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Aamann L, Ochoa-Sanchez R, Oliveira M, Tremblay M, Bémeur C, Dam G, Vilstrup H, Aagaard NK, Rose CF. Progressive resistance training prevents loss of muscle mass and strength in bile duct-ligated rats. Liver Int 2019; 39:676-683. [PMID: 30394651 DOI: 10.1111/liv.13997] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/04/2018] [Accepted: 10/27/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Loss of muscle mass and strength is common in cirrhosis and increases the risk of hyperammonaemia and hepatic encephalopathy. Resistance training optimizes muscle mass and strength in several chronic diseases. However, the beneficial effects of resistance training in cirrhosis remain to be investigated. Bile duct-ligated (BDL) rats develop chronic liver disease, hyperammonaemia, reduced muscle mass and strength. Our aim was to test the effects of resistance training on muscle mass, function and ammonia metabolism in BDL-rats. METHODS A group of BDL-rats underwent a progressive resistance training programme and a group of non-exercise BDL-rats served as controls. Resistance training comprised of ladder climbing with a progressive increase in carrying weights attached to the tail. Training was performed 5 days a week during 4 weeks. Muscle strength and body composition were assessed using grip strength and EchoMRI. Weight and circumference of the gastrocnemius muscle (normalized to bodyweight), plasma ammonia and glutamine synthetase protein expression and activity were assessed. RESULTS BDL + exercise rats had significantly larger gastrocnemius circumference compared to non-exercise BDL-rats: ratio 0.082 vs 0.075 (P < 0.05). Gastrocnemius muscle weight was higher in exercisers than controls: 0.006 vs 0.005 (P < 0.05). A tendency towards a lower plasma ammonia in the exercise group compared to controls was observed (P = 0.10). There were no differences in lean body mass, GS protein expression and activity between the groups. CONCLUSION Resistance training in rats with chronic liver disease beneficially effects muscle mass and strength. The effects were followed by non-significant reduction in blood ammonia; however, a tendency was observed.
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Affiliation(s)
- Luise Aamann
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Rafael Ochoa-Sanchez
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada
| | - Mariana Oliveira
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada
| | - Mélanie Tremblay
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada
| | - Chantal Bémeur
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada.,Department of Nutrition, Université de Montréal, Montréal, Québec, Canada
| | - Gitte Dam
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Niels Kristian Aagaard
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Québec, Canada
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Lima LCD, Miranda AS, Ferreira RN, Rachid MA, Simões E Silva AC. Hepatic encephalopathy: Lessons from preclinical studies. World J Hepatol 2019; 11:173-185. [PMID: 30820267 PMCID: PMC6393717 DOI: 10.4254/wjh.v11.i2.173] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 11/19/2018] [Accepted: 01/28/2019] [Indexed: 02/06/2023] Open
Abstract
Hepatic encephalopathy (HE) is a major complication that is closely related to the progression of end-stage liver disease. Metabolic changes in advanced liver failure can promote cognition impairment, attention deficits and motor dysfunction that may result in coma and death. HE can be subdivided according to the type of hepatic injury, namely, type A, which results from acute liver failure, type B, which is associated with a portosystemic shunting without intrinsic liver disease, and type C, which is due to chronic liver disease. Several studies have investigated the pathogenesis of the disease, and most of the mechanisms have been explored using animal models. This article aimed to review the use of preclinical models to investigate HE. The most used animal species are rats and mice. Experimental models of type A HE include surgical procedures and the administration of hepatotoxic medications, whereas models of types B and C HE are generally surgically induced lesions in liver tissue, which evolve to hepatic cirrhosis. Preclinical models have allowed the comprehension of the pathways related to HE.
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Affiliation(s)
- Luiza Cioglia Dias Lima
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais 31270-901, Brasil
| | - Aline Silva Miranda
- Departamento de Morfologia, Instituto de Ciências Biológicas, UFMG, Belo Horizonte, Minas Gerais 30130-100, Brasil
| | - Rodrigo Novaes Ferreira
- Departamento de Morfologia, Instituto de Ciências Biológicas, UFMG, Belo Horizonte, Minas Gerais 30130-100, Brasil
| | - Milene Alvarenga Rachid
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais 31270-901, Brasil
| | - Ana Cristina Simões E Silva
- Laboratório Interdisciplinar de Investigação Médica, Faculdade de Medicina, UFMG, Belo Horizonte, Minas Gerais 30130-100, Brasil.
