Dejiang Feng

Oxidative stress in rat striatum after pilocarpine-induced seizures is diminished by alpha-tocopherol

Alpha-tocopherol has numerous nonenzymatic actions and is a powerful liposoluble antioxidant. The objective of the present study was to evaluate the neuroprotective effects of alpha-tocopherol in rats against oxidative stress caused by pilocarpine-induced seizures. Wistar rats were intraperitoneally treated with 0.9% saline (control group), alpha-tocopherol (200 mg/kg, alpha-tocopherol group), pilocarpine (400 mg/kg, pilocarpine group), or the combination of alpha-tocopherol (200 mg/kg) and pilocarpine (400 mg/kg, i.p.; alpha-tocopherol plus pilocarpine group). After the treatments, all groups were observed for 24 h. The superoxide dismutase (Mn-SOD) and catalase activities, lipid peroxidation and nitrite concentrations were measured using spectrophotometrically methods. To clarify the mechanism of alpha-tocopherol on oxidative stress in pilocarpine model, Western blot analysis of Mn-SOD and catalase in rat striatum were performed. In the pilocarpine group, rats showed a significant increase in lipid peroxidation and nitrite levels. However, there were no alterations on Mn-SOD activity. On the other hand, the catalase activity augmented in pilocarpine group. In the alpha-tocopherol and pilocarpine co-administered rats, antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content and increased the Mn-SOD and catalase activities in rat striatum after seizures. Pilocarpine, alpha-tocopherol plus pilocarpine and alpha-tocopherol groups did not affect of the Mn-SOD and catalase mRNA or protein levels. Our findings strongly support the hypothesis that oxidative stress occurs in striatum during pilocarpine-induced seizures, indicating that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, which implies that strong protective effect could be achieved using alpha-tocopherol.

Evaluation of central nervous system effects of iso-6-cassine isolated from Senna spectabilis var. excelsa (Schrad) in mice

The depressant and anticonvulsant activities of iso-6-cassine (ISO) from Senna spectabilis (0.5, 1.0 and 1.5mg/kg) injected by oral route in mice caused a significant decrease in the motor activity of animals when compared with the control group, up to 30 days after the administration and at dose of 1.5mg/kg, it reduced the remaining time of animals on Rota-rod apparatus. Additionally, ISO at doses tested was also capable to promote an increase of latency for development of convulsions induced by pentylenetetrazole and picrotoxin. These results suggest possible depressant and anticonvulsant activities in mice that need further investigation.

Lipoic acid blocks seizures induced by pilocarpine via increases in δ-aminolevulinic dehydratase and Na+, K+-ATPase activity in rat brain

In the present study we investigated the effects of lipoic acid (LA) on delta-aminolevulinic dehydratase (delta-ALA-D) and Na(+), K(+)-ATPase activities in rat brain after seizures induction by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), lipoic acid (10mg/kg, i.p., LA group), pilocarpine (400mg/kg, i.p., pilocarpine group), or the combination of LA (10mg/kg, i.p.) with pilocarpine (400mg/kg, i.p.), 30 min before administration of LA (LA plus pilocarpine group). After the treatments all groups were observed for 1h. The enzyme activities (delta-ALA-D and Na(+), K(+)-ATPase) were measured using spectrophotometric methods, and the results were compared with that obtained from saline and pilocarpine-treated animals. Neuroprotective effects of LA against seizures were evaluated based on those enzyme activities. The pilocarpine group showed a reduction in delta-ALA-D and Na(+), K(+)-ATPase activities after seizures. In turn, LA plus pilocarpine abolished the appearance of seizures and reversed the decreased in delta-ALA-D and Na(+), K(+)-ATPase activities produced by seizures, when compared to the pilocarpine seizing group. The results from the present study demonstrate that preadministration of LA abolished seizure episodes induced by pilocarpine in rat, probably by increasing delta-ALA-D and Na(+), K(+)-ATPase activities in rat brain during seizures.

Lipoic acid inhibits caspase-dependent and -independent cell death pathways and is neuroprotective against hippocampal damage after pilocarpine-induced seizures.

Alpha-lipoic acid has some neuroprotective properties, but this action has not been investigated in models of epilepsy. The aim of the present study was to investigate the protective efficacy of α-lipoic acid (lipoic acid) against pilocarpine-induced cell death through the caspase-dependent or -independent mitochondrial apoptotic pathways. Wistar rats were injected intraperitoneally with 0.9% saline (control group), pilocarpine (400 mg/kg, pilocarpine group) alone, or α-lipoic acid (20 mg/kg) in association with pilocarpine (400 mg/kg) 30 min before administration of α-lipoic acid. After the treatments all groups were observed for 24 h. Cell death was reduced in lipoic acid-treated rats. Cytosolic translocation of cytochrome c and subsequent activation of caspase-3 were reduced by lipoic acid treatment. AIF nuclear translocation and subsequent large-scale DNA fragmentation were also decreased in lipoic acid-treated rats. Our study suggests that lipoic acid inhibits both caspase-dependent and -independent apoptotic pathways and may be neuroprotective against hippocampal damage during pilocarpine-induced seizures.

Effects of ubiquinone on hydroperoxide concentration and antioxidant enzymatic activities in the rat hippocampus during pilocarpine-induced seizures.

