**3. Oxygen stress and AEDs in animal models**

### **3.1. Acetazolamide (AZM)**

AZM or saline was given i.p. to Spragué Dawley rats before exposing to *hyperbaric oxygen model* – the pressure of 6 ATA of pure oxygen (Huang et al., 2004). There was a significant difference in the latency of hyperbaric oxygen-induced convulsions between AZM (200 mg/kg and 20 mg/kg) groups and saline controls (p< 0.01) and there was no significant difference between AZM (2 mg/kg) and saline group (p> 0.05). GSH-Px and MDA was increased in homogenized cortex, hippocampus and striatum in different ways and depending on the time of exposure to AZM. The results, according to the authors, suggest that AZM, which dilates the brain arteriolae, increases the supply of the oxygen breaking into the brain structures and aggravates the oxidation with its consequences.

### **3.2. Carbamazepine**

rats may be due to reduced lipid peroxidation and increased catalase activity following

*Vitamin E and status epilepticus*. Barros et al. (2007) applied the same model and found that administration of vitamin E (200 mg/kg i.p.) 30 minutes prior to the administration of pilocar‐ pine (400 mg/kg s.c.) leads to increased (214%) catalase activity in the hippocampus compared with rats which were only given policarpine (67%) or physiological saline. The authors conclude that increased catalase activity may be responsible for the regulation of free radicals

In pilocarpine-induced status epilepticus in rats autophagy – a process of bulk degeneration of cellular constituents through autophagosome-lysosomal pathways was studied (Cao et al., 2009). Status epilepticus induces an excess production of ROS resulting in an increase of autophagy which was a partially inhibited by pretreatment with vitamin E. The strong protective effect of vitamin E could be achieved in the same pilocarpine seizure model (Tome et al., 2010) The authors confirmed that oxidative stress occurs in rat hippocampus resulting

in the brain damage and this plays a crucial role in seizure pathogenic consequences.

*Melatonin and valproic acid*. Prolonged melatonin administration in rats congenitally predis‐ posed to audiogenic convulsions (the Krushinsky-Molodkina model) had no effect on seizures evoked by a 20 times more powerful auditory stimulus (Savina et al., 2006). VPA administra‐ tion significantly reduced convulsions but VPA and melatonin combination had a significantly larger anti-seizure effect: it lengthened latency time and reduced seizure severity. However, combined treatment led to much more rapid onset of myoclonia than in groups receiving either

AZM or saline was given i.p. to Spragué Dawley rats before exposing to *hyperbaric oxygen model* – the pressure of 6 ATA of pure oxygen (Huang et al., 2004). There was a significant difference in the latency of hyperbaric oxygen-induced convulsions between AZM (200 mg/kg and 20 mg/kg) groups and saline controls (p< 0.01) and there was no significant difference between AZM (2 mg/kg) and saline group (p> 0.05). GSH-Px and MDA was increased in homogenized cortex, hippocampus and striatum in different ways and depending on the time of exposure to AZM. The results, according to the authors, suggest that AZM, which dilates the brain arteriolae, increases the supply of the oxygen breaking into the brain

convulsions and status epilepticus.

14 Pharmacology and Nutritional Intervention in the Treatment of Disease

evoked by the status epilepticus.

*2.2.6. The audiogenic seizure model*

**3. Oxygen stress and AEDs in animal models**

structures and aggravates the oxidation with its consequences.

VPA or melatonin.

**3.1. Acetazolamide (AZM)**

Short term CBZ administration to roinbout trout and a low level of oxidative stress could induce adaptive responses of antioxidant enzymes, however, long-term exposure to CBZ could lead to serious oxidative damage of *fish brain* (Li et al., 2010).

### **3.3. Lamotrigine**

LTG does not lead to detectable increases in lipid peroxidation in rats in vivo (Lu and Uetrecht, 2007). The anti-epileptic effectiveness of LTG in the *partial complex epilepsy model* (stimulation of the dentate gyrus) in rats was in reverse proportion to the level of nitric oxide (Sardo and Ferraro, 2007).

