Seema Yousuf

Resveratrol exerts its neuroprotective effect by modulating mitochondrial dysfunctions and associated cell death during cerebral ischemia

Free radicals are known to cause secondary neuronal damage in cerebral ischemia/reperfusion (I/R). We investigated here the neuroprotective effect of resveratrol, a potent antioxidant present in grape seed, against cerebral I/R-induced mitochondrial dysfunctions in hippocampus. Transient rat middle cerebral artery occlusion (MCAO) model of brain ischemia was used to induce brain infarction. Resveratrol (10(-7) g/kg) was given twice intravenously: 15 min pre-occlusion and at the time of reperfusion (2 h post-occlusion). Resveratrol significantly restored ATP content and the activity of mitochondrial respiratory complexes in resveratrol treated group which were severely altered in MCAO group. Western blot analysis showed a marked decrease in cytochrome c release as a result of resveratrol treatment. Electrophoretic migration of hippocampal genomic DNA showed a marked decrease in DNA fragmentation after resveratrol treatment. Notably, expression of Hsp70 and metallothionein (MT) was significantly higher in MCAO group but their expression was more significant in resveratrol treated group. The status of mitochondrial glutathione (GSH), glucose 6-phosphate dehydrogenase (G6-PD) and serum lactate dehydrogenase (LDH) was restored by resveratrol treatment with a significant decrease in mitochondrial lipid peroxidation (LPO), protein carbonyl and intracellular H(2)O(2) content. Resveratrol significantly improved neurological deficits assessed by different scoring methods. Also, the brain infarct volume and brain edema were significantly reduced. Histological analysis of CA1 hippocampal region revealed that resveratrol treatment diminished intercellular and pericellular edema and glial cell infiltration. The findings of this study highlight the ability of resveratrol in anatomical and functional preservation of ischemic neurovascular units and its relevance in the treatment of ischemic stroke.

Neuroprotective effects of Withania somnifera on 6-hydroxydopamine induced Parkinsonism in rats

6-Hydroxydopamine (6-OHDA) is one of the most widely used rat models for Parkinsons disease. There is ample evidence in the literature that 6-OHDA elicits its toxic manifestations through oxidant stress. In the present study, we evaluated the anti-parkinsonian effects of Withania somnifera extract, which has been reported to have potent anti-oxidant, anti-peroxidative and free radical quenching properties in various diseased conditions. Rats were pretreated with 100, 200 and 300 mg/kg b.w. of the W. somnifera extract orally for 3 weeks. On day 21, 2 mL of 6-OHDA (10 mg in 0.1% in ascorbic acidsaline) was infused into the right striatum while sham operated group received 2 mL of the vehicle. Three weeks after 6-OHDA injections, rats were tested for neurobehavioral activity and were killed 5 weeks after lesioning for the estimation of lipidperoxidation, reduced glutathione content, activities of glutathione-S-transferase, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase, catecholamine content, dopaminergic D2 receptor binding and tyrosine hydroxylase expression. W. somnifera extract was found to reverse all the parameters significantly in a dose-dependent manner. Thus, the study demonstrates that the extract of W. somnifera may be helpful in protecting the neuronal injury in Parkinsons disease.

Amelioration of cognitive deficits and neurodegeneration by curcumin in rat model of sporadic dementia of Alzheimer's type (SDAT).

Recent evidence indicates that curcumin (CUR), the principal curcuminoid of turmeric, exhibits antioxidant potential and protects the brain against various oxidative stressors. The aim of the present study was to examine the modulating impacts of CUR against cognitive deficits and oxidative damage in intracerebroventricular-streptozotocin (ICV-STZ) infused rats. Rats were injected bilaterally with ICV-STZ (3 mg/kg), while sham rats received the same volume of vehicle and then supplemented with CUR (80 mg/kg) for three weeks. After two weeks of ICV-STZ infusion, rats were tested for cognitive performance using passive avoidance and water maze tasks and then sacrificed for biochemical and histopathological assays. ICV-STZ rats showed significant cognitive deficits, which were significantly improved by CUR supplementation. CUR supplementation significantly augmented increased 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA), thiobarbituric reactive substances (TBARS), hydrogen peroxide (H2O2), protein carbonyl (PC) and oxidized glutathione (GSSG); decreased levels of reduced glutathione (GSH) and its dependent enzymes (Glutathione peroxidase [GPx] and glutathione reductase [GR]) in the hippocampus and cerebral cortex; and increased choline acetyltransferase (ChAT) activity in the hippocampus of ICV-STZ rats. The study suggests that CUR is effective in preventing cognitive deficits, and might be beneficial for the treatment of sporadic dementia of Alzheimers type (SDAT).

