Survival Rate Of Neurons Research Articles

Jisuikang, a Chinese herbal formula, increases neurotrophic factor expression and promotes the recovery of neurological function after spinal cord injury.

The Chinese medicine compound, Jisuikang, can promote recovery of neurological function by inhibiting lipid peroxidation, scavenging oxygen free radicals, and effectively improving the local microenvironment after spinal cord injury. However, the mechanism remains unclear. Thus, we established a rat model of acute spinal cord injury using a modified version of Allen's method. Jisuikang (50, 25, and 12.5 g/kg/d) and prednisolone were administered 30 minutes after anesthesia. Basso, Beattie, and Bresnahan locomotor scale scores and the oblique board test showed improved motor function recovery in the prednisone group and moderate-dose Jisuikang group compared with the other groups at 3-7 days post-injury. The rats in the moderate-dose Jisuikang group recovered best at 14 days post-injury. Hematoxylin-eosin staining and transmission electron microscopy showed that the survival rate of neurons in treatment groups increased after 3-7 days of administration. Further, the structure of neurons and glial cells was more distinct, especially in prednisolone and moderate-dose Jisuikang groups. Western blot assay and immunohistochemistry showed that expression of brain-derived neurotrophic factor (BDNF) in injured segments was maintained at a high level after 7-14 days of treatment. In contrast, expression of nerve growth factor (NGF) was down-regulated at 7 days after spinal cord injury. Real-time fluorescence quantitative polymerase chain reaction showed that expression of BDNF and NGF mRNA was induced in injured segments by prednisolone and Jisuikang. At 3-7 days after injury, the effect of prednisolone was greater, while 14 days after injury, the effect of moderate-dose Jisuikang was greater. These results confirm that Jisuikang can upregulate BDNF and NGF expression for a prolonged period after spinal cord injury and promote repair of acute spinal cord injury, with its effect being similar to prednisolone.

Effects of treadmill training on learning and memory after cerebral ischemia

Objective To investigate the effects of exercise on learning and memory after cerebral ischemia. Methods Ninety Sprague-Dawley rats were randomly divided into a sham-operated group, a model group and a treadmill training group (n=30 for each), which were further subdivided into groups to receive 7 days, 14 days or 28 days of training with 10 rats in each. The training was treadmill running at 10 m/min for 30 min a day. Cerebral ischemia was induced in the model and training groups using permanent, bilateral common carotid artery occlusion. The training began three days after the operation. Morris water maze tests were used to measure the rats′ learning and memory ability, and Nissl staining was employed to detect the survival rates of pyramidal neurons in the CA1 area of the hippocampus. Results The average escape latency in the treadmill trained group had shortened significantly by day 7, then further by days 14 and 28. It was significantly shorter than the model group′s average at each time point. The average platform crossing time increased significantly compared with the model group′s average. Few dead neurons were observed in the sham-operated group. On days 14 and 28 the average survival rate of pyramidal neurons in the model group was significantly lower than in the treadmill training group or the sham-operated group, though there was no significant difference on day 7. Conclusion Treadmill training can improve learning and memory after cerebral ischemia, at least in rats. Better effects can be observed after longer training. Key words: Cerebral ischemia; Treadmill training; Learning and memory; Exercise

Ginseng Protein Reverses Amyloid Beta Peptide and H2 O2 Cytotoxicity in Neurons, and Ameliorates Cognitive Impairment in AD Rats Induced by a Combination of D-Galactose and AlCl3.

Ginseng (Panax ginseng C.A. Meyer) is one of the most widely used herbal medicines worldwide. The present study evaluated the neuroprotective effects of ginseng protein (GP) and its possible mechanisms in a cellular and animal model of AD. The results demonstrated that GP (10-100 µg/mL) significantly improved the survival rate of neurons and reduced the cells' apoptosis and the mRNA expression of caspase-3 and Bax/Bcl-2. In addition, GP (0.1 g/kg) significantly shortened the escape latency, prolonged the crossing times and the percentage of residence time; reduced the level of Aβ1-42 and p-tau, the activity of T-NOS and iNOS, and the content of MDA and NO, improved the activity of SOD, the concentration of cAMP and the protein expression of p-PKA/PKA and -CREB/CREB. The results demonstrated that GP significantly inhibited Alzheimer-like pathophysiological changes induced by Aβ25-35 or H2 O2 in cells or those induced by D-gal/ Al in animals. These neuroprotective effects of GP may be associated with the cAMP/PKA/CREB pathway. Also, in combination with our previous studies, these results indicate that the anti-AD mechanism of GP was likely to activate the CREB pathway through multiple channels. Copyright © 2016 John Wiley & Sons, Ltd.

