Neuroprotective effects of ganoderma lucidum polysaccharides against oxidative stress-induced neuronal apoptosis

Ganoderma lucidum polysaccharides have protective effects against apoptosis in neurons exposed to ischemia/reperfusion injury, but the mechanisms are unclear. The goal of this study was to investigate the underlying mechanisms of the effects of ganoderma lucidum polysaccharides against oxidative stress-induced neuronal apoptosis. Hydrogen peroxide（H_2O_2） was used to induce apoptosis in cultured cerebellar granule cells. In these cells, ganoderma lucidum polysaccharides remarkably suppressed H_2O_2-induced apoptosis, decreased expression of caspase-3, Bax and Bim and increased that of Bcl-2. These findings suggested that ganoderma lucidum polysaccharides regulate expression of apoptosis-associated proteins, inhibit oxidative stress-induced neuronal apoptosis and, therefore, have significant neuroprotective effects.

Protective Effect of Tetrandrine against Excitatory Amino Acids induced Neuronal Injury in Cortical Culture

The ability of tetrandrine (Tet), an alkaloid isolated from Radix Stephaniae Tetrandrae, to reduce cortical neuronal injury in cortical cultures derived from fetal rats was quantitatively assessed by examination of morphological changes and measurement of lactate dehydrogenase (LDH) released to the extracellular bathing media Cell cultures exposed to the excitatory amino acids (EAA) 50 μmol L 1 glutamate (Glu), 20 μmol L 1 N methyl D aspartate (NMDA), 300 μmol·L 1 β N oxalylamino L alanine (BMAA, NMDA receptor agonist) or 20 μmol·L 1 β N oxaly lamino L alanine (BOAA, non NMDA receptor agonist) for 24 h at 37℃ showed widespread neuronal injury Tet had little effect on the injury induced by 20 μmol·L 1 NMDA but 10 7 and 10 6 μmol·L 1 Tet did partially attenuate the neuronal degeneration, neuronal loss and LDH efflux resulting from prolonged exposures to 100 μmol·L 1 Glu, 300 μmol·L 1 BMAA and 20 μmol·L 1 BOAA respectively The ability of Tet to reduce the neuronal injury induced by prolonged exposure to EAA may contribute, at least in part, to the reduction of Ca 2+ influx through inhibiting the opening of voltagegated Ca 2+ channels Another mechanism that Tet might have a little inhibitory effect on NMDA receptor on neuronal membrane cannot be excluded, as BMAA has been considered to act as a weak NMDA receptor agonist

Oxidative damage of primary cultured hippocampal neurons Does androgen have an antagonistic effect?

BACKGROUND： Evidence illustrates that androgen has a neuroprotective role. However, whether androgen also has the protective effect on hippocampal neurons during free radical mediated injury remains unclear. OBJECTIVE： To investigate the neuroprotective effect of androgen on hippocampal neurons during free radical damage. DESIGN, TIME AND SETTING： A controlled in vitro experiment was performed at the Department of Human Anatomy, Cell Culture Lab, and Neuroendocrinology Lab, Basic Medical School, Hebei Medical University from February to June 2009. MATERIALS： Testosterone was provided by Tianjin Jinyao Amino Acid Company, China. METHODS： Primary cultured neurons from 24 Sprague Dawley rats were randomly assigned into four groups： control, H202, testosterone, and testosterone （pre-added） plus H2O2 groups. MAIN OUTCOME MEASURES： The positive cell ratio of microtubule associated protein-Ⅱ and neuron specific enolase was determined by immunocytochemistry. Neuronal morphology was observed by hematoxylin-eosin staining and Nissl staining. Cell vitality and viability were determined using an inverted phase contrast microscope. The content of nitric oxide synthase, malondialdehyde, and superoxide dismutase were measured with a spectrophotometer. RESULTS： As compared with the control group, cell vitality and viability, and superoxide dismutase level were significantly decreased in the H202 group （P 〈 0.05）, while nitric oxide synthase and malondialdehyde levels were significantly increased （P 〈 0.05）. Neuronal vitality and viability as well as superoxide dismutase level in the testosterone plus H2O2 group were significantly greater than in the H2O2 group （P 〈 0.05）, and nitric oxide synthase and malondialdehyde levels were significantly less than in the H2O2 group （P〈 0.05）. CONCLUSION： Androgen partially reversed H2O2-induced neuronal damage and protected neurons.

