Global Ischemia In Gerbils Research Articles

Effect of L-Deprenyl on the Putrescine Level and Neuronal Damage after Transient Global Cerebral Ischemia in Gerbils

L-Deprenyl is selective and irreversible monoamine oxidase B inhibitor, known to have neuroprotective properties. Putrescine, one of polyamine, is thought to be important in the neuronal cell damage associated with various type of excitatory neurotoxicity. We examined the effects of L-deprenyl on the changes in putrescine level and neuronal damage after transient global ischemia in ger-bils. Male Mongolian gerbils weighing 65 - 75 g were used in the experiment. Global ischemia was induced by occlusion of common carotid arteries for 3 min to observe neuronal injury in hippocampal pyramidal cells. L-Deprenyl group was given 10 mg/kg of L-deprenyl intraperitoneally immediately after, 3 h and 6 h after global ischemia. Treated animals were processed in parallel with ischemic animals receiving saline as a vehicle and with sham- operated controls. Hippocampal putrescine level was increased by global ischemia and inhibited by L-deprenyl treatment. In histological findings, counts of viable neurons were made in the pyramidal cell layer of the hippocampal CA1 area 3 days after ischemic insult. The number of viable neurons in the pyramidal cell layer of CA1 area was significantly increased in animals treated with L-deprenyl compared to vehicle-treated ischemic animals (p < 0.05). In terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick endlabeling (TUNEL) assay, semiquantitative analysis of dark-brown neuronal cells was made in the hippocampal CA1 area. There was also a significant difference in the degree of TUNEL staining in the hippocampal CA1 area between vehi-cle-treated and L-deprenyl-treated animals (p < 0.05). These data show L-deprenyl is effective as a prophylactic treatment for neuronal injury when it is administrated before ischemia but a further study need to know the effects of administration of L-deprenyl after ischemia and at given times after reper-fusion.

Dexmedetomidine alleviates cerebral ischemia-induced short-term memory impairment by inhibiting the expression of apoptosis-related molecules in the hippocampus of gerbils.

Cerebral ischemia results from cerebrovascular occlusion, which leads to neuronal cell death and eventually causes neurological impairments. Dexmedetomidine is a potent and highly selective α2-adrenoreceptor agonist with actions such as sedation, anxiolysis, analgesia and anesthetic-sparing effects. We investigated the effect of dexmedetomidine on apoptosis in the hippocampus after transient global ischemia in gerbils. Transient global ischemia was induced by ligation of both common carotid arteries. Dexmedetomidine was administrated intraperitoneally at three respective doses (0.1, 1 and 10 µg/kg) once per day for 14 consecutive days beginning a day after surgery. Short-term memory was assessed by use of a step-down avoidance task. Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay, immunohistochemistry for caspase-3, and western blot analysis of Bcl-2-associated X protein, B-cell lymphoma 2, Bid, cytochrome c, apoptotic protease activating factor-1 and caspase-9 in the hippocampus. Induction of global ischemia deteriorated short-term memory by enhancing the expression of apoptosis-related molecules in the hippocampus. Treatment with dexmedetomidine suppressed the expression of apoptosis-related molecules under ischemic conditions, resulting in short-term memory improvement. Under normal conditions, dexmedetomidine exerted no significant effect on apoptosis in the hippocampus. The present results suggest that the α2-adrenoceptor agonist dexmedetomidine may be a useful therapeutic agent for the treatment of ischemic brain diseases.

Aqueous extract of Cordyceps alleviates cerebral ischemia-induced short-term memory impairment in gerbils.

