A molecular study of pathways involved in the inhibition of cell proliferation in neuroblastoma B65 cells by the GSK-3 inhibitors lithium and SB-415286.

Pharmacological GSK-3 inhibitors are potential drugs for the treatment of neurodegenerative diseases, cancer and diabetes. We examined the antiproliferative effects of two GSK-3 inhibitors, lithium and SB-415286, on B65 neuroblastoma cell line. Treatment of B65 cells with either drug administered separately caused a decrease in cell proliferation that was associated with G(2)/M cell cycle arrest.

Dysfunction of astrocytes in senescence-accelerated mice SAMP8 reduces their neuroprotective capacity.

Early onset increases in oxidative stress and tau pathology are present in the brain of senescence-accelerated mice prone (SAMP8). Astrocytes play an essential role, both in determining the brain's susceptibility to oxidative damage and in protecting neurons. In this study, we examine changes in tau phosphorylation, oxidative stress and glutamate uptake in primary cultures of cortical astrocytes from neonatal SAMP8 mice and senescence-accelerated-resistant mice (SAMR1).

Modulation of SIRT1 expression in different neurodegenerative models and human pathologies.

We examined the expression of SIRT1 in several experimental paradigms of human pathologies. We used a neuroblastoma cell line (B65), neuronal primary cultures (hippocampus and cerebellar granule cells) and in vivo approaches in rat and senescence murine models (SAM). Cell cultures and rats were treated with several well-know neurotoxins, i.

Lithium treatment decreases activities of tau kinases in a murine model of senescence.

Lithium modulates glycogen synthase kinase 3beta (GSK-3beta), a kinase involved in Alzheimer disease-related tau pathology. To investigate mechanisms of aging and the potential therapy of lithium in neurodegenerative disease, we treated senescence-accelerated mouse (SAM)P8 mice, a murine model of senescence, and mice of the control SAMR1 strain with lithium. The treatment reduced hippocampal caspase 3 and calpain activation, indicating that it provides neuroprotection.

Novel donepezil-based inhibitors of acetyl- and butyrylcholinesterase and acetylcholinesterase-induced beta-amyloid aggregation.

A novel series of donepezil-tacrine hybrids designed to simultaneously interact with the active, peripheral and midgorge binding sites of acetylcholinesterase (AChE) have been synthesized and tested for their ability to inhibit AChE, butyrylcholinesterase (BChE), and AChE-induced A beta aggregation. These compounds consist of a unit of tacrine or 6-chlorotacrine, which occupies the same position as tacrine at the AChE active site, and the 5,6-dimethoxy-2-[(4-piperidinyl)methyl]-1-indanone moiety of donepezil (or the indane derivative thereof), whose position along the enzyme gorge and the peripheral site can be modulated by a suitable tether that connects tacrine and donepezil fragments. All of the new compounds are highly potent inhibitors of bovine and human AChE and BChE, exhibiting IC50 values in the subnanomolar or low nanomolar range in most cases.

GSK-3 beta inhibition and prevention of mitochondrial apoptosis inducing factor release are not involved in the antioxidant properties of SB-415286.

The antioxidant effects of lithium and SB-415286, two glycogen synthase kinase-3 beta (GSK-3 beta) inhibitors, were studied in cerebellar granule neurons by measuring changes in 2, 7-dichlorodihydrofluorescein diacetate (H2DCFDA) fluorescence. GSK-3 beta inhibitors inhibit apoptosis mediated by serum and potassium withdrawal (S/K withdrawal) and GSK-3 beta activation, as measured by beta-catenin degradation. Furthermore, as both drugs prevent mitochondrial apoptosis inducing factor (AIF) release, these data indicate that GSK-3 beta inhibitors prevent caspase-independent apoptosis in cerebellar granule neurons induced by S/K withdrawal.

Favorable effects of a prolonged treatment with melatonin on the level of oxidative damage and neurodegeneration in senescence-accelerated mice.

Senescence-accelerated mice (SAMP8) and senescence-accelerated resistant mice (SAMR1) were studied at 5 and 10 months of age, respectively. In the animals, neurodegenerative processes and how they were influenced by melatonin were examined. Melatonin (10 mg/kg) or vehicle (ethanol at 0.

