Regional vulnerability to oxidative stress in a model of experimental epilepsy

S. LORES ARNAIZ; M. TRAVACIO; S. LLESUY ; G. RODRÍGUEZ DE LORES ARNAIZ

NEUROCHEMICAL RESEARCH

SPRINGER/PLENUM PUBLISHERS

Año: 1998 vol. 23 p. 1477 - 1483

0364-3190

We evaluated oxidative stress associated with a model of experimental epilepsy. Male Wistar rats were injected i.p. with 150 mg/kg convulsant 3-mercaptopropionic acid and decapitated in two stages: during seizures or in the post-seizure period. Spontaneous chemiluminescence, levels of thiobarbituric acid reactive substances, total antioxidant capacity and antioxidant enzyme activities were measured in cerebellum, hippocampus, cerebral cortex and striatum. In animals killed at seizure, increases of 42% and 90% were observed in spontaneous chemiluminescence of cerebellum and cerebral cortex homogenates, respectively, accompanied by a 25% increase in cerebral cortexlevels of thiobarbituric acid reactive substances. In the post-seizure stage, emission completely returned to control levels in cerebral cortex and partly in cerebellum, thus showing oxidative stress reversibility in time. Hippocampus and striatum seemed less vulnerable areas to oxidative damage. A 30% decrease in glutathione peroxidase activity was only observed in cerebral cortex duringseizures, while catalase and superoxide dismutase remained unchanged in all four areas during either stage. Likewise, total antioxidant capacity was unaffected in any of the studied areas. It is suggested that oxidative stress in this model of epilepsy arises from an increase in oxidant species rather than from depletion of antioxidant defences.INTRODUCTIONThe brain appears to be particularly vulnerable tooxidative damage. It contains relatively high concentrationsof unsaturated fatty acids. Several enzymes expressedin the brain, including monoamine oxidase,tyrosine hydroxylase, and L-amino acid oxidase, lead tohydrogen peroxide formation as a normal byproduct oftheir activity. Various regions of the brain are particu-Cfitedra de Fisicoquimica, z Cfitedra de Quimica General, Facultadde Farmacia y Bioquimica, 3 Instituto de Biologia Celular y Neurociencias"Prof. Eduardo De Robertis", Facultad de Medicina, Universidadde Buenos Aires, Junin 956, 1113 Buenos Aires, Argentina.Address reprint requests to: G. Rodriguez de Lores Arnaiz, Institutode Biologia Celular y Neurociencias, Prof. Eduardo De Robertis, Faeultadde Medicina, Universidad de Buenos Aires, Paraguay 2155,(1121) Buenos Aires. Fax: (541) 962-5341; (541) 964-8274; E-mail:grodrig@ffyb.uba.ar.1477larly rich in iron, which promotes the production o