Cerebral ischemia is caused by reduced cerebral blood flow due to a transient or permanent cerebral artery occlusion. Ischemic injury in the brain leads to neuronal cell death, and eventually causes neurological impairments. Cordyceps, the name given to the fungi on insects, has abundant useful natural products with various biological activities. Cordyceps is known to have nephroprotective, hepatoprotective, anti-inflammatory, antioxidative, and antiapoptotic effects. We investigated the effects of Cordyceps on short-term memory, neuronal apoptosis, and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils. For this study, a step-down avoidance test, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunohistochemistry for caspase-3 and 5-bromo-2′-de-oxyuridine, and western blot for Bax, Bcl-2, brain-derived neurotrophic factor (BDNF), and tyrosin kinase B were performed. In the present study, Cordyceps alleviated cerebral ischemia-induced short-term memory impairment. Cordyceps showed therapeutic effects through inhibiting cerebral ischemia-induced apoptosis in the hippocampus. Cordyceps suppressed cerebral ischemia-induced cell proliferation in the hippocampal dentate gyrus due to the reduced apoptotic neuronal cell death. Cordyceps treatment also enhanced BDNF and TrkB expressions in the hippocampus of ischemic gerbils. It can be suggested that Cordyceps overcomes cerebral ischemia-induced neuronal apoptosis, thus facilitates recovery following cerebral ischemia injury.

Ulinastatin inhibits cerebral ischemia-induced apoptosis in the hippocampus of gerbils.

Ulinastatin is a urinary trypsin inhibitor, originally extracted and purified from human urine. Ulinastatin has cytoprotective effects against ischemic injury in several organs. In the present study, the neuroprotective effects of ulinastatin following ischemic cerebral injury in the hippocampus of gerbils was investigated. To induce transient global ischemia in gerbils, the common carotid arteries were occluded using aneurysm clips for 5 min, and the clips were then removed. Ulinastatin was subcutaneously injected into the gerbils once a day for 7 days at doses of 50,000 or 100,000 U/kg. The gerbils were confronted with a step-down avoidance task, following which tissue samples from the gerbils were examined using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, western blot analysis for B-cell lymphoma (Bcl-2) and Bcl-2-associated X protein (Bax), immunohistochemistry for caspase-3 and immunofluorescence for 5-bromo-2′-deoxyuridine. The numbers of TUNEL-positive and caspase-3-positive cells in the hippocampal CA1 region increased following cerebral ischemia. The expression of Bax in the hippocampus increased, while the expression of Bcl-2 in the hippocampus decreased following cerebral ischemia. These results confirmed that apoptosis in the hippocampus was enhanced following cerebral ischemia in gerbils. The levels of cell proliferation in the hippocampal dentate gyrus were also enhanced by ischemia, which is possibly an adaptive mechanism to compensate for excessive levels of apoptosis. Ulinastatin treatment inhibited ischemia-induced apoptosis by suppressing apoptosis-associated molecules, and thus ameliorated ischemia-induced short-term memory impairment. The cell proliferation in the hippocampus was also suppressed following ulinastatin treatment. These results suggested the use of ulinastatin as a therapeutic agent for patients with cerebral stroke.

Aerobic exercise alleviates ischemia-induced memory impairment by enhancing cell proliferation and suppressing neuronal apoptosis in hippocampus.

PurposeNeurogenic lower urinary tract dysfunction (NLUTD) is a possible consequence of several neurological disorders. NLUTD may produce debilitating symptoms and serious complications, such as chronic renal failure, and recurrent urinary tract infections. Many animal studies of NLUTD symptoms have focused on animal models of cerebral ischemia. In the present study, we investigated the effects of treadmill exercise on memory function and its relation to cell proliferation and apoptosis in the hippocampus, following transient global ischemia in gerbils.MethodsTo induce transient global ischemia in gerbil, both common carotid arteries were occluded for 5 minutes. Gerbils in the exercise groups were forced to run on a treadmill exercise for 30 minutes once a day for 2 weeks. Step-down avoidance task and Y maze task were performed. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-staining, immunohistochemistry for 5-bromo-2'-deoxyridine, doublecortin, caspase-3, and Western blot for brain-derived neurotrophic factor (BDNF), Bax, Bcl-2, cytochrome c, caspase-3 were conducted.ResultsIschemia caused memory impairment with an increase of cell proliferation, BDNF expression, and apoptosis in the hippocampus. Treadmill exercise improved memory function with further increase of cell proliferation and BDNF expression and a decrease of apoptosis.ConclusionsThe animal model that we have developed and our assessment of the relation between exercise and brain function can be useful tools for future investigations of NLUTD symptoms associated with stroke, particularly ischemic stroke. The present study suggests that treadmill exercise promoted the recovery of brain function after cerebral ischemia.