Apoptotic mechanisms involved in neurodegenerative diseases: experimental and therapeutic approaches.

Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most significant neurodegenerative disorders in the developed world. However, although these diseases were described almost a century ago, the molecular mechanisms that lead to the neuronal cell death associated with these diseases are not yet clear, and vigorous research efforts have failed to identify effective treatment options. In the present review, we evaluate the potential mechanisms underlying apoptosis and neuronal death in neurodegenerative disorders.

Neuroprotective effects of SB-415286 on hydrogen peroxide-induced cell death in B65 rat neuroblastoma cells and neurons.

Glycogen synthase kinase-3 (GSK-3) is involved in the pathogenesis of several neurodegenerative diseases. In addition, as oxidative stress has been implicated in all neurodegenerative disorders, the inhibition of both pathways offers a potential strategy for preventing or delaying neurodegeneration. We examined the cytoprotective effects of lithium and SB-415286, two inhibitors of GSK-3, using a rat B65 cell line and also in cerebellar granule cells (CGN).

The antiproliferative activity of melatonin in B65 rat dopaminergic neuroblastoma cells is related to the downregulation of cell cycle-related genes.

A potential application of melatonin is its ability to rescue many cell types from cell death, because of its antioxidant properties. Likewise, recent studies suggest that melatonin may also be used as an anti-tumor drug, due to its anti-proliferative properties in tumor cells when administered at physiologic or pharmacologic doses. In the present study, we investigated the mechanisms involved in the apoptosis induced by acute exposure to melatonin and roscovitine in the rat dopaminergic neuroblastoma B65 cell line.

DNA low-density array analysis of colchicine neurotoxicity in rat cerebellar granular neurons.

Cytoskeletal alteration is a key factor in neurodegenerative processes like Alzheimer's or Parkinson's disease. Colchicine is a microtubule-disrupting agent that binds to tubuline, inhibiting microtubule assembly, and which triggers apoptosis. The present research describes the transcriptional activation of molecules related to alternative forms of apoptosis, in an acute colchicine model of apoptosis in rat cerebellar granule neurons (CGNs).

Modulation of sirtuins: new targets for antiageing.

Aging is characterized by a progressive deterioration of physiological functions and metabolic processes. Healthy aging remains one of the ideals of modern society. In aging and in diseases associated with the elderly, such as Alzheimer's or Parkinson's, the loss of cells in vital structures or organs may be related to several factors, among which the production of reactive oxygen species (ROS) by mitochondria is a common denominator, one that leads to DNA damage, apoptosis and death.

Peroxisome proliferator-activated receptor alpha down-regulation is associated with enhanced ceramide levels in age-associated cardiac hypertrophy.

We used an experimental murine model of accelerated aging, the senescence-accelerated mouse (SAM), to examine the effect of age-associated cardiac hypertrophy on peroxisome proliferator-activated receptor alpha (PPARalpha) expression and activity in the heart. Senescence-accelerated prone mice (SAM-P8) showed cardiac hypertrophy compared with senescence-accelerated resistant mice (SAM-R1). Furthermore, a decrease in PPARalpha messenger RNA (mRNA; 28% reduction, p<.

Hypertriglyceridemia and hepatic steatosis in senescence-accelerated mouse associate to changes in lipid-related gene expression.

Aged rodents show increasing plasma and tissue triglycerides, and reductions in liver peroxisome proliferator-activated receptor alpha (PPARalpha) and its target genes. We determined whether a similar situation is present in a model of accelerated aging, the senescence-accelerated prone (SAM-P8) mouse. Five-month-old SAM-P8 mice were hypertriglyceridemic, and exhibited hepatic steatosis and reduced fatty acid oxidation versus control 5-month-old senescence-accelerated resistant (SAM-R1) mice, with no differences in PPARalpha expression and binding activity; in fact, fenofibrate administration to SAM-P8 mice induced a clear PPARalpha-driven response.

Inhibition of ataxia telangiectasia-p53-E2F-1 pathway in neurons as a target for the prevention of neuronal apoptosis.

Over the last few decades, understanding of the mechanisms involved in the process of neuronal cell death has grown. Recent findings have established that DNA damage, and specifically ataxia telangiectasia mutated protein (ATM), is key to the cascade of regulation of neuronal apoptosis. Another characteristic common to all neurodegenerative diseases is oxidative stress.

