SIRT3 Acts as a Neuroprotective Agent in Rotenone-Induced Parkinson Cell Model

Neurochemical Research - SIRT3 is a member of Sirtuins family, which belongs to NAD+ dependent class III histone deacetylases. Emerging evidence suggests that SIRT3 plays a pivotal role in...     

Estrogen as a Multi-Active Neuroprotective Agent in Traumatic Injuries

In the past decade, research has demonstrated that estrogens role in physiology and development is far more complicated than previously assumed. Among these discoveries, there has been an increased recognition of the impact estrogen has in neurodevelopment, central nervous system physiology, and neuropathophysiology. These observations have led many researchers to consider using estrogen pharmacotherapeutically, at physiologic or supraphysiologic doses, for a variety of injury and toxicity models. In this short review, the effects of estrogen as an anti-apoptotic agent, as an anti-oxidant, and as an anti-inflammatory agent are discussed. Finally, the possibility of using estrogen as a neuroprotectant in neurotrauma is addressed.Special issue dedicated to Dr. Lawrence F. Eng.     

Short-term Preoperative Dietary Restriction Is Neuroprotective in a Rat Focal Stroke Model

Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and over a million postoperative encephalopathies annually in the US and Europe. While mitigating damage from stroke after it occurs has proven elusive, opportunities to reduce the incidence and/or severity of stroke prior to surgery in at-risk individuals remain largely unexplored. We tested the potential of short-term preoperative dietary restriction to provide neuroprotection in rat models of focal stroke. Rats were preconditioned with either three days of water-only fasting or six days of a protein free diet prior to induction of transient middle cerebral artery occlusion using two different methods, resulting in either a severe focal stroke to forebrain and midbrain, or a mild focal stroke localized to cortex only. Infarct volume, functional recovery and molecular markers of damage and protection were assessed up to two weeks after reperfusion. Preoperative fasting for 3 days reduced infarct volume after severe focal stroke. Neuroprotection was associated with modulation of innate immunity, including elevation of circulating neutrophil chemoattractant C-X-C motif ligand 1 prior to ischemia and suppression of striatal pro-inflammatory markers including tumor necrosis factor α, its receptor and downstream effector intercellular adhesion molecule-1 after reperfusion. Similarly, preoperative dietary protein restriction for 6 days reduced ischemic injury and improved functional recovery in a milder cortical infarction model. Our results suggest that short-term dietary restriction regimens may provide simple and translatable approaches to reduce perioperative stroke severity in high-risk elective vascular surgery.     

The Neuroprotective Effects of Coccomyxa Gloeobotrydiformis on the Ischemic Stroke in a Rat Model

Stroke is a major cause of mortality and the leading cause of permanent disability. In this study, we adopted the classic middle cerebral artery occlusion(MCAO) stroke model to observe the therapeutic effects of coccomyxa gloeobotrydiformis(CGD) on ischemic stroke, and discuss the underlying mechanisms. Low dose (50 mg/kg.day) and high dose (100 mg/kg.day) concentrations of the drug CGD were intragastrically administrated separately for 8 weeks. Infarct volumes, neurologic deficits and degree of stroke-induced brain edema were measured 24 hours after reperfusion. Furthermore, oxidative stress related factors (SOD and MDA), mitochondrial membrane potential, and apoptosis regulatory factors (mitochondrial Cyt-C, Bcl-2, Bax, and caspase-3) were all investigated in this research. We found that CGD attenuated cerebral infarction, brain edema and neurologic deficits; CGD maintained the mitochondrial membrane potential and decreased mitochondrial swelling. It also prevented oxidative damage by reducing MDA and increasing SOD. In addition, CGD could effectively attenuate apoptosis by restoring the level of mitochondrial Cyt C and regulating the expression of Bcl-2, Bax and caspase 3. These results revealed that CGD has a therapeutic effect on ischemic stroke, possibly by inducing mitochondrial protection and anti-apoptotic mechanisms.     

