scholarly journals Iron absorption in hepcidin1 knockout mice

2011 ◽  
Vol 105 (11) ◽  
pp. 1583-1591 ◽  
Author(s):  
Patarabutr Masaratana ◽  
Abas H. Laftah ◽  
Gladys O. Latunde-Dada ◽  
Sophie Vaulont ◽  
Robert J. Simpson ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Iron Absorption ◽  
Fe Deficiency ◽  
Acute Effects ◽  
Regulatory Peptide ◽  
Fe Uptake

Hepcidin, the Fe-regulatory peptide, has been shown to inhibit Fe absorption and reticuloendothelial Fe recycling. The present study was conducted to explore the mechanism of in vivo Fe regulation through genetic disruption of hepcidin1 and acute effects of hepcidin treatment in hepcidin1 knockout (Hepc1− / − ) and heterozygous mice. Hepcidin1 disruption resulted in significantly increased intestinal Fe uptake. Hepcidin injection inhibited Fe absorption in both genotypes, but the effects were more evident in the knockout mice. Hepcidin administration was also associated with decreased membrane localisation of ferroportin in the duodenum, liver and, most significantly, in the spleen of Hepc1− / −  mice. Hypoferraemia was induced in heterozygous mice by hepcidin treatment, but not in Hepc1− / −  mice, 4 h after injection. Interestingly, Fe absorption and serum Fe levels in Hepc1− / −  and heterozygous mice fed a low-Fe diet were not affected by hepcidin injection. The present study demonstrates that hepcidin deficiency causes increased Fe absorption. The effects of hepcidin were abolished by dietary Fe deficiency, indicating that the response to hepcidin may be influenced by dietary Fe level or Fe status.

scholarly journals Studies on the control of iron uptake by rabbit small intestine

1982 ◽  
Vol 47 (2) ◽  
pp. 251-258 ◽  
Author(s):  
T. M. Cox ◽  
M. W. O'Donnell
Keyword(s):  
Regional Distribution ◽  
Maximum Velocity ◽  
Whole Body ◽  
Fe Deficiency ◽  
Distal Intestine ◽  
Body Retention ◽  
Fe Uptake ◽  
Active Transport Process

1. Whole-body retention in vivo and uptake of 59Fe-labelled ascorbate and nitrilotriacetate chelates by intestinal slices in vitro were determined in groups of normal control rabbits and rabbits with experimentally-induced Fe deficiency.2. Over-all absorption as measured by retention of doses of either chelate was greatly increased in conditions of Fe deficiency.3. Intestinal Fe uptake in vitro was inhibited up to 77% in the presence of 2,4-dinitrophenol and sodium fluoride. Initial rates showed saturation within the concentration range 18–450 μmol/l, suggesting that uptake was brought about by an active transport process.4. When studied at chelate concentrations of 450 μmol/l, significant regional differences in uptake rates were observed. Uptake in duodenal slices was increased when compared with slices from jejunum and ileum.5. Fe uptake from ferric and ferrous chelates was greatly enhanced in Fe deficiency. This was chiefly due to increases in uptake by slices from the duodenum, but uptake into slices of distal intestine was also stimulated.6. Kinetic analysis of Fe uptake by duodenal slices from animals rendered Fe deficient by diet or repeated bleeding indicated in both groups an increased apparent maximum velocity (Vmax) for influx of Fe without significant changes in apparent affinity for Fe.7. The experiments provide further insight into the nature and regional distribution of transport of Fe into the intestine and suggest, in the rabbit, that important control of Fe absorption may be exerted by an active process operating at this initial entry step.

scholarly journals Dietary ascorbic acid raises iron absorption in anaemic rats through enhancing mucosal iron uptake independent of iron solubility in the digesta

1997 ◽  
Vol 77 (1) ◽  
pp. 123-131 ◽  
Author(s):  
K. J. H. Wienk ◽  
J. J. M. Marx ◽  
M. Santos ◽  
A. G. Lemmens ◽  
E. J. Brink ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Iron Uptake ◽  
Iron Absorption ◽  
Iron Solubility ◽  
Fe Uptake ◽  
Isotope Technique ◽  
Proximal Intestine ◽  
Liquid And Solid Phases ◽  
Double Isotope

