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Wu C, Jin Y, Cui Y, Zhu Y, Yin S, Li C. Effects of bilirubin on the development and electrical activity of neural circuits. Front Cell Neurosci 2023; 17:1136250. [PMID: 37025700 PMCID: PMC10070809 DOI: 10.3389/fncel.2023.1136250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/06/2023] [Indexed: 04/08/2023] Open
Abstract
In the past several decades, bilirubin has attracted great attention for central nervous system (CNS) toxicity in some pathological conditions with severely elevated bilirubin levels. CNS function relies on the structural and functional integrity of neural circuits, which are large and complex electrochemical networks. Neural circuits develop from the proliferation and differentiation of neural stem cells, followed by dendritic and axonal arborization, myelination, and synapse formation. The circuits are immature, but robustly developing, during the neonatal period. It is at the same time that physiological or pathological jaundice occurs. The present review comprehensively discusses the effects of bilirubin on the development and electrical activity of neural circuits to provide a systematic understanding of the underlying mechanisms of bilirubin-induced acute neurotoxicity and chronic neurodevelopmental disorders.
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Kitchen ST, Tang N, He M, Ly E, Mooney SM, Bearer CF. Bilirubin inhibits lipid raft dependent functions of L1 cell adhesion molecule in rat pup cerebellar granule neurons. Pediatr Res 2021; 89:1389-1395. [PMID: 32937649 PMCID: PMC9323028 DOI: 10.1038/s41390-020-01156-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/07/2020] [Accepted: 09/01/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The mechanism of bilirubin neurotoxicity is poorly understood. We hypothesize that bilirubin inhibits the function of lipid rafts (LR), microdomains of the plasma membrane critical for signal transduction. To test this hypothesis, we measured the effect of free bilirubin (Bf) between 7.6 and 122.5 nM on LR-dependent functions of L1 cell adhesion molecule (L1). METHODS Cerebellar granule neurons (CGN) were plated on poly-L-lysine overnight, and neurite length was determined after 1 h treatment with L1 alone or L1 and bilirubin. L1 activation of ERK1/2 was measured in CGN in the presence or absence of bilirubin. The effect of bilirubin on L1 distribution in LR was quantitated, and the localization of bilirubin to LR was determined. RESULTS The addition of bilirubin to CGN treated with L1 significantly decreased neurite length compared to L1 alone. L1 activation of ERK1/2 was inhibited by bilirubin. Bilirubin redistributed L1 into LR. Bilirubin was associated only with LR-containing fractions of a sucrose density gradient. CONCLUSION Bf significantly inhibits LR-dependent functions of L1 and are found only associated with LR, suggesting one mechanism by which bilirubin may exert neurotoxicity is through the dysfunction of protein-LR interactions. IMPACT This article establishes lipid rafts as a target for the neurotoxic effects of bilirubin. This article provides clear evidence toward establishing one mechanism of bilirubin neurotoxicity, where little is understood. This article paves the way for future investigation into lipid raft dependent functions, and its role in neurodevelopmental outcome.
