Prevention Of Neurodegenerative Diseases Research Articles

Antioxidant effect of purslane (Portulaca oleracea) and its mechanism of action

Aqueous juice from purslane ( Portulaca oleracea ) was screened for its antioxidant activity in adult male Waster albino rats. The antioxidant activity was determined by measuring reduced glutathione, catalase, superoxide dismutase, glutathione reductase, glutathione-S-transferase and glutathione peroxidase, as well as the inhibition in lipid peroxidation, nitric oxide in liver, kidney and testis of rats. Liver and kidney function were also determined. Administered rats with aqueous juice of purslane, resulted in marked improvement in all studied parameters. On the basis of the above results, it can be concluded that purslane is a promising natural product, which could be useful for the prevention of cardiovascular, neurodegenerative and other chronic diseases caused by oxidative stress.

Maternal Fish Oil Supplementation: The Prodrom of Synaptic Protection in Alzheimers Disease

Prospective longevity is overshadowed by the high prevalence of mental decline in aging. Hence, nutritional indications are a crucial element in todays observed aging of the population. There is now growing epidemiological evidence suggesting that reduced levels of docosahexaenoic acid [DHA, 22:6, (n-3)] may be indicative of an increased risk of Alzheimers disease (AD). On the other hand, the Mediterranean diet includes high intake of fatty fish and has been associated with lower AD risk; fish is the major food source of DHA. Recently three new families of DHA-derived mediators - termed D series resolvins (RvDs, 17S epimers), protectins (NPDs, 17S epimers) and maresins - have been uncovered; these new bioactive lipids confer potent cellular protection. In the presence of aspirin (ASA), equipotent ASA-triggered 17R epimers (ASA-RvDs and ASA-NPDs) were produced in vivo. However, while enzymatic oxidation dramatically reduced the bioactivity of 17S epimers RvDs and NPDs, enzymatic conversion of ASA-17R epimers was sharply reduced. Specifically, as ASA-DHA-derived lipids have cellular protective actions, the resistance to rapid inactivation may contribute to the beneficial actions of omega-3 (n-3) fish oils and ASA in humans and offers new insights into the prevention of neurodegenerative diseases. Keywords: Alzheimer's disease, aspirin, DHA, EPA, maresin, neuroprotectin, resolvin, docosahexaenoic acid, maresins, inter alia, eicosapen-taenoic acid, n-3, ApoE4 genotype, rotoxins, methylmercury, microcephaly, cerebral palsy, institutional boilers, chlo-rine production, waste incineration, oceans - bio-concentrate, sporadic, vitro nitrosamine, neurodegeneration, cadaverine, biogenic amine, amyloid, beta amyloid, amy-loidosis, DHA-oxygenation pathways, ASA-generated, acetylating COX-2, COX, arachidonic acid (ARA), resolvins, protect-ins, neuroprotectin D1 (NPD1, neurite growth, A pep-tide, brain-derived neurotrophic factor, superoxide dismutase-1, catalase, Reactive oxygen species, catecholamine synthesis, n-3 family, PUFAs, glial cells, astro-cytes, BDNF protein

Potential Therapeutic Targets for Neurodegenerative Diseases: Lessons Learned from Calorie Restriction

It is well known that calorie restriction (CR) can retard the aging process in organisms ranging from yeast to non-human primates, and delay the onset of numerous age-related diseases including neurodegenerative disorders. Translation of the knowledge gained from CR research in animal models to disease prevention strategies in humans should provide therapeutic approaches for these diseases. Signaling pathways induced by CR are therefore potentially new therapeutic targets for neurodegenerative diseases. This review summarizes the evidence on key biological mechanisms underlying the beneficial effects of CR based on our current understanding, with particular emphasis on the recent impact of CR on neuroprotection, and on the emerging development of pharmacological agents that target signaling pathways induced by CR. We focus in particular on recent findings on sirtuins for prevention of neurodegenerative diseases.

Cellular Stress Responses, The Hormesis Paradigm, and Vitagenes: Novel Targets for Therapeutic Intervention in Neurodegenerative Disorders

Despite the capacity of chaperones and other homeostatic components to restore folding equilibrium, cells appear poorly adapted for chronic oxidative stress that increases in cancer and in metabolic and neurodegenerative diseases. Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This article introduces the concept of hormesis and its applications to the field of neuroprotection. It is argued that the hormetic dose response provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose-response relationships, their mechanistic foundations, and their relationship to the concept of biological plasticity, as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This article describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways, including sirtuin and Nrf2 and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. Particular attention is given to the emerging role of nitric oxide, carbon monoxide, and hydrogen sulfide gases in hormetic-based neuroprotection and their relationship to membrane radical dynamics and mitochondrial redox signaling.

