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Okkay U, Ferah Okkay I, Cicek B, Aydin IC, Ozkaraca M. Hepatoprotective and neuroprotective effect of taxifolin on hepatic encephalopathy in rats. Metab Brain Dis 2022; 37:1541-1556. [PMID: 35298730 DOI: 10.1007/s11011-022-00952-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/08/2022] [Indexed: 10/18/2022]
Abstract
This study was planned to assess the potential protective effects of taxifolin against thioacetamide-induced hepatic encephalopathy and subsequently to portray its behavioural results. The experimental model was induced with three doses of (200 mg/kg i.p.) thioacetamide and taxifolin (50 and 100 mg/kg, p.o.) was administered for fourteen days. Taxifolin effectively attenuated hepatic encephalopathy through decrease in AST, ALT, ALP and LDH concentrations and improvement of hyperammonemia, and increase in antioxidant capacity by decreasing MDA, ROS, and increasing CAT and GSH. In addition, the expressions of NF-κB, TNF-α, IL-1β, caspase-3 and Bax was down-regulated while IL-10 and Bcl-2 expressions were up-regulated with taxifolin treatment. The recovery was confirmed by downregulation of iNOS and 8-OHdG expressions in our immunohistochemical analysis. Taxifolin treatment reduced the disrupting role of thioacetamide as seen by corrected hyperammonemia as well as preservation of astrocyte and hepatocyte structure. Elevated plus maze and locomotor activity tests also proved that taxifolin might repeal the neurobehavioral disabilities. In conclusion, taxifolin has shown hepatoprotective and neuroprotective roles with antioxidant and anti-inflammatory effects, as well as suppressing the excessive release of ammonia, and it eventually reversed neurobehavioral impairments.
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Affiliation(s)
- Ufuk Okkay
- Medical Pharmacology Department, Faculty of Medicine, Ataturk University, 25100, Erzurum, Turkey.
| | - Irmak Ferah Okkay
- Pharmacology Department, Faculty of Pharmacy, Ataturk University, Erzurum, Turkey
| | - Betul Cicek
- Physiology Department, Faculty of Medicine, Erzincan Binali Yildirim University, Erzincan, Turkey
| | - Ismail Cagri Aydin
- Pharmacology Department, Faculty of Pharmacy, Erzincan Binali Yildirim University, Erzincan, Turkey
| | - Mustafa Ozkaraca
- Pathology Department, Faculty of Veterinary Medicine, Sivas Cumhuriyet University, Sivas, Turkey
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Ferah Okkay I, Okkay U, Gundogdu OL, Bayram C, Mendil AS, Ertugrul MS, Hacimuftuoglu A. Syringic acid protects against thioacetamide-induced hepatic encephalopathy: Behavioral, biochemical, and molecular evidence. Neurosci Lett 2021; 769:136385. [PMID: 34871743 DOI: 10.1016/j.neulet.2021.136385] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
The objective of this study was to elucidate the effects of syringic acid on thioacetamide-induced hepatic encephalopathy which is a complex serious syndrome with neuropsychiatric abnormalities related to acute liver dysfunctions like cirrhosis. Rats were treated with syringic acid (50 and 100 mg/kg, p.o.) for 14 days in treatment groups. Hepatic encephalopathy was induced by three doses of (200 mg/kg i.p.) thioacetamide injection. Syringic acid effectively alleviated thioacetamide-induced hepatic injury via reduction in ammonia, AST, ALT, ALP, LDH and decrease in oxidative stress (decreased MDA, ROS and increased SOD and GSH). Syringic acid also attenuated inflammatory injury by suppressing TNF-α, IL-1β, and NF-κB and increasing IL-10. The caspase-3 expression was also down-regulated in both liver and brain tissues. Immunohistochemical results confirmed the recovery with syringic acid by downregulation of iNOS, 8-OHdG and GFAP expression. Syringic acid decreased the deteriorating effects of thioacetamide as seen by reduced ammonia concentration and also preserved astrocyte and hepatocyte structure. The behavioral test results from elevated plus maze test, similar to the open-field locomotor test results, confirmed that syringic acid can reverse behavioral impairments. In conclusion, syringic acid exerted hepatoprotective and neuroprotective effects against hepatic encephalopathy by mitigating hepatotoxicity biomarkers, exerting antioxidant, anti-inflammatory effects in addition to suppressing hyperammonemia.