Intermittent Hypothermia Is Neuroprotective in an in vitro Model of Ischemic Stroke

Objective: To investigate whether the intermittent hypothermia (IH) protects neurons against ischemic insult and the potential molecular targets using an in vitro ischemic model of oxygen glucose deprivation (OGD).Methods: Fetal rat cortical neurons isolated from Day E18 rat embryos were subjected to 90-min OGD and hypothermia treatments during reoxygenation before examining the changes in microscopic morphology, cell viability, microtubule- associated protein 2 (MAP-2) release, intracellular pH value and calcium, reactive oxygen species (ROS) generation, mitochondrial membrane potential (△Ψm) and neuronal death using cell counting kit (CCK-8), enzyme-linked immunosorbent assay (ELISA), BCECF AM, Fluo-3 AM, DCFH-DA and dihydroethidium (DHE), JC-1 staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively.Results: 90-min OGD induced morphologic abnormalities, cell viability decline, MAP-2 release, intracellular acidosis, calcium overload, increased ROS generation, △Ψm decrease and cell death in primary neurons, which was partially inhibited by continuous hypothermia (CH) and intermittent hypothermia (IH). Interestingly, 6-h CH was insufficient to reduce intracellular calcium overload and stabilize mitochondrial membrane potential (△Ψm), while 12-h CH was effective in reversing the above changes. All IH treatments (6×1 h, 4×1.5 h or 3×2 h) effectively attenuated intracellular free calcium overload, inhibited ROS production, stabilized mitochondrial membrane potential (△Ψm) and reduced delayed cell death in OGD-treated cells. However, only IH intervals longer than 1.5 h appeared to be effective in preventing cell viability loss and intracellular pH decline.Conclusion: Both CH and IH were neuroprotective in an in vitro model of ischemic stroke, and in spite of shorter hypothermia duration, IH could provide a comparable neuroprotection to CH.     

Systems Neuroprotective Mechanisms in Ischemic Stroke

Ischemic stroke, although causing brain infarction and neurological deficits, can activate innate neuroprotective mechanisms, including regional mechanisms within the ischemic brain and distant mechanisms from non-ischemic organs such as the liver, spleen, and pancreas, supporting neuronal survival, confining brain infarction, and alleviating neurological deficits. Both regional and distant mechanisms are defined as systems neuroprotective mechanisms. The regional neuroprotective mechanisms involve release and activation of neuroprotective factors such as adenosine and bradykinin, inflammatory responses, expression of growth factors such as nerve growth factors and neurotrophins, and activation and differentiation of resident neural stem cells to neurons and glial cells. The distant neuroprotective mechanisms are implemented by expression and release of endocrine neuroprotective factors such as fibroblast growth factor 21, resistin like molecule γ, and trefoil factor 3 from the liver; brain-derived neurotrophic factor and nerve growth factor from the spleen; and neurotrophin 3 and vascular endothelial growth factor C from the pancreas. Furthermore, ischemic stroke induces mobilization of bone marrow hematopoietic stem cells and endothelial progenitor cells into the circulatory system and brain, contributing to neuroprotection. The regional and distant mechanisms may act in coordination and synergy to protect the ischemic brain from injury and death. This paper addresses these mechanisms and associated signaling networks.     

Flaxseed Oil as a Neuroprotective Agent on Lead Acetate-Induced Monoamineric Alterations and Neurotoxicity in Rats

Lead remains a considerable occupational and public health problem, which is known to cause a number of adverse effects in both man and animals. Here, the neuroprotective effect of flaxseed oil (1,000 mg/kg) on lead acetate (20 mg/kg) induced alternation in monoamines and brain oxidative stress was examined in rats. The levels of lead, dopamine (DA), norepinephrine (NE), serotonin (5-HT), lipid peroxidation, nitrite/nitrate (NO), and glutathione (GSH) were determined; also, the activity of acetylcholinesterase (AChE) and Na(+)-K(+)-ATPase were estimated on different brain regions of adult male albino rats. The level of lead was markedly elevated in different brain regions of rats. This leads to enhancement of lipid peroxidation and NO production in brain with concomitant reduction in AChE activity and GSH level. In addition, the levels of DA, NE, and 5-HT were decreased in the brain. These findings were associated with BAX over expression. Treatment of rats with flaxseed oil induced a marked improvement in most of the studied parameters as well as the immunohistochemistry features. These data indicated that dietary flaxseed oil provide protection against lead-induced oxidative stress and neurotoxic effects.     

Serum Diamine Oxidase as a Hemorrhagic Shock Biomarker in a Rabbit Model

Background

In prolonged hemorrhagic shock, reductions in intestinal mucosal blood perfusion lead to mucosal barrier damage and systemic inflammation. Gastrointestinal failure in critically ill patients has a poor prognosis, so early assessment of mucosal barrier injury in shock patients is clinically relevant. Unfortunately, there is no serum marker that can accurately assess intestinal ischemia-reperfusion injury.

Objective

The aim of this study was to assess if serum diamine oxidase levels can reflect intestinal mucosal injury subsequent to prolonged hemorrhagic shock.