We studied Fe absorption from FeSO4 in rats with Fe deficiency-induced anaemia that were given an Fe-sufficient purified diet without or with ascorbic acid (10·4 g/kg diet). Attention was focused on mucosal Fe uptake as measured in vivo by a double-isotope technique. Haemoglobin repletion and liver Fe levels were not affected when the ascorbic acid-supplemented diet was given, but apparent Fe absorption and retention of orally administered 59Fe were significantly enhanced. The distribution of Fe between liquid and solid phases of contents of both the stomach and the proximal intestine was not affected by the feeding of the ascorbic acid, but ascorbic acid significantly enhanced mucosal Fe uptake. It is concluded that ascorbic acid in the diet raises mucosal Fe uptake through a mechanism independent of the intestinal Fe solubility.

The neurophysiology of ketamine: an integrative review

2020 ◽  
Vol 31 (5) ◽  
pp. 457-503
Author(s):  
Rebecca McMillan ◽  
Suresh D. Muthukumaraswamy
Keyword(s):  
Spatial Scales ◽  
Integrative Review ◽  
Acute Effects ◽  
Future Work

AbstractThe drug ketamine has been extensively studied due to its use in anaesthesia, as a model of psychosis and, most recently, its antidepressant properties. Understanding the physiology of ketamine is complex due to its rich pharmacology with multiple potential sites at clinically relevant doses. In this review of the neurophysiology of ketamine, we focus on the acute effects of ketamine in the resting brain. We ascend through spatial scales starting with a complete review of the pharmacology of ketamine and then cover its effects on in vitro and in vivo electrophysiology. We then summarise and critically evaluate studies using EEG/MEG and neuroimaging measures (MRI and PET), integrating across scales where possible. While a complicated and, at times, confusing picture of ketamine’s effects are revealed, we stress that much of this might be caused by use of different species, doses, and analytical methodologies and suggest strategies that future work could use to answer these problems.

scholarly journals Sirt1 deacetylates and stabilizes p62 to promote hepato-carcinogenesis

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Lifeng Feng ◽  
Miaoqin Chen ◽  
Yiling Li ◽  
Muchun Li ◽  
Shiman Hu ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Overall Survival ◽  
Cell Growth ◽  
Knockout Mice ◽  
Liver Tumors ◽  
Underlying Mechanism ◽  
Carcinoma Cells ◽  
Conditional Knockout

Abstractp62/SQSTM1 is frequently up-regulated in many cancers including hepatocellular carcinoma. Highly expressed p62 promotes hepato-carcinogenesis by activating many signaling pathways including Nrf2, mTORC1, and NFκB signaling. However, the underlying mechanism for p62 up-regulation in hepatocellular carcinoma remains largely unclear. Herein, we confirmed that p62 was up-regulated in hepatocellular carcinoma and its higher expression was associated with shorter overall survival in patients. The knockdown of p62 in hepatocellular carcinoma cells decreased cell growth in vitro and in vivo. Intriguingly, p62 protein stability could be reduced by its acetylation at lysine 295, which was regulated by deacetylase Sirt1 and acetyltransferase GCN5. Acetylated p62 increased its association with the E3 ligase Keap1, which facilitated its poly-ubiquitination-dependent proteasomal degradation. Moreover, Sirt1 was up-regulated to deacetylate and stabilize p62 in hepatocellular carcinoma. Additionally, Hepatocyte Sirt1 conditional knockout mice developed much fewer liver tumors after Diethynitrosamine treatment, which could be reversed by the re-introduction of exogenous p62. Taken together, Sirt1 deacetylates p62 at lysine 295 to disturb Keap1-mediated p62 poly-ubiquitination, thus up-regulating p62 expression to promote hepato-carcinogenesis. Therefore, targeting Sirt1 or p62 is a reasonable strategy for the treatment of hepatocellular carcinoma.