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Affiliation(s)
- Spencer T. Kitchen
- Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio, 44106
| | - Ningfeng Tang
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, Maryland, 21201
| | - Min He
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21218
| | - Eric Ly
- Division of Neonatology, University of Maryland School of Medicine, Baltimore, Maryland, 21201
| | - Sandra M. Mooney
- Department of Nutrition, University of North Carolina School of Public Health, Chapel Hill, North Carolina, 27514
| | - Cynthia F. Bearer
- Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio, 44106,Corresponding author: Cynthia F. Bearer, M.D., Ph.D., Department of Pediatrics, 2109 Adelbert Rd, 8th floor, Cleveland, OH 44106, Tel. (410) 328-6003, Fax. (410) 328-1076,
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Hansen TWR, Wong RJ, Stevenson DK. Molecular Physiology and Pathophysiology of Bilirubin Handling by the Blood, Liver, Intestine, and Brain in the Newborn. Physiol Rev 2020; 100:1291-1346. [PMID: 32401177 DOI: 10.1152/physrev.00004.2019] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Bilirubin is the end product of heme catabolism formed during a process that involves oxidation-reduction reactions and conserves iron body stores. Unconjugated hyperbilirubinemia is common in newborn infants, but rare later in life. The basic physiology of bilirubin metabolism, such as production, transport, and excretion, has been well described. However, in the neonate, numerous variables related to nutrition, ethnicity, and genetic variants at several metabolic steps may be superimposed on the normal physiological hyperbilirubinemia that occurs in the first week of life and results in bilirubin levels that may be toxic to the brain. Bilirubin exists in several isomeric forms that differ in their polarities and is considered a physiologically important antioxidant. Here we review the chemistry of the bilirubin molecule and its metabolism in the body with a particular focus on the processes that impact the newborn infant, and how differences relative to older children and adults contribute to the risk of developing both acute and long-term neurological sequelae in the newborn infant. The final section deals with the interplay between the brain and bilirubin and its entry, clearance, and accumulation. We conclude with a discussion of the current state of knowledge regarding the mechanism(s) of bilirubin neurotoxicity.
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Affiliation(s)
- Thor W R Hansen
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - Ronald J Wong
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - David K Stevenson
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
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Review of bilirubin neurotoxicity I: molecular biology and neuropathology of disease. Pediatr Res 2020; 87:327-331. [PMID: 31600770 DOI: 10.1038/s41390-019-0608-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 12/11/2022]
Abstract
Despite the availability of successful prevention strategies to prevent excessive hyperbilirubinemia, the neurological sequelae of bilirubin neurotoxicity (BNTx) still occur throughout the world. Kernicterus, encephalopathy due to BNTx, is now understood to be a spectrum of severity and phenotypes known as kernicterus spectrum disorder (KSD). A better understanding of the selective neuropathology and molecular biology of BNTx and using consistent clinical definitions of KSDs as outcome measure can lead to more accurately predicting the risk and causes of BNTx and KSDs. In Part I of our two-part review, we will summarize current and recent advances in the understanding of the selective neuropathology and molecular biology of the disease. Herein we emphasize the role of unbound, free unconjugated bilirubin as well as genetic contributions to the susceptibility BNTx and the development of KSDs. In Part II, we focus on current and possible novel methods to prevent BNTx and ABE and treat ABE and KSDs.
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Le Pichon JB, Riordan SM, Shapiro SM. Hyperbilirubinemia and the Risk for Brain Injury. Neurology 2019. [DOI: 10.1016/b978-0-323-54392-7.00010-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Dani C, Pratesi S, Ilari A, Lana D, Giovannini MG, Nosi D, Buonvicino D, Landucci E, Bani D, Mannaioni G, Gerace E. Neurotoxicity of Unconjugated Bilirubin in Mature and Immature Rat Organotypic Hippocampal Slice Cultures. Neonatology 2019; 115:217-225. [PMID: 30645995 DOI: 10.1159/000494101] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/27/2018] [Indexed: 11/19/2022]
Abstract
BACKGROUND The physiopathology of bilirubin-induced neurological disorders is not completely understood. OBJECTIVES The aim of our study was to assess the effect on bilirubin neurotoxicity of the maturity or immaturity of exposed cells, the influence of different unconjugated bilirubin (UCB) and human serum albumin (HSA) concentrations, and time of UCB exposure. METHODS Organotypic hippocampal slices were exposed for 48 h to different UCB and HSA concentrations after 14 (mature) or 7 (immature) days of in vitro culture. Immature slices were also exposed to UCB and HSA for 72 h. The different effects of exposure time to UCB on neurons and astrocytes were evaluated. RESULTS We found that 48 h of UCB exposure was neurotoxic for mature rat organotypic hippocampal slices while 72 h of exposure was neurotoxic for immature slices. Forty-eight-hour UCB exposure was toxic for astrocytes but not for neurons, while 72-h exposure was toxic for both astrocytes and neurons. HSA prevented UCB toxicity when the UCB:HSA molar ratio was ≤1 in both mature and immature slices. CONCLUSIONS We confirmed UCB neurotoxicity in mature and immature rat hippocampal slices, although immature ones were more resistant. HSA was effective in preventing UCB neurotoxicity in both mature and immature rat hippocampal slices.
