons to GHS-R agonist and antagonist is different in normal and DIO mice and extend our knowledge about the further ARC neuronal phenotype responding to peripheral ghrelin. To bring insight into the understanding of the functional significance of the activated TH neurons in ARC, in the context of the ghrelin peripheral increase, further studies are required.

  3. [Antagonistic effects of selenium on the expression of c-fos in central nerval system of rat included by mercury contaminated rice].

    PubMed

    Cheng, Jin-ping; Wang, Wen-hua; Jia, Jin-ping; Qu, Li-ya; Zheng, Min; Shen, Zhe-ming; Shi, Wei

    2005-03-01

    The objective of this paper is to study the antagonisms between selenium and mercury and the effect of different species mercury on the brain injury. The expression of c-fos mRNA and c-FOS protein in rat brain induced by Hg-contaminated rice was observed by using reverse transcriptions polymerase chain reaction (RT-PCR) and immunocytochemical methods. The results show the Hg-contaminated rice induced significantly the expression of c-fos mRNA and c-FOS protein; selenium could antagonize mercury accumulative level in brain. Antagonistic effects of selenium on the expression of c-fos included by mercury and the molecule mechanism of the antagonisms between selenium and mercury was probed, too.

  4. Addition of positively charged tripeptide to N-terminus of the Fos basic region leucine zipper domain: implications on DNA bending, affinity, and specificity.

    PubMed

    Mahmoudi, T; Sarkar, B

    1999-09-01

    GKH-Fos(139-211)/Jun(248-334) (GKH: glycine-lysine-histidine) is a modified Fos/Jun heterodimer designed to contain a metal binding motif in the form of a GKH tripeptide at the amino terminus of Fos bZIP domain dimerized with the Jun basic region leucine zipper (bZIP) domain. We examined the effect of the addition of positively charged GKH motif to the N-terminus of Fos(139-211) on the DNA binding characteristics of the Fos(139-211)/Jun(248-334) heterodimer. Binding studies indicate that while the nonspecific DNA binding affinity of the GKH modified heterodimer increases 4-fold, it specifically binds the activating protein-1 (AP-1) site 6-fold less tightly than the control unmodified counterpart. Furthermore, helical phasing analysis indicates that GKH-Fos(139-211)/Jun(248-334) and control Fos(139-211)/Jun(248-334) both bend the DNA at the AP-1 site toward the minor groove. However, due to the presence of the positively charged GKH motif on Fos, the degree of the induced bend by GKH- Fos(139-211)/Jun(248-334) is greater than that induced by the unmodified Fos/Jun heterodimer. Our results suggest that the unfavorable energetic cost of the increased DNA bending by GKH-Fos(139-211)/Jun(248-334) results in a decrease in both specificity and affinity of binding of the heterodimer to the AP-1 site. These findings may have important implications in protein design as well in our understanding of