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Affiliation(s)
- Irmak Ferah Okkay
- Department of Pharmacology, Faculty of Pharmacy, Ataturk University, Turkey.
| | - Ufuk Okkay
- Department of Medical Pharmacology, Faculty of Medicine, Ataturk University, Turkey
| | - Omer Lutfi Gundogdu
- Department of Neurology, Faculty of Medicine, Recep Tayyip Erdogan University, Turkey
| | - Cemil Bayram
- Department of Medical Pharmacology, Faculty of Medicine, Ataturk University, Turkey
| | - Ali Sefa Mendil
- Department of Pathology, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | | | - Ahmet Hacimuftuoglu
- Department of Medical Pharmacology, Faculty of Medicine, Ataturk University, Turkey
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Hajipour S, Farbood Y, Dianat M, Rashno M, Khorsandi LS, Sarkaki A. Thymoquinone improves cognitive and hippocampal long-term potentiation deficits due to hepatic encephalopathy in rats. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2021; 24:881-891. [PMID: 34712417 PMCID: PMC8528250 DOI: 10.22038/ijbms.2021.52824.11913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 06/22/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that causes brain disturbances. Thymoquinone (TQ) has a wide spectrum of activities such as antioxidant, anti-inflammatory, and anticancer. This study aimed to evaluate the effects of TQ on spatial memory and hippocampal long-term potentiation (LTP) in rats with thioacetamide (TAA)-induced liver injury and hepatic encephalopathy. MATERIALS AND METHODS Adult male Wistar rats were divided into six groups randomly: 1) Control; 2) HE, received TAA (200 mg/kg); 3-5) Treated groups (HE+TQ5, HE+TQ10, and HE+TQ20). TQ (5, 10, and 20 mg/kg) was injected intraperitoneally (IP) for 12 consecutive days from day 18 to 29. Subsequently, spatial memory performance was evaluated by the Morris water maze paradigm and hippocampal LTP was recorded from the dentate gyrus (DG) region. Activity levels of Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in the hippocampal tissue. RESULTS Data showed that the hippocampal content of MDA was increased while SOD activities were decreased in TAA-induced HE. TQ treatment significantly improved spatial memory and LTP. Moreover, TQ restored the levels of MDA and SOD activities in the hippocampal tissue in HE rats. CONCLUSION Our data confirm that TQ could attenuate cognitive impairment and improve LTP deficit by modulating the oxidative stress parameters in this model of HE, which leads to impairment of spatial cognition and LTP deficit. Thus, these results suggest that TQ may be a promising agent with positive therapeutic effects against liver failure and HE defects.
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Affiliation(s)
- Somayeh Hajipour
- Persian Gulf Physiology Research Center. Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Yaghoob Farbood
- Persian Gulf Physiology Research Center. Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mahin Dianat
- Persian Gulf Physiology Research Center. Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohammad Rashno
- Department of Immunology, Cellular & Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of
| | | | - Alireza Sarkaki
- Persian Gulf Physiology Research Center. Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Anatomical Sciences, Cellular & Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University
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Heeba GH, El-Deen RM, Abdel-Latif RG, Khalifa MMA. Combined treatments with metformin and phosphodiesterase inhibitors alleviate nonalcoholic fatty liver disease in high-fat diet fed rats: a comparative study. Can J Physiol Pharmacol 2020; 98:498-505. [PMID: 32083947 DOI: 10.1139/cjpp-2019-0487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is an excessive accumulation of fats in the liver resulting in hepatic inflammation and fibrous tissue formation along with insulin resistance. This study was designed to investigate the possible protective effects of metformin alone and in combination with different phosphodiesterase inhibitors (PDEIs). Rats were fed a high-fat diet (HFD) for 16 weeks to induce NAFLD. Starting from week 12, rats received metformin alone or in combination with pentoxifylline, cilostazol, or sildenafil. HFD administration resulted in hepatic steatosis and inflammation in rats. In addition, liver index, body composition index, activities of liver enzymes, and serum lipids deviated from normal. Further, significant elevations were recorded compared to control in terms of serum glucose, insulin, and HOMA-IR (homeostasis model assessment index for insulin resistance), oxidative stress parameters, hepatic TNF-α and NF-κB gene expression, and iNOS protein expression. Rats treated with metformin showed a significant improvement in the aforementioned parameters. However, the addition of pentoxifylline to metformin treatment synergized its action and produced a fortified effect against HFD-induced NAFLD better than other PDEIs. Data from this study indicated that combined treatment of metformin and pentoxifylline had the most remarkable ameliorated effects against HFD-induced NAFLD; further clinical investigations are needed to approve PDEIs for NAFLD treatment.