Neuroprotection by crocetin in a hemi-parkinsonian rat model

Reactive oxygen species (ROS) are implicated as the leading biochemical cause of neuronal death in various neurologic disorders, including Parkinsons disease. In the present study, neuromodulatory effects of crocetin (active constituent of Crocus sativus) in a 6-hydroxydopamine (6-OHDA) model of rat Parkinsonism were investigated. Male Wistar rats were pre-treated with crocetin (25, 50 and 75 microg/kg body weight) for 7 days and subjected to unilateral intrastriatal injection of 10 microg 6-OHDA on day 8. Locomotion and rotation were observed on day 23 post-injection, and after 4 weeks, striatum and substantia nigra were dissected out by decapitation. Activity of antioxidant enzymes and content of dopamine (DA) and its metabolites were estimated in striatum, whereas glutathione (GSH) content and thiobarbituric acid reactive substance (TBARS) were evaluated in substantia nigra. Levels of GSH and dopamine were protected, while TBARS content was attenuated in crocetin-treated groups. The activity of antioxidant enzymes was decreased in the lesion group, but protected in the crocetin-treated groups. These findings were supported by the histopathologic findings in the substantia nigra that showed that crocetin protects neurons from deleterious effects of 6-OHDA. This study revealed that crocetin, which is an important ingredient of diet in India and also used in various systems of indigenous medicine, is helpful in preventing Parkinsonism and has therapeutic potential in combating this devastating neurologic disorder.

Selenium prevents cognitive decline and oxidative damage in rat model of streptozotocin-induced experimental dementia of Alzheimer's type

Selenium (Se), a nutritionally essential trace element with known antioxidant potential, protects the brain from oxidative damage in various models of neurodegeneration. Intracerebroventricular-streptozotocin (ICV-STZ) in rats causes impairment of brain glucose and energy metabolism along with oxidative damage and cholinergic dysfunction, and provides a relevant model for sporadic dementia of Alzheimers type (SDAT). The present study demonstrates the therapeutic efficacy of Se on cognitive deficits and oxidative damage in ICV-STZ in rats. Male Wistar rats were pre-treated with sodium selenite, a salt of Se (0.1 mg/kg; body weight) for 7 days and then were injected bilaterally with ICV-STZ (3 mg/kg), while sham rats received the same volume of vehicle. After two ICV-STZ infusions, rats were tested for memory deficits in passive avoidance and Morris water maze (MWM) tests and then were sacrificed for biochemical and histopathological assays. ICV-STZ-infused rats showed significant loss in learning and memory ability, which were significantly improved by Se supplementation. A significant increase in thio-barbituric acid reactive species (TBARS), protein carbonyl (PC) and a significant decrease in reduced glutathione (GSH), antioxidant enzymes (glutathione peroxidase [GPx] and glutathione reductase [GR]) and adenosine triphosphate (ATP) in the hippocampus and cerebral cortex and choline acetyltransferase (ChAT) in hippocampus were observed in ICV-STZ rats. Se supplementation significantly ameliorated all alterations induced by ICV-STZ in rats. Our study reveals that Se, as a powerful antioxidant, prevents cognitive deficits, oxidative damage and morphological changes in the ICV-STZ rats. Thus, it may have a therapeutic value for the treatment of SDAT.

