Byproducts of protein, lipid and DNA oxidative damage and antioxidant enzyme activities in seizure

Purpose: To get more insight into molecular mechanisms underlying oxidative stress and its role in different types of seizure, in this study, oxidative byproducts of proteins, lipids and DNA, as well as, antioxidant enzyme activities were studied in adult patients with epilepsy.

Methods: Study was performed in 60 patients with epilepsy and in 25 healthy controls. Plasma protein reactive carbonyl derivatives (RCD) and protein thiol groups (P-SH), byproducts of oxidative protein damage, as well as antioxidant enzyme activities, superoxide dismutase (SOD) and glutathione peroxidase (GPX) were studied spectrophotometrically. Urinary 8-epi-prostaglandin F(2alpha) (8-epi-PGF(2alpha)) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), representative byproducts of lipid and DNA oxidative damage, respectively, were determined by enzyme immunoassay.

Results: RCD levels were significantly increased (p=0.001), while P-SH content was decreased in patients with first seizure (p=0.052) compared to controls, independently of the seizure type. Urinary 8-epi-PGF(2alpha) and 8-OHdG were significantly increased in patients with epilepsy (p=0.001 and p=0.001). Rise in 8-epi-PGF(2alpha) was more pronounced in patients with generalized tonic-clonic seizure (GTCS) compared to those with partial seizure (PS). Both SOD and GPX activity were significantly increased in epileptic patients compared to controls (p=0.001 and p=0.001), but only SOD activity was significantly higher in patients with GTCS than in those with PS.

Conclusions: Data on enhanced protein, lipid and DNA oxidation, together with upregulated antioxidant enzyme activities, confirm the existence of systemic oxidative stress in patients with epilepsy. It might be speculated that post-translational modification to existing functional proteins, particularly alterations to ion channels, might be at least partially responsible for acute early changes in neuronal networks.