Alkaloids from piper longum protect dopaminergic neurons against inflammation-mediated damage induced by intranigral injection of lipopolysaccharide.

BackgroundAlkaloids from Piper longum (PLA), extracted from P. longum, have potent anti-inflammatory effects. The aim of this study was to investigate whether PLA could protect dopaminergic neurons against inflammation-mediated damage by inhibiting microglial activation using a lipopolysaccharide (LPS)-induced dopaminergic neuronal damage rat model.MethodsThe animal behaviors of rotational behavior, rotarod test and open-field test were investigated. The survival ratio of dopaminergic neurons and microglial activation were examined. The dopamine (DA) and its metabolite were detected by high performance liquid chromatography (HPLC). The effects of PLA on the expression of interleukin (IL)-6, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were detected by enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) and nitric oxide (NO) were also estimated.ResultsWe showed that the survival ratio of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra pars compacta (SNpc) and DA content in the striatum were reduced after a single intranigral dose of LPS (10 μg) treatment. The survival rate of TH-ir neurons in the SNpc and DA levels in the striatum were significantly improved after treatment with PLA for 6 weeks. The over-activated microglial cells were suppressed by PLA treatment. We also observed that the levels of inflammatory cytokines, including TNF-α, IL-6 and IL-1β were decreased and the excessive production of ROS and NO were abolished after PLA treatment. Therefore, the behavioral dysfunctions induced by LPS were improved after PLA treatment.ConclusionThis study suggests that PLA plays a significant role in protecting dopaminergic neurons against inflammatory reaction induced damage.

Morphine Preconditioning Downregulates MicroRNA-134 Expression Against Oxygen-Glucose Deprivation Injuries in Cultured Neurons of Mice.

Brain protection by narcotics such as morphine is clinically relevant due to the extensive use of narcotics in the perioperative period. Morphine preconditioning induces neuroprotection in neurons, but it remains uncertain whether microRNA-134 (miR-134) is involved in morphine preconditioning against oxygen-glucose deprivation-induced injuries in primary cortical neurons of mice. The present study examined this issue. After cortical neurons of mice were cultured in vitro for 6 days, the neurons were transfected by respective virus vector, such as lentiviral vector (LV)-miR-control-GFP, LV-pre-miR-134-GFP, LV-pre-miR-134-inhibitor-GFP for 24 hours; after being normally cultured for 3 days again, morphine preconditioning was performed by incubating the transfected primary neurons with morphine (3 μM) for 1 hour, and then neuronal cells were exposed to oxygen-glucose deprivation (OGD) for 1 hour and oxygen-glucose recovery for 12 hours. The neuronal cells survival rate and the amount of apoptotic neurons were determined by MTT assay or TUNEL staining at designated time; and the expression levels of miR-134 were detected using real-time reverse transcription polymerase chain reaction at the same time. The neuronal cell survival rate was significantly higher, and the amount of apoptotic neurons was significantly decreased in neurons preconditioned with morphine before OGD than that of OGD alone. The neuroprotection induced by morphine preconditioning was partially blocked by upregulating miR-134 expression, and was enhanced by downregulating miR-134 expression. The expression of miR-134 was significantly decreased in morphine-preconditioned neurons alone without transfection. By downregulating miR-134 expression, morphine preconditioning protects primary cortical neurons of mice against injuries induced by OGD.

Sodium transport through the cerebral sodium-glucose transporter exacerbates neuron damage during cerebral ischaemia.