Coenzyme Q10 modulates cognitive impairment against intracerebroventricular injection of streptozotocin in rats

Coenzyme Q10 (CoQ10), a peculiar lipophilic antioxidant, is an essential component of the mitochondrial electron-transport chain. It is involved in the manufacturing of adenosine triphosphate (ATP) and has been linked with improving cognitive functions. The present study shows the neuroprotective effect of CoQ10 on cognitive impairments and oxidative damage in hippocampus and cerebral cortex of intracerebroventricular-streptozotocin (ICV-STZ) infused rats. Male Wistar rats (1-year old) were infused bilaterally with an ICV injection of STZ (1.5 mg/kg b.wt., in normal saline), while sham group received vehicle only. After 24 h, the rats were supplemented with CoQ10 (10 mg/kg b.wt. i.p.) for 3 weeks. The learning and memory tests were monitored 2 weeks after the lesioning. STZ-infused rats showed the loss of cognitive performance in Morris water maze and passive avoidance tests. Three weeks after the lesioning, the rats were sacrificed for estimating the contents of thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), protein carbonyl (PC), ATP and the activities of glutathione peroxidase (GPx), glutathione reductase (GR), cholineacetyltransferase (ChAT) and acetylcholinesterase (AChE). Significant alteration in the markers of oxidative damage (TBARS, GSH, PC, GPx and GR) and a decline in the level of ATP were observed in the hippocampus and cerebral cortex of ICV-STZ rat. A significant decrease in ChAT activity and a concomitant increase in AChE activity were observed in the hippocampus. However, supplementation with CoQ10 in STZ-infused rats reversed all the parameters significantly. Thus, the study demonstrates that CoQ10 may have a therapeutic importance in the treatment of Alzheimers type dementia.

Ginkgo biloba affords dose‐dependent protection against 6‐hydroxydopamine‐induced parkinsonism in rats: neurobehavioural, neurochemical and immunohistochemical evidences

Ginkgo biloba extract (EGb), a potent antioxidant and monoamine oxidase B (MAO‐B) inhibitor, was evaluated for its anti‐parkinsonian effects in a 6‐hydroxydopamine (6‐OHDA) rat model of the disease. Rats were treated with 50, 100, and 150 mg/kg EGb for 3 weeks. On day 21, 2 µL 6‐OHDA (10 µg in 0.1% ascorbic acid saline) was injected into the right striatum, while the sham‐operated group received 2 µL of vehicle. Three weeks after 6‐OHDA injection, rats were tested for rotational behaviour, locomotor activity, and muscular coordination. After 6 weeks, they were killed to estimate the generation of thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) content, to measure activities of glutathione‐S‐transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), and to quantify catecholamines, dopamine (DA) D2 receptor binding, and tyrosine hydroxylase‐immunoreactive (TH‐IR) fibre density. The increase in drug‐induced rotations and deficits in locomotor activity and muscular coordination due to 6‐OHDA injections were significantly and dose‐dependently restored by EGb. The lesion was followed by an increased generation of TBARS and significant depletion of GSH content in substantia nigra, which was gradually restored with EGb treatment. EGb also dose‐dependently restored the activities of glutathione‐dependent enzymes, catalase, and SOD in striatum, which had reduced significantly by lesioning. A significant decrease in the level of DA and its metabolites and an increase in the number of dopaminergic D2 receptors in striatum were observed after 6‐OHDA injection, both of which were significantly recovered following EGb treatment. Finally, all of these results were exhibited by an increase in the density of TH‐IR fibers in the ipsilateral substantia nigra of the lesioned group following treatment with EGb; the lesioning had induced almost a complete loss of TH‐IR fibers. Considering our behavioural studies, biochemical analysis, and immunohistochemical observation, we conclude that EGb can be used as a therapeutic approach to check the neuronal loss following parkinsonism.

Selenium plays a modulatory role against cerebral ischemia-induced neuronal damage in rat hippocampus

During cerebral ischemic cascade, a unifying factor which leads to mitochondrial dysfunctions is lack of oxygen followed by decrease in ATP production. The present study demonstrates the effect of selenium pretreatment (0.1 mg/kg as sodium selenite, i.p, 7 days) on cerebral ischemia-induced altered levels of mitochondrial ATP content, intracellular calcium (Ca(i)(2+)) in synaptosomes, expression of heat stress protein (Hsp70) and caspase-3 activity in hippocampus followed by neurobehavioral deficits and histopathological changes in Wistar rats. Cerebral ischemia was induced for 2 h followed by reperfusion for 22 h. It was observed that levels of (Ca(i)(2+)), Hsp70 and caspase-3 activity were significantly (p<0.01-0.001) higher with a marked decrease in ATP level in hippocampus of ischemic group as compared to sham values. Subsequently, a marked change was observed in neurobehavioral activities in ischemic animals as compared to control one. As a result of selenium pretreatment, a significant (p<0.05-0.001) trend of restoration was observed in the level of ATP, (Ca(i)(2+)), Hsp70, caspase-3 and behavioral outputs as compared to ischemic group. Histopathological analysis confirmed the protective effect of selenium against cerebral ischemia induced histological alterations as evidenced by lesser edema formation and separation of cells with minimal microglial cell infiltration in selenium pretreated group as compared to ischemic animals. The present study suggests that selenium may be able to salvage the ischemic penumbral zone neurons, thereby limiting ischemic cell death.

