Enhanced Neuron Survival Research Articles

Assembling a Coculture System to Prepare Highly Pure Induced Pluripotent Stem Cell-Derived Neurons at Late Maturation Stages.

Generation of human induced pluripotent stem cell (hiPSC)-derived motor neurons (MNs) offers an unprecedented approach to modeling movement disorders such as dystonia and amyotrophic lateral sclerosis. However, achieving survival poses a significant challenge when culturing induced MNs, especially when aiming to reach late maturation stages. Utilizing hiPSC-derived motor neurons and primary mouse astrocytes, we assembled two types of coculture systems: direct coculturing of neurons with astrocytes and indirect coculture using culture inserts that physically separate neurons and astrocytes. Both systems significantly enhance neuron survival. Compared with these two systems, no significant differences in neurodevelopment, maturation, and survival within 3 weeks, allowing to prepare neurons at maturation stages. Using the indirect coculture system, we obtained highly pure MNs at the late mature stage from hiPSCs. Transcriptomic studies of hiPSC-derived MNs showed a typical neurodevelopmental switch in gene expression from the early immature stage to late maturation stages. Mature genes associated with neurodevelopment and synaptogenesis are highly enriched in MNs at late stages, demonstrating that these neurons achieve maturation. This study introduces a novel tool for the preparation of highly pure hiPSC-derived neurons, enabling the determination of neurological disease pathogenesis in neurons at late disease onset stages through biochemical approaches, which typically necessitate highly pure neurons. This advancement is particularly significant in modeling age-related neurodegeneration.

Triboelectric nanogenerators stimulated electroacupuncture (EA) treatment for promoting the functional recovery after spinal cord injury

Electroacupuncture (EA), as a particular type of electrostimulation treatment, has an extensive application in the field of biomedicine. Triboelectric nanogenerator (TENG) has sparked significant concern attributed to the high electrical output with low cost, whose electrical signals can also be directly usable for electrical stimulation. Here we propose a Chinese medicine EA treatment with the assistance of TENG technology, in which a bidirectional continuous current from a soft-contact freestanding rotary TENG (FR-TENG) is applied to two effective acupoints of rats by inserting electric needles. The TENG-driven EA treatment promotes the performance of gait 2 weeks after as well as the Basso–Beattie–Bresnahan (BBB) score. This elevation last as long as 4 weeks post injury. Moreover, the TENG-driven EA treatment enhances neuron survival in the ventral horn and inhibits astrocyte activation in the lesion site. Therefore, the TENG-driven EA treatment provides a significant neuroprotection effect on spinal cord contusion in rats. Our studies not only demonstrate the possibility of the TENG-driven EA treatment for traumatic central nervous system injuries but also provide an experimental basis for the prevention and treatment of diseases by traditional Chinese medicine treatment.

Reduction of Traumatic Brain Damage by Tspo Ligand Etifoxine.

Experimental studies have shown that ligands of the 18 kDa translocator protein can reduce neuronal damage induced by traumatic brain injury by protecting mitochondria and preventing metabolic crisis. Etifoxine, an anxiolytic drug and 18 kDa translocator protein ligand, has shown beneficial effects in the models of peripheral nerve neuropathy. The present study investigates the potential effect of etifoxine as a neuroprotective agent in traumatic brain injury (TBI). For this purpose, the effect of etifoxine on lesion volume and modified neurological severity score at 4 weeks was tested in Sprague–Dawley adult male rats submitted to cortical impact contusion. Effects of etifoxine treatment on neuronal survival and apoptosis were also assessed by immune stains in the perilesional area. Etifoxine induced a significant reduction in the lesion volume compared to nontreated animals in a dose-dependent fashion with a similar effect on neurological outcome at four weeks that correlated with enhanced neuron survival and reduced apoptotic activity. These results are consistent with the neuroprotective effect of etifoxine in TBI that may justify further translational research.