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Affiliation(s)
- Gehan H Heeba
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, El-Minia 61111, Egypt
| | - Reham M El-Deen
- Ministry of Health and Population, Undersecretary preventive sector, General administration viral hepatitis, Cairo, Egypt
| | - Rania G Abdel-Latif
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, El-Minia 61111, Egypt
| | - Mohamed M A Khalifa
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Minia University, El-Minia 61111, Egypt
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França MER, Ramos RKLG, Oliveira WH, Duarte-Silva E, Araújo SMR, Lós DB, Peixoto CA. Tadalafil restores long-term memory and synaptic plasticity in mice with hepatic encephalopathy. Toxicol Appl Pharmacol 2019; 379:114673. [PMID: 31323263 DOI: 10.1016/j.taap.2019.114673] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/10/2019] [Accepted: 07/15/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIM Tadalafil displays important neuroprotective effects in experimental models of neurodegenerative diseases, however its mechanisms of action remain poorly understood. The aim of the present study was to investigate the action of Tadalafil on learning and memory, neuroinflammation, glial cell activation and neuroprotection in the experimental model of hepatic encephalopathy (HE) induced by Thioacetamide (TAA) in mice. METHODS Mice received intraperitoneal injections of TAA, for 3 consecutive days, reaching the final dose of 600 mg/kg. Tadalafil 15 mg/kg body weight was administered by gavage during 15 days after TAA induction. Mice underwent a Barnes maze for learning and memory evaluation. RESULTS Animals with hepatic encephalopathy showed reduced learning and spatial memory in the Barnes Maze, presented astrocyte and microglia activation and increased neuroinflammatory markers such as TNF-α, IL-1β, IL-6, p-p38, p-ERK and p-NF-kB. In addition, the signaling pathway PKA/PKG/CREB/BDNF/NeuN/synaptophysin and glutamate receptors were deregulated by TAA. Tadalafil treatment regulated the inflammation signaling pathways restoring learning and spatial memory. CONCLUSION Tadalafil significantly reduced neuroinflammation, promoted neuroprotection and plasticity, regulated the expression of hippocampal glutamate receptor and restored spatial learning ability and memory.
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Affiliation(s)
- Maria Eduarda Rocha França
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Postgraduate Program in Biological Sciences (PPGCB), Federal University of Pernambuco Recife, Pernambuco, Brazil.