Attenuation by Nardostachys jatamansi of 6-hydroxydopamine-induced parkinsonism in rats: Behavioral, neurochemical, and immunohistochemical studies

Parkinsons disease (PD) is one of the commonest neurodegenerative diseases, and oxidative stress has been evidenced to play a vital role in its causation. In the present study, we evaluated whether ethanolic extract of Nardostachys jatamansi roots (ENj), an antioxidant and enhancer of biogenic amines, can slow the neuronal injury in a 6-OHDA-rat model of Parkinsons. Rats were treated with 200, 400, and 600 mg/kg body weight of ENj for 3 weeks. On day 21, 2 microl of 6-OHDA (12 microg in 0.01% in ascorbic acid-saline) was infused into the right striatum, while the sham-operated group received 2 microl of vehicle. Three weeks after the 6-OHDA injection, the rats were tested for neurobehavioural activity and were sacrificed after 6 weeks for the estimation of lipid peroxidation, reduced glutathione content, the activities of glutathione-S-transferase, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase, quantification of catecholamines, dopaminergic D2 receptor binding and tyrosine hydroxylase expression. The increase in drug-induced rotations and deficits in locomotor activity and muscular coordination due to 6-OHDA injections were significantly and dose-dependently restored by ENj. Lesioning was followed by an increased lipid peroxidation and significant depletion of reduced glutathione content in the substantia nigra, which was prevented with ENj pretreatment. The activities of glutathione-dependent enzymes, catalase and superoxide dismutase in striatum, which were reduced significantly by lesioning, were dose-dependently restored by ENj. A significant decrease in the level of dopamine and its metabolites and an increase in the number of dopaminergic D2 receptors in striatum were observed after 6-OHDA injection, and both were significantly recovered following ENj treatment. All of these results were exhibited by an increased density of tyrosine hydroxylase immunoreactive (TH-IR) fibers in the ipsilateral striatum of the lesioned rats following treatment with ENj; 6-OHDA injection had induced almost a complete loss of TH-IR fibers. This study indicates that the extract of Jatamansi might be helpful in attenuating Parkinsonism.

Restraint stress-induced oxidative damage and its amelioration with selenium

Stress is a state of threatened cellular homeostasis which results in free radical generations and subsequent oxidative damage. The aim of this study was to evaluate the effect of selenium on restraint stress-induced oxidative damage in hippocampus, striatum and frontal cortex. Rats were pre-treated with sodium selenite (0.3 mg/kg; intraperitoneally) for 15 days and divided into six groups (n=8). Rats were then subjected to restraint stress for 1 h and 4 h. Lipid peroxidation, glutathione (GSH) and activities of antioxidant enzymes viz. selenium-dependent glutathione peroxidase (Se-GPx), glutathione reductase (GR), glutathione S-transferase (GST) and catalase were evaluated in the frontal cortex, striatum and hippocampus. Restraint stress-induced for 1 h and 4 h caused a significant decrease (P<0.001) in intracellular GSH content and the activity of Se-GPx, GR, GST and catalase with a significant increase (P<0.001) in the level of lipid peroxidation in all 3 regions of the brain. Selenium pre-treatment exhibited restoration of antioxidant enzymes activity, GSH content and decrease in the level of lipid peroxidation in hippocampus, striatum and frontal cortex in both 1 h and 4 h restraint stress groups. Protective effect of selenium pre-treatment was found to be more pronounced in 4 h restraint stress group as compared to 1 h restraint stress group. Selenium per se had no effect on GSH, lipid peroxidation level or activities of antioxidant enzymes in hippocampus, striatum and frontal cortex. In conclusion, selenium pre-treatment protected the brain against restraint stress-induced oxidative damage at 4 h in hippocampus, striatum and frontal cortex.