Pharmacokinetics and Tissue Distribution of14C-Labeled Grape Polyphenols in the Periphery and the Central Nervous System Following Oral Administration

Grape polyphenols confer potential health benefits, including prevention of neurodegenerative diseases. To determine the absorption and tissue distribution of the complex grape polyphenol mixture, (14)C-labeled polyphenols were biosynthesized by grape cell suspension cultures, during co-incubation with radioisotopically labeled sucrose, and fractionated into polyphenolic subfractions. The pharmacokinetics and distribution of grape polyphenols into blood, brain, and peripheral interstitial fluid were determined by tracking the (14)C label. The blood peak (14)C concentration of the fractions ranged from 15 minutes to 4 hours. Absorption and tissue distribution varied greatly between fractions. Concentrations in interstitial fluid were lower than in blood. The amount of residual label in the brain at 24 hours ranged from 0.1% to 1.7% of the dose, depending on the fraction. (14)C label found in the brain tissue and brain microdialysate indicated that grape polyphenols or their metabolites are able to cross the blood-brain barrier. Using (14)C-labeled plant polyphenols it is possible to track the compounds or their metabolic products into any tissue and determine distribution patterns in spite of low concentrations. A central question regarding the potential role of dietary polyphenolics in neurodegenerative research is whether they are bioavailable in the brain. Our observations indicate that some grape-derived polyphenolics do reach the brain, which suggests their potential value for applications in neurodegenerative disorders.

Antioxidant Activity and Protective Effects of Tripterygium regelii Extract on Hydrogen Peroxide-Induced Injury in Human Dopaminergic Cells, SH-SY5Y

The present work was conducted to investigate the antioxidant activity and neuroprotective effects of Tripterygium regelii extract (TRE) on H2O2-induced apoptosis in human dopaminergic cells, SH-SY5Y. TRE possessed considerable amounts of phenolics (282.73 mg tannic acid equivalents/g of extract) and flavonoids (101.43 mg naringin equivalents/g of extract). IC50 values for reducing power and DPPH radical scavenging activity were 52.51 and 47.83 μg, respectively. The H2O2 scavenging capacity of TRE was found to be 57.68 μM × μg−1 min−1. By examining the effects of TRE on SH-SY5Y cells injured by H2O2, we found that after incubation of cells with TRE prior to H2O2 exposure, the H2O2 induced cytotoxicity was significantly reversed and the apoptotic features such as change in cellular morphology, nuclear condensation and DNA fragmentation was inhibited. Moreover, TRE was very effective attenuating the disruption of mitochondrial membrane potential and apoptotic cell death induced by H2O2. TRE extract effectively suppressed the up-regulation of Bax, Caspase-3 and -9, and down-regulation of Bcl-2. Moreover, TRE pretreatment evidently increased the tyrosine hydroxylase (TH) and brain-derived neurotrophic factor (BDNF) in SH-SY5Y cells. These findings demonstrate that TRE protects SH-SY5Y cells against H2O2-induced injury and antioxidant properties may account for its neuroprotective actions and suggest that TRE might potentially serve as an agent for prevention of neurodegenerative disease associated with oxidative stress.

Mutant protein kinase C gamma that causes spinocerebellar ataxia type 14 (SCA14) is selectively degraded by autophagy

Several causal missense mutations in the protein kinase Cgamma (gammaPKC) gene have been found in spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously showed that mutant gammaPKC found in SCA14 is susceptible to aggregation and causes apoptosis. Aggregation of misfolded proteins is generally involved in the pathogenesis of many neurodegenerative diseases. Growing evidence indicates that macroautophagy (autophagy) is important for the degradation of misfolded proteins and the prevention of neurodegenerative diseases. In the present study, we examined whether autophagy is involved in the degradation of the mutant gammaPKC that causes SCA14. Mutant gammaPKC-GFP was transiently expressed in SH-SY5Y cells by using an adenoviral tetracycline-regulated system. Subsequently, temporal changes in clearance of aggregates and degradation of gammaPKC-GFP were evaluated. Rapamycin, an autophagic inducer, accelerated clearance of aggregates and promoted degradation of mutant gammaPKC-GFP, but it did not affect degradation of wild-type gammaPKC-GFP. These effects of rapamycin were not observed in embryonic fibroblast cells from Atg5-deficient mice, which are not able to perform autophagy. Furthermore, lithium, another type of autophagic inducer, also promoted the clearance of mutant gammaPKC aggregates. These results indicate that autophagy contributes to the degradation of mutant gammaPKC, suggesting that autophagic inducers could provide therapeutic potential for SCA14.

