Protective Effects of Humanin on Okadaic Acid-Induced Neurotoxicities in Cultured Cortical Neurons

Neurofibrillary tangles are pathological hallmarks of Alzheimer’s disease (AD), which are mostly composed of hyperphosphorylated tau and directly correlate with dementia in AD patients. Okadaic acid (OA), a toxin extracted from marine life, can specifically inhibit protein phosphatases (PPs), including PP1 and Protein phosphatase 2A (PP2A), resulting in tau hyperphosphorylation. Humanin (HN), a peptide of 24 amino acids, was initially reported to protect neurons from AD-related cell toxicities. The present study was designed to test if HN could attenuate OA-induced neurotoxicities, including neural insults, apoptosis, autophagy, and tau hyperphosphorylation. We found that administration of OA for 24 h induced neuronal insults, including lactate dehydrogenase released, decreased of cell viability and numbers of living cells, neuronal apoptosis, cells autophagy and tau protein hyperphosphorylation. Pretreatment of cells with HN produced significant protective effects against OA-induced neural insults, apoptosis, autophagy and tau hyperphosphorylation. We also found that OA treatment inhibited PP2A activity and HN pretreatment significantly attenuated the inhibitory effects of OA. This study demonstrated for the first time that HN protected cortical neurons against OA-induced neurotoxicities, including neuronal insults, apoptosis, autophagy, and tau hyperphosphorylation. The mechanisms underlying the protections of HN may involve restoration of PP2A activity.     

Effect of Different Mild Hypoxia Manipulations on Kainic Acid-Induced Seizures in the Hippocampus of Rats

The protective effect of the mild hypoxia to the epilepsy has been widely tested. Although it is found that the hypoxia protects the brain by up-regulation of hypoxia-inducible factor-1α, few focused on systematic comparisons between different mild hypoxia manipulations and their effects. The male Sprague–Dawley rats were observed following exposure to hypoxia before and after epilepsy for 3 days with 90 min per day. The effects of different mild hypoxia manipulations on kainic acid-induced epilepsy were compared from the perspective of morphology, molecular biology and behavioral test. Results showed that different mild hypoxia manipulations could inhibit the cell apoptosis of kainic acid-induced rat hippocampus and improve their physiological functions. The effect of preconditioning group was better than that of postconditioning group and that of preconditioning and postconditioning with mild hypoxia group was the best among all the groups. The result showed that the preconditioning and postconditioning of mild hypoxia was recommended pre- and post-epilepsy and exposure to mild hypoxia should be prolonged. These findings might provide new ideas and methods for the clinical treatment of epilepsy.     

Effect of Bicuculline-Induced Status Epilepticus on Prostaglandins and Hydroxyeicosatetraenoic Acids in Rat Brain Subcellular Fractions

Abstract: Rat cerebrum, prelabeled in vivo by intraventric-ular injection of [1-¹⁴C]arachidonic acid, was used to assess cyclooxygenase and lipoxygenase reaction products in total homogenates, cytosol, synaptosomes, and microsomes. Effects of bicuculline-induced status epilepticus on arachi-donic acid metabolism in synaptosomes and microsomes were also measured. Lipoxygenase activity, resulting in the synthesis of hydroxyeicosatetraenoic acids (HETEs), and cyclooxygenase activity, resulting in the synthesis of prostaglandins (PGs), were measured by reverse-phase and normal-phase HPLC with flow scintillation detection. Endogenous lipoxygenase products in synaptosomes were identified by capillary gas chromatography-mass spectrometry. PGs and HETEs were detected in all subcellular fractions. The synaptosomal fraction showed the highest lipoxygenase activity, with 5-HETE, 12-HETE, and leukotriene B₄ as the major products. Following bicuculline-induced status epilepticus, endogenous free arachidonic acid and other fatty acids accumulated in synaptosomes, but not in microsomes. Incorporation of [1-^l4C]arachidonic acid into synaptosomal and microsomal phospholipids was decreased after bicuculline treatment. Bicuculline-induced status epilepticus resulted in increased synthesis of HETEs in synaptosomes. PG synthesis increased in the microsomal fraction. When [1-¹⁴C]arachidonic acid-labeled synaptosomes and microsomes were incubated for 1 h at 37°C the synthesis of eicosa-noids, particularly PGD₂, was increased significantly in bi-cuculline-treated rats, as compared with untreated rats. Depolarization (45 mM K⁺) of synaptosomes induced a loss of [1-¹⁴C]arachidonic acid from phosphatidylinositol, and increased the synthesis of PGD₂ and HETEs, an effect that was enhanced in bicuculline-treated rats. This study localizes changes in arachidonic acid metabolism and lipoxygenase activity resulting from bicuculline-induced status epilepticus in the brain subcellular fraction enriched in nerve endings.     