LncRNA SNHG14 promotes inflammatory response induced by cerebral ischemia/reperfusion injury through regulating miR-136-5p /ROCK1

Recently, long non-coding RNAs (lncRNAs) are considered as critical regulators in pathogenesis progression of cerebral ischemia. In present study, lncRNA-small nucleolar RNA host gene 14 (SNHG14) was found upregulated in middle cerebral artery occlusion/reperfusion (MCAO/R) treated brain tissues and oxygen-glucose deprivation and reoxygenation (OGD/R) treated PC-12 cells. Interference of SNHG14 by shRNA vector enhanced neuron survival and suppressed inflammation in response to OGD/R insult. SNHG14 positively regulated the expression of Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) via acting as a sponge of microRNA (miR)-136–5p. SNHG14 promoted neurological impairment and inflammatory response through elevating the expression of ROCK1 while decreasing miR-136–5p level in OGD/R induced damage. Collectively, we illustrated that SNHG14 could be a novel strategy for treatment ischemia stoke.

Translational Advances in the Management of Acute Spinal Cord Injury

Translational Advances in the Management of Acute Spinal Cord Injury

Effects of α-synuclein on axonal transport

Lewy bodies and Lewy neurites composed primarily of α-synuclein characterize synucleinopathies including Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB). Despite decades of research on the impact of α-synuclein, little is known how abnormal inclusion made of this protein compromise neuronal function. Emerging evidence suggests that defects in axonal transport caused by aggregated α-synuclein contribute to neuronal dysfunction. These defects appear to occur well before the onset of neuronal death. Susceptible neurons in PD such as dopamine neurons with long elaborate axons may be particularly sensitive to abnormal axonal transport. Axonal transport is critical for delivery of signaling molecules to the soma responsible for neuronal differentiation and survival. In addition, axonal transport delivers degradative organelles such as endosomes and autophagosomes to lysosomes located in the soma to degrade damaged proteins and organelles. Identifying the molecular mechanisms by which axonal transport is impaired in PD and DLB may help identify novel therapeutic targets to enhance neuron survival and even possibly prevent disease progression. Here, we review the evidence that axonal transport is impaired in synucleinopathies, and describe potential mechanisms by which contribute to these defects.

MiR-155 Deletion in Mice Overcomes Neuron-Intrinsic and Neuron-Extrinsic Barriers to Spinal Cord Repair.

Axon regeneration after spinal cord injury (SCI) fails due to neuron-intrinsic mechanisms and extracellular barriers including inflammation. microRNA (miR)-155-5p is a small, noncoding RNA that negatively regulates mRNA translation. In macrophages, miR-155-5p is induced by inflammatory stimuli and elicits a response that could be toxic after SCI. miR-155 may also independently alter expression of genes that regulate axon growth in neurons. Here, we hypothesized that miR-155 deletion would simultaneously improve axon growth and reduce neuroinflammation after SCI by acting on both neurons and macrophages. New data show that miR-155 deletion attenuates inflammatory signaling in macrophages, reduces macrophage-mediated neuron toxicity, and increases macrophage-elicited axon growth by ∼40% relative to control conditions. In addition, miR-155 deletion increases spontaneous axon growth from neurons; adult miR-155 KO dorsal root ganglion (DRG) neurons extend 44% longer neurites than WT neurons. In vivo, miR-155 deletion augments conditioning lesion-induced intraneuronal expression of SPRR1A, a regeneration-associated gene; ∼50% more injured KO DRG neurons expressed SPRR1A versus WT neurons. After dorsal column SCI, miR-155 KO mouse spinal cord has reduced neuroinflammation and increased peripheral conditioning-lesion-enhanced axon regeneration beyond the epicenter. Finally, in a model of spinal contusion injury, miR-155 deletion improves locomotor function at postinjury times corresponding with the arrival and maximal appearance of activated intraspinal macrophages. In miR-155 KO mice, improved locomotor function is associated with smaller contusion lesions and decreased accumulation of inflammatory macrophages. Collectively, these data indicate that miR-155 is a novel therapeutic target capable of simultaneously overcoming neuron-intrinsic and neuron-extrinsic barriers to repair after SCI. Axon regeneration after spinal cord injury (SCI) fails due to neuron-intrinsic mechanisms and extracellular barriers, including inflammation. Here, new data show that deleting microRNA-155 (miR-155) affects both mechanisms and improves repair and functional recovery after SCI. Macrophages lacking miR-155 have altered inflammatory capacity, which enhances neuron survival and axon growth of cocultured neurons. In addition, independent of macrophages, adult miR-155 KO neurons show enhanced spontaneous axon growth. Using either spinal cord dorsal column crush or contusion injury models, miR-155 deletion improves indices of repair and recovery. Therefore, miR-155 has a dual role in regulating spinal cord repair and may be a novel therapeutic target for SCI and other CNS pathologies.