We recently demonstrated that the cerebral sodium-glucose transporter (SGLT) is involved in postischaemic hyperglycaemia-induced exacerbation of cerebral ischaemia. However, the associated SGLT-mediated mechanisms remain unclear. Thus, we examined the involvement of cerebral SGLT-induced excessive sodium ion influx in the development of cerebral ischaemic neuronal damage. [Na+]i was estimated according to sodium-binding benzofuran isophthalate fluorescence. In the in vitro study, primary cortical neurons were prepared from fetuses of ddY mice. Primary cortical neurons were cultured for 5 days before each treatment with reagents, and these survival rates were assessed using biochemical assays. In in vivo study, a mouse model of focal ischaemia was generated using middle cerebral artery occlusion (MCAO). In these experiments, treatment with high concentrations of glucose induced increment in [Na+]i, and this phenomenon was suppressed by the SGLT-specific inhibitor phlorizin. SGLT-specific sodium ion influx was induced using a-methyl-D-glucopyranoside (a-MG) treatments, which led to significant concentration-dependent declines in neuronal survival rates and exacerbated hydrogen peroxide-induced neuronal cell death. Moreover, phlorizin ameliorated these effects. Finally, intracerebroventricular administration of a-MG exacerbated the development of neuronal damage induced by MCAO, and these effects were ameliorated by the administration of phlorizin. Hence, excessive influx of sodium ions into neuronal cells through cerebral SGLT may exacerbate the development of cerebral ischaemic neuronal damage.

Effect of obstructive sleep apnea hypoxia on learning memory capacity after cerebral ischemia-reperfusion in rats

To investigate the effect of obstructive sleep apnea hypoxia on learning memory capacity in rat after ischemia. Eighty healthy male wister rats were randomly divided into: sham operation group (SO group, n=20), merely ischemia group (I/R group, n=20), and obstructive sleep apnea hypoxia for 7 days ischemia group (IH7+ I/R group, n=20), obstructive sleep apnea hypoxia for 21 days ischemia group (IH21+ I/R group, n=20). Obstructive sleep apnea hypoxia ischemia groups were respectively given obstructive sleep apnea hypoxia for 7 days and 21 days. Ischemia animals were prepared cerebral ischemia-reperfusion model by improved pulsinelli four vessels block (4-VO), the morphological changes of hippocampus nerve cells of rat brain were detected with HE, neuron pathology in hippocampal regin was observed using electron microscope, and learning memory capacity of rats were assessed by the Morris water maze test. Compared with the SO group, the I/R group demonstrated shortened escaping latency, increased frequency of crossing the platform in the water maze test, decreased survival rate of neurons, and increased apoptotic cells and ultrastructure damages(P<0.05). Compared with the I/R group, obstructive sleep apnea hypoxia ischemia groups showed shortened escaping latency, increased frequency of crossing the platform, decreased survival rate of neurons, and increased apoptotic cells and ultrastructure damages(P<0.05), especially in the IH21+ I/R group(P<0.05). Obstructive sleep apnea hypoxia can increase the damage of learning memory capacity. This damage is related to hippocampus nerve loss and ultrastructure injury from obstructive sleep apnea hypoxia.

Effects of treadmill running pretreatment on the expression of CyclinA and CyclinE protein in hippocampus of rats after global cerebral ischemia and reperfusion