Structural Conservation and Effects of Alterations in T Cell Receptor Transmembrane Interfaces

T cell receptors (TCRs) are octameric assemblies of type-I membrane proteins in which a receptor heterodimer (αβ, δγ, or pre-Tαβ) is associated with three dimeric signaling modules (CD3δε, CD3γε, and ζζ) at the T cell or pre-T cell surface. In the human αβTCR, the α and β transmembrane (TM) domains form a specific structure that acts as a hub for assembly with the signaling modules inside the lipid bilayer. Conservation of key polar contacts across the C-terminal half of this TM interface suggests that the structure is a common feature of all TCR types. In this study, using molecular dynamics simulations in explicit lipid bilayers, we show that human δγ and pre-Tαβ TM domains also adopt stable αβ-like interfaces, yet each displays unique features that modulate the stability of the interaction and are related to sequences that are conserved within TCR types, but are distinct from the αβ sequences. We also performed simulations probing effects of previously reported mutations in the human αβ TM interface, and observed that the most disruptive mutations caused substantial departures from the wild-type TM structure and increased dynamics. These simulations show a strong correlation between structural instability, increased conformational variation, and the severity of structural defects in whole-TCR complexes measured in our previous biochemical assays. These results thus support the view that the stability of the core TM structure is a key determinant of TCR structural integrity and suggest that the interface has been evolutionarily optimized for different forms of TCRs.     

Effect of Seizures Induced by Intra-Amygdaloid Kainic Acid on Kainic Acid Binding Sites in Rat Hippocampus and Amygdala

[3H]Kainic acid binding sites with a slow dissociation rate in the rat limbic system were investigated in detail. Extensively washed membranes prepared from the hippocampal formation and from the region comprising the amygdala and the piriform cortex yielded non-linear Scatchard plots. Microdissection showed that the high-affinity component (affinity constant around 1 nM) was present in the hippocampal CA3 region (4.2 fmol/mg wet tissue) and the amygdaloid complex (4.6 fmol/mg wet tissue), whereas the remaining part of the hippocampal formation and the piriform lobe contained the low-affinity component (affinity constant 5-20 nM; 11.6 and 11.3 fmol/mg wet tissue, respectively). In the lateral + medial septum we detected only the low-affinity component. Severe limbic seizures, induced by unilateral injection of 0.7 or 0.8 microgram kainic acid in 0.3 microliter of phosphate-buffered saline into the amygdala, reduced kainic acid binding sites in the ipsilateral amygdala and CA3 region. The decline of kainic acid binding sites in the injected amygdala was followed by a similar effect in the contralateral amygdala ("mirror focus") and later by a moderate loss also in the contralateral CA3 region. Kainic acid receptor autoradiography demonstrated that binding sites were lost from the stratum lucidum in hippocampus. Septal lesion had no effect on kainic acid binding sites in the hippocampus. Comparison with previous results on the histopathological changes after this lesion shows that high-affinity kainic acid binding sites are preferentially located on neurons that undergo selective degenerations after severe kainic acid-induced seizures.     