Recent researches have shown that antioxidant compounds may have certain neuroprotective effect against the neurotoxicity of seizures at cellular level. Ubiquinone (UQ), an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. The objective of the present study was to evaluate the neuroprotective effects of UQ in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with either 0.9% saline (i.p., control group), UQ (5, 10 or 20 mg/kg, i.p., UQ5, UQ10 and UQ20 groups), pilocarpine (400 mg/kg, i.p., P400 group), or co-administration of pilocarpine with UQ group rats 30 min prior to UQ administration. After the treatments all groups were observed for 24 h. The antioxidant enzymatic activities as well as the hydroperoxide concentrations were measured using spectrophotometric methods and the results were analyzed. In pilocarpine group there was a significant increase in hydroperoxides concentration and glutathione peroxidase activity. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the hydroperoxide content and increased the superoxide dismutase, catalase and glutathione peroxidase activities in rat hippocampus during seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, which indicates that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences. Our result also suggests that ubiquinone can exert significant neuroprotective effects that might be useful in the treatment of neurodegenerative diseases.

Neuropharmacological effects of lipoic acid and ubiquinone on δ‐aminolevulinic dehydratase, Na+, K+‐ATPase, and Mg2+‐ATPase activities in rat hippocampus after pilocarpine‐induced seizures

In this study, we investigated the effects of lipoic acid (LA) in the hippocampus oxidative stress caused by pilocarpine‐induced seizures in adult rats. Wistar rats were treated with 0.9% saline (i.p., control group), LA (10 mg/kg, i.p., LA group), ubiquinone [20 mg/kg, i.p., ubiquinone (UQ) group], pilocarpine (400 mg/kg, i.p., P400 group), and the association of LA (10 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.) or UQ (20 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before of administration of P400 (LA plus P400 group and UQ plus P400 group, respectively). After the treatments, all groups were observed for 1 h. The enzyme activities (δ‐aminolevulinic dehydratase (δ‐ALA‐D), Mg2+‐ATPase, and Na+, K+‐ATPase) were measured using spectrophotometric methods, and the results compared to values obtained from saline and pilocarpine‐treated animals. Protective effects of LA and UQ were also evaluated on the same parameters. We reported here for the first time that Na+, K+‐ATPase and δ‐ALA‐D activities inhibition and Mg2+‐ATPase stimulation in the pilocarpine model are probably attributed to the oxidative stress caused by seizures in the rat hippocampus. The addition of the antioxidants LA and UQ may reverses the previously mentioned Na+, K+‐ATPase and δ‐ALA‐D inhibitions and Mg2+‐ATPase stimulation. Conclusions: The oxidative stress plays an important signaling role in pilocarpine‐induced seizures, and antioxidant drugs might be considered as therapeutical tools in this pathology.

Antioxidant mechanisms of iso-6-cassine in suppressing seizures induced by pilocarpine

The aim of this study was to evaluate the in vitro antioxidant effects of 12-[(2R,5R,6R)-5-hydroxy-6-methylpiperidin-2-yl]dodecan-2-one (iso-6-cassine; ISO) and the anticonvulsant effects of ISO on pilocarpine-induced seizures in rats. Wistar rats were treated with 0.9% saline (i.p., control group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of ISO (1.0 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min after administration of ISO (ISO plus pilocarpine group). After the treatments all groups were observed for 1h. The antioxidant effect of ISO on the pilocarpine model was assessed by determining the activity of glutathione peroxidase (GPx), glutathione-S-transferase (GST) and catalase (CAT) as well as the levels of reactive species (RS) and lipid peroxidation (LP). In vitro, ISO (5 μM) reduced RS and LP. ISO (1.0 mg/kg) and abolished seizures and death induced by pilocarpine in rats. ISO protected against the increase in the RS and LP levels, GST activity as well as the inhibition of GPx activity caused by pilocarpine. In addition, ISO increased the catalase activity in hippocampus of seized rats. In conclusion, the dta suggest that ISO can present anticonvulsant and antioxidant properties in the pilocarpine model of seizures in rats.

Lipoic acid effects on monoaminergic system after pilocarpine-induced seizures

Systemic injection of pilocarpine has been shown to induce recurrent seizures and epileptic discharges demonstrated by EEG monitoring. It also has been reported that antioxidants are able to diminish or prevent the occurrence of epileptic discharges induced by pilocarpine through the inhibition of free radical formation and neurotransmitter metabolic alterations. The purpose of this work was to determine the effects of lipoic acid (LA) on the levels of dopamine (DA), serotonin (5-HT), norepinephrine (NE) and subsequent metabolites in the hippocampus of rats after seizure induction by pilocarpine. Seizures dramatically decreased the levels of DA, 5-hydroxyindoleacetic acid (5-HIAA) and NE, whereas significantly increased the levels of neurotransmitter metabolites. The administration of lipoic acid before seizure induction resulted in normalized levels of DA and 5-HA. However, the lipoic acid administration in similar conditions produced a reduction of the metabolites levels when compared with the pilocarpine group. These results suggest that the establishment of acute phase of seizures induced by pilocarpine might be produced by consequent the activation of serotonergic neurons. In addition, the lipoic acid inhibits hyperactivity of this system during the installation of pilocarpine-induced seizures.