Galanin Protects Against Intracellular Amyloid Toxicity in Human Primary Neurons

Galanin and galanin receptors are upregulated in the brain regions associated with Alzheimer's disease (AD). However, the consequence of this overexpression is still unknown, particularly in human neurons. Here, we investigate the possible protective effects of galanin against intracellular amyloid-beta (Abeta)1-42 toxicity, as well as other insults including staurosporine, etoposide, hydrogen peroxide, and serum depletion in cultured human primary neurons. The results show that galanin is protective against intracellular Abeta cytotoxicity and all of the above insults at sub-nanomolar physiological concentrations. The galanin protection may be mediated by galanin receptor 2 and down-regulation of Bax level. The data from the present study provide a potential drug target for therapy or prevention of neurodegenerative diseases, including AD.

Glucosamine induces autophagy via an mTOR-independent pathway

Autophagy is a cellular process that nonspecifically degrades cytosolic components and is involved in many cellular responses. We found that amino sugars with a free amino group such as glucosamine, galactosamine and mannosamine induced autophagy via an mTOR-independent pathway. Glucosamine-induced autophagy at concentrations of at least 500 μM to over 40 mM. In the presence of 40 mM glucosamine, autophagy induction was initiated at 6 h and reached a plateau at 36 h. Glucosamine-induced autophagy could remove accumulated ubiquitin-conjugated proteins as well as 79-glutamine repeats. Therefore, orally administered glucosamine could contribute to the prevention of neurodegenerative diseases and promotion of antiaging effects.

A study of the toxic effect of oxidized sunflower oil containing 4-hydroperoxy-2-nonenal and 4-hydroxy-2-nonenal on cortical TrkA receptor expression in rats

Sunflower oil at a specific oxidation stage (when several oxygenated α,β-unsaturated aldehydes are generated, mainly 4-hydroperoxy-trans-2-alkenals and 4-hydroxy-trans-2-alkenals), caused at 70°C with aeration for 7 days, was administered intraperitoneally to rats. This oil was studied by means of solid phase micro-extraction followed by gas chromatography/mass spectrometry (SPME-GC/MS) and by proton nuclear magnetic resonance (1H-NMR). Oxidized sunflower oil (3 ml/kg/day) was administered to male Sprague–Dawley rats for 21 days. The control group was administered non-oxidized sunflower oil in the same volume and for the same duration as the experimental group. A significant decrease in the number of neural cells positively immunostained for TrkA receptor was detected in the frontal cortex of the experimental group, with respect to controls, suggesting both neuronal damage as well as a deficit in neuronal survival signalling at this level. This could lead to apoptosis of cholinergic neurons, which play a key role in memory and attention function. These results indicate that toxic substances present in the oxidized sunflower oil, among them 4-hydroxy-trans-2-nonenal (HNE) and 4-hydroperoxy-trans-2-nonenal (HPNE), could disrupt survival signalling of frontal cortex cholinergic neurons, which could lead to apoptosis and neurodegenerative diseases. In the case of humans, this fact reinforces the necessity of avoiding the re-utilization of oxidized sunflower oil, in order to contribute to long-term neurodegenerative diseases prevention.

Potential Mechanisms Involved in the Prevention of Neurodegenerative Diseases by Lithium

Lithium is a monovalent cation that was introduced in 1949 by John Cade for the treatment of bipolar disorder. Clinical reports and subsequent studies confirmed this application and the beneficial effects of this compound. However, over the last 15 years, various authors have also demonstrated the neuroprotective effects of lithium against several neurotoxic paradigms. Thus, experimental studies in neuronal cell cultures and animal models of Alzheimer disease and others pathologies have provided strong evidence for the potential benefits of lithium. The main mechanism underlying its neuroprotective effects is thought to be inhibition of glycogen synthase kinase-3 (GSK-3), although other biochemical pathways in the brain could also be affected. In this review, the main mechanisms of lithium action are summarized, including the modulation of glutamate receptors, effects on arachidonic acid metabolism, its role with respect to AKT, and other potential mechanisms. In addition, its effects on neuroprotective proteins such as Bcl-2 and p53 are also discussed. Although the cellular and molecular biological effects of lithium may constitute an effective therapeutic strategy for Alzheimer disease, further clinical and experimental studies with this drug and specific GSK-3 inhibitors are necessary to confirm the use of lithium in therapeutic approaches to neurodegenerative diseases.