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Affiliation(s)
- Carlo Dani
- Division of Neonatology, Careggi University Hospital of Florence, Florence, Italy, .,Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy,
| | - Simone Pratesi
- Division of Neonatology, Careggi University Hospital of Florence, Florence, Italy
| | - Alice Ilari
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Maria Grazia Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Daniele Nosi
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Daniele Buonvicino
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Elisa Landucci
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Daniele Bani
- Department of Clinical and Experimental Medicine, Research Unit of Histology and Embryology, University of Florence, Florence, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Elisabetta Gerace
- Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
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Yan R, Han D, Ren J, Zhai Z, Zhou F, Cheng J. Diagnostic value of conventional MRI combined with DTI for neonatal hyperbilirubinemia. Pediatr Neonatol 2018; 59:161-167. [PMID: 28864243 DOI: 10.1016/j.pedneo.2017.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/13/2017] [Accepted: 07/28/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Neonatal hyperbilirubinemia (NHB) is a common clinical disease and can cause bilirubin encephalopathy in severe cases. It is now widely accepted that increased signal intensity in the globus pallidus on MR T1WI is an important sign of neonatal bilirubin encephalopathy. And brain diffusion tensor imaging (DTI) has not been used extensively to study hyperbilirubinemia (HB). So we compared newborns with different hyperbilirubinemia of different severities and healthy newborns in order to determine the relationships among MRI signal intensities, serum bilirubin levels, and the molecular changes in brain water diffusion in hyperbilirubinemia. METHODS Seventy-three newborns with hyperbilirubinemia were grouped into three groups: the mild increase group (M, 27 cases), the moderate increase group (O, 28 cases), and the severe group (S, 18 cases). The groups were based on serum bilirubin levels. We performed cranial MRI in these newborns, as well as 29 healthy full-term infants (group N). We compared and analyzed the mean signal values for the globus pallidus and the relationship between the bilirubin level and the score on the neonatal behavioral neurological assessment. Fifteen, 10, and 10 patients in groups M, O + S, and N were successfully examined using diffusion tensor imaging (DTI). We assessed the relationships among the signal from the globus pallidus, fractional anisotropy (FA), and average diffusion coefficient (DCav) of the posterior limb of the internal capsule (PLIC). RESULTS There were significant differences in the mean signal value of bilateral globus pallidus between group O/S and group N [p = 0.029 and 0.000 (left), 0.038 and 0.000 (right)]. There were no significant differences in bilateral FA or DCav values between the patient groups and group N. The bilateral PLIC-FA and DCav values were significantly different between the patient groups and group N (P = 0.014 and 0.047, respectively). CONCLUSIONS Increased signal intensity in the globus pallidus on T1-weighted imaging can be used as an objective index to evaluate neonatal bilirubin encephalopathy. Globus pallidus and PLIC injuries are likely to occur when the total serum bilirubin level is ≥20 mg/dl.
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Affiliation(s)
- Ruifang Yan
- Department of Magnetic Resonance, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China; Center of Imaging, The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
| | - Dongming Han
- Center of Imaging, The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
| | - Jipeng Ren
- Center of Imaging, The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
| | - Zhansheng Zhai
- Center of Imaging, The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
| | - Fengmei Zhou
- Center of Imaging, The First Affiliated Hospital of Xinxiang Medical University, Weihui 453100, China
| | - Jingliang Cheng
- Department of Magnetic Resonance, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
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Magnetic Resonance Imaging Abnormalities in Advanced Acute Bilirubin Encephalopathy Highlight Dentato-Thalamo-Cortical Pathways. J Pediatr 2016; 174:260-3. [PMID: 27113379 DOI: 10.1016/j.jpeds.2016.03.065] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/19/2016] [Accepted: 03/24/2016] [Indexed: 11/20/2022]
Abstract
A distinct pattern of acute restricted diffusion on magnetic resonance imaging localized to key regions within the dentato-thalamo-cortical pathway was observed early in a term newborn during advanced stages of acute bilirubin encephalopathy. These findings demonstrate that vulnerability to bilirubin toxicity extends across specific neuroanatomic tracts.