丙酮酸对细胞寒冷应激损伤的保护作用研究

目的:细胞冻存、移植器官保存过程中,机体细胞会产生细胞寒冷应激过程,导致细胞产生损伤作用,而其作用机制尚不清楚,本研究通过观察4℃冷暴露对HEK293细胞增殖活性及凋亡的影响,分析线粒体分裂蛋白Drp1在此过程中的表达变化,阐明Drp1在细胞寒冷应激中作用及其机制.方法:采用MTT法观察4℃环境暴露对HEK293细胞损伤的影响,流式细胞术检测细胞凋亡;Western blot方法检测蛋白Drp1、Bcl2表达水平变化,提取线粒体观察线粒体中Drp1表达水平.结果:4℃冷暴露抑制HEK293细胞增殖(P＜0.05),Drp1线粒体表达水平增高,并向线粒体转位;丙酮酸可以逆转4℃冷暴露对细胞增值抑制,抑制Drp1线粒体表达水平增高,并向线粒体转位,增加细胞中Bcl2表达水平.结论:研究发现细胞寒冷应激可以使细胞凋亡,细胞增殖出现显著抑制,而寒冷应激引起细胞Drp1的线粒体转位,丙酮酸干预后可以对细胞起到保护作用,研究发现丙酮酸可以逆转Drp1的线粒体转位过程,增加Bcl2表达水平,可能是其产生保护作用的机制之一.     

Simulation of Cell Patterning Triggered by Cell Death and Differential Adhesion in Drosophila Wing

The Drosophila wing exhibits a well-ordered cell pattern, especially along the posterior margin, where hair cells are arranged in a zigzag pattern in the lateral view. Based on an experimental result observed during metamorphosis of Drosophila, we considered that a pattern of initial cells autonomously develops to the zigzag pattern through cell differentiation, intercellular communication, and cell death (apoptosis) and performed computer simulations of a cell-based model of vertex dynamics for tissues. The model describes the epithelial tissue as a monolayer cell sheet of polyhedral cells. Their vertices move according to equations of motion, minimizing the sum total of the interfacial and elastic energies of cells. The interfacial energy densities between cells are introduced consistently with an ideal zigzag cell pattern, extracted from the experimental result. The apoptosis of cells is modeled by gradually reducing their equilibrium volume to zero and by assuming that the hair cells prohibit neighboring cells from undergoing apoptosis. Based on experimental observations, we also assumed wing elongation along the proximal-distal axis. Starting with an initial cell pattern similar to the micrograph experimentally obtained just before apoptosis, we carried out the simulations according to the model mentioned above and successfully reproduced the ideal zigzag cell pattern. This elucidates a physical mechanism of patterning triggered by cell apoptosis theoretically and exemplifies, to our knowledge, a new framework to study apoptosis-induced patterning. We conclude that the zigzag cell pattern is formed by an autonomous communicative process among the participant cells.     

<Emphasis Type="Italic">In vivo</Emphasis> Evaluation of the Effect of Zonisamide on the Hippocampal Redox State During Kainic Acid-Induced Seizure Status in Rats

The aim in this study is to observe the hippocampal redox state during kainic-acid (KA)-induced seizure status, and examine the effect of systemic preinjection of anticonvulsant zonisamide (ZNS) on the hippocampal redox. To perform under a freely moving state, in vivo microdialysis method was applied to electron paramagnetic resonance (EPR) spectroscopy. Half-life of 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM), a five-membered ring nitroxide radical, was used for the indicator of the hippocampal antioxidant ability. The changes in EPR signal intensities of PCAM decreased exponentially in all rats used. The average half-lives of PCAM was significantly shorter in the rats pretreated with ZNS than that of control group, and while the average half-lives of PCAM in the perfusate was significantly longer in the rats KA-induced status epilepticus than that of control (P < 0.01). Those of PCAM in the ZNS-pretreated rats followed by KA-injection were almost the same as those of control. These findings indicate that the pretreatment of ZNS increased the antioxidant ability in the hippocampus during KA-induced seizure. This study is the first in vivo evaluation of the antioxidant ability of ZNS as neuroprotective role against the free radicals performed under the condition of freely moving rats during seizure status.     

Alterations in the Neurobehavioral Phenotype and ZnT3/CB-D28k Expression in the Cerebral Cortex Following Lithium-Pilocarpine-Induced Status Epilepticus: the Ameliorative Effect of Leptin

Biological Trace Element Research - Zinc transporter 3 (ZnT3)-dependent “zincergic” vesicular zinc accounts for approximately 20% of the total zinc content of the mammalian...     