The role of Wnt signaling in neuroprotection

The Wnt signaling pathway has a role in several cellular processes, including cellular communication, embryonic development and cancer. Recent studies show that the Wnt pathway also has an important role in some aspects of neuronal circuit development, such as neuronal migration, synaptic differentiation, mature synapse modulation and synaptic plasticity. Wnt signaling begins during neural development and is crucial for long-term potentiation in the adult brain. The Wnt pathway may have potential in the prevention of neurodegenerative diseases that involve synaptic impairment. Several years ago our laboratory found a relationship between the loss of Wnt signaling and amyloid-beta-peptide (Abeta) neurotoxicity, which is involved in Alzheimer's disease (AD). The activation of the Wnt signaling cascade prevents Abeta-dependent cytotoxic effects. We proposed that beta-catenin-dependent Wnt ligands have a role in the modulation of presynaptic processes such as neurotransmitter release. beta-catenin-independent Wnt signaling controls the postsynaptic site, increasing the incorporation of PSD-95 and glutamatergic receptors in the postsynaptic region. This could prevent the effects of Abeta exposure at the postsynaptic level. The study of the Wnt pathway is a promising approach in the search for possible targets to fight the deleterious effects of neurodegenerative conditions such as AD.

The role of Wnt signaling in neuroprotection

The Wnt signaling pathway has a role in several cellular processes, including cellular communication, embryonic development and cancer. Recent studies show that the Wnt pathway also has an important role in some aspects of neuronal circuit development, such as neuronal migration, synaptic differentiation, mature synapse modulation and synaptic plasticity. Wnt signaling begins during neural development and is crucial for long-term potentiation in the adult brain. The Wnt pathway may have potential in the prevention of neurodegenerative diseases that involve synaptic impairment. Several years ago our laboratory found a relationship between the loss of Wnt signaling and amyloid-beta-peptide (Abeta) neurotoxicity, which is involved in Alzheimer's disease (AD). The activation of the Wnt signaling cascade prevents Abeta-dependent cytotoxic effects. We proposed that beta-catenin-dependent Wnt ligands have a role in the modulation of presynaptic processes such as neurotransmitter release. beta-catenin-independent Wnt signaling controls the postsynaptic site, increasing the incorporation of PSD-95 and glutamatergic receptors in the postsynaptic region. This could prevent the effects of Abeta exposure at the postsynaptic level. The study of the Wnt pathway is a promising approach in the search for possible targets to fight the deleterious effects of neurodegenerative conditions such as AD.

Use of liquid chromatography with electrochemical detection for the determination of antioxidants in less common fruits.

Neurodegenerative disorders (NDD) have become the common global health burden over the last several decades. According to World Health Organization (WHO), a staggering 30 million people will be affected by Alzheimer’s disease in Europe and the USA by 2050. Effective therapies in this complex field considering the multitude of symptoms associated with NDD indications, have not been found yet. Based on the results of NDD related studies, prevention appears to be the promise alternative. Antioxidative and anti-inflammatory properties are hypothesized for natural phenolics, a group of plant secondary products that may positively impact neurodegenerative diseases. In these studies, phenolic-rich extracts from less common fruit species: Blue honeysuckle (Lonicera edulis, Turcz. ex. Freyn), Saskatoon berry (Amelanchier alnifolia Nutt.), and Chinese hawthorn (Crateagus pinnatifida Bunge) were obtained and analyzed to detect neuroprotective substances content and establish a potential therapeutic value. High performance liquid chromatography with electrochemical detection was optimized and further applied on analysis of the extracts of less common fruit species. It was observed that Chinese hawthorn and Blue honeysuckle extracts are potent source of neuroprotective phenolic antioxidants. In accordance the results, it appears that the fruit or formulated products may have the potential for the prevention of neurodegenerative diseases.

