Hydrogen peroxide distribution and neuronal cell death in a rat hippocampal slice

Hydrogen peroxide (H₂O₂), a by-product of a degenerative reaction of reactive oxygen species in mammalian cells, has been examined in association with the pathology of neurodegenerative disorders. In this study, we monitor the H₂O₂ release from a rat hippocampal slice culture at multiple positions using our novel electrochemical sensor array. The H₂O₂ sensor array is fabricated by modifying a 64-channel ITO electrode array with an enzyme, horseradish peroxidase, and an electron transfer mediator. A hippocampal slice is placed on the array and the current at each sensor is monitored using a multipotentiostat. When we introduce kainate (KA) into the solution to stimulate the slice, the H₂O₂ concentration remained largely unchanged. In contrast, in the presence of 3-amino-1,2,4-triazol (3-AT), a catalase inhibitor, we can observe a distinct increase in the H₂O₂ concentration as a result of KA stimulation especially in the CA3 region in the hippocampus. KA exposure is also shown to cause neuronal cell death in the CA3 region by Cresyl Violet staining. These results reveal that our H ₂O₂ sensor array can detect H₂O₂ released from neurons by KA stimulation under catalase inhibition and that this H₂O₂ is associated with neuronal cell death.