title: Ibuprofen augments bilirubin toxicity in rat cortical neuronal culture.
abstract: Premature infants are at risk for bilirubin-associated brain damage. In cell cultures bilirubin causes neuronal apoptosis and necrosis. Ibuprofen is used to close the ductus arteriosus, and is often given when hyperbilirubinemia is at its maximum. Ibuprofen is known to interfere with bilirubin-albumin binding. We hypothesized that bilirubin toxicity to cultured rat embryonic cortical neurons is augmented by coincubation with ibuprofen. Incubation with ibuprofen above a concentration of 125 microg/mL reduced cell viability, measured by methylthiazole tetrazolium reduction, to 68% of controls (p < 0.05). Lactate dehydrogenase (LDH) release increased from 29 to 38% (p < 0.01). The vehicle solution did not affect cell viability. Coincubation with 10 microM unconjugated bilirubin (UCB)/human serum albumin in a molar ratio of 3:1 and 250 microg/mL ibuprofen caused additional loss of cell viability and increased LDH release (p < 0.01), DNA fragmentation, and activated caspase-3. Preincubation with the pan-caspase inhibitor z-val-ala-asp-fluoromethyl ketone abolished ibuprofen- and UCB-induced DNA fragmentation. The study demonstrates that bilirubin in low concentration of 10 microM reduces neuron viability and ibuprofen increases this effect. Apoptosis is the underlying cell death mechanism.
authors.affiliation: Department of Neonatology, Charité-Universitätsmedizin Berlin, Berlin 13353, Germany. monika.berns@charite.de
authors.forename: Monika
authors.initials: M
authors.lastname: Berns
authors.forename: Margit
authors.initials: M
authors.lastname: Toennessen
authors.forename: Petra
authors.initials: P
authors.lastname: Koehne
authors.forename: Rodica
authors.initials: R
authors.lastname: Altmann
authors.forename: Michael
authors.initials: M
authors.lastname: Obladen
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D001663:Bilirubin / Q000633:toxicity*; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002470:Cell Survival / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005865:Gestational Age; D007052:Ibuprofen / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000894:Anti-Inflammatory Agents, Non-Steroidal; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C505410:Casp3 protein, rat; D053148:Caspase 3; D001663:Bilirubin; D007052:Ibuprofen