Dorsal root ganglia neurons and differentiated adipose-derived stem cells: an in vitro co-culture model to study peripheral nerve regeneration.

Dorsal root ganglia (DRG) neurons, located in the intervertebral foramina of the spinal column, can be used to create an in vitro system facilitating the study of nerve regeneration and myelination. The glial cells of the peripheral nervous system, Schwann cells (SC), are key facilitators of these processes; it is therefore crucial that the interactions of these cellular components are studied together. Direct contact between DRG neurons and glial cells provides additional stimuli sensed by specific membrane receptors, further improving the neuronal response. SC release growth factors and proteins in the culture medium, which enhance neuron survival and stimulate neurite sprouting and extension. However, SC require long proliferation time to be used for tissue engineering applications and the sacrifice of an healthy nerve for their sourcing. Adipose-derived stem cells (ASC) differentiated into SC phenotype are a valid alternative to SC for the set-up of a co-culture model with DRG neurons to study nerve regeneration. The present work presents a detailed and reproducible step-by-step protocol to harvest both DRG neurons and ASC from adult rats; to differentiate ASC towards a SC phenotype; and combines the two cell types in a direct co-culture system to investigate the interplay between neurons and SC in the peripheral nervous system. This tool has great potential in the optimization of tissue-engineered constructs for peripheral nerve repair.

Dorsal Root Ganglia Neurons and Differentiated Adipose-derived Stem Cells: An <em>In Vitro</em> Co-culture Model to Study Peripheral Nerve Regeneration

Dorsal root ganglia (DRG) neurons, located in the intervertebral foramina of the spinal column, can be used to create an in vitro system facilitating the study of nerve regeneration and myelination. The glial cells of the peripheral nervous system, Schwann cells (SC), are key facilitators of these processes; it is therefore crucial that the interactions of these cellular components are studied together. Direct contact between DRG neurons and glial cells provides additional stimuli sensed by specific membrane receptors, further improving the neuronal response. SC release growth factors and proteins in the culture medium, which enhance neuron survival and stimulate neurite sprouting and extension. However, SC require long proliferation time to be used for tissue engineering applications and the sacrifice of an healthy nerve for their sourcing. Adipose-derived stem cells (ASC) differentiated into SC phenotype are a valid alternative to SC for the set-up of a co-culture model with DRG neurons to study nerve regeneration. The present work presents a detailed and reproducible step-by-step protocol to harvest both DRG neurons and ASC from adult rats; to differentiate ASC towards a SC phenotype; and combines the two cell types in a direct co-culture system to investigate the interplay between neurons and SC in the peripheral nervous system. This tool has great potential in the optimization of tissue-engineered constructs for peripheral nerve repair.