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The role of gamma-aminobutyric acid/glycinergic synaptic transmission in mediating bilirubin-induced hyperexcitation in developing auditory neurons. Toxicol Lett 2016; 240:1-9. [DOI: 10.1016/j.toxlet.2015.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 09/14/2015] [Accepted: 10/11/2015] [Indexed: 10/22/2022]
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Schreuder AB, Rice AC, Vanikova J, Vitek L, Shapiro SM, Verkade HJ. Albumin administration protects against bilirubin-induced auditory brainstem dysfunction in Gunn rat pups. Liver Int 2013; 33:1557-65. [PMID: 23742048 DOI: 10.1111/liv.12219] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 05/11/2013] [Indexed: 02/13/2023]
Abstract
BACKGROUND Free bilirubin (Bf), the unbound fraction of unconjugated bilirubin (UCB), can induce neurotoxicity, including impairment of the auditory system, which can be assessed by brainstem auditory evoked potentials (BAEPs). We hypothesized that albumin might reduce the risk of neurotoxicity by decreasing Bf and its translocation into the brain. AIM To determine the effects of albumin on BAEPs and brain bilirubin content in two Gunn rat pup models of acute hyperbilirubinemia. METHODS We used Gunn rat pups, which have a deficiency of the bilirubin-conjugating enzyme UGT1A1. We induced haemolysis by injection of phenylhydrazine (phz) into 14-days old pups. Subsequently, pups were treated with either i.p. human serum albumin (HSA; 2.5 g/kg; n = 8) or saline (control, n = 8). We induced acute neurotoxicity by injecting 16-days old pups with sulphadimethoxine (sulpha) and treated them with either HSA (n = 9) or saline (control, n = 10). To assess bilirubin neurotoxicity, we used the validated BAEP method and compared relevant parameters; i.e. peak latency values and interwave interval (IWI) between peak I and peak II, a marker of acute neurotoxicity. RESULTS Phz and sulpha significantly increased IWI I-II by 26% and 29% (P < 0.05) in the haemolysis and the displacement model, respectively. Albumin completely prevented the increase of IWI I-II in either model. The beneficial effect of albumin in the displacement-model by means of normal BAEPs was in line with less bilirubin in the brain (NS). Interestingly, in the haemolysis model the accumulation of total bilirubin in the brain was unaltered, and BAEPs still appeared normal. This might advocate for a role of brain Bf which was calculated and showed that albumin treatment non-significantly reduces Bf concentrations in brain, compared with saline treatment. CONCLUSIONS Albumin treatment is neuroprotective in acute hyperbilirubinemia in Gunn rat pups. Our present results underline the importance of functional diagnostic test of neurotoxicity above biochemical concentrations.
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Affiliation(s)
- Andrea B Schreuder
- Pediatric Gastroenterology and Hepatology, Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, Beatrix Children's Hospital - University Medical Center Groningen, Groningen, the Netherlands
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Brites D. The evolving landscape of neurotoxicity by unconjugated bilirubin: role of glial cells and inflammation. Front Pharmacol 2012; 3:88. [PMID: 22661946 PMCID: PMC3361682 DOI: 10.3389/fphar.2012.00088] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 04/23/2012] [Indexed: 12/13/2022] Open
Abstract
Unconjugated hyperbilirubinemia is a common condition in the first week of postnatal life. Although generally harmless, some neonates may develop very high levels of unconjugated bilirubin (UCB), which may surpass the protective mechanisms of the brain in preventing UCB accumulation. In this case, both short-term and long-term neurodevelopmental disabilities, such as acute and chronic UCB encephalopathy, known as kernicterus, or more subtle alterations defined as bilirubin-induced neurological dysfunction (BIND) may be produced. There is a tremendous variability in babies' vulnerability toward UCB for reasons not yet explained, but preterm birth, sepsis, hypoxia, and hemolytic disease are comprised as risk factors. Therefore, UCB levels and neurological abnormalities are not strictly correlated. Even nowadays, the mechanisms of UCB neurotoxicity are still unclear, as are specific biomarkers, and little is known about lasting sequelae attributable to hyperbilirubinemia. On autopsy, UCB was shown to be within neurons, neuronal processes, and microglia, and to produce loss of neurons, demyelination, and gliosis. In isolated cell cultures, UCB was shown to impair neuronal arborization and to induce the release of pro-inflammatory cytokines from microglia and astrocytes. However, cell dependent sensitivity to UCB toxicity and the role of each nerve cell type remains not fully understood. This review provides a comprehensive insight into cell susceptibilities and molecular targets of UCB in neurons, astrocytes, and oligodendrocytes, and on phenotypic and functional responses of microglia to UCB. Interplay among glia elements and cross-talk with neurons, with a special emphasis in the UCB-induced immunostimulation, and the role of sepsis in BIND pathogenesis are highlighted. New and interesting data on the anti-inflammatory and antioxidant activities of different pharmacological agents are also presented, as novel and promising additional therapeutic approaches to BIND.
