Oxidative stress in human epilepsy

Introduction: A series of oxidative stress studies in Kanic Acid induced epileptic brain, found that malondialdehyde (MDA) was about 51% higher (Gupta, 2002), mitochondrial superoxide(O₂–) and DNA (8-Hydroxy-2-deoxyguanosine) were increased (Liang, 2000), and extracellular fluid hydrogen peroxide was increased (Layton, 1999). Clinically higher Hcy tended to developed seizures. In epileptic patients, plasmaVit. 6, folic acid andVit. 12 all decreased. Thus a oxidative stress may play and important role in epilepsy.

Material and methods: We recruit 15 cases of epilepsy surgery. The epileptic focus was localized according to preoperative and intra-operative ECoG spikes. The resected epileptic brain and non-epileptic brain was used for oxidative stress and antioxidant study including: 1. ROS, Hcy MDA, 2. Vit. C, B6, 3. SOD, catalase, GPx, GR GSH/GSSG.

Results: Among these 15 patients, their age ranged from 8 to 63 year-old with a mean of 32±16, and gender of 5 males and 10 females. The ROS (RLU/mg tissue/s) were 10,890±9541 in epileptic hippocampus, 10,887±8704 in epileptic cortex and 5112±2077 in non-epileptic cortex respectively. The MDA (μM/g tissue) were 8570±4181 in epileptic hippocampus, 8821±5953 in epileptic cortex and 8300±4757 in non-epileptic cortex respectively. The SOD (unit/mg protein) was 42,798±34,372 in epileptic hippocampus, 42,082±20,599 in epileptic cortex and 36,947±17,035 in non-epileptic cortex respectively. There were no prominent differences of GPx, GR, GSH, GSSG, GSH/GSSG and ATP. It seemed that ROS MDA and SOD all increased in epileptic brain. ROS and MDA were also higher in post-operative non-seizure freedom patients. ROS was also higher in seizure history longer than 1 year.

Conclusion: Higher oxidative stress and lower anti-oxidant patient tended to have seizure recurrence after epilepsy surgery. Longer seizure history may have higher free radicals.