Lead-Induced Hearing Loss in Rats and the Protective Effect of Copper

Lead is a common environmental pollutant which can induce various toxic effects to humans and/or animals. This work aimed to study the hearing loss in rats induced by lead and the protective effect of copper. The auditory brainstem response (ABR) was used to study the hearing loss in rats. The results showed that lead prolonged the latencies of wave I to V of ABRs of the rats but did not affect the interpeak latencies of waves I-III, III-V, and I-V, indicating that lead could cause hearing loss in rats by impairing the cochlea. After receiving copper, the quality and the wave latencies of the ABR of the rats were restored to a certain extent, indicating that copper played a protective role in lead-induced hearing impairment. The mechanisms were also proposed that lead could cause hearing loss in rats mainly through damaging the cochlea component, and copper might antagonize the toxicity of lead in three primary ways.     

The Protective Effect of Selenium on Bovine Mammary Epithelial Cell Injury Caused by Depression of Thioredoxin Reductase

To elucidate the effect of selenium (Se) on antioxidant function of mammary glands in dairy cows and the underlying mechanism, an experiment was conducted using a single-factor completely randomized design study. Bovine mammary epithelial cells (BMECs) were randomly divided into four groups: control, Se treatment, 2,4-dinitrochlorobenzene (DNCB) inhibition, and Se prevention. Treatment of BMECs with Se was found to significantly reverse decreased cell proliferation and the expression of thioredoxin reductase (TrxR) after DNCB exposure. DNCB-induced activation of apoptosis signaling kinase-1 (ASK-1), which activates the mitogen-activated protein kinase (MAPK) pathway, was reduced in BMECs treated with Se. Additionally, our results indicated that Se treatment resulted in lower intracellular accumulation of arachidonic acid (ARA) and 15-hydroperoxyeicosatetraenoic acid (15-HPETE) due to suppressed expression of cytosolic phospholipase A₂ (cPLA₂) regulated by p38MAPK and c-Jun N-terminal kinase (JNK) in DNCB-stimulated BMECs. Taken together, these findings suggest that Se treatment improved the antioxidant function of dairy cow mammary glands and protected cells from oxidative damage primarily by increasing the activity of TrxR, inhibiting the activation of the MAPK signaling pathway, and thus decreasing the content of ARA and its related metabolites.     

Effect of Exercise Interventions on Kainate Induced Status Epilepticus and Associated Co-morbidities; A Systematic Review and Meta-Analysis

Purpose

To conduct a systematic review and meta-analysis of studies testing the effect of exercise in Kainic-acid (KA) induced status-epilepticus (SE) and to quantify the efficacy of exercise strategies in the prognosis of SE and co-morbidities.

Methods

Two authors searched online databases (Pubmed and Web of Science) independently for studies testing the efficacy of exercise programs in KA-induced SE models. Reviewers autonomously extracted data on models used, exercise interventions and prognosis in all reported outcomes (behavioral, histological, biochemical and cognitive outcomes). All studies were summarized and relevant outcomes’ data were pooled by means of a meta-analysis.

Results

Among 14 selected studies; Quantitative analysis of studies with pre-SE exercise interventions showed significant reduction in mortality rate among 76 animals of four studies (RR?=?0.57, [95% CI 0.34, 0.95], p?=?0.03, I²?=?57%) and seizure rating score among three studies (n?=?56) with MD?=???1.04, [95% CI ??2.07, ??0.00], p?=?0.05, I²?=?71%. Three studies (n?=?62) presented with improved anti-oxidant enzymes’ profile (SMD?=?0.75, [95% CI 0.55, 2.31], p?=?0.0008, I²?=?44%) as a result of exercise intervention. Same intervention failed to show any significant measure for BDNF level and neuroprotection assessed through neuronal number in different brain areas with MD?=???1.22, [95% CI ??136.66, 134.22], p?=?0.99, I²?=?0% and SMD?=???0.05, [95% CI ??0.62, 0.52], p?=?0.86, I²?=?61% respectively. Qualitative review concluded in the reduction of median seizure score, depression and anxiety-like behaviors with improved cognitive performances in pre-SE exercised animals while improved memory and learning capabilities with increased neurogenesis were observed in post-SE exercised models.

