Table 1.

Evidence of the GSH system in experimental epilepsy models.

Model	Procedure model	Observations	References
Electrical implants in male Sprague-Dawley rats (300–500 g)	Insulated stainless steel electrodes were implanted in the left dentate gyrus and angular bundle. During the experiments, video-EEG was continuously recorded (24 h/day) until the animals were sacrificed. Plasma was used by biochemical determinations.	The glutathione PEGylated (GSH-PEG) liposomal methylprednisolone (MP) treatment did not have any effect on SE duration and subsequent seizure development. Both the GSH-PEG liposomal MP-treated and vehicle-treated rats developed spontaneous seizures, indicating that GSH-PEG liposomal MP could not prevent epileptogenesis.	[108]
Hippocampal glutamine synthetase deficiency by continuous microinfusion of methionine sulfoximine (MSO) in male Sprague-Dawley rats (180–220 g)	An osmotic pump was introduced through a burr hole in the skull and then into the right hippocampus. The pumps were filled with MSO to achieve the following drug delivery rates: 2.5, 1.25, and 0.625 µg/h for approximately 28 days. Separate pumps were filled with saline (0.9% NaCl) as a control. For the GSH determination, the hippocampi were isolated. GSH was measured using the spectrophotometric method with 5-thio-2-nitrobenzoic acid in a reaction coupled with GR.	Recurrent behavioral seizures occurred with all doses of MSO. The intrahippocampal infusion of MSO was associated with a dose-dependent loss of neurons in the hippocampal formation and nearby brain areas. No decrease in hippocampal GSH was observed in the lower-dosed animals (0.625 µg/h), whereas a 21% decrease was observed in the higher-dosed animals (2.5 µg/h) 10 days after the onset of MSO infusion.	[109]
Lithium-pilocarpine in male Sprague-Dawley rats (260–300 g)	Lithium chloride (LiCl) (127 mg/kg) was injected intraperitoneally (i.p.) into both the experimental and control groups. Status epilepticus (SE) was induced by a subcutaneous injection of pilocarpine hydrochloride (25 mg/kg) 20 h after the LiCl treatment. For the GSH determination, the hippocampus, dentate gyrus, amygdala, entorhinal, piriform cortices (hippocampal formation), cerebral cortex, and cerebellum were removed and evaluated by high-performance liquid chromatography (HPLC).	The concentration of GSH was decreased in the hippocampal formation (22.6%) and cerebellum (6%) in the epileptic rats.	[110]
Pilocarpine in 7- to 8-week-old male CD1 mice (25–40 g)	A single dose of pilocarpine was administered (330–345 mg/kg subcutaneously). All determinations with pilocarpine and controls were realized within 3.5–4 weeks after treatment, and the cerebral cortices, HF, and blood samples were obtained. The GSH levels were measured by HPLC.	The level of GSH was significantly decreased (18%) in the hippocampal formation, whereas it was not significantly altered in the cortex in the pilocarpine mice.	[111]
Pilocarpine in 2-month-old male Wistar rats (250–280 g)	The control animals received 0.9% i.p. saline, and in the experimental group, the animals were treated with a dose of pilocarpine hydrochloride (400 mg/kg, i.p.). To determine the lipid peroxidation level, nitrite content, GSH concentration, and SOD and CAT activities, the rats (pilocarpine and control groups) were sacrificed 24 h after the treatment, and the brains were dissected on ice to remove the frontal cortex and striatum.	After pilocarpine-induced SE, significant increases (i.e., 47 and 59%) in the thiobarbituric acid reactive substance (TBARS) levels in the striatum and frontal cortex were observed. Marked increases were presented in nitrite content: 49 and 73% in the striatum and frontal cortex, respectively; the GSH concentrations decreased by 54 and 58% in the striatum and frontal cortex, respectively; the SOD in frontal cortex was verified by its increase of 24% after the seizures; and CAT increases of 39 and 49% were observed in the striatum and frontal cortex, respectively.	[112]
Pilocarpine-lithium in 80- to 90-day-old male and female Wistar rats	SE was induced by administering pilocarpine hydrochloride (30 mg/kg i.p.) 22 h after LiCl (127 mg/kg i.p.). SE was interrupted after 2 h, and the rats were sacrificed 24 h later. The piriform and entorhinal cortices, temporal neocortex, thalamus, and hippocampus were dissected. Neurochemical determinations were performed using spectrophotometric methods: lipid peroxidation was analyzed by measuring the TBARS levels; SOD activity was analyzed with the xanthine-xanthine oxidase system, and GPx was analyzed by reducing the cumene hydroperoxide using GSH as a reducing agent.	The TBARS levels in all of the examined structures were significantly higher in the rats with SE: approximately 41% higher in the piriform and entorhinal cortices; 22% higher in the temporal neocortex; 25.7% higher in the thalamus and 15% higher in the hippocampus. SOD activities were significantly higher in the rats with SE in the piriform and entorhinal cortices (11.7%) and temporal neocortex (19.7%). The GPx activities were significantly higher in the animals with SE in the piriform and entorhinal cortices (22.1%) and thalamus (8.9%). The authors did not observe significant sex-treatment interactions in the results in any of the investigated brain regions.	[113]
Pilocarpine in male Wistar rats (250–350 g)	The experimental group was injected with pilocarpine (350 mg/kg i.p.), and the control rats were injected with a physiological salt solution. The rats were sacrificed by decapitation 2 h after drug administration, and the cortical regions were removed. Neurochemical determinations were performed by spectrophotometric methods: lipid peroxidation was analyzed by measuring the oxidative marker malondialdehyde (MDA); SOD activity was measured with the xanthine/xanthine oxidase system; GPx was measured with H2O2 as the substrate and GR and NADPH as the enzymatic and nonenzymatic indicators, respectively; CAT activity was measured by H2O2 decomposition and GR and NADPH as the enzymatic and nonenzymatic indicators, respectively. The mRNA expression of the antioxidant enzymes was determined by real-time RT-PCR.	Pilocarpine increased the MDA levels (64%). All enzymatic activities were measured, and CAT, GPx, and SOD significantly increased in response to pilocarpine (28%, 28%, and 21%, resp.). The GPx gene expression significantly increased in the pilocarpine group (1.47-fold), and the Mn-SOD expression also significantly increased (1.33-fold). The CAT expression was unchanged.	[114]
Kainite in male Sprague-Dawley rats (300–350 g)	The rats were subcutaneously administered saline or 11 mg/kg kainite. The rats were sacrificed after 1 min of carbon dioxide inhalation and then were immediately decapitated at 8 h, 24 h, 48 h, 1 week, 3 weeks, and 6 weeks after injection to determine the acute, latent, and chronic periods of epileptogenesis. The hippocampal tissue was prepared for biochemical analysis. GSH and GSSG were determined by HPLC.	Whole hippocampal tissue GSH decreased during the acute, latent, and chronic stages of the experimental temporal lobe epilepsy (TLE). Hippocampal tissue GSSG levels increased substantially at 48 h after kainate treatment. Acute GSSG was increased at the 8 and 24 h time points. During the latent period, GSSG was elevated from 1 to 6 weeks after the kainite treatment. The GSH/GSSG ratio was significantly decreased in the kainate treatment groups from 24 h through 6 weeks.	[115]