Alzheimers Disease and n-3 Polyunsaturated Fatty Acids: Beneficial Effects and Possible Molecular Pathways Involved

Elderly dementia is rising dramatically in Western countries. In particular, the irreversible memory impairment, continuous cognitive decline and behavioural disturbances present in Alzheimers disease patients make this neurodegenerative disorder highly disabiliting. Different epidemiological studies and experimental researches on transgenic mouse models suggest that dietary consumption of the two main long chain n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may modify the risk and progression of this neurodegenerative disorder. In addition, decreased blood levels of n-3 PUFAs have been associated with this disease in humans. In particular, among n-3 PUFAs, DHA is known to be the most prevalent PUFA in neuronal tissues. Animals specifically deficient in dietary n-3 PUFAs have shown to possess low DHA content in their membranes and impaired learning ability. Moreover, studies on non breast-fed infants have shown that DHA added to formula milk augments the levels of this fatty acid in infant blood improving their mental development. The potential mechanisms by which these fatty acids may function in normal neuronal activity and in neurodegenerative disease prevention and treatment are not well understood, even though these topics are now under investigation in numerous laboratories. In this review the current knowledge about the molecular mechanisms by which n-3 PUFAs are thought to regulate neuronal function, survival and degeneration will be examined. Since the pathological neuronal lesions of Alzheimer disease have been pathogenetically related to alterations of inflammatory and survival/apoptotic responses, molecular modulation of these pathways by n-3 PUFAs in neuronal tissues and cells will be particularly considered. Keywords: n-3 PUFAs, DHA, EPA, Alzheimer's disease, signal-transduction

Rosmarinic acid protects human dopaminergic neuronal cells against hydrogen peroxide-induced apoptosis

In this study, we investigated the protective effects of rosmarinic acid (RA) on H 2O 2-induced neurotoxicity in human dopaminergic cell line, SH-SY5Y. Results showed that RA significantly attenuated H 2O 2-induced reactive oxygen species (ROS) generation and apoptotic cell death. Rosmarinic acid effectively suppressed the up-regulation of Bax and down-regulation of Bcl-2. Furthermore, RA stimulated the antioxidant enzyme heme oxygenase-1 (HO-1). We also demonstrated that the HO-1 induction by RA was associated with the protein kinase A (PKA) and phosphatidylinositiol-3-kinase (PI3K) signaling pathways. These results suggest that RA can protect SH-SY5Y cells under oxidative stress conditions by regulating apoptotic process. Thus, RA should be clinically evaluated for the prevention of neurodegenerative diseases.

S5-01-06: Update on the relationship between homocysteine, B-vitamins, and one-carbon metabolism in aging and neurodegenerative disease

Over the past decade many cross-sectional and prospective epidemiologic studies have consistently identified a relationship between elevated plasma homocysteine (Hcy) and age-related cognitive decline, vascular dementia, and Alzheimers disease (AD). These observations led to several randomized clinical trials (RCTs) of B-vitamin supplementation in elderly individuals with vascular disease and dementia. Additionally, studies on the mechanism(s) potentially underlying the epidemiologic associations have identified novel molecular pathways important in neurodegeneration and AD pathogenesis. This presentation has three goals: (1). Review data from recent RCTs of B-vitamin supplementation for dementia and age-related cognitive decline. (2). Review new information from animal models of hyperhomocysteinemia as well as from recent observational studies in humans that point to novel molecular mechanisms that may underlie the epidemiologic observations. (3) Discuss how these new insights will inform the next phase of clinical investigations attempting to define the role of Hcy-lowering therapy as primary or secondary prevention of neurodegenerative disease. The Alzheimers Disease Cooperative Study (ADCS) recently completed a RCT of B-vitamin therapy for slowing cognitive decline in AD. This trial found no benefit of B-vitamin therapy, despite significant Hcy reduction. These results are consistent with other recenly completed trials that studied cognitive outcomes in elderly, non-demented individuals. Ongoing studies in animal models have identified novel molecular mechanisms that may explain the association between elevated Hcy, particularly the finding that Hcy elevations are a marker of disturbed methylation of proteins, DNA, and other molecules. In addition, Hcy is associated with oxidative stress, and B-vitamin supplements in the face of oxidative stress may be ineffective in correcting the presumptive metabolic defect. This new mechanistic information may explain the failure of RCTs of high-dose B-vitamin therapy, and suggests new areas for clinical research designed to elucidate the role of Hcy in aging and neurodegenerative disease. Despite disappointing results of recently completed RCTs, there remains substantial interest in studies designed to establish a possible role of Hcy-lowering therapy in aging and neurodegenerative disease. The next generation of clinical research in this area will incorporate new insights from preclinical models and human observations.