Objective To investigate the effect of treadmill running pretreatment on the expression of CyclinA and CyclinE protein in hippocampus of rats after global cerebral ischemia and reperfusion. Methods 60 healthy male wister rats were randomly divided into control group, model group and experiment group. Global cerebral ischemia reperfusion model was generated by improved four-vessel occlusion as described according to the description of Pulsinelli's method. Rats in the experiment group were performed treadmill running for 2 weeks before injury. The water maze test was performed at 24 h and 48 h respectively after injury to determine the spatial memory ability of rats. Morphological changes of hippocampus were observed by HE staining (hematoxylin-eosin staining) at 3 h, 6 h, 24 h, 48 h after injury and the expression of CyclinA and CyclinE were detected by immunohistochemical staining. Results Compared with control group, the survival rate of neurons in the model group was significantly decreased at each time point. Morris water maze test showed that the escaping latency of rats in the model group was significantly prolonged(24 h(24.35±3.99)s, 48 h(33.08±5.85)s), and the frequency of crossing the platform was decreased(24 h(6.80±0.79), 48 h(4.00±0.67)). The expression of CyclinA was increased significantly in the model group((8.40±0.52)/high view, (11.70±1.06)/ high view, (15.50±0.53)/ high view, (22.40±0.52)/ high view) as well as the expression of CyclinE((20.30±0.48)/ high view, (15.20±0.63)/ high view, (10.00±0.82)/ high view, (7.70±0.68)/ high view) (P<0.05). Compared with model group, the survival rate of neurons in the model group was significantly increased at each time point. Morris water maze test showed that the escaping latency of rats in the experiment group was significantly shorten(24 h(13.21±2.73)s, 48 h(24.20±4.66)s), and the frequency of crossing the platform was increased(24 h(9.70±0.95), 48 h(6.30±1.16)). The expression of CyclinA was significantly increased in the model group((10.60±0.84)/ high view), (16.70±0.68)/ high view), (24.50±0.53)/ high view), (36.20±1.40)/ high view) as well as the expression of CyclinE((31.60±0.70)/ high view), (24.50±0.70)/ high view), (16.80±0.63)/ high view), (9.10±0.74)/ high view) (P<0.05). Conclusion The treadmill running pretreatment improves the function of spatial memory after global cerebral ischemia and reperfusion, potenlially mediated by regulating the expression for cell cycle proteins, which have a protective effect on cerebral brain tissue. Key words: Global cerebral ischemia; Treadmill running; CyclinA; CyclinE

Rosiglitazone ameliorates astrocyte over-activation and inflammatory cytokine release induced by global cerebral ischemia/reperfusion.

Global cerebral ischemia (GCI) is a leading cause of mortality worldwide and remains the primary cause of long-term neurological disability. Astrocyte over-activation and extensive neuron loss in the ischemic brain are the characteristic pathological features of cerebral ischemia. Rosiglitazone (RSG) is a peroxisome-proliferating activating receptor-γ agonist known for its anti-inflammatory activity. Previous studies have suggested that RSG is able to exert neuroprotection in numerous acute and chronic brain injury models. However, whether RSG treatment is involved in astrocyte over-activation and inflammatory reaction in the cortex remains unclear. The aim of the present study was to investigate whether RSG treatment improved functional impairment induced following GCI and protected against cortex neuron loss, and to elucidate the potential mechanisms underlying these functions. Rats were randomly divided into three groups: Sham-operated, GCI and RSG treatment groups. The RSG treatment group was treated with 2 mg/kg RSG immediately following GCI. The results demonstrated that RSG treatment significantly reduced infarct volume and neuron survival rates in addition to increasing function recovery. Furthermore, these results correlate with a reduction in astrocyte over-activation and inflammatory cytokines in the rat cortex. However, no significant changes in glutamate transporter-1 expression levels were observed following RSG treatment compared with the GCI rats. The results of this investigation provide in vivo evidence that RSG significantly protected rats against ischemia-reperfusion-induced brain injury. In addition, RSG may exert neuroprotective effects by inhibiting astrocyte over-activation, and thereby reducing the levels of inflammatory cytokines in the GCI-injured brain. All data revealed that RSG may be a potential neuroprotective agent for cerebral ischemia.

Neuroserpin Protects Rat Neurons and Microglia-Mediated Inflammatory Response Against Oxygen-Glucose Deprivation- and Reoxygenation Treatments in an In Vitro Study