Ladostigil: A Novel Multimodal Neuroprotective Drug with Cholinesterase and Brain-Selective Monoamine Oxidase Inhibitory Activities for Alzheimers Disease Treatment

Ladostigil [(N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate] is a dual acetylcholine-butyrylcholineesterase and brain selective monoamine oxidase (MAO)-A and -B inhibitor in vivo (with little or no MAO inhibitory effect in the liver and small intestine), intended for the treatment of dementia co-morbid with extrapyramidal disorders and depression (presently in a Phase IIb clinical study). This suggests that the drug should not cause a significant potentiation of the cardiovascular response to tyramine, thereby making it a potentially safer antidepressant than other irreversible MAO-A inhibitors. Ladostigil was shown to antagonize scopolamine-induced impairment in spatial memory, indicating that it can cause significant increases in rat brain cholinergic activity. Furthermore, ladostigil prevented gliosis and oxidative-nitrative stress and reduced the deficits in episodic and spatial memory induced by intracerebroventricular injection of streptozotocin in rats. Ladostigil was demonstrated to possess potent anti-apoptotic and neuroprotective activities in vitro and in various neurodegenerative rat models, (e.g. hippocampal damage induced by global ischemia in gerbils and cerebral oedema induced in mice by closed head injury). These neuroprotective activities involve regulation of amyloid precursor protein processing; activation of protein kinase C and mitogen-activated protein kinase signaling pathways; inhibition of neuronal death markers; prevention of the fall in mitochondrial membrane potential and upregulation of neurotrophic factors and antioxidative activity. Recent findings demonstrated that the major metabolite of ladostigil, hydroxy-1-(R)-aminoindan has also a neuroprotective activity and thus, may contribute to the overt activity of its parent compound. This review will discuss the scientific evidence for the therapeutic potential use of ladostigil in Alzheimer's and Lewy Body diseases and the molecular signaling pathways that are considered to be involved in the biological activities of the drug.

Neuroprotective effect of forsythiaside against transient cerebral global ischemia in gerbil

Forsythiaside, a phenylethanoside, has been reported to have anti-oxidative activity and memory ameliorating effects against a scopolamine-induced memory deficit model. The aim of this study was to determine whether forsythiaside has neuroprotective activity on transient cerebral global ischemia in gerbil. Transient cerebral ischemia was induced by bilateral common carotid artery occlusion for 5min and followed by reperfusion for 7days. Oral administration of forsythiaside was conducted immediately after reperfusion and once a day over the next 7days. The forsythiaside administration significantly increased the number of viable neurons detected by neuronal nuclei immunostaining and decreased degenerating neuronal cells detected by Fluoro-Jade B staining in the hippocampal CA1 region, at the 7th day post-ischemia (P<0.05). Forsythiaside also significantly decreased the number of ionized calcium-binding adaptor molecule-1-detected activated microglia and glial fibrillary acidic protein-detected astrocytes, both of which were increased after ischemic insults, and decreased interleukin-1β and tumor necrosis factor-α expression levels, which were also increased after the insults (P<0.05). In addition, forsythiaside significantly improved ischemia-induced cognitive impairments in the Y-maze task (P<0.05). These results suggest that forsythiaside exhibits neuroprotective properties, which are, in part, mediated by its anti-inflammatory activities supported by forsythiaside-induced reductions of activated glial cells and expression levels of interleukin-1β and tumor necrosis factor-α.