Dual effects of 3,4-methylenedioxymethamphetamine (ecstasy) on survival and apoptosis of primary hippocampal neurons

BACKGROUND： 3, 4-methylenedioxymethamphetamine （MDMA, also known as ＂ecstasy＂） has been shown to exhibit neurotoxic effects on the hippocampus. However, exposure to sub-lethal insults of MDMA has been reported to result in neuroprotection. OBJECTIVE： To investigate the effects of MDMA on hippocampal neuronal viability, caspase-3 activity, and mRNA expression of the N-methyI-D-aspartate （NMDA） receptor 2B （NR2B） subunit. DESIGN, TIME AND SETTING： A cytological, in vitro experiment was performed at the Department of Anatomy, School of Medicine, and Department of Toxicology-Pharmacology, Faculty of Pharmacy Tehran University of Medical Sciences in 2008. MATERIALS： MDMA was extracted from ecstasy tablets, which were kindly supplied by the Pharmacology-Toxicology Department, Faculty of Pharmacy, Tehran University of Medical Sciences, Iran. METHODS： Hippocampal neurons were isolated from Wistar rats at gestational day 18. Following primary culture, hippocampal neuronal viability was detected by MTT assay. Varying concentrations of MDMA （100-5 000 μmol/L） were used to determine lethal concentration 50 （LC50）, which was around 1 500 μmol/L. Five concentrations of MDMA below 1 500 μmol/L （100, 200, 400, 800, and 1 050 μmol/L） were used for the remaining experiments. After 24 hours of MDMA treatment, NR2B mRNA expression was detected by RT-PCR, and caspase-3 relative activity was determined by colorimetric assay. MAIN OUTCOME MEASURES： Hippocampal neuronal viability, caspase-3 activity, and NR2B mRNA expression. RESULTS： MDMA-induced neurotoxicity in hippocampal neuronal cultures was dose-dependent. In high concentrations （1 000-5 000μmol/L） of MDMA, neuronal viability was decreased. However, with a 500 μmol/L dose of MDMA, neuronal viability was significantly increased （P 〈 0.01）. Low concentrations of MDMA （200 and 400μmol/L） significantly decreased caspase-3 activity （P 〈 0.01）, whereas high concentrations of MDMA significantly increased caspase-3 activity （P 〈 0.01）. NR2B subunit mRNA expression was not significantly altered after 100 -1 050 μmol/L MDMA exposure. CONCLUSION： MDMA exhibits dual effects on hippocampal neuronal viability and caspase-3 activity. These effects are independent from NR2B subunit expression levels.

Bis(7)-Tacrine, a Promising Anti-Alzheimer's Agent,Attenuates Glutamate-Induced Cell Injury in Primary Cultured Cerebrocortical Neurons of Rats

The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (12 days after plating) to 0.5 mmol/L glutamate for 30 min resulted in significant cell damage. Pretreatment with bis(7) tacrine (0.03 1.0 μmol/L) reduced the glutamate induced neurotoxicity in a concentration dependent manner and the maximal response was seen at 1 μmol/L with approximately 30% protection. A receptor binding assay showed that bis(7) tacrine can completely displace MK 801 binding to rat cortical membrane with an IC 50 of 0.57 μmol/L. These findings suggest that bis(7) tacrine can directly interact with N methyl D aspartate receptor channel complex, which may contribute to the inhibitor's protective effects against glutamate induced excitotoxicity. Thus, it is possible that anti glutamate/anti AChE synergism is responsible for potentially better Alzheimer's therapy of bis(7) tacrine relative to tacrine.

EFFECT OF THE TOTAL SAPONIN OF DIPSACUS ASPER ON INTRACELLULAR FREE CALCIUM CONCENTRATION IN THE CELLULAR MODEL OF ALZHEIMER'S DISEASE-SCANNING CONFOCAL MICROSCOPY

Objective To study the effect of ginsenoside Rb1 and total saponin of dipsacus asper on intracellular free calcium concentration mediated by β amyloid protein.So as to lay a foundation for developing effective Chinese traditional medicine to treat Alzheimer’s disease.Methods The technique of laser scanning confocal microscopy combining primary cultured neurons was adopted to quantitatively analyze the change of [Ca 2+ ] i.Results The [Ca 2+ ] i of primary cultured hippocampal neurons was nmol·L -1 on basal levels.Control group showed obvious change of calcium vibration,[Ca 2+ ] i was elevated to nmol·L -1 .The peak of [Ca 2+ ] i of Rb1 group reached nmol·L -1 and was lower than that of control group .The tSDA group displayed distinct change of calcium vibration too,and [Ca 2+ ] i reached nmol·L -1 .There was a significant difference in [Ca 2+ ] i between control and tSDA group .Conclusion The research indicated that one of mechanisms by which Rb1 and tSDA protected the neurons was to maintain the balance of [Ca 2+ ] i.