Background/Aims: Neuroserpin (NSP) is known for its neuroprotective role in cerebral ischemic animal models and patients. Our laboratory conducted a series of investigations on the neuroprotection of NSP in different cells in the brain. In the present study, we further observe the effects of NSP on neurons and microglia-mediated inflammatory response following oxygen-glucose deprivation (OGD), and explore possible mechanisms related to neuroprotection of OGD in the central nervous system (CNS). Methods: Neurons and microglia from neonatal rats were treated with OGD followed by reoxygenation (OGD/R). To confirm the effects of NSP, the neuronal survival, neuronal apoptosis, and lactate dehydrogenase (LDH) release were measured in cultured neurons. Furthermore, the levels of IL-1β and nitric oxide (NO) release were also detected in cultured microglia. The possible mechanisms for the neuroprotective effect of NSP were explored using Western blot analysis. Results: NSP administration can reverse abnormal variations in neurons and microglia-mediated inflammatory response induced by OGD/R processes. The neuronal survival rate, neuronal apoptosis rate, and LDH release were significantly improved by NSP administration in neurons. Simultaneously, the release of IL-1β and NO were significantly reduced by NSP in microglia. Western blot showed that the expression of ERK, P38, and JNK was upregulated in microglia by the OGD/R treatment, and these effects were significantly inhibited by NSP. Conclusion: These data verified the neuroprotective effects of NSP on neurons and microglia-mediated inflammatory response. Inhibition of the mitogen-activated protein kinase (MAPK) signaling pathways might play a potential role in NSP neuroprotection on microglia-mediated inflammatory response, which needs further verification.

Naturally occurring marine steroid 24-methylenecholestane-3β,5α,6β,19-tetraol functions as a novel neuroprotectant

Steroids have been shown to have multiple effects on the nervous system including neuroprotective activities, and they have the potential to be used for the treatment of neurodegenerative diseases. In this current study, we tested the hypothesis that the marine steroid 24-methylenecholestane-3β,5α,6β,19-tetraol (Tetrol) has a neuroprotective effect. (1) We synthesized Tetrol through a multiple step reaction starting from hyodeoxycholic acid (HDCA). (2) We then evaluated the neuroprotective effect of Tetrol with a glutamate-induced neuronal injury model in vitro. Tetrol concentration dependently increased the survival rate of cerebellar granule neurons challenged with toxic concentration of glutamate. Consistently, Tetrol significantly decreased glutamate-induced lactate dehydrogenase (LDH) release with a threshold concentration of 2.5μM. (3) We further evaluated the neuroprotective effect of Tetrol in a middle cerebral artery occlusion (MCAO)-induced cerebral ischemia model in rat. Tetrol, at a dose of 12mg/kg, significantly decreased MCAO-induced infarction volume by ∼50%. (4) Finally, we probed the mechanism and found that Tetrol concentration dependently attenuated N-methyl-d-aspartate (NMDA)-induced intracellular calcium ([Ca2+]i) increase with an IC50 of 7.8±0.62μM, and inhibited NMDA currents in cortical neurons with an IC50 of 10.28±0.71μM. Taken together, we have synthesized and characterized Tetrol as a novel neuroprotectant through negative modulation of NMDA receptors.

Atorvastatin attenuates cognitive deficits through Akt1/caspase-3 signaling pathway in ischemic stroke

Neuronal damage in the hippocampal formation is more sensitive to ischemic stimulation and easily injured, causing severe learning and memory impairment. Therefore, protection of hippocampal neuronal damage is the main contributor for learning and memory impairment during cerebral ischemia. Atorvastatin has been reported to ameliorate ischemic brain damage after ischemia reperfusion (I/R). However, its molecular mechanism has not been elucidated clearly. In this study, we established four-vessel occlusion model in rats with cerebral ischemia. Here, we demonstrated that atorvastatin significantly improves the behavior of I/R-rat in open field tasks. We also found that atorvastatin significantly shortens the distance and time of loading onto the hidden platform in the positioning navigation process, decreases the latency in the space exploration process when cognitive testing with Morris water maze was performed during ischemic stroke in rats. Furthermore, the survival rate of neurons in the CA1 area of the hippocampus and the phosphorylation of Akt (Ser473) in the neurons are increased, whereas the expression of caspase-3 are inhibited by atorvastatin. However, after an intracerebroventricular injection of LY294002 (an inhibitor of Akt1), the above neuroprotective effects of atorvastatin are attenuated. In summary, our results imply atorvastatin may improve the survival rate of hippocampal neurons and reduce the impairment of learning and memory by downregulating the activation of the caspase-3 via increasing the phosphorylation of Akt1 during ischemia/reperfusion.

SynCAM 1 improves survival of adult-born neurons by accelerating synapse maturation.