| | | | - Wilma Helena Oliveira
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Postgraduate Program in Biological Sciences (PPGCB), Federal University of Pernambuco Recife, Pernambuco, Brazil
| | - Eduardo Duarte-Silva
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Postgraduate Program in Biosciences and Biotechnology for Health (PPGBBS), Oswaldo Cruz Foundation (FIOCRUZ-PE)/ Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil
| | - Shyrlene Meyre Rocha Araújo
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Postgraduate Program in Biological Sciences (PPGCB), Federal University of Pernambuco Recife, Pernambuco, Brazil
| | - Deniele Bezerra Lós
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Institute of Science and Technology on Neuroimmunomodulation (INCT-NIM), Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Christina Alves Peixoto
- Laboratory of Ultrastructure, Aggeu Magalhães Institute (IAM), Recife, Pernambuco, Brazil; Institute of Science and Technology on Neuroimmunomodulation (INCT-NIM), Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
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Patel VC, White H, Støy S, Bajaj JS, Shawcross DL. Clinical science workshop: targeting the gut-liver-brain axis. Metab Brain Dis 2016; 31:1327-1337. [PMID: 26446022 DOI: 10.1007/s11011-015-9743-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 10/02/2015] [Indexed: 02/08/2023]
Abstract
A clinical science workshop was held at the ISHEN meeting in London on Friday 11th September 2014 with the aim of thrashing out how we might translate what we know about the central role of the gut-liver-brain axis into targets which we can use in the treatment of hepatic encephalopathy (HE). This review summarises the integral role that inter-organ ammonia metabolism plays in the pathogenesis of HE with specific discussion of the roles that the small and large intestine, liver, brain, kidney and muscle assume in ammonia and glutamine metabolism. Most recently, the salivary and gut microbiome have been shown to underpin the pathophysiological changes which culminate in HE and patients with advanced cirrhosis present with enteric dysbiosis with small bowel bacterial overgrowth and translocation of bacteria and their products across a leaky gut epithelial barrier. Resident macrophages within the liver are able to sense bacterial degradation products initiating a pro-inflammatory response within the hepatic parenchyma and release of cytokines such as tumour necrosis factor alpha (TNF-α) and interleukin-8 into the systemic circulation. The endotoxemia and systemic inflammatory response that are generated predispose both to the development of infection as well as the manifestation of covert and overt HE. Co-morbidities such as diabetes and insulin resistance, which commonly accompany cirrhosis, may promote slow gut transit, promote bacterial overgrowth and increase glutaminase activity and may need to be acknowledged in HE risk stratification assessments and therapeutic regimens. Therapies are discussed which target ammonia production, utilisation or excretion at an individual organ level, or which reduce systemic inflammation and endotoxemia which are known to exacerbate the cerebral effects of ammonia in HE. The ideal therapeutic strategy would be to use an agent that can reduce hyperammonemia and reduce systemic inflammation or perhaps to adopt a combination of therapies that can address both.
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Affiliation(s)
- Vishal C Patel
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Helen White
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Sidsel Støy
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Jasmohan S Bajaj
- McGuire VA Medical Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Debbie L Shawcross
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK.
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Kanimozhi S, Subramanian P, Shanmugapriya S, Sathishkumar S. Role of Bioflavonoid Quercetin on Expression of Urea Cycle Enzymes, Astrocytic and Inflammatory Markers in Hyperammonemic Rats. Indian J Clin Biochem 2016; 32:68-73. [PMID: 28149015 DOI: 10.1007/s12291-016-0575-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/28/2016] [Indexed: 12/01/2022]
Abstract
This study evaluates the role of quercetin on the expression of urea cycle enzymes, astrocytic, neuronal and inflammatory markers in hyperammonemic rats. Hyperammonemia (provoked by intraperitonial injections of (ammonium chloride-100 mg/kg b.w for 56 days), showed diminished expression of urea cycle enzymes [carbamyl phosphate synthetase-1 (CPS-1), ornithine transcarbamylase (OTC), argininosuccinate synthetase (ASS) and arginase (ARG)] in liver and decreased expression of neuronal and astrocytic markers-glutamine synthase (GS) and phosphate activated glutaminase (PAG) in brain and increased expression of brain inflammatory markers such as interleukin 6 (IL6), inducible nitric oxide synthase (iNOS) and nuclear transcription factor kappa B (NF-κB) (by western blot analysis) and exhibited downregulated expression of soluble guanylate cyclase (sGC), glial fibrillary acidic protein (GFAP) in brain and ASS in liver investigated (by RT-PCR). Oral treatment of quercetin (50 mg/kg b.w) to hyperammonemic rats (1) increased the expression of urea cycle enzymes (CPS-1, OTC, ASS and ARG), neuronal and astrocytic markers (GS and PAG) (2) decreased the expression of IL6, iNOS and NF-κB and (3) upregulated mRNA expression of SGC, GFAP and ASS. Our results specify that quercetin's antihyperammonemic effects could be through its, anti-inflammatory, neuroprotective and hepatoprotective effects.