Effect of Interleukin-1β on the Elevation of Cytoplasmic Free Calcium of the Cultured Hippocampal Neurons Induced by L-Glutamate

To investigate the intracellular mechanism that interleukin 1β (IL 1β) facilitates epileptic seizure and neuronal damage, the effect of IL 1β alone or IL 1β plus glutamate (Glu) on the intracellular free calcium ([Ca 2+ ] i) of single cultured hippocampal neuron was examined by using EPC 9 light electricity measurement system. The results showed that IL 1β of different concentrations (5×10 3 U/L, 10×10 3 U/L, 20×10 3 U/L, 30×10 3 U/L, 50×10 3 U/L, 100×10 3 U/L) failed to affect the neuronal [Ca 2+ ] i, but IL 1β could facilitate the augmentation of neuronal [Ca 2+ ] i induced by Glu in a dose dependent pattern. MK 801 inhibited the effect of Glu on [Ca 2+ ] i, and also inhibited the effect of IL 1β on [Ca 2+ ] i induced by Glu, while verapamil did not influence the effect of Glu or IL 1β. It is concluded that IL 1β, as a neuromodulator, can facilitate the activation of NMDA receptor by Glu, induce the increase of intracellular calcium, which enhances the excitement of neuron.

pFTAA: a high affinity oligothiophene probe that detects filamentous tau in vivo and in cultured neurons

Tauopathies describe a group of neurodegenerative diseases in which the protein tau,encoded by the gene MAPT,is aberrantly misfolded,leading to tau aggregation,neural dysfunction,and cell death（Spillantini and Goedert,2013）.In Alzheimer＇s disease（AD）,tau forms the characteristic intracellular neurofibrillary tangles（NFTs）,which are thought to be the major cause of neurodegeneration（Bloom,2014）.In other tauopathies,including frontotemporal dementia with Parkinsonism linked to chromo- some 17 （FTDP-17T）, corticobasal degeneration and progressive supranuclear palsy, there are specific forms of tau aggregates and filaments without any amyloid pathology, demonstrating tau＇s po- tent disease-causing potential （Spillantini and Goedert, 2013）. Tau is a microtubule （MT） binding protein, which becomes abnormally hyperphosphorylated on several residues prior/during the process of aggregation, thereby causing loss of its MT binding activity （Mandelkow and Mandelkow, 2012）.

EFFECT OF SIBELIUM ON HYPOXIC CULTURED NEURONS FROM NEWBORN RATS CEREBRAL CONTEX IN VITRO

Primary cultures of rat cerebral corticai neurons were prepared from conices or 2 days Sprague-Dawlley rats.We made an attempt to imitate the hypoxic neurons injury for testing neuroprotective erfect or Sibelium. It was found that Sibelium could significantly decrease the amounts of LDH leaking from intracellular fluid and increase the neuron-membrane fluidity of hypoxic neurons.Hypoxic group had significantly higher incorporation of 3H-TDR and 3H-UR than control group,while Sibelium could decrease the incorporation of 3H-TDR and 3H-UR. In addition,Sibelium could decrease the incorporation of 3H-TDR and 3H-UR in normal cultured neurons.The results showed that Sibelium could protect the neuronmembranes against alteration caused by hypoxia and regulate the synthesis of DNA and RNA.

Effect of polygonatum polysaccharide on the hypoxia-induced apoptosis and necrosis in in vitro cultured cerebral cortical neurons from neonatal rats