The survival of adult-born dentate gyrus granule cells critically depends on their synaptic integration into the existing neuronal network. Excitatory inputs are thought to increase the survival rate of adult born neurons. Therefore, whether enhancing the stability of newly formed excitatory synapses by overexpressing the synaptic cell adhesion molecule SynCAM 1 improves the survival of adult-born neurons was tested. Here it is shown that overexpression of SynCAM 1 improves survival of adult-born neurons, but has no effect on the proliferation rate of precursor cells. As expected, overexpression of SynCAM 1 increased the synapse density in adult-born granule neurons. While adult-born granule neurons have very few functional synapses 15 days after birth, it was found that at this age adult-born neurons in SynCAM 1 overexpressing mice exhibited around three times more excitatory synapses, which were stronger than synapses of adult-born neurons of control littermates. In summary, the data indicated that additional SynCAM 1 accelerated synapse maturation, which improved the stability of newly formed synapses and in turn increased the likelihood of survival of adult-born neurons.

Effects of different culture media on optimization of primary neuronal cell culture for in vitro models assay

Background: In vitro model studies are becoming increasingly popular for experimental research designs. They include isolation and expansion of cells of a particular tissue, such as the nervous tissue which contributes to understanding the underlying mechanisms in many pathologies. It enables the scrutinization of intracellular signaling pathways responsible for cell death. OBJECTIVES: In the literature, there are different methods for the isolation and culture of rat embryonic cortical neurons. However, this study developed a feasible, rapid and easily performable method. METHODS: Isolation of neurons was performed without using enzymatic digestion. Primary cortical cultures neurite outgrowth and neuron numbers per field of common mediums were compared for neuronal cells isolation and expansion. In this study, three different culture mediums were considered: Medium I: Neurobasal medium, B-27 and L-glutamine; Medium II: DMEM, FBS and L-glutamine; and Medium III: DMEM/F-12, FBS and L-glutamine. RESULTS: High survival rate and number of neurons was obtained with the current method. The best neuronal growth was achieved by Medium I, while Medium II and III had moderate effect on the neurite outgrowth. CONCLUSIONS: Enzyme-free treatment was introduced and Medium I was used as an alternative method for optimal neuron isolation and expansion. The neuronal cultures are similar to nervous tissue in physiological aspects. Hence, Medium I is more similar to the in vivo condition compared to Mediums II and III.

Protective effects of the specific cyclooxygenase-2 inhibitor on microglia activation-mediated neuronal damage

Objective To investigate the protective effect of NS398, a specific cyclooxygenase-2 inhibitor, on microglial activation-mediated neuronal damage. Methods The microglia of neonatal SD rat were isolated and cultured in the medium containing 1μg/ml of LPS. The morphological changes of microglial were observed. The IL-1β and TNF-α levels were detected by Western blot in LPS group (group L) and control group (group C). The hippocampal neurons of neonatal SD rats were cultured in the control medium (group C), LPS-activated microglial conditioned medium (group L) and LPS-activated microglial conditioned medium with NS398 (group N ), respectively.The survival rate of neurons were detected by MTT. The respiration of hippocampus neurons was determined by detecting the ratio of lactic acid/pyruvic acid. Results LPS-induced microglial activation was characterized by the morphological change and increased secretion of IL-1β and TNF-α.The survival rate of neurons cultured by microglia activated conditioned medium was 64.37%, while the group N was 80.25%(P<0.01). In group L, the ratio of lactic acid/pyruvic acid (27.34±8.53) was significantly higher than that of group N (20.32±6.05, P<0.01) and group C (14.95±4.72, P<0.01). Conclusion NS398, a specific cyclooxygenase-2 inhibitor, has a protective effect on rat hippocampus neuron damaged by activated microglia. Key words: Cyclooxygenase 2 inhibitors; Microglia; Hippocampus; Neurons

Chronic Alcohol Exposure is Associated with Decreased Neurogenesis, Aberrant Integration of Newborn Neurons, and Cognitive Dysfunction in Female Mice.