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Abstract
Hepatic encephalopathy describes the array of neurological complications that arise due to liver insufficiency and/or portal-systemic shunt. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation. Recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy due to acute liver failure including neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in hepatic encephalopathy and speculates on the possible downstream consequences of bile acid signaling.
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Key Words
- ASBT, Apical Sodium-Dependent Bile Acid Transporter
- CCL2, Chemokine Ligand 2
- CCR2, Chemokine Receptor 2
- Cyp46A1, Cytochrome p450 46A1
- FXR, Farnesoid X Receptor
- GR, Glucocorticoid Receptor
- NTCP, Sodium Taurocholate Cotransporting Polypeptide
- PXR, Pregnane X Receptor
- S1P2R, Sphingosine 1 Phosphate Receptor 2
- TGR5, Takeda G-Protein Receptor 5
- Takeda G-protein coupled receptor 5 (TGR5)
- VDR, Vitamin D Receptor
- blood–brain barrier
- farnesoid X receptor
- neuroinflammation
- sphingosine-1-phosphate receptor 2
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Dhanda S, Sunkaria A, Halder A, Sandhir R. Mitochondrial dysfunctions contribute to energy deficits in rodent model of hepatic encephalopathy. Metab Brain Dis 2018; 33:209-223. [PMID: 29138968 DOI: 10.1007/s11011-017-0136-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/12/2017] [Indexed: 12/12/2022]
Abstract
Perturbations in the cerebral energy metabolism are anticipated to be an important factor by which ammonia may exert its toxic effects on the central nervous system. The present study was designed to investigate the role of impaired mitochondrial functions and cerebral energy metabolism in the development hepatic encephalopathy (HE) induced by of bile duct ligation (BDL). After four weeks of BDL, a significant increase in hepatic hydroxyproline and collagen content was observed which confirmed biliary fibrosis. Brain regions viz. cortex, hippocampus, striatum and cerebellum of BDL rats had impaired activity of mitochondrial respiratory chain enzymes. This was accompanied by increase in mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl levels in the brain. Mitochondrial redox ratio was significantly reduced in the brain of BDL rats. In addition, mitochondria from brain of BDL rats were depolarized and swollen compared to the sham controls. Ultrastructure analysis of mitochondria from cortex and hippocampus of BDL animals revealed aberrant cristae, ruptured membranes and non-dense matrix. Further, a significant decrease was observed in creatine kinase activity, glucose uptake and CO2 production in the brain regions of BDL rats. ATP/ADP ratio, a critical parameter of cellular energy status, was also significantly reduced in brain regions of rats with HE. Overall, the findings clearly demonstrate that BDL induced HE involves mitochondrial respiratory chain dysfunctions, mitochondrial depolarization and swelling that accentuates oxidative stress which in turn leads to compromise in cerebral energy metabolism thereby contributing to the pathophysiology of chronic HE.
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Affiliation(s)
- Saurabh Dhanda
- Department of Biochemistry, Panjab University, Basic Medical Science Block-II, Sector-25, Chandigarh, 160014, India
| | - Aditya Sunkaria
- Department of Biochemistry, Panjab University, Basic Medical Science Block-II, Sector-25, Chandigarh, 160014, India
| | - Avishek Halder
- Department of Biochemistry, Panjab University, Basic Medical Science Block-II, Sector-25, Chandigarh, 160014, India
| | - Rajat Sandhir
- Department of Biochemistry, Panjab University, Basic Medical Science Block-II, Sector-25, Chandigarh, 160014, India.
