A novel online fluorescence method for in-vivo measurement of hydrogen peroxide during oxidative stress produced in a temporal lobe epilepsy model

Abstract

Status epilepticus (SE) can result in an overproduction of hydrogen peroxide (H2O2), which contributes to oxidative stress and brain injury during different phases of epileptogenesis and seizures. In this study, we measured the extracellular H2O2 concentration in the rat hippocampus in a temporal lobe epilepsy model. A new fluorescent technique for measuring H2O2 in vivo simultaneously with electroencephalography recording was tested. The method consists of mixing microdialysate with an enzymatic reactor to produce a fluorescent compound. The fluorescence intensity was measured every second and was proportional to the H2O2 concentration. The results showed that H2O2 was released during SE; we detected a significant increase of up to five times over the baseline value that correlated with changes in electrical activity. We also observed that H2O2 was produced for days after SE and was associated with continuous neuronal death and seizure generation. Therefore, we monitored H2O2 48 h and 15 days after SE, observing increases of up to 96 and 124%, respectively, accompanied by changes in electrical activity with spontaneous discharges of large amplitude. These changes may reflect the oxidative stress generated during epileptogenesis that remains during the chronic period (458% increased) with the presence of large spikes, indicating that the H2O2 could also participate in the generation and maintenance of spontaneous recurrent seizures. There are no previous reports on the detection of H2O2 at this temporal resolution; thus, this study contributes a novel technique for studying and understanding epileptogenesis to develop new antioxidant strategies for the treatment of temporal lobe epilepsy.

ROS/Electro Dual-Reactive Nanogel for Targeting Epileptic Foci to Remodel Aberrant Circuits and Inflammatory Microenvironment

“…We continue to use H 2 O 2 to simulate ROS and stimulate the nanogel to investigate its ROS responsiveness and drug release properties . It has been reported that the highest concentration of extracellular H 2 O 2 in epileptic foci can be close to 50 μmol/L, so we choose 50 μmol/L H 2 O 2 to stimulate the nanogel . We find that the DLS particle size and PDI of our nanogel become larger and larger over time (Figure A).…”

“…We continue to use H 2 O 2 to simulate ROS and stimulate the nanogel to investigate its ROS responsiveness and drug release properties. 65 20 We find that the DLS particle size and PDI of our nanogel become larger and larger over time (Figure 2A).…”

“…19 It has been found that ROS can be produced by damaged neurons and activated glial cells with an extracellular concentration close to 50 μmol/L and form a continuous oxidative microenvironment. 20 Oxidative stress, accompanied by excitotoxicity caused by a high concentration of Glu, constitutes neuronal damage factors in epileptic foci. 21 Furthermore, it has also been reported that ROS contribute to the transmission of proinflammatory signals, promoting gliosis and inflammation, where the NLRP3-caspase-1-IL-1β signal axis is rather representative.…”

“…In the circle, oxidative stress induced by a high concentration of ROS is one of the most typical characteristics of epileptogenesis . It has been found that ROS can be produced by damaged neurons and activated glial cells with an extracellular concentration close to 50 μmol/L and form a continuous oxidative microenvironment . Oxidative stress, accompanied by excitotoxicity caused by a high concentration of Glu, constitutes neuronal damage factors in epileptic foci .…”

Evaluation of the Antioxidant Activity of Levetiracetam in a Temporal Lobe Epilepsy Model

“…In a TLE model, it was demonstrated that H 2 O 2 was released during SE and correlated with changes in electrical activity. The increase in H 2 O 2 levels was observed after 15 days of SE, and this increase persisted during the chronic period, indicating that this reactive species could participate in the generation and maintenance of seizures [ 60 ]. Another study detected an increase in 8-OHdG in mitochondria isolated from the hippocampus of rats with TLE immediately after SE.…”