Neurological deficits of alcohol use disorder (AUD) have been attributed to dysfunctions of specific brain structures. Studies of alcoholic patients and chronic alcohol exposure animal models consistently identify reduced hippocampal mass and cogntive dysfunctions as a key alcohol-induced brain adaptation. However, the precise substrate of chronic alcohol exposure that leads to structural and functional impairments of the hippocampus is largely unknown. Using a calorie-matched alcohol feeding method, we tested whether chronic alcohol exposure targets neural stem cells and neurogenesis in the adult hippocampus. The effect of alcohol on proliferation of neural stem cells as well as cell fate determination and survival of newborn cells was evaluated via bromodeoxyuridine pulse and chase methods. A retrovirus-mediated single-cell labeling method was used to determine the effect of alcohol on the morphological development and circuitry incorporation of individual hippocampal newborn neurons. Finally, novel object recognition (NOR) and Y-maze tests were performed to examine whether disrupted neurogenesis is associated with hippocampus-dependent functional deficits in alcohol-fed mice. Chronic alcohol exposure reduced proliferation of neural stem cells and survival rate of newborn neurons; however, the fate determination of newborn cells remained unaltered. Moreover, the dendritic spine density of newborn neurons significantly decreased in alcohol-fed mice. Impaired spine formation indicates that alcohol interfered the synaptic connectivity of newborn neurons with excitatory neurons originating from various areas of the brain. In the NOR test, alcohol-fed mice displayed deficits in the ability to discriminate the novel object. Our study revealed that chronic alcohol exposure disrupted multiple steps of neurogenesis, including the production and development of newborn neurons. In addition, chronic alcohol exposure altered connectivity of newborn neurons with other input neurons. Decreased neurogenesis and aberrant integration of newborn neurons into hippocampal networks are closely associated with deficits in hippocampus-dependent cognitive functions of alcohol-fed mice.

Transplantation of human mesenchymal stem cells into the cisterna magna and its neuroprotective effects in a parkinsonian animal model

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases in the elderly, and therefore, the demand for effective therapies against PD has greatly increased. Therapeutic applications of stem cells have been considered to be one of the promising approaches in PD therapy. In the present study, the neuroprotective effects of hMSCs were evaluated in a parkinsonian rat model. The animal model was established by injecting 6-hydroxydopamine into the striatum of rats. Two weeks later, cultured hMSCs were transplanted into the cisterna magna. We subsequently identified changes in the expression of inflammatory cytokines, neurotrophic factors, microglial activation, and the survival rate of dopaminergic neurons in SNc. Behavioral recovery was also examined. The results indicated that hMSC transplantation increased the expression of anti-inflammatory cytokines as well as neurotrophic factors, and decreased the number of activated microglia. Compared to the sham-grafted group, relatively large numbers of TH-positive neurons were found in the ipsilateral SNc, and amphetamine-induced asymmetrical rotation was significantly reduced after hMSC transplantation. These findings suggest that hMSCs might be neuroprotective, probably through up-regulation of neurotrophic factors and anti-inflammatory cytokines, and this could have a functional impact in reversing PD symptoms.

Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

The rate of neurogenesis is determined by 1) the number of neural stem/progenitor cells (NSCs), 2) proliferation of NSCs, 3) neuron lineage specification, and 4) survival rate of the newborn neurons. Aging lowers the rate of hippocampal neurogenesis, while exercise (Ex) increases this rate. However, it remains unclear which of the determinants are affected by aging and Ex. We characterized the four determinants in different age groups (3, 6, 9, 12, 21 months) of mice that either received one month of Ex training or remained sedentary. Bromodeoxyuridine (BrdU) was injected two hours before sacrificing the mice to label the proliferating cells. The results showed that the number of newborn neurons massively decreased (>95%) by the time the mice reached nine months of age. The number of NSC was mildly reduced during aging, while Ex delayed such decline. The proliferation rates were greatly decreased by the time the mice were 9-month-old and Ex could not improve the rates. The rates of neuron specification were decreased during aging, while Ex increased the rates. The survival rate was not affected by age or Ex. Aging greatly reduced newborn neuron maturation, while Ex potently enhanced it. In conclusion, age-associated decline of hippocampal neurogenesis is mainly caused by reduction of NSC proliferation. Although Ex increases the NSC number and neuron specification rates, it doesn't restore the massive decline of NSC proliferation rate. Hence, the effect of Ex on the rate of hippocampal neurogenesis during aging is limited, but Ex does enhance the maturation of newborn neurons.