Methods

Thirty New Zealand white rabbits were divided into three groups: a control group, a medium blood pressure (BP) group (exsanguinated to a shock BP of 50 to 41 mm Hg), and a low BP group (exsanguinated to a shock blood pressure of 40 to 31 mm Hg), in which the shock BP was sustained for 180 min prior to fluid resuscitation.

Results

The severity of hemorrhagic shock in the low BP group was significantly greater than that of the medium BP group according to the post-resuscitation BP, serum tumor necrosis factor (TNF)-α, and arterial lactate. Intestinal damage was significantly more severe in the low BP group according to Chiu’s scoring, claudin-1, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase expression. Serum diamine oxidase was significantly increased in the low BP group compared to the medium BP and control groups and was negatively correlated with shock BP.

Conclusion

Serum diamine oxidase can be used as a serological marker in evaluating intestinal injury and shows promise as an indicator of hemorrhagic shock severity.     

Neuroprotective Mechanisms of Melatonin in Hemorrhagic Stroke

Hemorrhagic stroke which consists of subarachnoid hemorrhage and intracerebral hemorrhage is a dominant cause of death and disability worldwide. Although great efforts have been made, the physiological mechanisms of these diseases are not fully understood and effective pharmacological interventions are still lacking. Melatonin (N-acetyl-5-methoxytryptamine), a neurohormone produced by the pineal gland, is a broad-spectrum antioxidant and potent free radical scavenger. More importantly, there is extensive evidence demonstrating that melatonin confers neuroprotective effects in experimental models of hemorrhagic stroke. Multiple molecular mechanisms such as antioxidant, anti-apoptosis, and anti-inflammation, contribute to melatonin-mediated neuroprotection against brain injury after hemorrhagic stroke. This review article aims to summarize current knowledge regarding the beneficial effects of melatonin in experimental models of hemorrhagic stroke and explores the underlying mechanisms. We propose that melatonin is a promising neuroprotective candidate that is worthy of further evaluation for its potential therapeutic applications in hemorrhagic stroke.     

Crucial Roles of Glu60 in Human Neuroglobin as a Guanine Nucleotide Dissociation Inhibitor and Neuroprotective Agent

Mammalian neuroglobin (Ngb) protects neuronal cells under conditions of oxidative stress. We previously showed that human Ngb acts as a guanine nucleotide dissociation inhibitor (GDI) for the α-subunits of heterotrimeric G_i/o proteins and inhibits reductions in cAMP concentration, leading to protection against cell death. In the present study, we created human E60Q Ngb mutant and clarified that Glu60 of human Ngb is a crucial residue for its GDI and neuroprotective activities. Moreover, we investigated structural and functional properties of several human Ngb mutants and demonstrated that the neuroprotective effect of human Ngb is due to its GDI activity and not due to its scavenging activity against reactive oxygen species.     

High-Intensity Focused Ultrasound (HIFU) for Dissolution of Clots in a Rabbit Model of Embolic Stroke

It is estimated that only 2-6% of patients receive thrombolytic therapy for acute ischemic stroke suggesting that alternative therapies are necessary. In this study, we investigate the potential for high intensity focused ultrasound (HIFU) to initiate thrombolysis in an embolic model of stroke. Iron-loaded blood clots were injected into the middle cerebral artery (MCA) of New Zealand White rabbits, through the internal carotid artery and blockages were confirmed by angiography. MRI was used to localize the iron-loaded clot and target the HIFU beam for treatment. HIFU pulses (1.5 MHz, 1 ms bursts, 1 Hz pulse repetition frequency, 20 s duration) were applied to initiate thrombolysis. Repeat angiograms and histology were used to assess reperfusion and vessel damage. Using 275 W of acoustic power, there was no evidence of reperfusion in post-treatment angiograms of 3 rabbits tested. In a separate group of animals, 415 W of acoustic power was applied and reperfusion was observed in 2 of the 4 (50%) animals treated. In the last group of animals, acoustic power was further increased to 550 W, which led to the reperfusion in 5 of 7 (～70%) animals tested. Histological analysis confirmed thatthe sonicated vessels remained intact after HIFU treatment. Hemorrhage was detected outside of the sonication site, likely due to the proximity of the target vessel with the base of the rabbit skull. These results demonstrate the feasibility of using HIFU, as a stand-alone method, to cause effective thrombolysis without immediate damage to the targeted vessels. HIFU, combined with imaging modalities used to identify and assess stroke patients, could dramatically reduce the time to achieve flow restoration in patients thereby significantly increasing the number of patients which benefit from thrombolysis treatments.     