Establishment of an immortalized GABAergic neuronal progenitor cell line from embryonic ventral mesencephalon in the rat

Effective cell replacement therapies for neurological disease require neuron-restricted precursors as grafted cells. The problem of obtaining sufficient grafts for transplantation can be resolved by creating an appropriate immortalized cell line. In the present study, a thermally controlled immortalized GABAergic neuronal progenitor cell line (RMNE6) was established from E13 rat ventral mesencephalon cells immortalized using the temperature-sensitive mutant of SV40 large T antigen (ts-TAg). RMNE6 cells proliferated rapidly and expressed a neuron-like phenotype at the permissive temperature (33 °C), but eventually stopped growing at the non-permissive temperature (39 °C). Expression of the neuronal markers PSA-NCAM, β-tubulin III and MAP2 by RMNE6 cells was confirmed by RT-PCR or immunocytochemistry. Furthermore, these cells exhibited functional GABAergic neuron properties, as evidenced by the expression of glutamate decarboxylase (GAD) as well as the synthesis and release of the neurotransmitter GABA in a calcium-dependent manner. Moreover, RMNE6 cells spontaneously expressed and secreted several neurotrophic factors, such as NGF, BDNF, NT-3, NT-4/5, and GDNF. The cells survived well and kept expression of SV40 Tag, GAD65/67 and GABA in the striatum, at least 28 days after being transplanted in the rat brain. Tumorigenesis assays confirmed the safety of the immortalized cell line in vivo. Taken together, the results support the use of RMNE6 cells as an ideal cell model for transplantation research aimed at the treatment and prevention of neurodegenerative disease.

Statins in the spectrum of neurologic disease

Overwhelming evidence now shows that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (ie, statins) are safe and effective in primary and secondary prevention of cardiovascular disease. Atherosclerosis, the primary cause of heart disease, is directly and independently related to hypercholesterolemia and inflammation, and statins have multiple and independent effects on these conditions. New evidence for the use of statins in neurologic disease is mounting, and the range of therapeutic applications is formidable. Statins are beginning to show benefits in a wide range of neurologic conditions, from common ischemic stroke to rare congenital neurometabolic storage diseases, from acute brain injury to chronic central nervous system inflammation, and from prevention of neurodegenerative disease to acute neuroprotection. A diverse therapeutic spectrum is explained by shared pathogenetic mechanisms of neurologic disease and the manifold pharmacodynamic effects of statins.

Estradiol-17β-Induced Human Neural Progenitor Cell Proliferation Is Mediated by an Estrogen Receptor β-Phosphorylated Extracellularly Regulated Kinase Pathway

Estradiol-17beta (E(2)) induces rodent hippocampal neural progenitor cell (NPC) proliferation in vitro, in vivo, and after brain injury. The purpose of the present investigation was to determine whether E(2)-induced proliferation observed in rodent model systems generalized to cells of human neural origin and the signaling pathway by which E(2) promotes mitosis of human NPCs (hNPCs). Results of these analyses indicate that E(2) induced a significant increase in hNPC proliferation in a time- and dose-dependent manner. E(2)-induced hNPC DNA replication was paralleled by elevated cell cycle protein expression and centrosome amplification, which was associated with augmentation of total cell number. To determine whether estrogen receptor (ER) and which ER subtype were required for E(2)-induced hNPC proliferation, ER expression was first determined by real-time RT-PCR, followed by Western blot analysis, and subsequently verified pharmacologically using ERalpha or beta-selective ligands. Results of these analyses indicated that ERbeta expression was predominant relative to ERalpha, which was barely detectable in hNPCs. Activation of ERbeta by the ERbeta-selective ligand, diarylpropionitrile, led to an increase in phosphorylated extracellular signal-regulated kinase, and subsequent centrosome amplification and hNPC proliferation, which were blocked by the MEKK antagonist, UO126, but not its inactive analog, UO124. These findings, for the first time, demonstrate the molecular cascade and related cell biology events involved in E(2)-induced hNPC proliferation in vitro. Therapeutic implications of these findings relevant to hormone therapy and prevention of neurodegenerative disease are discussed.