BACKGROUND： Cardiocerebrovascular diseases induced cerebral circulation insufficiency and senile vascular dementia can result in ischemic/hypoxic apoptosis of central neurons, which we should pay more attention to and prevent and treat as early as possible. Traditional Chinese medicine possesses the unique advantage in this field. Polygonatum, a Chinese herb for invigorating qi, may play a role against the hypoxic apoptosis of brain neurons. OBJECTIVE ： To observe the protective effect of polygonatum polysaccharide on hypoxia-induced apoptosis and necrosis in cerebral cortical neurons cultured in vitro. DESIGN： A comparative experiment.SETTING： Laboratory of Cell Biology, Institute of Basic Medical Sciences, Jiangxi Provincial Academy of Traditional Chinese Medicine. MATERIALS： The experiment was carried out in the Laboratory of Cell Biology, Institute of Basic Medical Sciences, Jiangxi Provincial Academy of Traditional Chinese Medicine from November 2003 to April 2005. Totally 218 Wistar rats （male or female） of clean degree within 24 hours after birth were purchased from the animal center of Jiangxi Medical College （certification number was 021-97-03）. METHODS：① Preparation of cerebral cortical neurons of rats： The cerebral cortical tissues were isolated from the Wistar rats within 24 hours after birth, and prepared to single cell suspension, and the cerebral cortical neurons of neonatal rats were in vitro cultured in serum free medium with Neurobasal plus B27 Supplement. ② Observation on the non-toxic dosage of polygonatum polysaccharide on neurons： After the neurons were cultured for 4 days, polygonatum polysaccharide of different dosages （1-20 g/L） was added for continuous culture for 48 hours, the toxicity and non-toxic dosage of polygonatum polysaccharide on neurons were observed and detected with trypan blue staining. ③Grouping： After hypoxia/reoxygenation, the cultured neurons were divided into normal control group, positive apoptotic group and polygonatum polysaccharide group. In the normal control group, the neurons were cultured at 37℃ in CO2 with the volume fraction of 0.05 under saturated humidity for 6 days. In the apoptotic positive group, the neurons were cultured with hypoxia for 12 hours after 4-day culture, and followed by reoxygenation for 48 hours. In the polygonatum polysaccharide group, polygonatum polysaccharide with the terminal concentration of 0.5, 1 and 1.5 g/L was added to some neurons at 10 hours before the hypoxia culture, and then the neurons were cultured with hypoxia for 12 hours, followed by reoxygenation for 48 hours; polygonatum polysaccharide with the terminal concentration of 0.5, 1 and 1.5 g/L was added to the other neurons at 12 hours after hypoxia followed by reoxygenation for 48 hours.④ The Hoechst33342 fluorescence staining, Annexin V/PI flow cytometer, appearance of DNA agarose gel electrophoresis gradient strap and immunohistochemical staining were used to observe the expressions of Bcl-2, Bax and Caspase-3 apoptotic and anti-apoptotic proteins and the ratio of Bcl-2/Bax, and observe the effect of polygonatum polysaccharide against the hypoxic apoptosis of cerebral cortical neurons of neonatal rats. MAIN OUTCOME MEASURES： ① Toxicity and non-toxic dosage of polygonatum polysaccharide on neurons;② Apoptotic rate of neurons detected with Hoechst33342 fluorescence staining;③ Early apoptotic rate and necrotic rate of neurons detected with Annexin V/PI flow cytometer; ④DNA agarose gel electrophoresis ladder-like strap appeared or not;⑤ Expressions of Bcl-2, Bax and Caspase-3 apoptotic and anti-apoptotic proteins and the ratio of Bcl-2/Bax. RESULTS：① Polygonatum polysaccharide within 6 g/L had no cytotoxicity on the normal cultured cerebral cortical neurons （P 〉 0.05）. ②The apoptotic rates of neurons detected with Hoechst33342 fluorescence staining had significant differences between the polygonatum polysaccharide groups and positive apoptosis group added to neurons at 10 hours before the hypoxia culture [（13.00±4.52）%,（12.72±2.15）%, （11.80±1.18）%,（38.03±1.05）%, P 〈 0.01], and had no significant differences between the polygonatum polysaccharide groups and positive apoptosis group added to neurons at 12 hours after the hypoxia culture （36.77±1.45）%, （36.60±1.61）%, （36.37±2.02）%, （38.03±1.05）%, P 〉 0.05].③ Annexin V/PI flow cytometer detected that the anti-necrotic effect was enhanced with the increased concentration of polygonatum polysaccharide within 0.5-1.5 g/L （P 〈 0.01）. Polygonatum polysaccharide of 0.5-1.5 g/L added before hypoxia could significantly decrease the apoptotic rate of neurons induced by hypoxia/reoxygenation （P 〈 0.01）. ④ No DNA agarose gel electrophoresis ladder-like strap appeared in the groups with polygonatum polysaccharide of 0.5-1.5 g/L added at 10 hours before hypoxia;⑤ After Polygonatum polysaccharide of 0.5-1.5 g/L was added before hypoxia, the expression of Bcl-2 protein of hypoxic neurons was increased （P 〈 0.01）, and those of Bax protein and Caspase-3 protein were reduced （P 〈 0.01）, and the ratio of Bcl-2/Bax was increased （P 〈 0.01）. CONCLUSION： Polygonatum polysaccharide within 6 g/L has no cytotoxicity on the normal cultured cerebral cortical neurons. Polygonatum polysaccharide of 0.5-1.5 g/L added before hypoxia plays a role agains necrosis of neurons induced by hypoxia. Polygonatum polysaccharide of 0.5-1.5 g/L can significantly reduce the apoptosis of neurons induced by hypoxia through up-regulating the expression of Bcl-2 protein, down-regulating the expressions of Bax protein and Caspase-3 protein, and increasing the ratio of Bcl-2/Bax.