NutriSim© Protects-Against Apoptosis in Hippocampus Induced by Transient Ischemia in Mongolian Gerbils (Meriones Unguiculatus)

Mongolian gerbil model has been extensively used for the study of neuroprotective drugs since transient bilateral common carotid artery occlusion induces neuronal cell death to selectively vulnerable regions, including the CA1 sector of the hippocampus. Previously we have shown that NutriSim©, a nutritive supplement used empirically in the treatment of several degenerative disorders protects against brain damage induced by ischemia-reperfusion in Mongolian gerbils. These effects are partly attributed to its antioxidant action. The purpose of this study was to further investigate the potential neuroprotective effects of NutriSim© with histological measures of global ischemia in gerbils. We found that a single dose of NutriSim© was able to prevent significantly the ischemia-induced pyramidal cell loss as well as the number of hyperchromatic cells and glial cells after a week of treatment. In consonance with these data, increased TUNEL positive cells after ischemia is reduced in NutriSim© treated animal after a week.

MK-801 effect on regional cerebral oxidative stress rate induced by different duration of global ischemia in gerbils

We investigated MK-801 effect on ischemia-induced oxidative stress-the most important factor that exacerbates brain damage by reperfusion. The common carotid arteries of gerbils were occluded for 5, 10, or 15 min. Immediately after the occlusion, MK-801 (3 mg/kg i.p.) or saline were given in normothermic conditions. The MK-801 effects were followed in vivo by monitoring the neurological status of animals and at the intracellular level by standard biochemical assays. We investigated nitric oxide levels, superoxide production, superoxide dismutase activity, index of lipid peroxidation (ILP), and reduced glutathione content in hippocampus, striatum, forebrain cortex, and cerebellum. The measurements took place at different times (1, 2, 4, 7, 14, and 28 days) after reperfusion. Increased duration of cerebral ischemia resulted in a progressive induction of oxidative stress. Our results revealed pattern of dynamic changes in each oxidative stress parameter level which corresponded with ischemia duration in all tested brain structures. Most sensitive oxidative stress parameters were ILP and superoxide production. Our study confirmed spatial distribution of ischemia-induced oxidative stress. Tested brain structures showed different sensitivity to each oxidative stress parameter. As judged by biochemical and neurological data, applied MK-801 showed neuroprotective efficiency by reduction of ischemia-induced oxidative stress in brain.

Tadalafil improves short-term memory by suppressing ischemia-induced apoptosis of hippocampal neuronal cells in gerbils

Cerebral ischemia resulting from transient or permanent cerebral artery occlusion leads to neuronal cell death, and eventually causes neurological impairments. Tadalafil (Cialis ®) is a long-acting phosphodiesterase type-5 (PDE-5) inhibitor used to treat erectile dysfunction. The therapeutic effects of PDE-5 inhibitors on chronic obstructive pulmonary disease, prostate hyperplasia, hypertension, and coronary heart disease have been reported. The present study investigated the effects of tadalafil on short-term memory, cyclic guanosine monophosphate (cGMP) level, apoptotic neuronal cell death, and cell proliferation in the hippocampus following transient global ischemia in gerbils. For this study, a step-down avoidance task, cGMP assay, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and immunohistochemistry for caspase-3 and 5-bromo-2′-deoxyuridine were performed. The results revealed that ischemic injury increased apoptotic neuronal cell death in the hippocampal CA1 region, impaired short-term memory, and decreased cGMP level. Ischemic injury enhanced cell proliferation in the hippocampal dentate gyrus. Tadalafil treatment improved short-term memory by suppressing ischemia-induced apoptotic neuronal cell death in the hippocampal CA1 region, and decreased cGMP level. Also, tadalafil suppressed the ischemia-induced increase in cell proliferation in the hippocampal dentate gyrus. We showed that tadalafil can overcome ischemia-induced apoptotic neuronal cell death, thus facilitates recovery following ischemic cerebral injury.