Zinc, a Neuroprotective Agent Against Aluminum-induced Oxidative DNA Injury

Aluminum (Al) has been considered as one of the most abundant elements and comprises nearly 8 % of the Earth's crust. Despite of its immense presence, studies regarding the molecular basis of its interaction with the physiological system are rather sparse. On the other hand, zinc (Zn), an essential micronutrient, has been regarded as the second most important metal for brain functioning. The objective of the present study was to investigate the protective potential of Zn, if any, during Al-induced detrimental effects on DNA, tritiated thymidine uptake as well as expression of stress marker genes and proteins in rat brain. Male Sprague–Dawley rats weighing 140–160 g were divided into four different groups viz.: normal control, Al treated (100 mg/kg b wt/day via oral gavage), Zn treated (227 mg/l in drinking water), and combined Al and Zn treated. All the treatments were carried out for a total duration of 8 weeks. Agarose gel electrophoresis revealed DNA laddering pattern and comets in the rat brain following Al treatment, which however, were attenuated upon Zn treatment. Further, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells, number of apoptotic brain cells, and uptake of tritiated thymidine were increased after Al treatment but were decreased upon Zn supplementation. Western blot and mRNA expressions of p53 and nuclear factor κB (NF-κB) were also found to be significantly elevated after Al treatment, which however, were reversed following Zn treatment. Hence, Zn shall prove to be an effective agent in mitigating the detrimental effects caused by Al in the rat brain.     

Neuroprotective Role of Astrocytic Gap Junctions in Ischemic Stroke

The role of astrocytic gap junctions in ischemia remains controversial. Several studies support that astrocytic gap junctions play a role in the spread of hypoxic injury, while other reports have demonstrated that blocking astrocytic gap junctions increases neuronal death. Using a stroke model on animals in which the astrocytic gap junction protein connexin43 (Cx43) was compromised, we explored the neuroprotective role of astrocytic gap junctions. A focal brain stroke was performed on heterozygous Cx43 null [Cx43(+/?)] mice, wild type [Cx43(+/+)] mice, astrocyte-directed Cx43 deficient [Cx43^{fl/ fl}/hGFAP-cre] mice (here designated as Cre(+) mice), and their corresponding controls [Cx43^fl/fl] (here designated as Cre(?) mice). Four days following stroke, ischemic lesions were measured for size and analyzed immunohistochemically. Stroke volume was significantly larger in Cx43(+/?) and Cre(+) mice compared to Cx43(+/+) and Cre(?) mice, respectively. Apoptosis as detected by TUNEL labeling and caspase-3 immunostaining was amplified in Cx43(+/?) and Cre(+) mice compared to their control groups. Furthermore, increased inflammation as characterized by the immunohistochemical staining of the microglial marker CD11b was observed in the Cre(+) mice penumbra. Astrocytic gap junctions may reduce apoptosis and inflammation in the penumbra following ischemic insult, suggesting that coupled astrocytes fulfill a neuroprotective role under ischemic stroke conditions.     

Bee Venom and Its Component Apamin as Neuroprotective Agents in a Parkinson Disease Mouse Model

Bee venom has recently been suggested to possess beneficial effects in the treatment of Parkinson disease (PD). For instance, it has been observed that bilateral acupoint stimulation of lower hind limbs with bee venom was protective in the acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. In particular, a specific component of bee venom, apamin, has previously been shown to have protective effects on dopaminergic neurons in vitro. However, no information regarding a potential protective action of apamin in animal models of PD is available to date. The specific goals of the present study were to (i) establish that the protective effect of bee venom for dopaminergic neurons is not restricted to acupoint stimulation, but can also be observed using a more conventional mode of administration and to (ii) demonstrate that apamin can mimic the protective effects of a bee venom treatment on dopaminergic neurons. Using the chronic mouse model of MPTP/probenecid, we show that bee venom provides sustained protection in an animal model that mimics the chronic degenerative process of PD. Apamin, however, reproduced these protective effects only partially, suggesting that other components of bee venom enhance the protective action of the peptide.     

细胞穿透肽应用的研究进展

细胞穿透肽是一类具有特殊细胞膜穿透作用的短肽,研究发现其为药物大分子物质的细胞内转运提供了有力工具,现已得到了广泛关注和大量研究.一方面,近年来发现,细胞穿透肽的应用面临着药物释放率、代谢降解、细胞系的分化状态和Rho-GTPases活性的依赖性等问题,从而阻碍了其研究开发的进程.另一方面,细胞穿透肽在肿瘤治疗、抗菌和抗炎靶向药物等方面的研究却取得了显著的进展,甚至进入了临床前和临床研究阶段.本文围绕细胞穿透肽在应用开发中所面临的挑战和机遇两方面,综述了近期的研究进展,并对细胞穿透肽在新领域中的应用进行了展望.     

