In Vivo EPR Estimation of Bilateral Hippocampal Antioxidant Ability of Rats with Epileptogenesis Induced by Amygdalar FeCl3 Microinjection


Address correspondence and reprint requests to Dr. Yuto Ueda, Section of Psychiatry, Department of Clinical Neuroscience, University of Miyazaki, 5200 Kihara, Kiyotake-cho, Miyazaki 889-1692, Japan. E-mail:


Summary: Purpose: To measure the neural antioxidant function in the hippocampus of rats with epileptogenesis induced by microinjection of FeCl3 into the amygdala using the decay rate of the nitroxide radical as estimated by L-band electron paramagnetic resonance (EPR) spectroscopy.

Materials and Methods: Region-selected intensity determination (RSID) was used for the estimation of the nitroxide decay ratio. It is possible to estimate the in vivo hippocampal antioxidant ability using the half-life of the EPR signal of the blood–brain barrier-permeable nitroxide radical. Rats were microinjected with aqueous FeCl3 into the right amygdaloid body. Recording from chronically implanted depth electrodes showed the development of spike discharges with recurrent seizures arising from amygdalar regions with propagation into both hippocampi. Rats with unilateral aqueous FeCl3 lesions were injected systemically with the nitroxide radical and then had EPR for RSID estimation at 5, 15, and 30 days after the iron salt injection.

Results: The in vivo antioxidant ability of the dorsal hippocampus was significantly decreased bilaterally in animals with FeCl3-induced seizures when compared to the control.

Conclusion: Neural antioxidant function in the hippocampi of rats with chronic seizures induced by amygdalar FeCl3was decreased early and both ipsilaterally and bilaterally.