Bilirubin is cytotoxic to rat oligodendrocytes in vitro.
High levels of unconjugated bilirubin can be neurotoxic and gliotoxic. However, the effect of bilirubin on oligodendrocyte viability has never been investigated. In the present study, we searched the possible toxic effect of bilirubin on differentiated rat oligodendrocytes. Bilirubin was added to oligodendrocyte cultures at different concentrations varied between 10 and 100 microM, and cultures were incubated for different times (24, 48 and 72 h). Cell viability was evaluated by trypan blue exclusion. The results showed that bilirubin decreased oligodendroglial cell viability in a concentration and time-dependent manner. Bilirubin induced apoptotic cell death as revealed by TUNEL staining and poly(ADP-ribose) polymerase cleavage. We found that bilirubin induced inducible nitric oxide synthase (NOS) mRNA expression in rat oligodendrocytes. Bilirubin also increased oligodendroglial nitrite production in a concentration-dependent manner and NOS inhibitor partly blocked bilirubin-induced cytotoxicity. These results suggest that bilirubin induces cytotoxicity, at least partly, via the induction of nitric oxide production in oligodendrocytes.
Genc
Sermin
S
Department of Medical Biology and Genetics, School of Medicine, Dokuz Eylul University, Inciralti, 35340 Izmir, Turkey. sermingenc@hotmail.com
Genc
Kursad
K
Kumral
Abdullah
A
Baskin
Huseyin
H
Ozkan
Hasan
H
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D001663:Bilirubin / Q000378:metabolism / Q000633:toxicity*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005698:Galactosylceramidase / Q000378:metabolism; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D007211:Indoles / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D009836:Oligodendroglia / Q000145:classification / Q000187:drug effects* / Q000378:metabolism; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D007211:Indoles; D009573:Nitrites; D012333:RNA, Messenger; D011064:Poly Adenosine Diphosphate Ribose; D009569:Nitric Oxide; C007293:DAPI; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D005698:Galactosylceramidase; D001663:Bilirubin