Maturation, iron deficiency, and ligands in enteric radioiron transport in vitro

1963 ◽  
Vol 204 (1) ◽  
pp. 171-175 ◽  
Author(s):  
W. S. Ruliffson ◽  
J. M. Hopping
Keyword(s):  
Ascorbic Acid ◽  
Iron Deficiency ◽  
Iron Absorption ◽  
Deficiency Anemia ◽  
Anaerobic Incubation ◽  
Reverse Effect ◽  
Factors Affecting ◽  
Everted Gut Sac

The effects in rats, of age, iron-deficiency anemia, and ascorbic acid, citrate, fluoride, and ethylenediaminetetraacetate (EDTA) on enteric radioiron transport were studied in vitro by an everted gut-sac technique. Sacs from young animals transported more than those from older ones. Proximal jejunal sacs from anemic animals transported more than similar sacs from nonanemic rats, but the reverse effect appeared in sacs formed from proximal duodenum. When added to media containing ascorbic acid or citrate, fluoride depressed transport as did anaerobic incubation in the presence of ascorbic acid. Anaerobic incubation in the presence of EDTA appeared to permit elevated transport. Ascorbic acid, citrate, and EDTA all enhanced the level of Fe59 appearing in serosal media. These results appear to agree with previously established in vivo phenomena and tend to validate the in vitro method as one of promise for further studies of factors affecting iron absorption and of the mechanism of iron absorption.

Further pharmacological evaluation of a novel synthetic peptide bradykinin B2 receptor agonist

2013 ◽  
Vol 394 (3) ◽  
pp. 353-360 ◽  
Author(s):  
Martin Savard ◽  
Julie Labonté ◽  
Céléna Dubuc ◽  
Witold Neugebauer ◽  
Pedro D’Orléans-Juste ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Synthetic Peptide ◽  
Receptor Agonist ◽  
Rabbit Lung ◽  
Hypotensive Action ◽  
Duration Of Action ◽  
Selective Agonist ◽  
Comparable Magnitude

Abstract We recently identified a novel human B2 receptor (B2R) agonist [Hyp3,Thi5,NChg7,Thi8]-bradykinin (NG291) with greater in vitro and in vivo potency and duration of action than natural bradykinin (BK). Here, we further examined its stability and selectivity toward B2R. The hypotensive, antithrombotic, and profibrinolytic functions of NG291 relative to BK and its analogue ([Hyp3,Thi5,(4-Me)Tyr8(ΨCH2NH)Arg9]-BK) (RMP-7) were also tested. Contraction assays using isolated mouse stomachs (containing kinin B1R, B2R, and kininase I- and II-like activities) showed that NG291 is a more potent contractant than BK and is inhibited by HOE-140 (B2R antagonist) but unaffected by R954 (B1R antagonist), whereas both decreased the potency of BK. In stomach tissues from B2R knockout mice, BK maintained its activity via B1R, whereas NG291 had no contractile effect, indicating that it was selective for B2R. Unlike BK, NG291 was not degraded by rabbit lung ACE. Comparing intravenously administered BK and NG291 revealed that NG291 exhibited more potent and prolonged hypotensive action and greater antithrombotic and profibrinolytic activities. These effects were of comparable magnitude to RMP-7 and were absent in B2R knockout mice. We concluded that NG291 is a novel biostable B2R-selective agonist that may prove suitable for investigating the (pre)clinical cardioprotective efficacy of B2R activation.

PRMT5 Prevents Dilated Cardiomyopathy via Suppression of Protein O-GlcNAcylation

2021 ◽  
Author(s):  
Zhenhua Li ◽  
Jingping Xu ◽  
Yao Song ◽  
Chong Xin ◽  
Lantao Liu ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Knockout Mice ◽  
Rna Splicing ◽  
Gene Knockout ◽  
Major Type ◽  
Integrated Analysis ◽  
Arginine Methyltransferase ◽  
Potential Strategy ◽  
Glcnac Transferase