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Affiliation(s)
- Sivamani Kanimozhi
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu 608 002 India
| | - Perumal Subramanian
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu 608 002 India
| | - Sakkaravarthy Shanmugapriya
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu 608 002 India
| | - Subramanian Sathishkumar
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Chidambaram, Tamil Nadu 608 002 India
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Umar T, Hoda N. Selective inhibitors of phosphodiesterases: therapeutic promise for neurodegenerative disorders. MEDCHEMCOMM 2015. [DOI: 10.1039/c5md00419e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PDE inhibitors: significant contributors to the treatment of neurodegenerative diseases.
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Affiliation(s)
- Tarana Umar
- Department of Chemistry
- Jamia Millia Islamia
- Central University
- New Delhi
- 110025 India
| | - Nasimul Hoda
- Department of Chemistry
- Jamia Millia Islamia
- Central University
- New Delhi
- 110025 India
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9
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Sturgeon JP, Shawcross DL. Recent insights into the pathogenesis of hepatic encephalopathy and treatments. Expert Rev Gastroenterol Hepatol 2014; 8:83-100. [PMID: 24236755 DOI: 10.1586/17474124.2014.858598] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) encompasses a spectrum of neuropsychiatric disorders related to liver failure. The development of HE can have a profound impact on mortality as well as quality of life for patients and carers. Ammonia is central in the disease process contributing to alteration in neurotransmission, oxidative stress, and cerebral edema and astrocyte swelling in acute liver failure. Inflammation in the presence of ammonia coactively worsens HE. Inflammation can result from hyperammonemic responses, endotoxemia, innate immune dysfunction or concurrent infection. This review summarizes the current processes implicated in the pathogenesis of HE, as well as current and potential treatments. Treatments currently focus on reducing inflammation and/or blood ammonia levels and provide varying degrees of success. Optimization of current treatments and initial testing of novel therapies will provide the basis of improvement of care in the near future.
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Affiliation(s)
- Jonathan P Sturgeon
- Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, Denmark Hill, London, SE5 9RS, UK
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Nitric oxide mediates the beneficial effect of chronic naltrexone on cholestasis-induced memory impairment in male rats. Behav Pharmacol 2013; 24:195-206. [PMID: 23591123 DOI: 10.1097/fbp.0b013e3283618a8c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent studies suggest an augmentation of endogenous opioids following bile duct ligation (BDL) and their pivotal role in the pathophysiology of cholestasis. In this study, the effect of naltrexone, an opioid receptor antagonist, was determined on cholestasis-induced memory impairment and the possible involvement of nitric oxide (NO) in this effect. Male Albino-Wistar rats were randomized to sham-operated and BDL-operated groups. In each group, animals were treated for up to 28 days with saline; naltrexone (10 mg/kg); naltrexone and N(G)-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) inhibitor (3, 10 mg/kg); naltrexone and aminoguanidine, an inducible NOS inhibitor (100 mg/kg); or methylnaltrexone, a peripherally acting opioid receptor antagonist (3 mg/kg, intraperitoneal). Spatial recognition memory was determined in a Y-maze task on the day before surgery and days 7, 14, 21, and 28 after surgery. Memory performance was impaired 14 days after BDL in cholestatic rats and was significantly reversed by chronic treatment with naltrexone at days 14, 21, and 28 after BDL. On day 21 after BDL, chronic L-NAME produced only a nonsignificant decrease in the beneficial effect of naltrexone, whereas on day 28, chronic administration of both L-NAME and aminoguanidine significantly reversed this effect of naltrexone. It is therefore shown in this study that naltrexone improves BDL-induced memory deficit in rats. We conclude that the memory impairment in cholestatic rats might be because of an increase in the level of endogenous opioids and that naltrexone improved the spatial recognition memory by antagonizing opioid receptors. The observation that the procognitive effect of naltrexone is counteracted either by general inhibition of NOS enzymes or by selective inhibition of inducible NOS suggests the nitrergic pathway as a probable mechanism involved in the amelioration of spatial recognition memory by naltrexone in BDL rats.