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Fabrication and characterization of TiO2-loaded Moringa oleifera gum-activated carbon and the photo-catalytic degradation of phosphate in aqueous solutions. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/s41204-017-0031-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ghiassy B, Rahimi N, Javadi-Paydar M, Gharedaghi MH, Norouzi-Javidan A, Dehpour AR. Nitric oxide mediates effects of acute, not chronic, naltrexone on LPS-induced hepatic encephalopathy in cirrhotic rats. Can J Physiol Pharmacol 2016; 95:16-22. [PMID: 28044452 DOI: 10.1139/cjpp-2016-0188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Recent studies suggest endogenous opioids and nitric oxide (NO) are involved in the pathophysiology of hepatic encephalopathy (HE). In this study, the interaction between the opioid receptor antagonist and NO was investigated on lipopolysaccharide (LPS)-induced HE in cirrhotic rats. Male rats were divided in the sham- and bile duct ligation (BDL)-operated groups. Animals were treated with saline; naltrexone (10 mg/kg, i.p.); or L-NAME (3 mg/kg, i.p.), alone or in combination with naltrexone. To induce HE, LPS (1 mg/kg, i.p.) was injected 1 h after the final drug treatment. HE scoring, hepatic histology, and plasma NO metabolites levels and mortality rate were recorded. Deteriorated level of consciousness and mortality after LPS administration significantly ameliorated following both acute and chronic treatment with naltrexone in cirrhotic rats. However, acute and chronic administration of L-NAME did not change HE scores in cirrhotic rats. The effects of acute but not chronic treatment of naltrexone on HE parameters were reversed by L-NAME. Plasma NOx concentrations elevated in BDL rats, which were decreased after acute and chronic treatment by naltrexone or L-NAME, significantly. We suggest both acute and chronic treatment with naltrexone improved LPS-induced HE. But, only acute treatment with naltrexone may affect through NO pathway.
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Affiliation(s)
- Bentolhoda Ghiassy
- a Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran.,b Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran
| | - Nastaran Rahimi
- a Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran.,c Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran 1417613151, Iran
| | - Mehrak Javadi-Paydar
- c Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran 1417613151, Iran
| | - Mohammad Hadi Gharedaghi
- a Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran.,c Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran 1417613151, Iran
| | - Abbas Norouzi-Javidan
- b Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran
| | - Ahmad R Dehpour
- a Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran 1417613151, Iran.,c Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran 1417613151, Iran
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Leke R, de Oliveira DL, Mussulini BHM, Pereira MS, Kazlauckas V, Mazzini G, Hartmann CR, Silveira TR, Simonsen M, Bak LK, Waagepetersen HS, Keiding S, Schousboe A, Portela LV. Impairment of the organization of locomotor and exploratory behaviors in bile duct-ligated rats. PLoS One 2012; 7:e36322. [PMID: 22586467 PMCID: PMC3346757 DOI: 10.1371/journal.pone.0036322] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 03/30/2012] [Indexed: 12/16/2022] Open
Abstract
Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to several problems, including motor impairment. Animal models of chronic liver disease have extensively investigated the mechanisms of this disease. Impairment of locomotor activity has been described in different rat models. However, these studies are controversial and the majority has primarily analyzed activity parameters. Therefore, the aim of the present study was to evaluate locomotor and exploratory behavior in bile duct-ligated (BDL) rats to explore the spatial and temporal structure of behavior. Adult female Wistar rats underwent common bile duct ligation (BDL rats) or the manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent open-field, plus-maze and foot-fault behavioral tasks. The BDL rats developed chronic liver failure and exhibited a decrease in total distance traveled, increased total immobility time, smaller number of rearings, longer periods in the home base area and decreased percentage of time in the center zone of the arena, when compared to the control rats. Moreover, the performance of the BDL rats was not different from the control rats for the elevated plus-maze and foot-fault tasks. Therefore, the BDL rats demonstrated disturbed spontaneous locomotor and exploratory activities as a consequence of altered spatio-temporal organization of behavior.
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Affiliation(s)
- Renata Leke
- Department of Biochemistry, ICBS, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sol, Brazil.
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Huang HC, Chang CC, Wang SS, Chan CY, Lee FY, Chuang CL, Hsin IF, Teng TH, Lin HC, Lee SD. Pravastatin for thioacetamide-induced hepatic failure and encephalopathy. Eur J Clin Invest 2012; 42:139-45. [PMID: 21749370 DOI: 10.1111/j.1365-2362.2011.02566.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Nitric oxide (NO) inhibition aggravates hepatic damage and encephalopathy and increases mortality in rats with thioacetamide (TAA)-induced acute liver failure. Statins enhance NO production but whether they influence the above parameters are unknown. MATERIAL AND METHODS Male Sprague-Dawley rats were used. In the first series, TAA (350 mg/kg per day, i.p. for 3 days) was administered to induce acute liver failure. Control rats received saline. Rats received distilled water or pravastatin (20 mg/kg per day, p.o.) from 2 days before to 3 days after TAA or saline injection. In the second series, liver cirrhosis was induced by common bile duct ligation (BDL). Sham-operated rats served as controls. Rats received distilled water or pravastatin for 5 or 14 days until the 42nd day after operation. On the last day of treatment, survival, motor activities, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, ammonia and brain histology were evaluated. RESULTS Thioacetamide and BDL rats showed higher ALT, AST, bilirubin and ammonia levels and lower motor activity counts compared with their corresponding control groups. In TAA rats, pravastatin elicited higher total and ambulatory motor activity counts and lower AST and total bilirubin levels. Survival was improved, whereas brain H&E staining was not significantly different in TAA rats with or without pravastatin treatment. In BDL groups, rats with or without pravastatin treatment were not different in motor activity counts and liver biochemistry. CONCLUSIONS Pravastatin ameliorates hepatic encephalopathy and liver biochemistry and improves survival in rats with acute liver failure, but not in those with cirrhosis.