Rationale: Protein O-GlcNAcylation is dynamically regulated by two key enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Excessive protein O-GlcNAcylation contributes to dilated cardiomyopathy (DCM), but its regulatory mechanisms are not fully understood. The protein arginine methyltransferase 5 (PRMT5) is the major type II arginine methyltransferase, which plays critical physiological roles by symmetrically dimethylating various downstream targets including proteins involved in RNA splicing. However, its function in regulating protein O-GlcNAcylation and DCM is unexplored. Objective: To elucidate the physiological function of PRMT5 and the mechanism underlying its role in regulating cardiac O-GlcNAcylation and homeostasis. Methods and Results: Conditional gene knockout was used to study the in vivo function of Prmt5 in regulating cardiac homeostasis. An integrated analysis of transcriptomic and metabolomic profiles was performed to investigate the molecular mechanism. Adeno-associated virus 9 (AAV9)-mediated gene delivery in the mouse was used to study the protein O-GlcNAcylation in Prmt5 deficiency-induced DCM. PRMT5 mRNA was decreased in human DCM hearts, and cardiomyocyte-specific Prmt5 deletion in mice resulted in DCM and heart failure. Transcriptomic and metabolomic profiling identified increased O-GlcNAcylation in the hearts of Prmt5-knockout mice. Mechanistically, Prmt5 deletion suppressed O-GlcNAcase (OGA) expression by inhibiting the transcription of Oga and triggering its aberrant splicing. Consistently, a positive correlation of PRMT5 and OGA was identified in human DCM hearts. Notably, gene therapy with AAV9 encoding the correctly spliced Oga normalized the cardiac protein O-GlcNAcylation levels and partially rescued the dilation and dysfunction of the hearts in Prmt5-knockout mice. Conclusions: Our data demonstrate a novel function of PRMT5 in regulating protein O-GlcNAcylation to maintain cardiac homeostasis, suggesting that targeting the PRMT5-OGA axis could be a potential strategy for treating DCM.

scholarly journals Vascular Endothelin-B Receptor System In Vivo Plays a Favorable Inhibitory Role in Vascular Remodeling After Injury Revealed by Endothelin-B Receptor–Knockout Mice

Circulation ◽  
2002 ◽  
Vol 106 (15) ◽  
pp. 1991-1998 ◽  
Author(s):  
Nobuyuki Murakoshi ◽  
Takashi Miyauchi ◽  
Yoshihiko Kakinuma ◽  
Takashi Ohuchi ◽  
Katsutoshi Goto ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Vascular Remodeling ◽  
Receptor System ◽  
Endothelin B Receptor ◽  
Inhibitory Role ◽  
Endothelin B

scholarly journals Preoperative administration of the 5-HT4 receptor agonist prucalopride reduces intestinal inflammation and shortens postoperative ileus via cholinergic enteric neurons

Gut ◽  
2018 ◽  
Vol 68 (8) ◽  
pp. 1406-1416 ◽  
Author(s):  
Nathalie Stakenborg ◽  
Evelien Labeeuw ◽  
Pedro J Gomez-Pinilla ◽  
Sebastiaan De Schepper ◽  
Raymond Aerts ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Postoperative Ileus ◽  
Intestinal Inflammation ◽  
Electrical Field Stimulation ◽  
Enteric Neurons ◽  
Postoperative Treatment ◽  
Wild Type ◽  
Clinical Recovery ◽  
Preoperative Administration

ObjectivesVagus nerve stimulation (VNS), most likely via enteric neurons, prevents postoperative ileus (POI) by reducing activation of alpha7 nicotinic receptor (α7nAChR) positive muscularis macrophages (mMφ) and dampening surgery-induced intestinal inflammation. Here, we evaluated if 5-HT4 receptor (5-HT4R) agonist prucalopride can mimic this effect in mice and human.DesignUsing Ca2+ imaging, the effect of electrical field stimulation (EFS) and prucalopride was evaluated in situ on mMφ activation evoked by ATP in jejunal muscularis tissue. Next, preoperative and postoperative administration of prucalopride (1–5 mg/kg) was compared with that of preoperative VNS in a model of POI in wild-type and α7nAChR knockout mice. Finally, in a pilot study, patients undergoing a Whipple procedure were preoperatively treated with prucalopride (n=10), abdominal VNS (n=10) or sham/placebo (n=10) to evaluate the effect on intestinal inflammation and clinical recovery of POI.ResultsEFS reduced the ATP-induced Ca2+ response of mMφ, an effect that was dampened by neurotoxins tetrodotoxin and ω-conotoxin and mimicked by prucalopride. In vivo, prucalopride administered before, but not after abdominal surgery reduced intestinal inflammation and prevented POI in wild-type, but not in α7nAChR knockout mice. In humans, preoperative administration of prucalopride, but not of VNS, decreased Il6 and Il8 expression in the muscularis externa and improved clinical recovery.ConclusionEnteric neurons dampen mMφ activation, an effect mimicked by prucalopride. Preoperative, but not postoperative treatment with prucalopride prevents intestinal inflammation and shortens POI in both mice and human, indicating that preoperative administration of 5-HT4R agonists should be further evaluated as a treatment of POI.Trial registration numberNCT02425774.

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