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Uthayathas S, Parameshwaran K, Karuppagounder SS, Ahuja M, Dhanasekaran M, Suppiramaniam V. Selective inhibition of phosphodiesterase 5 enhances glutamatergic synaptic plasticity and memory in mice. Synapse 2013; 67:741-7. [PMID: 23620198 DOI: 10.1002/syn.21676] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Accepted: 04/11/2013] [Indexed: 01/06/2023]
Abstract
Phosphodiesterases (PDEs) belong to a family of proteins that control metabolism of cyclic nucleotides. Targeting PDE5, for enhancing cellular function, is one of the therapeutic strategies for male erectile dysfunction. We have investigated whether in vivo inhibition of PDE5, which is expressed in several brain regions, will enhance memory and synaptic transmission in the hippocampus of healthy mice. We have found that acute administration of sildenafil, a specific PDE5 inhibitor, enhanced hippocampus-dependent memory tasks. To elucidate the underlying mechanism in the memory enhancement, effects of sildenafil on long-term potentiation (LTP) were measured. The level of LTP was significantly elevated, with concomitant increases in basal synaptic transmission, in mice treated with sildenafil (1 mg/kg/day) for 15 days compared to control mice. These results suggest that moderate PDE5 inhibition enhances memory by increasing synaptic plasticity and transmission in the hippocampus.
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Affiliation(s)
- Subramaniam Uthayathas
- Department of Pharmacal Sciences, Harrison School of Pharmacy, Auburn University, Auburn, Alabama; Department of Pharmacology, Howard University College of Medicine, Washington, DC
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Häussinger D, Sies H. Hepatic encephalopathy: clinical aspects and pathogenetic concept. Arch Biochem Biophys 2013; 536:97-100. [PMID: 23643660 DOI: 10.1016/j.abb.2013.04.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Wen S, Schroeter A, Klöcker N. Synaptic plasticity in hepatic encephalopathy - a molecular perspective. Arch Biochem Biophys 2013; 536:183-8. [PMID: 23624147 DOI: 10.1016/j.abb.2013.04.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/13/2013] [Accepted: 04/15/2013] [Indexed: 01/04/2023]
Abstract
Hepatic encephalopathy (HE)(1) is a common neuropsychiatric complication of both acute and chronic liver disease. Clinical symptoms may include motor disturbances and cognitive dysfunction. Available animal models of HE mimic the deficits in cognitive performance including the impaired ability to learn and memorize information. This review explores the question how HE might affect cognitive functions at molecular levels. Both acute and chronic models of HE constrain the plasticity of glutamatergic neurotransmission. Thus, long-lasting activity-dependent changes in synaptic efficiency, known as long-term potentiation (LTP) and long-term depression (LTD) are significantly impeded. We discuss molecules and signal transduction pathways of LTP and LTD that are targeted by experimental HE, with a focus on ionotropic glutamate receptors of the AMPA-subtype. Finally, a novel strategy of functional proteomic analysis is presented, which, if applied differentially, may provide molecular insight into disease-related dysfunction of membrane protein complexes, i.e. disturbed ionotropic glutamate receptor signaling in HE.
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Affiliation(s)
- Shuping Wen
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf D-40225 Düsseldorf, Germany
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Huang LT, Chen CC, Sheen JM, Chen YJ, Hsieh CS, Tain YL. The interaction between high ammonia diet and bile duct ligation in developing rats: assessment by spatial memory and asymmetric dimethylarginine. Int J Dev Neurosci 2009; 28:169-74. [PMID: 19941949 DOI: 10.1016/j.ijdevneu.2009.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 09/22/2009] [Accepted: 11/18/2009] [Indexed: 11/26/2022] Open
Abstract
Bile duct ligation (BDL) in developing rats causes cholestasis, impaired liver function and cognition. Because both nitric oxide (NO) and ammonia are implicated in hepatic encephalopathy (HE), we hypothesized that asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor, and ammonia affect cognition in young rats with BDL. Four groups of young male Sprague-Dawley rats ages 17 days were used: rat underwent laparotomy (SC group), rat underwent laparotomy plus a 30% ammonium acetate diet (SC+HA group), rat underwent BDL (BDL group), rats underwent BDL plus high ammonia diet (BDL+HA group). Spatial memory was assessed by Morris water maze task. Plasma was collected for biochemical and ADMA analyses. Liver and brain cortex were collected for determination of protein arginine methyltransferase-1 (PRMT1, ADMA-synthesizing enzyme) and dimethylarginine dimethylaminohydrolase (DDAH, ADMA-metabolizing enzyme). We found BDL group had significantly higher plasma direct/total bilirubin, aspartate aminotransferase, alanine aminotransferase, ADMA, liver p22(phox), and worse spatial performance as compared with SC group. High ammonia diet increased plasma ammonia and ADMA concentration, and aggravated spatial deficit in the presence of BDL-induced cholestasis. We conclude plasma ADMA plays a role in BDL-induced spatial deficit. High ammonia aggravated the spatial deficits encountered in cholestatic young rats.