Digoxin Exhibits Neuroprotective Properties in a Rat Model of Dementia

Neurochemical Research - Alzheimer's disease (AD) is by far the most common cause of cognitive impairment in older adults. Current treatments are entirely focused on the symptoms of AD. A...     

The Neuroprotective Roles of Sonic Hedgehog Signaling Pathway in Ischemic Stroke

Ischemic stroke is characterized by high morbidity, mortality and disability rate worldwide. Because of its complexity in pathogenesis and lack of effective therapeutic strategies and drugs, great breakthrough has not yet been made in the treatment of cerebral ischemic stroke. Therefore, to explore a more effective and safer therapeutic strategy for cerebral ischemic stroke has been the focus of numerous researchers. Neuroprotective effects of sonic hedgehog (Shh) signaling pathway in ischemic stroke have been reported in recent studies, but have not been fully elucidated. In our review, we elaborate the roles of Shh signaling in ischemic stroke from different aspects, including oxidative stress, excitotoxicity, neuroinflammation, apoptosis, angiogenesis, neuroplasticity, neurogenesis, astrogliosis and oligodendrogenesis. Meanwhile, Shh signaling based therapeutic approaches for cerebral ischemic stroke are also included in our review. We hope it will benefit the readers to better understand the roles of Shh signaling pathway in cerebral ischemic stroke and provide more comprehensive insights for basic research and novel strategies for the clinical treatment of cerebral ischemic stroke.     

Rabbit as a Novel Animal Model for Hepatitis E Virus Infection and Vaccine Evaluation

Background

The identification of hepatitis E virus (HEV) from rabbits motivated us to assess the possibility of using rabbits as a non-human primate animal model for HEV infection and vaccine evaluation.

Methodology/Principal Findings

First, 75 rabbits were inoculated with seven strains of genotypes 1, 3, 4, and rabbit HEV, to determine the appropriate strain, administrative route and viral dosage. Second, 15 rabbits were randomly divided into three groups and vaccinated with 0 µg (placebo), 10 µg and 20 µg of HEV candidate vaccine, HEV p179, respectively. After three doses of the vaccination, the rabbits were challenged with 3.3×10⁵ genome equivalents of genotype 4 HEV strain H4-NJ703. The strain of genotype 1 HEV was not found to be infectious for rabbits. However, approximately 80% of the animals were infected by two rabbit HEV strains. All rabbits inoculated with a genotype 3 strain were seroconverted but did not show viremia or fecal viral shedding. Although two genotype 4 strains, H4-NJ153 and H4-NJ112, only resulted in part of rabbits infected, another strain of genotype 4, H4-NJ703, had an infection rate of 100% (five out of five) when administrated intravenously. However, only two out of fifteen rabbits showed virus excretion and seroconversion when inoculated orally with H4-NJ703 of three different dosages. In the vaccine evaluation study, rabbits vaccinated with 20 µg of the HEV p179 produced anti-HEV with titers of 1∶10⁴–1∶10⁵ and were completely protected from infection. Rabbits vaccinated with 10 µg produced anti-HEV with titers of 1∶10³–1∶10⁴ and were protected from hepatitis, but two out of the five rabbits showed virus shedding.

Conclusions/Significance

Rabbits may be served as an alternative to the non-human primate models for HEV infection and vaccine evaluation when certain virus strains, appropriate viral dosages, and the intravenous route of inoculation are selected.     

The Transgenic Rabbit as Model for Human Diseases and as a Source of Biologically Active Recombinant Proteins

Until recently, transgenic rabbits were produced exclusively by pronuclear microinjection which results in additive random insertional transgenesis; however, progress in somatic cell cloning based on nuclear transfer will soon make it possible to produce rabbits with modifications to specific genes by the combination of homologous recombination and subsequent prescreening of nuclear donor cells. Transgenic rabbits have been found to be excellent animal models for inherited and acquired human diseases including hypertrophic cardiomyopathy, perturbed lipoprotein metabolism and atherosclerosis. Transgenic rabbits have also proved to be suitable bioreactors for the production of recombinant protein both on an experimental and a commercial scale. This review summarizes recent research based on the transgenic rabbit model.