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Affiliation(s)
- Dora Brites
- Neuron Glia Biology in Health and Disease Unit, Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon Lisbon, Portugal
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Silva SL, Vaz AR, Diógenes MJ, van Rooijen N, Sebastião AM, Fernandes A, Silva RFM, Brites D. Neuritic growth impairment and cell death by unconjugated bilirubin is mediated by NO and glutamate, modulated by microglia, and prevented by glycoursodeoxycholic acid and interleukin-10. Neuropharmacology 2012; 62:2398-408. [PMID: 22361233 DOI: 10.1016/j.neuropharm.2012.02.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 02/01/2012] [Accepted: 02/07/2012] [Indexed: 12/28/2022]
Abstract
Neuronal oxidative damage and cell death by unconjugated bilirubin (UCB) showed to be mediated by overstimulation of glutamate receptors and nitric oxide (NO) production, which was abrogated by the bile acid glycoursodeoxycholic acid (GUDCA). Microglia, a crucial mediator of CNS inflammation, evidenced to react to UCB by releasing glutamate and NO before becoming senescent. Our studies demonstrated that neurite outgrowth deficits are produced in neurons exposed to UCB and that conditioned media from these UCB-treated neurons further stimulate NO production by microglia. Nevertheless, microglia protective and/or harmful effects in neonatal jaundice are poorly understood, or unrecognized. Here, we investigated the role of microglia, glutamate and NO in the impairment of neurite sprouting by UCB. Therapeutic potential of the anti-inflammatory cytokine interleukin (IL)-10 and GUDCA was also evaluated. By using MK-801 (a NMDA glutamate-subtype receptor antagonist) and L-NAME (a non-specific NO synthase inhibitor) we found that glutamate and NO are determinants in the early and enduring deficits in neurite extension and ramification induced by UCB. Both GUDCA and IL-10 prevented these effects and decreased the production of glutamate and NO. Only GUDCA was able to counteract neuronal death and synaptic changes. Data from organotypic-cultured hippocampal slices, depleted or non-depleted in microglia, supported that microglia participate in glutamate homeostasis and contribute to NO production and cell demise, which were again abrogated by GUDCA. Collectively our data suggest that microglia is a key player in UCB-induced neurotoxicity and that GUDCA might be a valuable preventive therapy in neonates at risk of UCB encephalopathy.
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Affiliation(s)
- Sandra L Silva
- Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Av. Professor Gama Pinto, 1649-003 Lisbon, Portugal.