Neuritogenic and Neuroprotective Activities of Fruit Residues

Neuritogenic and neuroprotective activities of litchi (Litchi chinensis Sonn., Sapindaceae) and salacca (Salacca edulis Reinw., Arecaceae) pericarp, and sapodilla (Achras sapota L., Sapotaceae) and tamarind Srichompu cultivar (Tamarindus indica L., Caesalpiniaceae) seed coat extracts were evaluated on cultured cholinergic P19-derived neurons. All the extracts, at a very low concentration (1 ng/mL of litchi and salacca pericarp extracts, 10 ng/mL of sapodilla and 100 ng/mL of tamarind seed coat extracts), enhanced the survival of cultured neurons (% viability more than 100%) by XTT reduction assay. The extracts were further evaluated for their neuritogenicity by observing cell morphology by phase-contrast microscopy and neuroprotective activity in serum deprivation and pre- and co-administration of hydrogen peroxide models. The phase-contrast micrographs displayed that all of the extracts possessed neurogenic activity by promoting the neurite outgrowth of the cultured neurons. Moreover, these extracts can protect neurons from oxidative stress-caused cell death in a serum deprivation model, and prevent and protect neuron cells from the toxicity of hydrogen peroxide. In this study we assured that the neuritogenic and neuroprotective activities of these extracts derived from the phenolic components and flavonoids contained in the extracts by acting as signaling molecules to enhance neuron survival and promote neurite outgrowth. These results suggest that all of the extracts are potentially sources of neuritogenic and neuroprotective components which might be used either as pharmaceutical products or dietary supplements for neurodegenerative disorder patients, for example, those suffering from Alzheimer's disease.

Cognitive enhancement and neuroprotection by catechin‐rich oil palm leaf extract supplement

Catechin-rich oil palm (Elaeis guineensis) leaf extract (OPLE) has good cardiovascular and phytoestrogenic properties. The OPLE (0.5 g day(-1) ) was supplemented to young, healthy, adult human volunteers, and their cognitive learning abilities were compared to placebo-controlled groups (N = 15). Their short-term memories, spatial visualisations, processing speeds, and language skills, were assessed over 2 months by cognitive tests computer programs. Relative to the controls, volunteers taking OPLE had improved (P < 0.05) short-term memory, after 1 month of intervention which became highly significant (P < 0.005) after 2 months. The spatial visualisation ability and processing speed improved (P < 0.05) after 2 months consumption. The dietary OPLE showed neuroprotection in nitric oxide-deficient rats. The mechanisms involved systemic and cellular modulations that eventually enhance neuron survival. The longer the duration of OPLE consumption, the more significant was the enhancement, as shown for short-term memory. This is the first report on the cognitive-enhancing effects of dietary OPLE in humans. The computer-assisted cognitive tests were simple, low in cost, errors and man hours, and hence are better than conventional cognitive test methods. In rats, the equivalent OPLE dose showed brain antioxidant enzymes modulating properties and neuroprotection under nitric oxide deficiency, with possibly neurogenesis in normal rats. This supported the effects in humans.

Serum response factor modulates neuron survival during peripheral axon injury

BackgroundThe transcription factor SRF (serum response factor) mediates neuronal survival in vitro. However, data available so far suggest that SRF is largely dispensable for neuron survival during physiological brain function.FindingsHere, we demonstrate that upon neuronal injury, that is facial nerve transection, constitutively-active SRF-VP16 enhances motorneuron survival. SRF-VP16 suppressed active caspase 3 abundance in vitro and enhanced neuron survival upon camptothecin induced apoptosis. Following nerve fiber injury in vitro, SRF-VP16 improved survival of neurons and re-growth of severed neurites. Further, SRF-VP16 enhanced immune responses (that is microglia and T cell activation) associated with neuronal injury in vivo. Genome-wide transcriptomics identified target genes associated with axonal injury and modulated by SRF-VP16.ConclusionIn sum, this is a first report describing a neuronal injury-related survival function for SRF.