#### **3.4. Levetiracetam**

LEV (2000 mg/kg i.p.) administered prior to *pilocarpine administration* (400 mg/kg s.c.) in mice prevented lipid peroxidation increase in the hippocampus (but did not increase nitrate level or reduce catalase activity in the hippocampus or cortical glutathione) (Oliveira et al., 2007). Perhaps the anti-oxidising, neuroprotective effect of LEV and the consequent reduction of oxygen stress can be attributed to a different mechanism than the one which is active in the case of other AEDs.

#### **3.5. Phenobarbital (PB)**

Male Sprague – Dawley rats were pretreated with PB – a well known cytochrome P450 inducer (Dostalek et al., 2007). The markers of in vivo oxygen stress were influenced by PB resulting in significantly increased malondialdehyde, H2O2 generation and NADPH oxidation in vitro and significantly enhanced formation in vivo in liver and plasma.

#### **3.6. Phenytoin (PHT)**

PHT is known to produce ROS, which are involved in mechanism of the PHT-evoked terato‐ genesis and developmental toxicity. PHT initiates the oxidation damage to proteins and fats in the *maternal and embryonic liver tissue* organelle in murine rodents (Mahle and Dasgupta, 1997).

Gallagher and Sheehy (2010) used *cultured human prenatal liver slices* to study the effects of the human teratogen PHT on cell toxicity. Their findings in a relevant human model system are supportive of a protective role of GSH and alpha class glutathione S – transferases izoenzymes A1 against PHT toxicity and teratogenesis.

Using mutant catalase deficient mice and transgenic mice expressing human catalase, Abramov and Wells (2011) investigated protective importance of *embryonic catalase* against endogenous ROS and the ROS-imitating teratogen PHT in embryo culture. They provided evidence that the low level of embryonic catalase protects from developmental and xenobioticenhanced oxygen stress and that embryonic variations of this enzyme affect development.

### **3.7. Topiramate**

TPM with its many mechanisms of action has undoubted effectiveness in the treatment of epilepsy in children. However, TPM administered to rat stomach for 3 months may lead to such adverse effects as toxic liver dysfunction (Huang et al., 2007). In a study of young rats it was found that small doses of TPM (40 mg/kg a day) may reduce total antioxidant capacity in the organism and lead to minor liver pathology. Large doses of TPM (80 mg/kg a day) or a combination of TPM (40 mg/kg) and VPA (300 mg/kg a day) significantly increased the risk of such adverse effects. GSH levels in the liver were significantly lower in the group taking large doses of TPM and the TPM+VPA group compared with the group taking small doses of TPM and the control group which was only given distilled water. Histopathological examination also revealed disseminated punctual necrosis, and as well lipid and degenerative changes in some hepatocytes.

that these effects were well inhibited by pretreatment of isolated mitochondria with *cyclosporin A* and *butylated hydroxytoluene.* The data show that VPA exerts mitochondrial toxicity by impairing mitochondrial functions leading to oxidative stress and Cytochrome C expulsion

Epilepsy Treatment and Nutritional Intervention

http://dx.doi.org/10.5772/57484

17

The major mechanisms of antiepileptic ZNS are inhibition of voltage-gated Na(+) channel, Ttype voltage sensitive Ca(2+)channel, Ca(2+) relasing system and neuronal depolarization-

*In the KA convulsion model* in rats, pretreatment with ZNS led to increased anti-oxidant level in the hippocampus (Ueda et al., 2005). The study was performed in freely moving rats using in vivo microanalysis and electron paramagenetic resonance spectroscopy. In the authors'

Neuroprotective properties of ZNS also have been shown *in iron-induced epileptogenic foci* in the rat brain (Komatsu et al., 2000). The authors found that the level of 8-hydroxy-2. deoksy‐ guanosine (8-OHdG), which is used as a marker for oxidative DNA damage, increased 15 min after ferric chloride solution injections reaching maximum after 30 min. ZNS prevented the increase of the 8-OHdG within 30 min after iron solution injection. This effect may be due to the ZNS antioxidant activity and might be interesting to use it in prevention of posttraumatic epilepsy development due to blood extravasation and epileptogenic affect of free ferrum.