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Affiliation(s)
- Hui-Chun Huang
- Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taiwan
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Ji MK, Park WB, Khan MA, Abou-Shanab RAI, Kim Y, Cho Y, Choi J, Song H, Jeon BH. Nitrate and ammonium ions removal from groundwater by a hybrid system of zero-valent iron combined with adsorbents. ACTA ACUST UNITED AC 2012; 14:1153-8. [DOI: 10.1039/c2em10911e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Ji MK, Ahn YT, Khan MA, Abou-Shanaba RAI, Cho Y, Choi JY, Kim YJ, Song H, Jeon BH. Removal of nitrate and ammonium ions from livestock wastewater by hybrid systems composed of zero-valent iron and adsorbents. ENVIRONMENTAL TECHNOLOGY 2011; 33:1851-1857. [PMID: 22439573 DOI: 10.1080/09593330.2011.565079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The feasibility of hybrid systems for simultaneous removal of nitrate (NO3-) and ammonium ions (NH4+) from livestock wastewater was examined in batch experiments. As a part of efforts to remove nitrate and ammonium simultaneously, Fe0 and adsorbents including coconut-based granular activated carbon (GAC), sepiolite and filtralite were used. Various parameters such as adsorbent dosages and temperature were studied. Removal of NO3- increased with increase in temperature. Maximum NO3- removal (85.3%) was observed for the Fe0-filtralite hybrid system at 45 degrees C for a 24 h reaction time. Increase in GAC and sepiolite dosages had significant (P < 0.01) effect on the NH4+ removal efficiency, which was primarily due to the net negative surface charge of the adsorbents. The efficiency of hybrid systems for the removal of NO3- was in the order of filtralite > sepiolite > GAC, and the order of the removal of NH4+ was GAC > sepiolite > filtralite. The results of the present study suggest that the use of hybrid systems could be a promising innovative technology for achieving simultaneous removal of NO3- and NH4 from livestock wastewater.
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Affiliation(s)
- Min-Kyu Ji
- Department of Environmental Engineering, Yonsei University, Wonju, Gangwon-do, 220-710, South Korea
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Chang CC, Wang SS, Huang HC, Chan CY, Lee FY, Lin HC, Nong JY, Chuang CL, Lee SD. Selective cyclooxygenase inhibition improves hepatic encephalopathy in fulminant hepatic failure of rat. Eur J Pharmacol 2011; 666:226-32. [DOI: 10.1016/j.ejphar.2011.04.060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 04/15/2011] [Accepted: 04/18/2011] [Indexed: 01/01/2023]
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Butterworth RF, Norenberg MD, Felipo V, Ferenci P, Albrecht J, Blei AT. Experimental models of hepatic encephalopathy: ISHEN guidelines. Liver Int 2009; 29:783-8. [PMID: 19638106 DOI: 10.1111/j.1478-3231.2009.02034.x] [Citation(s) in RCA: 228] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Objectives of the International Society for Hepatic Encephalopathy and Nitrogen Metabolism Commission were to identify well-characterized animal models of hepatic encephalopathy (HE) and to highlight areas of animal modelling of the disorder that are in need of development. Features essential to HE modelling were identified. The best-characterized animal models of HE in acute liver failure, the so-called Type A HE, were found to be the hepatic devascularized rat and the rat with thioacetamide-induced toxic liver injury. In case of chronic liver failure, surgical models in the rat involving end-to-side portacaval anastomosis or bile duct ligation were considered to best model minimal/mild (Type B) HE. Unfortunately, at this time, there are no satisfactory animal models of Type C HE resulting from end-stage alcoholic liver disease or viral hepatitis, the most common aetiologies encountered in patients. The commission highlighted the urgent need for such models and of improved models of HE in chronic liver failure in general as well as a need for models of post-transplant neuropsychiatric disorders. Studies of HE pathophysiology at the cellular and molecular level continue to benefit from in vitro and or ex vivo models involving brain slices or exposure of cultured cells (principally cultured astrocytes) to toxins such as ammonia, manganese and pro-inflammatory cytokines. More attention could be paid in the future to in vitro models involving the neurovascular unit, microglia and neuronal co-cultures in relation to HE pathogenesis.