Conclusions

Exercise before SE reduces behavioral seizures and oxidative stress with improvements in cognitive abilities. Post-SE exercise enhances learning and memory with neurogenesis in KA models. More extensive research on morphological and biochemical profiles is needed to explore underlying mechanisms.

     

Effect of Agmatine Against Cell Death Induced by NMDA and Glutamate in Neurons and PC12 Cells

1. Aims: Agmatine is an endogenous guanido amine and has been shown to be neuroprotective in vitro and in vivo. The aims of this study are to investigate whether agmatine is protective against cell death induced by different agents in cultured neurons and PC12 cells.2. Methods: Cell death in neurons, cultured from neonatal rat cortex, was induced by incubating with (a) NMDA (100 M) for 10 min, (b) staurosporine (protein kinase inhibitor, 100 nM) for 24 h, and (c) calcimycin (calcium ionophore, 100 nM) for 24 h in the presence and absence of agmatine (1 M to 1 mM). Cell death in PC12 cells was induced by exposure to glutamate (10 mM), staurosporine (100 nM), and calcimycin (100 nM). The activity of lactate dehydrogenase (LDH) in the medium was measured as the marker of cell death and normalized to cellular LDH activity.3. Results: Agmatine significantly reduced the medium LDH in NMDA-treated neurons but failed to reduce the release of LDH induced by staurosporin or calcimycin. In PC12 cells, agmatine significantly reduced LDH release induced by glutamate exposure, but not by staurosporine or calcimycin. Agmatine itself neither increased LDH release nor directly inhibited the enzyme activity.4. Conclusion: We conclude that agmatine protects against NMDA excitotoxicity in neurons and PC12 cells but not the cell death induced by protein kinase blockade or increase in cellular calcium.     

The Effect of Organophosphate Exposure on Neuronal Cell Coenzyme Q10 Status

Neurochemical Research - Organophosphate (OP) compounds are widely used as pesticides and herbicides and exposure to these compounds has been associated with both chronic and acute forms of...     

Neuroprotective Effect of a Chuk-Me-Sun-Dan on Neurons from Ischemic Damage and Neuronal Cell Toxicity

Chukmesundan (CMSD), composed of the following 8 medicinal herbs including Panex ginseng C.A. MEYER, Atractylodes macrocephala KOID, Poria cocos WOLF, Pinellia ternata BREIT, Brassica alba BOISS, Aconitum carmichaeli DEBX, Cynanchum atratum BGE and Cuscuta chinensis LAM. CMSD is being used in Korea for the treatment of various symptoms accompanying hypertension and cerebrovascular disorders. This study was carried out to examine the effects of CMSD on cultured primary neuron cell, cell cytotoxicity and lipid peroxidation in Aβ-treated cells. Cell death was enhanced by addition of Aβ. Pretreatment of CMSD attenuated in cell killing induced by Aβ. The protective effect of the CMSD water extracts on Aβ-induced neuronal death was also observed by lactate dehydrogenase assay using cultured astrocyte cells. Aβ-induced cell death was protected by the water extract of CMSD in a dose-dependent manner, and 25–50 μg/ml was the most effective concentration. CMSD has been also shown to protect primary cultured neurons from N-methyl-d-aspartate receptor-mediated glutamate toxicity. It was in vivo evidenced that CMSD protects neurons against ischemia-induced cell death. Moreover, oral administration of CMSD into mice prevented ischemia-induced learning disability and rescued hippocampal CA1 neurons from lethal ischemic damage. The neuroprotective action of exogenous CMSD was also confirmed by counting synapses in the hippocampal CA1 region. The presence of CMSD in neuron cultures rescued the neurons from nitrogen oxide (NO)-induced death. From these, it was suggested that CMSD may exert its neuroprotective effect by reducing the NO-mediated formation of free radicals or antagonizing their toxicity.     

