Investigation of the cytoprotective properties of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) against cisplatin and diethyldithiocarbamate (DDC) toxicity in rat hippocampal astrocytes

Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), is a seleno-organic compound with documented cytoprotective properties. Little work has been done demonstrating cytoprotection by ebselen in neural cell lines. In order to examine the effects of this compound and its mechanism of action, astrocytes were exposed to two known neurotoxicants, cisplatin and diethyldithiocarbamate (DDC). To determine cytoprotection, cells were pretreated with 30μM ebselen and subsequently treated with either 150 μM DDC for one hr or 250 and 500 μM cisplatin for 24 hrs. Phase contrast and scanning electron microscopy were performed to assess morphological changes. In order to examine the mechanism of protection of this compound, glutathione status and cytoprotection under conditions of glutathione depletion were examined. The induction of the stress protein heme oxygenase-1, (HO-1) was also investigated. Induction was assessed after treatment with 15 and 30 μM ebselen for 24 hrs. Production of HO-1 with ebselen was blocked using antisense oligonucleotides directed against this protein. Changes in viability were examined as a measure of antisense treatment. Lipid peroxidation products malondialdehyde (MDA) and 4-hydroxy-2-nonenal(4-HNE) were measured in cells treated with 30 μM ebselen and subsequently treated with 250 μM cisplatin to determine if ebselen pretreatment lessens lipid peroxidation (LP). Results indicate significant increases in viability in cells pretreated with ebselen and exposed to cisplatin when compared to cells treated with cisplatin alone. Ebselen pretreatment did not significantly increase viability in cells exposed to DDC when compared to cells treated with DDC alone. Light and scanning electron microscopy studies confirm the viability studies. Morphological damage was seen in cells treated with cisplatin, however, cells pretreated with ebselen and then exposed to cisplatin, appeared similar to controls. No differences were noted in cells pretreated with ebselen and then exposed to DDC when compared to cells treated with DDC alone. No significant increases in reduced or oxidized glutathione (GSH, GSSG) were noted in cells treated with ebselen. All cell groups treated with cisplatin showed an increase in GSH and GSSG levels. Glutathione depletion resulted in decreases in viability previously noted with ebselen pretreatment followed by 250 and 500μM cisplatin treatment, however, ebselen pretreatment followed by 250μM cisplatin treatment still resulted in a significant increase in viability from its matched pair treated with cisplatin alone. (Abstract shortened by UMI.)...