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Affiliation(s)
- Roger F Butterworth
- Neuroscience Research Unit, St-Luc Hospital (CHUM), University of Montreal, Montreal, QC, Canada.
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García-Ayllón MS, Cauli O, Silveyra MX, Rodrigo R, Candela A, Compañ A, Jover R, Pérez-Mateo M, Martínez S, Felipo V, Sáez-Valero J. Brain cholinergic impairment in liver failure. Brain 2008; 131:2946-56. [PMID: 18772221 PMCID: PMC2577805 DOI: 10.1093/brain/awn209] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The cholinergic system is involved in specific behavioural responses and cognitive processes. Here, we examined potential alterations in the brain levels of key cholinergic enzymes in cirrhotic patients and animal models with liver failure. An increase (∼30%) in the activity of the acetylcholine-hydrolyzing enzyme, acetylcholinesterase (AChE) is observed in the brain cortex from patients deceased from hepatic coma, while the activity of the acetylcholine-synthesizing enzyme, choline acetyltransferase, remains unaffected. In agreement with the human data, AChE activity in brain cortical extracts of bile duct ligated (BDL) rats was increased (∼20%) compared to controls. A hyperammonemic diet did not result in any further increase of AChE levels in the BDL model, and no change was observed in hyperammonemic diet rats without liver disease. Portacaval shunted rats which display increased levels of cerebral ammonia did not show any brain cholinergic abnormalities, confirming that high ammonia levels do not play a role in brain AChE changes. A selective increase of tetrameric AChE, the major AChE species involved in hydrolysis of acetylcholine in the brain, was detected in both cirrhotic humans and BDL rats. Histological examination of BDL and non-ligated rat brains shows that the subcellular localization of both AChE and choline acetyltransferase, and thus the accessibility to their substrates, appears unaltered by the pathological condition. The BDL-induced increase in AChE activity was not parallelled by an increase in mRNA levels. Increased AChE in BDL cirrhotic rats leads to a pronounced decrease (∼50–60%) in the levels of acetylcholine. Finally, we demonstrate that the AChE inhibitor rivastigmine is able to improve memory deficits in BDL rats. One week treatment with rivastigmine (0.6 mg/kg; once a day, orally, for a week) resulted in a 25% of inhibition in the enzymatic activity of AChE with no change in protein composition, as assessed by sucrose density gradient fractionation and western blotting analysis. In conclusion, this study is the first direct evidence of a cholinergic imbalance in the brain as a consequence of liver failure and points to the possible role of the cholinergic system in the pathogenesis of hepatic encephalopathy.
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Affiliation(s)
- María-Salud García-Ayllón
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, San Juan de Alicante, Spain
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Chang CC, Chen YC, Huang HC, Lee FY, Chang FY, Lin HC, Chan CY, Wang SS, Lee SD. Methimazole alleviates hepatic encephalopathy in bile-duct ligated cirrhotic rats. J Chin Med Assoc 2006; 69:563-8. [PMID: 17182349 DOI: 10.1016/s1726-4901(09)70330-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Acute or chronic liver damage may lead to hepatic encephalopathy. Previous studies have indicated the hemodynamic and hormonal mimicry between portal hypertension and hyperthyroidism. Furthermore, medically or surgically induced hypothyroidism has been found to be beneficial in ameliorating hyperdynamic circulation in the portal hypertensive state and in alleviating acute or chronic liver injury in rats. However, the effect of chronic thyroid hormone inhibition on chronic hepatic encephalopathy in cirrhosis remains unknown. METHODS Liver cirrhosis was induced by bile-duct ligation (BDL) in male Sprague-Dawley rats. Three weeks after BDL, rats were randomized to receive either tap water (control) or 0.04% methimazole in drinking water for 3 weeks. At the end of 6 weeks after BDL, severity of encephalopathy was assessed by the Opto-Varimex animal activity meter and hemodynamic parameters were measured. Blood samples were collected for determination of thyroid stimulating hormone, ammonia and liver biochemistry. RESULTS The heart rate of the methimazole-treated group was significantly lower than that of the control group (p = 0.015), whereas there were no differences in the mean arterial pressure and portal pressure. The total amount of movements were significantly increased in the methimazole group (p = 0.029). Plasma levels of ammonia, aspartate aminotransferase and alkaline phosphatase were significantly lower (p = 0.01) and thyroid stimulating hormone significantly higher (p = 0.035) in the methimazole group. CONCLUSION Chronic methimazole treatment alleviates hepatic encephalopathy and liver damage in rats with BDL-induced hepatic cirrhosis.