Effect of Frusemide,Lactose, and Urea on Urinary Cell Loss

With the use of a staining method by which cells in the urine can be differentiated, the effect of oral frusemide, lactose, and urea on the rate of excretion of these cells was investigated in five healthy persons.It is shown that frusemide greatly increases the urinary excretion of red cells, white cells, and renal tubular cells. Similar though not so marked changes were produced by both lactose and urea. Possible reasons for the increased excretion of cells are discussed. One is that it may be the result of an increase in the rate of urinary flow.     

The Anticonvulsant Effect of a Novel Indole-Related Compound in the Kainate-Induced Status Epilepticus in Mice: The Role of the Antioxidant and Anti-inflammatory Mechanism

Neurochemical Research - We synthesized a series of novel indole compounds containing aroylhydrazone moieties and evaluated them in mice to check their anticonvulsant activity. In the present study...     

H2O2致体外培养动脉内皮细胞损伤及山莨菪碱保护

目的:实验以过氧化氢(H2O2)损伤体外培养动脉内皮细胞(AEC),对过氧化氢介导内皮细胞损伤、凋亡的机制进行探讨,观察山莨菪碱(Ani)是否抑制H2O2介导的AEC损伤、凋亡,并探讨Ani保护损伤、凋亡的机制.方法:体外培养AEC随机分组:对照组(正常培养AEC);H2O2损伤组(0.5 mmol/L H2O2损伤12 h);Ani组(不同浓度Ani:0.05,0.1,0.2 mg/mL处理45 min后加0.5 mmol/L H2O2损伤12 h).结果:1.低浓度H2O2(0.5 mmol/L)可以损伤AEC并诱导凋亡.H2O2损伤组台盼蓝着染率及LDH释放率均高于对照组(P<0.01);细胞总抗氧化能力(T-AOC)下降(比对照组P<0.01);琼脂糖凝胶电泳发现凋亡细胞的梯状电泳条带;细胞荧光染色见凋亡形态特征.2.Ani对H2O2诱导的内皮细胞损伤具保护作用.Ani组与H2O2损伤组比较,台盼蓝着染率及LDH释放率下降;T-AOC上升;在Ani 0.2 mg/mL组DNA琼脂糖凝胶电泳未见凋亡细胞特征性的梯状电泳条带;荧光染色未见凋亡细胞特征.结论:1.低浓度过氧化氢使AEC总抗氧化能力明显下降,耗竭细胞抗氧化能力,可致AEC的损伤、凋亡.2.山莨菪碱能减少AEC抗氧化能力的消耗,维持抗氧化能力平衡,保护0.5 mmol/L H2O2 介导的AEC损伤、凋亡.     

自噬对高糖诱导的人冠状动脉内皮细胞凋亡的保护作用

目的:研究自噬对高糖诱导的人冠状动脉内皮细胞凋亡的影响。方法:将人冠状动脉内皮细胞,分别用常规培养基(正常对照组)、含30 mmol/L D-葡萄糖的高糖培养基(高糖组)、高糖培养基合并雷帕霉素(Rapamycin,RAPA;100 nmol/L)干预(RAPA组)和高糖培养基合并3-甲基腺嘌呤(3-Methyladenine,3-MA,5 mmol/L)干预(3-MA组)培养。利用CCK-8法检测细胞生长活力,使用流式细胞术检测细胞凋亡水平,western blot检测细胞自噬标记蛋白(Beclin1)的表达水平。结果:(1)高糖溶液刺激内皮细胞24 h后,细胞生长活力为正常组的55.0%(P0.01),自噬标记蛋白Beclin1的表达水平明显增加,凋亡水平为正常组的2.0倍;(2)与高糖组相比,RAPA组细胞生长活力明显增加,Beclin1的表达明显升高(P0.01),凋亡水平为高糖组的70.1%;(3)与高糖组相比,3-MA组细胞生长活力明显减少,Beclin1的表达明显降低(P0.01),凋亡水平为高糖组的1.42倍。结论:细胞自噬可能对高糖诱导的人冠状动脉内皮细胞具有凋亡保护作用。