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Li CY, Shi HB, Wang J, Ye HB, Song NY, Yin SK. Bilirubin facilitates depolarizing GABA/glycinergic synaptic transmission in the ventral cochlear nucleus of rats. Eur J Pharmacol 2011; 660:310-7. [DOI: 10.1016/j.ejphar.2011.03.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 02/22/2011] [Accepted: 03/15/2011] [Indexed: 12/22/2022]
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Rice AC, Chiou VL, Zuckoff SB, Shapiro SM. Profile of minocycline neuroprotection in bilirubin-induced auditory system dysfunction. Brain Res 2010; 1368:290-8. [PMID: 20971088 DOI: 10.1016/j.brainres.2010.10.052] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 10/08/2010] [Accepted: 10/14/2010] [Indexed: 12/17/2022]
Abstract
Excessive hyperbilirubinemia in human neonates can cause permanent dysfunction of the auditory system, as assessed with brainstem auditory evoked potentials (BAEPs). Jaundiced Gunn rat pups (jjs) exhibit similar BAEP abnormalities as hyperbilirubinemic neonates. Sulfadimethoxine (sulfa) administration to jjs, which displaces bilirubin from serum albumin into tissues including brain, exacerbates acute toxicity. Minocycline administered prior to sulfa in jjs protects against BAEP abnormalities. This study evaluates the neuroprotective capabilities of minocycline HCl (50 mg/kg) administered 30 or 120 min after sulfa (200 mg/kg) in 16 days old jjs. BAEPs are recorded at 6 or 24 h post-sulfa. Abnormal BAEP waves exhibit increased latency and decreased amplitude. The sulfa/saline treated jjs exhibited a significantly increased interwave interval between waves I and II (I-II IWI) and significantly decreased amplitudes of waves II and III compared to the saline/saline jjs. The minocycline 30 min post-sulfa (sulfa/mino+30) group was not significantly different from the saline/saline control group, indicating neuroprotection. The minocycline 120 min post-sulfa (sulfa/mino+120) group had a significantly decreased amplitude of wave III at both 6 and 24h. These studies indicate that minocycline has a graded neuroprotective effect when administered after acute bilirubin neurotoxicity.
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Affiliation(s)
- Ann C Rice
- Department of Neurology, Box 980599, Virginia Commonwealth University, Richmond, VA 23298-0599, USA.
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Brito MA, Vaz AR, Silva SL, Falcão AS, Fernandes A, Silva RFM, Brites D. N-methyl-aspartate receptor and neuronal nitric oxide synthase activation mediate bilirubin-induced neurotoxicity. Mol Med 2010; 16:372-80. [PMID: 20593111 PMCID: PMC2935951 DOI: 10.2119/molmed.2009.00152] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 06/28/2010] [Indexed: 01/02/2023] Open
Abstract
Hyperbilirubinemia may lead to neurotoxicity and neuronal death. Although the mechanisms of nerve cell damage by unconjugated bilirubin (UCB) appear to involve a disruption of the redox status and excitotoxicity, the contribution of nitric oxide (NO·) and of N-methyl-D-aspartate (NMDA) glutamate receptors is unclear. We investigated the role of NO· and NMDA glutamate receptors in the pathways of nerve cell demise by UCB. Neurons were incubated with 100 micromol/L UCB, in the presence of 100 micromol/L human serum albumin for 4 h at 37ºC, alone or in combination with N-ω-nitro-L-arginine methyl ester (L-NAME) (an inhibitor of neuronal nitric oxide synthase [nNOS]), hemoglobin (an NO· scavenger) or (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) (an NMDA-receptor antagonist). Exposure to UCB led to increased expression of nNOS and production of both NO· and cyclic guanosine 3',5'-monophosphate (cGMP), along with protein oxidation and depletion of glutathione. These events concurred for cell dysfunction and death and were counteracted by L-NAME. Moreover, the UCB-induced loss of neuronal viability was abolished by hemoglobin, whereas the activation of nNOS and production of both NO· and cGMP were counteracted by MK-801, resulting in significant protection from cell dysfunction and death. These results reinforce the involvement of oxidative stress by showing that nerve cell damage by UCB is mediated by NO· and therefore is counteracted by NO· inhibitors or scavengers. Our findings strongly suggest that the activation of nNOS and neurotoxicity occur through the engagement of NMDA receptors. These data reveal a role for overstimulation of glutamate receptors in mediating oxidative damage by UCB.
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Affiliation(s)
- Maria A Brito
- Research Institute for Medicines and Pharmaceutical Sciences, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal.
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