Zonisamide reduces the increase in 8-hydroxy-2'-deoxyguanosine levels formed during iron-induced epileptogenesis in the brains of rats

PURPOSE: To examine the change of 8-hydroxy-2'deoxyguanosine (8-OHdG) levels, which are used as a marker for oxidative DNA damage, in iron-induced epileptogenic foci of the rat cerebrum. METHOD: Male Wistar rats were given a cortical injection of ferric chloride, and their 8-OHdG levels were determined over time. Additional animals were pretreated with the antiepileptic drug zonisamide (ZNS) before the ferric chloride injection, and their 8-OHdG levels were compared with the nonpretreated rats. RESULTS: Fifteen minutes after ferric chloride solution injection, the level of 8-OHdG increased, reaching a maximum 30 minutes after injection. Sixty minutes after injection, the levels coincided with those of controls. ZNS, in concentrations of 50 and 100 mg/kg body weight, prevented the increase of 8-OHdG levels within the cerebrum 30 minutes after iron solution injection. CONCLUSIONS: These results indicate that the formation of iron-induced epileptogenic foci in rats is related to DNA-damage-induced reactive oxygen species and that the inhibition of 8-OHdG formation by ZNS after iron injection may be due to the drug's antioxidant activity. The data suggest that free radical species known to be formed during iron salts-induced focal epileptogenesis cause damage to isocortical DNA. Furthermore, ZNS appears to inhibit the focal injuring response to DNA that occurs following iron salts-induced acute epileptogenesis.