It has been suggested that free oxygen radicals play a role in the genesis of epilepsy and in post-seizure neuronal death. The aim of this study was to investigate the dose dependent effect of ghrelin on pentylenetetrazole (PTZ)-induced oxidative stress in a rat seizure model. For this purpose, the ghrelin groups were treated with intraperitoneal injections of ghrelin at doses of 20, 40, 60 and 80 microg/kg before the PTZ injection. Superoxide dismutase (SOD) and catalase (CAT) activities, and reduced glutathione (GSH) and thiobarbituric acid-reactive substance (TBARS) levels were measured in erythrocytes, liver and brain tissue. TBARS, the indicator of lipid peroxidation, was significantly increased in erythrocytes, liver and brain tissue, while antioxidant enzyme activities and glutathione levels were significantly decreased in PTZ injected rats. Ghrelin pretreatment prevented lipid peroxidation and the reduction in antioxidant enzyme activities and GSH levels against PTZ-induced oxidative stress in a dose dependent manner. The present data indicates that PTZ at a convulsive dose induces an oxidative stress response by depleting the antioxidant defense systems and increasing lipid peroxidation in the erythrocytes, liver and brain of rats. Ghrelin pretreatment diminished oxidative stress and prevented the decrease in antioxidant enzyme activities, and thus may reduce neuronal death in the brain during seizures. However, further studies are needed in order to confirm our hypothesis.