Effect of pentylenetetrazol-induced epileptic seizure on the antioxidant enzyme activities, glutathione and lipid peroxidation levels in rat erythrocytes and liver tissues S. Halide Akbas a, * , Aysenur Yegin b , Tomris Ozben c a Central Laboratory, Faculty of Medicine, Akdeniz University, Antalya, Turkey b Antalya State Hospital, Antalya, Turkey c Department of Biochemistry, Faculty of Medicine, Akdeniz University, Antalya, Turkey Received 31 May 2005; received in revised form 13 July 2005; accepted 25 July 2005 Available online 24 August 2005 Abstract Objectives: In order to clarify whether oxidative stress accompanies epilepsy, we examined the effects of pentylenetetrazol (PTZ)- induced epilepsy on the lipid peroxidation and antioxidant enzyme activities in erythrocytes and liver tissues of adult Wistar rats. Materials and methods: The activities of antioxidative enzymes (glucose-6-phosphate dehydrogenase (G-6-PD)), copper, zinc- superoxide dismutase (Cu,Zn-SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px) and the levels of reduced glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) were measured in erythrocytes and liver tissues of pentylenetetrazol (PTZ)-induced epileptic adult Wistar rats. Results: Single PTZ treatment in a convulsive dose of 50 mg/kg significantly reduced the erythrocyte Cu,Zn-SOD, CAT enzyme activities and GSH levels compared to controls (P < 0.001, P < 0.001, P < 0.05, respectively). Erythrocyte and liver tissue TBARS levels in the epileptic group were significantly higher than controls (P < 0.0001). There was a significant decrease in liver tissue Cu,Zn-SOD activity and GSH levels in the epileptic group (P < 0.0001), whereas significantly higher activities of G-6-PD and Se-GSH-Px were found in the epileptic group. Conclusions: Our results demonstrate a generalized diminished antioxidant activity and increased TBARS level indicating enhanced oxidative stress in the liver and erythrocytes of epileptic rats. Increased oxidative stress in the liver of epileptic rats might be due to the activation of the recently found glutamate receptors in the liver. These findings suggest that the use of antioxidants with antiepileptic drugs and new drugs such as type-5 metabotropic glutamate receptor (mGlu5) antagonist (MPEP) might protect erythrocytes and liver tissue against anoxic damage and oxidative stress. D 2005 The Canadian Society of Clinical Chemists. All rights reserved. Keywords: Antioxidants; Epilepsy; Erythrocyte; Liver; Oxidative stress; Pentylenetetrazol Introduction In accordance with the present state of scientific knowl- edge, the excessive production of free radicals in the organism, and the imbalance between the concentrations of these and the antioxidant defenses may be related to the pathogenesis of various diseases such as atherosclerosis, stroke, diabetes mellitus, cancer and inflammatory diseases [1,2]. Epilepsies constitute a large group of neurological diseases with an incidence of 0.5–1% in the general population [3]. Many reports suggest a cascade of biological events underlying development and progression of epilepsy. Generalized epilepsy is a chronic disorder characterized by recurrent seizures which can increase the content of reactive oxygen species (ROS) generation in the brain [2]. Brain is susceptible to free radical damage, considering the large lipid content of myelin sheaths and the high rate of brain oxidative metabolism [4]. 0009-9120/$ - see front matter D 2005 The Canadian Society of Clinical Chemists. All rights reserved. doi:10.1016/j.clinbiochem.2005.07.012 * Corresponding author. Fax: +90 242 227 25 35. E-mail address: halideakbas@akdeniz.edu.tr (S..H. Akbas). Clinical Biochemistry 38 (2005) 1009 – 1014