Opuntia ficus-indica attenuates neuronal injury in in vitro and in vivo models of cerebral ischemia

We examined whether the methanol extract of Opuntia ficus-indica (MEOF) has a neuroprotective action against N-methyl-d-aspartate (NMDA)-, kainate (KA)-, and oxygen–glucose deprivation (OGD)-induced neuronal injury in cultured mouse cortical cells. We also evaluated the protective effect of MEOF in the hippocampal CA1 region against neuronal damage evoked by global ischemia in gerbils. Treatment of neuronal cultures with MEOF (30, 300, and 1000μg/ml) inhibited NMDA (25μM)-, KA (30μM)-, and OGD (50min)-induced neurotoxicity dose-dependently. The butanol fraction of Opuntia ficus-indica (300μg/ml) significantly reduced NMDA (20μM)-induced delayed neurotoxicity by 27%. Gerbils were treated with MEOF every 24h for 3 days (0.1, 1.0, and 4.0g/kg, p.o.) or for 4 weeks (0.1 and 1.0g/kg, p.o.), and ischemic injury was induced after the last dose. Neuronal cell damage in the hippocampal CA1 region was evaluated quantitatively at 5 days after the ischemic injury. When gerbils were given doses of 4.0g/kg (3 days) and 1.0g/kg (4 weeks), the neuronal damage in the hippocampal region was reduced by 32 and 36%, respectively. These results suggest that the preventive administration of Opuntia ficus-indica extracts may be helpful in alleviating the excitotoxic neuronal damage induced by global ischemia.

Long-term treadmill exercise overcomes ischemia-induced apoptotic neuronal cell death in gerbils

It has been suggested that exercise may ameliorate neurologic impairment by impeding neuronal loss following various brain insults. In the present study, the effect of long-term treadmill exercise on short-term memory and apoptotic neuronal cell death in the hippocampus following transient global ischemia in gerbils was investigated. A step-down inhibitory avoidance task, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, and immunohistochemistry for caspase-3 were used for this study. Ischemia was induced by occlusion of both the common carotid arteries of gerbils for 5 min. Gerbils in the exercise groups were forced to run on a treadmill for 30 min once a day for 4 consecutive weeks. The present results reveal that treadmill exercise for 4 weeks improved short-term memory by suppressing the ischemia-induced apoptotic neuronal cell death in the hippocampus. Here in this study, we show that long-term treadmill exercise for 4 weeks overcomes the ischemia-induced apoptotic neuronal cell death and thus facilitates the recovery of short-term memory impairment induced by ischemic cerebral injury.

Lack of evidence of direct mitochondrial involvement in the neuroprotective effect of minocycline

Minocycline has been reported to exert neuroprotection through inhibition of inflammatory processes and of mitochondrial cell death pathway. To further characterize the neuroprotective effect of minocycline, we determined its efficacy in different neuronal damage paradigms involving inflammation or mitochondrial dysfunction. In transient global ischaemia in gerbils, minocycline reduced hippocampal neuronal damage measured by peripheral type benzodiazepine binding sites density, a marker of microglial activation. The antiinflammatory properties of minocycline were confirmed on the model of carrageenan-induced paw oedema in rats. The use of two experimental animal models involving administration of mitochondrial toxins inhibiting a different complex of the mitochondrial respiratory chain permitted the exploration of the mitochondrial impact of minocycline. Although minocycline exhibited a marked efficacy in 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP; complex I inhibitor)-induced neurotoxicity in mice, it was ineffective in malonate (complex II inhibitor)-induced striatal lesion in rats. In vitro investigations on energized mitochondria isolated from rat liver showed that minocycline (1 μM) did not inhibit the swelling induced by MPP +(1-methyl-4-phenylpyridinium). Moreover, higher concentrations of minocycline induced swelling. From these experiments, the neuroprotective activity of minocycline appears more related to its antiinflammatory activity than to a direct beneficial action on mitochondria.