Release of Nerve Growth Factor from HEMA Hydrogel-Coated Substrates and Its Effect on the Differentiation of Neural Cells

Local pharmacological intervention may be needed to ensure the long-term performance of neural prosthetic devices because of insertion-related neuron loss and reactive cell responses that form compact sheaths, leading to decreased device performance. We propose that local delivery of neurotrophins would enhance neuron survival and promote neuron sprouting toward device electrodes, thus providing improved electrode-neuron communication and device performance for recording and stimulating CNS activity. In this study, three different types of poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels were developed and assessed for storage capacity and release rates of the neurotrophin, nerve growth factor (NGF). Additionally, a method was developed for routine coating of microfabricated neuroprosthetic devices with the different pHEMA hydrogels. Biological responses to hydrogel-delivered NGF from the devices were measured using primary cell cultures of dorsal root ganglion (DRG) neurons. Neuron process growth was used to assess biological responses to released NGF. When targeted media concentrations were the same, responses to bath-applied NGF and NGF released from pHEMA hydrogels were not significantly different. When NGF was released from lysine-conjugated pHEMA hydrogels, a significant increase in process growth was observed. Our studies demonstrate that pHEMA coatings can be used on neural devices consistent with the needs for local neurotrophin delivery in the brain.

Physical Activity and Neuroprotection in Amyotrophic Lateral Sclerosis

Physical exercise exerts a wide range of benefits on an organism's overall health and well-being. Exercise contributes positively toward an individual's healthy weight, muscle strength, immune system, and cardiovascular health. Indeed, exercise has been demonstrated to reduce life-threatening conditions such as high blood pressure, heart disease, obesity, and diabetes. Of particular interest to this review, exercise has also been shown to be neuroprotective in both the central and peripheral nervous systems. Naturally, such findings apply broadly to the study of neurodegenerative disease with numerous reports demonstrating that exercise has beneficial effects on disease progression. One of the most devastating neurodegenerative diseases is amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig's disease in the United States, or motor neuron disease in the United Kingdom, resulting from the progressive loss of brain and spinal cord motor neurons. Several human studies show that moderate exercise regimens improve ALS patients' scoring on functionality tests and ameliorate disease symptoms. Other promising recent works using transgenic mouse models of familial ALS have shown markedly slowed disease progression, improved function, and extension of survival in moderately exercised animals. Possible explanations for these findings include the exercise-induced changes in motor neuron morphology, muscle-nerve interaction, glial activation, and altering levels of gene expression of anti-apoptotic proteins and neurotrophic factors in the active tissue. Here we review the current literature on exercise and motor neuron disease, focusing on rodent and human studies to define the proper type, intensity, and duration of exercise necessary to enhance neuron survival as well discuss current mechanistic studies to further define the exercise-mediated pathways of neuroprotection.

Persistent increases in the pool of doublecortin-expressing neurons in the hippocampus following spatial navigation training

In addition to its role in neuronal migration during embryonic development, doublecortin (DCX) plays a role in hippocampal neurogenesis across the lifespan. Hippocampal neurons exhibit a high degree of synaptic plasticity while they are in the DCX phase. While previous studies have reported that behavioral training on hippocampus-dependent tasks can enhance neuron survival, little was known about the stage of development of those neurons and, particularly, whether a large pool of the surviving new neurons remains in the DCX phase for a prolonged period after training. Here we report that spatial navigation training increases the pool of neurons that are in the DCX phase 4 weeks after training ended. Thus, the stock of DCX-expressing neurons in the hippocampus is affected by whether a hippocampus-dependent task has been encountered during the preceding few weeks.

Astroglia growth retardation and increased microglia proliferation by lithium and ornithine decarboxylase inhibitor in rat cerebellar cultures: Cytotoxicity by combined lithium and polyamine inhibition