Pavone and Cardile (2003) studied effects of AEDs on oxygen stress in an *astrocyte culture from rats.* Selected list of studied variables includes: lactate dehydrogenase (LDH) and glutamine synthtase (GS) levels, ROS production, lipid peroxidation and DNA fragmentation. Drugs such as CBZ, TPM and OXC caused oxygen stress whatever their dose. Gabapentin (GBP), LEV, LTG, tiagabine (TGB) and ZNS on the other hand, caused no significant metabolic changes in large or small doses. Cortical astrocytes seem to tolerate this latter group of AEDs

Animal models of seizures, in particular, epilepsy and oxidative processes are useful for developing antiepileptic drugs (Majkowski et al., 2011; Rowles and Olsen, 2012). However, one of the main problems in transferring animal-based data to humans is to define effectiveness

*Omaga-3 fatty acids supplementation* was added to standard laboratory food for 6 weeks to aged 24 months old Wistar rats (Avramovic et al., 2012). The results showed befeneficial effects of omega-3 fatty acid on the brain cortex with increased SOD activity and decreased lipid peroxidation in contrast to the control grup. The changes in oxidative/antioxidative balance

induced glutamate release, and increased release of inhibitory neurotransmitters.

opinion, ZNS has neuroprotective properties against free radicals.

**4. Aging and anti-oxidants of omega-3 fatty acid**

which starts cell death signaling (Jafarian et al., 2013).

**3.9. Zonisamide (ZNS)**

**3.10. Old and new AEDs**

better than the former ones.

of a dose.

TPM (40 and 80 mg/kg i.p.) had no effect on either rats' KA-induced status epilepticus or mortality but larger doses significantly reduced KA-produced lipid peroxidation (Kubera et al., 2004).

Treatment of diabetic mice with TPM, a potent mitochondrial carbonic anhydrazes (CA) inhibitor, prevented the oxidative stress caused by diabetes (Price et al., 2012). The authors studied the effects of pharmacological inhibition of mitochondrial CA activity on *streptozotocin induced-oxidative stress* and pericytes loss in the mouse brain. Pericytes are in immediate contact with endothelial cells and are vital for blood-brain barier integrity. These results provide for the first time evidence that inhibition of mitochondrial CA activity reduces diabetes-reduced oxidative stress in the mouse brain and rescuses cerebral policytes dropout. Mitochondrial CA may provide a new therapeutic targed for oxidative stress related impairments of the brain.

Anti-oxidant activity of TPM was shown also in vitro study (Cardenas-Rodrigues et al., 2013a). The results show that TPM displays scavenging capacity of superoxide, hydroxyl radical, hypochlorus acid, hydrogen peroxide, signled oxygen but not to peroxynitrite. Although TPM was less efficient than *nordihydroguaiaretic acid*, *dimethylthiourea, ascorbic acid, sodium pyruvate and glutathione* in its scavenging capacity. The authors conclude that antioxidant properties of TPM could explain it's the neuroprotective effect.

#### **3.8. Valproic acid**

In model of rat *cortical cell culture*, VPA was found to protect against the negative effects of oxygen stress (Wang et al., 2003). Administration of VPA for 7 days prevented lipid and protein oxidization anomalies and accumulation of free radicals. Short-term administration of VPA affects one or more of the neuroprotective processes.

Several mechanisms were suggested for VPA hepatotoxicity, however, most of them are associated with oxygen stress resulting in mitochondrial dysfunction. Rat liver mitochondria were obtained by differential ultra centrifugation and then incubated with different concen‐ tration of VPA (25-200µM) (Jafarian et al., 2013). The results showed that VPA could induce oxidative stress via rising in mitochondrial ROS, lipid peroxidation, mitochondrial membrane potential collapse, mitochondrial swelling and release of Cytochrome C. The authors found that these effects were well inhibited by pretreatment of isolated mitochondria with *cyclosporin A* and *butylated hydroxytoluene.* The data show that VPA exerts mitochondrial toxicity by impairing mitochondrial functions leading to oxidative stress and Cytochrome C expulsion which starts cell death signaling (Jafarian et al., 2013).