TNF-Α Protection of Hippocampal Neurons from Kainic Acid Induced Neurodegeneration is Associated with Up-Regulation of Nfκb and AKT as well as Down-Regulation of P38 MAPK Signaling Molecules

Background: Previously, our study showed that TNF-α plays a protective role in kainic acid (KA) induced neurodegeneration in vivo in mice. Here, we further clarified the protective role of TNF-α in KA-induced hippocampal neuronal damage in vitro and elucidated the potential signaling pathways. Methods: Hippocampal neurons were isolated from embryonic 16 days (E16) TNF-α knockout (KO) and wild-type (WT) mice with C57BL/6 background, respectively, and exposed to KA with and without recombinant TNF-α, as well as anti-TNF-α antibody. After 24-hours exposure to KA, lactate dehydrogenase (LDH) production and neurotoxicity were detected for evaluating neuronal survival rates. The production of nitric oxide (NO) from supernatants and the expression of nuclear factor kappa B (NFкB), inhibitor of NFкB alpha (IκBα), p38 mitogen-activated protein kinase (MAPK) and AKT in hippocampal neurons were measured. Results: Comparing with WT mice, the neurons of TNF-α KO mice showed more susceptibility to KA-induced neurotoxicity, as demonstrated by higher production of LDH and lower neuronal survival rates, as well as elevated NO production. It is also evidenced that pre-blocked TNF-α molecule in the neuron cultures of WT mice with anti-TNF-α antibody significantly enhanced the production of LDH and NO, and decreased the neuronal survival rate. In contrast, the neurons from WT mice pre-exposed to recombinant TNF-α were more resistant to KA induced neurotoxicity. TNF-α deficiency down-regulated phospho-IκBα, NFкB, total AKT and phospho-AKT, as well as up-regulated phospho-p38 MAPK expressions after KA insult. The reverse results were achieved in WT hippocampal neurons with TNF-α pre-administration. Conclusion: Our findings demonstrated an association between the protective effect of TNF-α on neurons as assessed following KA insult, with the up-regulation of NFκB and AKT, as well as down-regulation of p38 MAPK signaling molecules.

Characterization of a Synthetic Steroid 24-keto-cholest-5-en-3β, 19-diol as a Neuroprotectant.

Neuroactive steroids represent promising candidates for the treatment of neurological disorders. Our previous studies identified an endogenous steroid cholestane-3β, 5α, 6β-triol (Triol) as a novel neuroprotectant. We aimed to identify a potent candidate for stroke treatment through a screening of Triol analogs. Hypoxia- and glutamate-induced neuronal injury models in vitro, middle cerebral artery occlusion (MCAO)-induced cerebral ischemia model in vivo, fluorescein diacetate (FDA) for alive and propidium iodide (PI) for dead staining, LDH assay, and calcium imaging techniques were used. 24-keto-cholest-5-en-3β, 19-diol (Diol) showed the most potent neuroprotective effect among the screened structurally related compounds. FDA and PI staining showed that Diol concentration dependently increased the survival rate of cerebellar granule neurons (CGNs) challenged with glutamate or hypoxia, with an effective threshold concentration of 2.5μM. Consistently, the quantitative LDH release assay showed the same concentration-dependent protection in both models. Diol, at 10μM, potently decreased glutamate- and hypoxia-induced LDH release from 51.6 to 18.2% and 62.1 to 21.7%, respectively, which values are close to the normal LDH release (~16-18%). Moreover, we found Diol effectively decreased MCAO-induced infarction volume in mice from ~23% to 7%, at a dose of 6mg/kg. We further explored the underlying mechanism and found that Diol attenuated NMDA-induced intracellular calcium ([Ca(2+) ]i ) increase in cortical neurons, suggesting a negative modulatory effect on NMDA receptor. Taken together, we identified Diol as a potent neuroprotectant. It may represent a novel and promising neuroprotectant for stroke intervention.