Neurotoxicity of Unconjugated Bilirubin in Mature and Immature Rat Organotypic Hippocampal Slice Cultures

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.

[1]  C. Mancuso.  Bilirubin and brain: A pharmacological approach , 2017, Neuropharmacology.

[2]  C. Tiribelli,et al.  Evaluation of region selective bilirubin-induced brain damage as a basis for a pharmacological treatment , 2017, Scientific Reports.

[3]  D. Bani,et al.  Ethanol Toxicity During Brain Development: Alterations of Excitatory Synaptic Transmission in Immature Organotypic Hippocampal Slice Cultures. , 2016, Alcoholism, clinical and experimental research.

[4]  Simone Pratesi,et al.  Italian guidelines for management and treatment of hyperbilirubinaemia of newborn infants ≥ 35 weeks’ gestational age , 2014, Italian Journal of Pediatrics.

[5]  Rui F. M. Silva,et al.  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 , 2012, Neuropharmacology.

[6]  D. Brites.  The Evolving Landscape of Neurotoxicity by Unconjugated Bilirubin: Role of Glial Cells and Inflammation , 2012, Front. Pharmacol..

[7]  F. Moroni,et al.  Rat hippocampal slice culture models for the evaluation of neuroprotective agents. , 2012, Methods in molecular biology.

[8]  D. Brites,et al.  Selective vulnerability of rat brain regions to unconjugated bilirubin , 2011, Molecular and Cellular Neuroscience.

[9]  Rui F. M. Silva,et al.  N-Methyl-d-Aspartate Receptor and Neuronal Nitric Oxide Synthase Activation Mediate Bilirubin-Induced Neurotoxicity , 2010, Molecular medicine.

[10]  K. Hsu,et al.  Unconjugated Bilirubin Exposure Impairs Hippocampal Long-Term Synaptic Plasticity , 2009, PloS one.

[11]  S. Sombati,et al.  NMDA Channel Antagonist MK-801 Does Not Protect against Bilirubin Neurotoxicity , 2007, Neonatology.

[12]  E. Hankø,et al.  Recovery after short-term bilirubin exposure in human NT2-N neurons , 2006, Brain Research.

[13]  Rui F. M. Silva,et al.  Bilirubin-induced immunostimulant effects and toxicity vary with neural cell type and maturation state , 2006, Acta Neuropathologica.

[14]  Rui F. M. Silva,et al.  Bilirubin-induced inflammatory response, glutamate release, and cell death in rat cortical astrocytes are enhanced in younger cells , 2005, Neurobiology of Disease.

[15]  S. Shapiro,et al.  Bilirubin toxicity in the developing nervous system. , 2003, Pediatric neurology.

[16]  M. J. Maisels,et al.  Treatment of jaundice in low birthweight infants , 2003, Archives of disease in childhood. Fetal and neonatal edition.

[17]  M. J. Maisels,et al.  Jaundice in low birthweight infants: pathobiology and outcome , 2003, Archives of disease in childhood. Fetal and neonatal edition.

[18]  C. Tiribelli,et al.  Reassessment of the Unbound Concentrations of Unconjugated Bilirubin in Relation to Neurotoxicity In Vitro , 2003, Pediatric Research.

[19]  C. Ahlfors,et al.  Unbound bilirubin in a term newborn with kernicterus. , 2003, Pediatrics.

[20]  Lorella Pascolo,et al.  Affinity of Human Serum Albumin for Bilirubin Varies with Albumin Concentration and Buffer Composition , 2001, The Journal of Biological Chemistry.

[21]  V. Koziel,et al.  Bilirubin Induces Apoptosis via Activation of NMDA Receptors in Developing Rat Brain Neurons , 2000, Experimental Neurology.

[22]  M. Johnston,et al.  Role of Glutamate Receptor-Mediated Excitotoxicity in Bilirubin-Induced Brain Injury in the Gunn Rat Model , 1998, Experimental Neurology.

[23]  J. Altman,et al.  Timetables of neurogenesis in the human brain based on experimentally determined patterns in the rat. , 1993, Neurotoxicology.

[24]  S. Turkel.  Autopsy findings associated with neonatal hyperbilirubinemia. , 1990, Clinics in perinatology.

[25]  J. Aase.  Neonatal hyperbilirubinemia. , 1969, Pediatrics.