Effect of neuronal excitotoxicity on Munc18-1 distribution in nuclei of rat hippocampal neuron and primary cultured neuron

Objective Muncl8-1 has an important role in neurotransmitter release, and controls every step in the exocy- totic pathway in the central nervous system. In the present study, whether epileptic seizure causes a change of Muncl8 localization in neuronal nuclei was analyzed. Methods Epilepsy models were established by injection of kainic acid （KA） solution into hippocampus of Sprague-Dawley （SD） rats or intraperitoneal injection of KA in Kunming mice. The hippocampal neurons were prepared from embryonic day 18 SD rats, and cultured in neurobasal medium, followed by treatment with glutamate for 3 h. Neuronal and glial nuclei of hippocampus were separated by sucrose density gradient centrifugation. The nucleus-enriched fractions were stained with 0.1% Cresyl Violet for morphological assay. Immuno- chemistry and immunoelectron microscopy with anti-Muncl 8-1 antibody were used to determine the nuclear locatization of Munc 18-1. Immunoblotting was used to detect the protein level of Munc 18-1. Results The localization of Munc 18-1 in nucleus of rat hippocampal neuron was confirmed by immunochemistry, immunoelectron microscopy, and immunob- lotting detection of neuronal nucleus fraction. In animals receiving intrahippocampal or intraperitoneal injection of KA, immunostaining revealed that the expression of Muncl 8-1 decreased in pyramidal cell layer of CA regions, as well as in hilus and granular cell layer of dentate gyrus in hippocampus. Moreover, immunoblotting analysis showed that the expres- sion level of Muncl 8-1 in nucleus fraction of hippocampus significantly decreased in KA-treated animals. The relation- ship between the change of Muncl8-1 expression in neuronal nuclei and neuronal over-activation was also tested in pri- mary cultured neurons. After treatment with 50 ~tmol/L glutamate acid for 3 h, Muncl8-1 level was decreased in nucleus fraction and increased in cytoplasmic fraction of primary cultured neurons. Conclusion These results suggest that excit- atory stimulation can induce the distribution change of Munc 18-1 in neuron, which may subsequently modulate neuronal functions in brain.

Transcriptome Sequencing Reveals Astrocytes as a Therapeutic Target in Heat-Stroke

Heat-stroke is a serious form of hyperthermia with high mortality, and can induce severe central nervous system disorders. The neurovascular unit（NVU）, which consists of vascular cells, glial cells, and neurons, controls blood-brain barrier（BBB） permeability and cerebral blood flow, and maintains the proper functioning of neuronal circuits. However, the detailed function of each BBB component in heat-stroke remains unknown. In order to interpret alterations caused by heat stress, we performed transcriptome comparison of neuron and astrocyte primary cultures after heat treatment. Differentially-expressed genes were then selected and underwent Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis. Gene-act networks were also constructed, and the expression of pivotal genes was validated by quantitative PCR, as well as single-cell q PCR in heatstroke rats. Our work provides valuable information on the transcriptional changes in NVU cells after heat stress,reveals the diverse regulatory mechanisms of two of these cellular components, and shows that a cell-type-specificapproach may be a promising therapeutic strategy for heatstroke treatments.

Effects of Single and Repeated Exposure to a 50-Hz 2-mT Electromagnetic Field on Primary Cultured Hippocampal Neurons

The prevalence of domestic and industrial electrical appliances has raised concerns about the health risk of extremely low-frequency magnetic fields（ELF-MFs）. At present, the effects of ELF-MFs on the central nervous system are still highly controversial, and few studies have investigated its effects on cultured neurons. Here, we evaluated the biological effects of different patterns of ELF-MF exposure on primary cultured hippocampal neurons in terms of viability, apoptosis, genomic instability,and oxidative stress. The results showed that repeated exposure to 50-Hz 2-mT ELF-MF for 8 h per day after different times in culture decreased the viability and increased the production of intracellular reactive oxidative species in hippocampal neurons. The mechanism was potentially related to the up-regulation of Nox2 expression.Moreover, none of the repeated exposure patterns had significant effects on DNA damage, apoptosis, or autophagy, which suggested that ELF-MF exposure has no severe biological consequences in cultured hippocampal neurons.