Treadmill exercise improves short-term memory by suppressing ischemia-induced apoptosis of neuronal cells in gerbils

In the present study, the effect of treadmill exercise on short-term memory, apoptotic neuronal cell death, and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils was investigated. Step-down inhibitory avoidance task, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, and immunohistochemistry for caspase-3 and 5-bromo-2′-deoxyuridine (BrdU) were used. Ischemia was induced by the occlusion of both common carotid arteries (CCA) of gerbils for 5 min. Gerbils in exercise groups were forced to run on a treadmill for 30 min once a day for 10 consecutive days. Such treadmill exercise improved short-term memory by suppressing the ischemia-induced apoptotic neuronal cell death in the dentate gyrus. In addition, treadmill running suppressed the ischemia-induced cell proliferation in the dentate gyrus. The present results suggest that treadmill exercise overcomes the ischemia-induced apoptotic neuronal cell death and thus facilitates the recovery following ischemic cerebral injury.

7‐Nitroindazole reduces ischemia‐induced increment of apoptosis and cell proliferation in the dentate gyrus of rats

AbstractNitric oxide is synthesized from L‐arginine by nitric oxide synthase (NOS), and it is a free radical with signaling functions. Neuronal nitric oxide synthase (nNOS) is mainly expressed in the central nervous system, and it has been implicated in the pathogenesis of brain injury such as ischemia. In the present study, the effects of 7‐nitroindazole, which specifically inhibits nNOS, on apoptosis and cell proliferation int he dentate gyrus after transient global ischemia in gerbils were investigated. Enhanced apoptotic neuronal cell death and cell proliferation were observed in the dentate gyrus of ischemic gerbils. However, 7‐nitroindazole suppressed the ischemia‐induced apoptosis and cell proliferation. These results suggest that 7‐nitroindazole has an inhibitive effect on apoptosis and cell proliferation following transient global ischemia. The present study shows that nitric oxide, the synthesis of which is augmented by ischemia, plays an important role in the regulation of apoptosis and cell proliferation following ischemic injury.

Postischemic administration of Sendai virus vector carrying neurotrophic factor genes prevents delayed neuronal death in gerbils.

Sendai virus (SeV) vector-mediated gene delivery of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) prevented the delayed neuronal death induced by transient global ischemia in gerbils, even when the vector was administered several hours after ischemia. Intraventricular administration of SeV vector directed high-level expression of the vector-encoded neurotrophic factor genes, which are potent candidates for the treatment of neurodegenerative diseases. After occlusion of the bilateral carotid arteries of gerbils, SeV vector carrying GDNF (SeV/GDNF), NGF (SeV/NGF), brain-derived neurotrophic factor (SeV/BDNF), insulin-like growth factor-1 (SeV/IGF-1) or vascular endothelial growth factor (SeV/VEGF) was injected into the lateral ventricle. Administration of SeV/GDNF, SeV/NGF or SeV/BDNF 30 min after the ischemic insult effectively prevented the delayed neuronal death of the hippocampal CA1 pyramidal neurons. Furthermore, the administration of SeV/GDNF or SeV/NGF as late as 4 or 6 h after the ischemic insult also prevented the death of these neurons. These results indicate that SeV vector-mediated gene transfer of neurotrophic factors has high therapeutic potency for preventing the delayed neuronal death induced by transient global ischemia, and provides an approach for gene therapy of stroke.

The neuronal nitric oxide synthase inhibitor, TRIM, as a neuroprotective agent: effects in models of cerebral ischaemia using histological and magnetic resonance imaging techniques