Lithium, the most prevalent treatment for manic-depressive illness, might have a neuroprotective effect after brain injury. In culture, lithium can exert neurotoxic effects associated with reduction in polyamine synthesis but neuroprotective effects as cultured neurons mature. Cumulative evidence suggests that lithium may exert some of its effects on neurons indirectly, by initially acting on glial cells. We used rat cerebellar cultures to ascertain the effects of lithium on ornithine decarboxylase (ODC) activity, the enzyme catalyzing the first step in polyamine synthesis, and to compare effects of lithium with those of the ODC inhibitor alpha-difluoromethylornithine (DFMO) on neuron survival and glial growth. Switching cultures from high (25 mM) to low (5 mM) KCl concentrations served as the traumatic neuronal insult. The results indicate the following. 1) Whereas high depolarizing KCl concentration enhances neuron survival, it inhibits astroglial growth. 2) Lithium (LiCl; 1-5 mM) enhances neuronal survival but inhibits astroglial growth. 3) Lithium treatment leads to reduced ODC activity. 4) DFMO enhances neuron survival but inhibits astroglial growth. 5) Lithium and DFMO lead to transformation of astroglia from epithelioid (flat) to process-bearing morphology and to increased numbers of microglia. 6) Combined lithium plus DFMO treatment is cytolethal to both neurons and glia in culture. In conclusion, lithium treatment results in growth retardation and altered cell morphology of cultured astroglia and increased microglia proliferation, and these effects may be associated with inhibition of polyamine synthesis. This implies that direct effects on astrocytes and microglia may contribute to the effects of lithium on neurons.

Growth factor dependent cholinergic function and survival in primary mouse spinal cord cultures

In primary embryonic spinal cord cultures, synaptic transmission can be conveniently studied by monitoring radiolabeled neurotransmitter release or by recording of electrophysiological responses. However, while the mature spinal cord contains an appreciable number of cholinergic motoneurons, cultures of embryonic spinal cord have a paucity of these neurons and release little or no acetylcholine upon stimulation. To determine whether the proportion of cholinergic neurons in primary mouse spinal cord cultures can be augmented, the effects of several classes of growth factors were examined on depolarization- and Ca 2+-evoked release of choline/acetylcholine (Ch/ACh). In the absence of growth factors, little or no evoked release of radiolabeled Ch/ACh could be demonstrated. Media supplemented with brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF) or basic fibroblast growth factor (bFGF) were examined for their ability to preserve the population of neurons in culture. CNTF was found to increase the number of surviving neurons and to enhance the release of radiolabeled Ch/ACh; the other factors were without effect. The action of CNTF was transient, and the neuronal population decreased to levels observed in cultures lacking growth factor after 20 days in vitro. The correlation between enhanced neuron survival and increased Ch/ACh release suggests that CNTF protected cholinergic neurons, albeit transiently, from cell death.

Gene therapy for ischemic neuronal injury

Advances in the area of stroke and other related disorders have identified a variety of molecular targets for potential therapeutic intervention. The use of modified viral vectors has now made it possible to introduce foreign DNA into central nervous system cells, permitting overexpression of a protein of interest. A particular advantage of the herpes simplex system is that the virus is neurotropic, and is therefore suited for relatively selective gene therapy to neurons. The vectors used by our group to date utilize an amplicon based bipromoter system which permits expression of both the gene of interest as well as a reporter gene. Using this strategy, we have shown that potentially neuroprotective genes can be transferred to individual central nervous system cells, and can confer a relative resistance to cerebral ischemic and excitotoxic insults. We previously reported that gene therapy using a neurotropic herpes simplex viral (HSV) vector system containing bipromoter vectors to transfer various protective genes to neurons. Using this system in experimental models of stroke, cardiac arrest and excitotoxicity, we have found that it is possible to enhance neuron survival against such cerebral insults by overexpressing genes that target various facets of injury. Of the genes studied by our labs, we have shown that glucose transporter (GLUT-1), the calcium binding protein calbindin D28 K (CaBP), anti-oxidant genes glutathione peroxidase (GPx) and catalase (CAT), the anti-apoptotic protein Bcl-2 and the 70 kDa heat shock protein (HSP70) improve neuron survival after ischemia and excitotoxicity. Bcl-2, GPx and HSP70 also appear to protect when administered post insult. Because the extent of vector uptake is limited, it is not generally possible to affect overall infarct size or behavior. Regardless, we have demonstrated that for some cases, gene transfer may also improve cell function. Gene transfer can also be used in combination with other potential neuroprotective strategies with synergistic effects. For instance, mild hypothermia is well known to protect the brain from experimental brain ischemia provided brain cooling begins within hours of ischemia onset. This hypothermic neuroprotection is also associated with Bcl-2 upregulation in some instances, and hypothermia suppresses many aspects of apoptotic death. Our recent work has shown that two different kinds of protective therapies, Bcl-2 overexpression and hypothermia, both inhibit aspects of apoptotic cell death cascades, and combination of hypothermia with Bcl-2 gene transfer will prolong the temporal therapeutic window for Bcl-2 gene therapy. Some limitations of this technique exist, the main ones being that of delivery and extent and duration of transfection. Part of the limited duration of gene expression may be due to a localized tissue inflammatory response to the vectors themselves. This problem may be partially surmounted by the coadministration of anti-inflammatory treatments to prolong survival of transfected cells. While neuronal gene therapy for cerebral ischemia is still limited by the numbers of cells which vectors can transfect, it provides a powerful tool to understand mechanisms of cell death and identify potential molecular targets for therapy.