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Affiliation(s)
- Li-Tung Huang
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
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Selective phosphodiesterase inhibitors: a promising target for cognition enhancement. Psychopharmacology (Berl) 2009; 202:419-43. [PMID: 18709359 PMCID: PMC2704616 DOI: 10.1007/s00213-008-1273-x] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 07/23/2008] [Indexed: 12/15/2022]
Abstract
RATIONALE One of the major complaints most people face during aging is an impairment in cognitive functioning. This has a negative impact on the quality of daily life and is even more prominent in patients suffering from neurodegenerative and psychiatric disorders including Alzheimer's disease, schizophrenia, and depression. So far, the majority of cognition enhancers are generally targeting one particular neurotransmitter system. However, recently phosphodiesterases (PDEs) have gained increased attention as a potential new target for cognition enhancement. Inhibition of PDEs increases the intracellular availability of the second messengers cGMP and/or cAMP. OBJECTIVE The aim of this review was to provide an overview of the effects of phosphodiesterase inhibitors (PDE-Is) on cognition, the possible underlying mechanisms, and the relationship to current theories about memory formation. MATERIALS AND METHODS Studies of the effects of inhibitors of different PDE families (2, 4, 5, 9, and 10) on cognition were reviewed. In addition, studies related to PDE-Is and blood flow, emotional arousal, and long-term potentiation (LTP) were described. RESULTS PDE-Is have a positive effect on several aspects of cognition, including information processing, attention, memory, and executive functioning. At present, these data are likely to be explained in terms of an LTP-related mechanism of action. CONCLUSION PDE-Is are a promising target for cognition enhancement; the most suitable candidates appear to be PDE2-Is or PDE9-Is. The future for PDE-Is as cognition enhancers lies in the development of isoform-specific PDE-Is that have limited aversive side effects.
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Cropp CD, Komori T, Shima JE, Urban TJ, Yee SW, More SS, Giacomini KM. Organic anion transporter 2 (SLC22A7) is a facilitative transporter of cGMP. Mol Pharmacol 2008; 73:1151-8. [PMID: 18216183 PMCID: PMC2698938 DOI: 10.1124/mol.107.043117] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The second messenger, cGMP, mediates a host of cellular responses to various stimuli, resulting in the regulation of many critical physiologic functions. The existence of specific cGMP transporters on the plasma membrane that participate in the regulation of cGMP levels has been suggested in a large number of studies. In this study, we identified a novel plasma membrane transporter for cGMP. In particular, we showed that hOAT2 (SLC22A7), a member of the solute carrier (SLC) superfamily, was a facilitative transporter for cGMP and other guanine nucleotides. hOAT2, which is ubiquitously expressed at high levels in many cell types, was previously thought to primarily transport organic anions. Among purine and pyrimidine nucleobases, nucleosides, and nucleotides, hOAT2 showed the greatest preference for cGMP, which transported cGMP with a K(m) value of 88 +/- 11 muM and exhibited between 50- and 100-fold enhanced uptake over control cells. Our data revealed that hOAT2 is a bidirectional facilitative transporter that can control both intracellular and extracellular levels of cGMP. In addition, we observed that a common alternatively spliced variant of hOAT2 demonstrated a complete loss of transport function as a result of a low expression level on the plasma membrane. We conclude that hOAT2 is a highly efficient, facilitative transporter of cGMP and may be involved in cGMP signaling in many tissues. Our study suggests that hOAT2 represents a potential new drug target for regulating cGMP levels.