Most neuroprotective compounds that appear promising in the pre-clinical phase of testing are subsequently dismissed as relatively ineffective when entered into large-scale clinical trials. Many pre-clinical studies of potential neuroprotective candidates evaluate efficacy in only one or possibly two different models of ischaemia. In this study we examined the effects of 1,2-trifluoromethylphenyl imidazole (TRIM), a novel neuronal nitric oxide synthase (nNOS) inhibitor, in three models of cerebral ischaemia (global gerbil, global rat and focal rat). In addition, to follow the progression of the pathology, we also compared traditional histology methods with more advanced magnetic resonance imaging (MRI) as endpoint measures for neurological damage and neuroprotection. TRIM (50 mg/kg i.p.) prevented ischaemia-induced hippocampal damage following global ischaemia in gerbils when administered before or immediately post-occlusion, but failed to protect when administration was delayed until 30 min post-occlusion. Further studies indicated that the compound (administered at 50 mg/kg, i.p., immediately after occlusion) also protected in a rat four-vessel occlusion (4-VO) model using both histological and diffusion-weighted (DW) imaging techniques. In a final study, TRIM (50 mg/kg i.p. 30 min after occlusion) provided a significant reduction in infarct volume at 4 and 24 h as measured using diffusion-weighted (DW) and proton density (PD)-weighted magnetic resonance imaging (MRI). This was confirmed using histological techniques. These studies confirm that nNOS inhibitors may have utility in stroke and provide evidence that combined magnetic resonance and histological methods can provide a powerful method of assessing neuronal damage in rodent models of cerebral ischaemia.

Ether fraction of methanol extracts of Gastrodia elata, medicinal herb protects against neuronal cell damage after transient global ischemia in gerbils.

Gastrodia elata (GE), a medicinal herb, has been used traditionally for the treatment of convulsive diseases such as epilepsy in oriental countries including South Korea and still occupies an important place in traditional medicine in Asia. We designed this study to examine whether the ether fraction of methanol extracts (EFME) of GE protects the hippocampal neuronal damage induced by transient global ischemia in a gerbil model. Gerbils were treated with the EFME of GE (200 or 500 mg/kg per day, p.o.) for 14 days before brain ischemia. The lower dose of EFME of GE failed to attenuate the hippocampal neuronal damage in the CA1 region. However, the higher dose of EFME of GE attenuated the hippocampal neuronal damage in the CA1 region. The present results show that the EFME of GE has a protective effect against neuronal damage following global ischemia in gerbils.

Treadmill exercise suppresses ischemia-induced increment in apoptosis and cell proliferation in hippocampal dentate gyrus of gerbils

Cerebral ischemia resulting from transient or permanent occlusion of cerebral arteries leads to neuronal cell death and eventually causes neurological impairments. In the present study, the effects of treadmill exercise on apoptosis and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils were investigated using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistochemistry for caspase-3 and 5-bromo-2′-deoxyuridine (BrdU). It was shown that apoptotic cell death and cell proliferation in the hippocampal dentate gyrus were significantly increased following transient global ischemia in gerbils and that treadmill exercise suppressed the ischemia-induced increase in apoptosis and cell proliferation in the dentate gyrus. The present results suggest that treadmill exercise may protect cells from apoptotic death and aid in recovery from the central nervous system sequelae following stroke.

Temporal assessment of caspase activation in experimental models of focal and global ischemia

Rodent models of focal and global ischemia were used to examine caspase activation. Several readouts were employed on identical tissue to provide correlative measurement of caspase induction, activation and enzymatic activity. In a rat focal ischemia model, caspase-3 enzymatic activity, as recorded by DEVD–AMC cleavage, peaked in penumbral cortex at 6–12 h following ischemia, correlating with increases in caspase 3-cleaved substrates of PARP and α-spectrin and subsequent disappearance of caspase-3 zymogen. Although induction of caspases 8 and 2 proteins was detectable as early as 6 h following ischemia, examination of the same tissues for caspase 8 or 2 enzymatic activities did not show significant modulation up to 12 h after ischemic insult. Caspase 9 induction was evident only after 24 h postischemia and did not correlate with elevated LDHD–AMC cleavage. Following global ischemia in gerbils, levels of caspase-3 enzyme activity peaked at 12 h in hippocampal tissue extracts. Cleaved caspase-3 signal was prominent in NeuN-positive layers in the CA1 region 6–12 h following ischemia. Interestingly, strong caspase-3 immunoreactivity was also detected in the subgranular zone of the dentate gyrus, a known region of ischemia-induced neurogenesis. Caspase-3 activation may be responsible for the loss of these cells, thereby hindering the endogenous recovery process.