Mechanisms of Suppression of α-Synuclein Neurotoxicity by Geldanamycin in Drosophila

Parkinson's disease is a common neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta and the accumulation of the protein alpha-synuclein into aggregates called Lewy bodies and Lewy neurites. Parkinson's disease can be modeled in Drosophila where directed expression of alpha-synuclein induces compromise of dopaminergic neurons and the formation of Lewy body-like aggregates. The molecular chaperone Hsp70 protects cells from the deleterious effects of alpha-synuclein, indicating a potential therapeutic approach to enhance neuron survival in Parkinson's disease. We have now investigated the molecular mechanisms by which the drug geldanamycin protects neurons against alpha-synuclein toxicity. Our studies show that geldanamycin sensitizes the stress response within normal physiological parameters to enhance chaperone activation, offering protection against alpha-synuclein neurotoxicity. Further, geldanamycin uncouples neuronal toxicity from Lewy body and Lewy neurite formation such that dopaminergic neurons are protected from the effects of alpha-synuclein expression despite the continued presence of (and even increase in) inclusion pathology. These studies indicate that compounds that modulate the stress response are a promising approach to treat Parkinson's disease.

Glutathione monoethyl ester improves functional recovery, enhances neuron survival, and stabilizes spinal cord blood flow after spinal cord injury in rats

Secondary damage after spinal cord (SC) injury remains without a clinically effective drug treatment. To explore the neuroprotective effects of cell-permeable reduced glutathione monoethyl ester (GSHE), rats subjected to SC contusion using the New York University impactor were randomly assigned to receive intraperitoneally GSHE (total dose of 12 mg/kg), methylprednisolone sodium succinate (total dose of 120 mg/kg), or saline solution as vehicle. Motor function, assessed using the Basso–Beattie–Bresnahan scale for 8 weeks, was significantly better in GSHE (11.2±0.6, mean±S.E.M., n=8, at 8 weeks) than methylprednisolone (9.3±0.6) and vehicle (9.4±0.7) groups. The number of neurons in the red nuclei labeled with FluoroRuby placed caudally to the injury site was significantly higher in GSHE (158±9.3 mean±S.E.M., n=4) compared with methylprednisolone (53±14.7) and vehicle (46±16.4) groups. Differences in the amount of spared SC tissue at the epicenter and neighboring areas were not significant among experimental groups. In a second series of experiments, using similar treatment groups ( n=6), regional changes in microvascular SC blood flow were evaluated for 100 min by laser-Doppler flowmetry after clip compression injury. SC blood flow fell in vehicle-treated rats 20% below baseline and increased significantly with methylprednisolone approximately 12% above baseline; changes were not greater than 5% in rats given GSHE. In conclusion, GSHE given to rats early after moderate SC contusion/compression improves functional outcome and red nuclei neuron survival significantly better than methylprednisolone and vehicle, and stabilizes SC blood flow. These results support further investigation of reduced glutathione supplementation after acute SC injury for future clinical application.