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Affiliation(s)
- Cheryl D Cropp
- Department of Biopharmaceutical Sciences, 1550 4th Street, RH584, Box 2911, University of California, San Francisco, CA 94158-2911, USA.
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Ma YP, Ma MM, Ge S, Guo RB, Zhang HJ, Frey WH, Xu GL, Liu XF. Intranasally delivered TGF-beta1 enters brain and regulates gene expressions of its receptors in rats. Brain Res Bull 2007; 74:271-7. [PMID: 17720549 DOI: 10.1016/j.brainresbull.2007.06.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 06/25/2007] [Accepted: 06/28/2007] [Indexed: 02/02/2023]
Abstract
This study is aimed to evaluate the brain distribution of transforming growth factor-beta1 (TGF-beta1) following intranasal administration and the subsequent biological effects of TGF-beta1. Adult rats were given recombinant human TGF-beta1 (rhTGF-beta1) or vehicle solution intranasally. TGF-beta1 concentrations were significantly raised in several brain regions and the trigeminal nerve following intranasal delivery. The elevation appeared within 30 min and was sustained for at least 6 h, reaching its greatest level at 60 min. A concentration gradient in the central nervous system (CNS) regions was produced during the first 2 h after intranasal administration, with the OB presenting a significantly higher concentration than any other CNS regions. The nasally administered TGF-beta1 subsequently regulated gene expressions of its two receptors (TGF-beta receptor types I and II) in vivo, but did not affect mRNA level of TGF-beta1 itself. Our results suggest that TGF-beta1 can be transported into the CNS via the olfactory and trigeminal pathways, and may consequently exert its biological effects by regulating gene expressions of its receptors. Intranasal administration of neurotrophic factors may offer a potential strategy for treating some CNS disorders.
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Affiliation(s)
- Yu-Ping Ma
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, 305# East Zhongshan Road, Nanjing 210002, Jiangsu Province, People's Republic of China
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Svoboda N, Zierler S, Kerschbaum HH. cAMP mediates ammonia-induced programmed cell death in the microglial cell line BV-2. Eur J Neurosci 2007; 25:2285-95. [PMID: 17445227 DOI: 10.1111/j.1460-9568.2007.05452.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although ammonia is a well-known neuropathogenic factor, the cellular mechanisms of ammonia toxicity are less characterized. Up to now, the main focus of ammonia toxicity has been on astrocytes and neurons. Despite the significance of microglia in neurodegenerative diseases, little is known about their responsiveness to ammonia. In the present study, we found that ammonia triggered mitosis at concentrations between 30 microm and 3.0 mm but apoptosis at concentrations >or= 1.0 mm in the murine microglial cell line BV-2. Most apoptotic cells showed an accumulation of condensed chromatin at the nuclear envelope, blebbing of the plasma membrane, formation of apoptotic bodies and an increase in caspase 3/7 activity. Blockade of caspase 3/7 activity by Ac-DEVD-CHO suppressed ammonia-induced apoptosis. Surprisingly, some BV-2 cells exposed to ammonia displayed clear signs of mitotic catastrophe, a type of cell death occurring during mitosis. In a further series of experiments, we found that cyclic adenosine 3',5'-monophosphate (cAMP) mediated the apoptogenic effects of ammonia, because (i) ammonia dose-dependently elevated the intracellular cAMP level, (ii) blockade of the adenylyl cyclase by SQ-22536 suppressed ammonia-induced apoptosis, (iii) inhibition of phosphodiesterases (PDEs) by the nonselective PDE inhibitor IBMX, or by the PDE4-selective inhibitor rolipram, increased the relative number of apoptotic cells, and (iv) the cAMP analogues 8-bromoadenosine cAMP and Sp-cAMP mimicked the effect of ammonia and triggered apoptosis. Taken together, our results indicate that distinct concentrations of ammonia trigger opposite signalling pathways in microglial cells.
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Affiliation(s)
- Nina Svoboda
- Department of Cell Biology, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria
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