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Chan CY, Lee FY, Wang TF, Huang SW, Chang FY, Lu RH, Chen YC, Wang SS, Huang HC, Lee SD. Lack of detrimental or therapeutic effects of cyclooxygenase inhibition in bile duct-ligated rats with hepatic encephalopathy. J Gastroenterol Hepatol 2006; 21:1483-7. [PMID: 16911697 DOI: 10.1111/j.1440-1746.2006.04261.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND The pathogenetic mechanisms of hepatic encephalopathy (HE) are not fully understood. Cerebral blood flow regulated by cyclooxygenase (COX) may be involved in the development of HE. There are no comprehensive data concerning the effects of COX inhibition on HE in chronic liver disease. METHODS Male Sprague-Dawley rats weighing 240-270 g at the time of surgery were selected for experiments. Secondary biliary cirrhosis was induced by bile duct ligation (BDL). Those rats were then divided into two groups to receive i.p. injection of indomethacin (5 mg/kg per day) or distilled water for 7 days from day 36 to day 42 after BDL. The control group consisted of rats receiving a sham operation. Severity of encephalopathy was assessed by counts of motor activity. Plasma levels of tumor necrosis factor (TNF)-alpha and 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)), and liver biochemistry tests were determined after treatment. RESULTS The motor activity in both groups of BDL rats were significantly lower than that of the control group (P < 0.001). As compared with the BDL rats treated with distilled water, BDL rats treated with indomethacin had significant lower levels of 6-keto-PGF(1alpha), but the motor activity, TNF-alpha levels and serum biochemistry tests were not significantly different between both BDL groups. CONCLUSIONS Chronic indomethacin administration did not have significantly detrimental or therapeutic effects on the severity of encephalopathy in BDL rats.
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Affiliation(s)
- Cho-Yu Chan
- Division of Gastroenterology, Taipei Veterans General Hospital, Taipei, Taiwan.
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Jover R, Madaria E, Felipo V, Rodrigo R, Candela A, Compañ A. Animal models in the study of episodic hepatic encephalopathy in cirrhosis. Metab Brain Dis 2005; 20:399-408. [PMID: 16382350 DOI: 10.1007/s11011-005-7925-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The availability of an animal model is crucial in studying the pathophysiological mechanisms of disease and to test possible therapies. Now, there are several models for the study of liver diseases, but there still remains a lack of a satisfactory animal model of chronic liver disease with hepatic encephalopathy (HE) and abnormalities in nitrogen metabolism, as seen in humans. In rats, two models of chronic HE are widely used: rats after portacaval anastomosis (PCA) and rats with chronic hyperammonemia. The first one mimics the situation induced in cirrhosis by collateral circulation, and has the problem of the absence of hepatocellular injury. The model of hyperammonemia is useful to study the effect of ammonia as a brain toxic substance, but also lacks liver failure. Bile-duct ligation has been used to induce cirrhosis and could also be a model of HE, probably with the addition of a precipitant factor. An ideal model of HE in chronic liver disease must have liver cirrhosis and a precipitant factor of HE; it must also show neuropathological characteristic findings of HE, neurochemical alterations in the main pathways impaired in these complications of cirrhosis, and low-grade brain edema.
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Affiliation(s)
- Rodrigo Jover
- Gastroenterology Department, Hospital General Universitario de Alicante, Alicante, Spain
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