Activation of the calpain/cdk5/p25 pathway in the girus cinguli in Parkinson's disease.

The mechanisms involved in neuronal loss in Parkinson's disease (PD) are not known, although recent studies performed in PD experimental models suggest that cdk5/p25 plays a predominant role. In the present study, we examined the gyrus cinguli of cases with PD and compared them with age-matched controls, and we demonstrated an activation of the calpain/cdk5 pathway. We found an increase in the p25/p35 immunoreactivity ratio and in the expression of transcription factor E2F-1.

Increased permeability of blood-brain barrier on the hippocampus of a murine model of senescence.

SAMP8 mice show several indicative characteristics of accelerated aging and have been used to study the physiological and physiopathological processes that take place during senescence. There is some controversy about the presence of a functional blood-brain barrier (BBB) disturbance on these animals, which could be related to the oxidative stress or the amyloidosis present in their brain. In order to elucidate BBB status in the hippocampus of SAMP8 mice, in this study we have determined the extravasation from brain microvessels of endogenous IgG in SAMP8 mice aged 3, 7 and 12 months and in age-matched control SAMR1 mice.

Neuroprotective effects of caffeine against complex I inhibition-induced apoptosis are mediated by inhibition of the Atm/p53/E2F-1 path in cerebellar granule neurons.

The aim of the present study was to evaluate the neuroprotective effects of caffeine, an inhibitor of ataxia telangiectasia mutated (ATM) enzyme and an antagonist of adenosine receptors, in two models of apoptosis in cerebellar granule neurons (CGNs): the inhibition of mitochondrial complex I by the neurotoxin MPP(+) and serum and potassium deprivation. We used cerebellar granule neurons because of low glial contamination. Cell viability was measured by the MTT method, and apoptosis was evaluated by assessing DNA fragmentation with flow cytometry or quantification of nuclear condensation.

Glycogen synthase kinase-3 is involved in the regulation of the cell cycle in cerebellar granule cells.

Recent studies have demonstrated that neuronal reentry in the cell cycle and specifically the expression of the transcription factor E2F-1, constitutes a pathway that may be involved in neuronal apoptosis after serum and potassium withdrawal. Other enzymes such as glycogen synthase kinase-3beta (GSK-3beta) are also involved in this apoptotic stimulus, and thus in the process of neuronal cell death. Primary cerebellar granule cells (CGNs) were used in this study to determine whether pharmacological inhibition of GSK-3beta is involved in neuronal modulation of the cell cycle, and specifically in the regulation of E2F-1 and retinoblastoma protein (Rb).

Comparative analysis of the effects of resveratrol in two apoptotic models: inhibition of complex I and potassium deprivation in cerebellar neurons.

The mechanism involved in neuronal apoptosis is largely unknown. Studies performed on neuronal cell cultures provide information about the pathways which orchestrate the process of neuronal loss and potential drugs for the treatment of neurological disorders. In the present study we select resveratrol, a natural antioxidant, as a potential drug for the treatment of neurodegenerative diseases.

3-Nitropropionic acid activates calpain/cdk5 pathway in rat striatum.

3-Nitropropionic acid (3-NP) is a neurotoxin that inhibits mitochondrial complex II and is used in an experimental model of Huntington's disease. Treatment of rats with 3-NP 30mgkg(-1) i.p.

Chronic administration of melatonin reduces cerebral injury biomarkers in SAMP8.

Certain effects of melatonin on senescence were investigated. The experimental model used was 10-month-old senescence-accelerated mouse prone 8 (SAMP8). The mice in the experiment were administered melatonin (10 mg/kg) from the age of 1 month.

Inhibition of cyclin-dependent kinases is neuroprotective in 1-methyl-4-phenylpyridinium-induced apoptosis in neurons.

The biochemical pathways involved in neuronal cell death in Parkinson's disease are not completely characterized. Mitochondrial dysfunction, specifically alteration of the mitochondrial complex I, is the primary target of the parkinsonian neurotoxin 1-methyl-4-phenylpyridinium (MPP+) induced apoptosis in neurons. In the present study, we examine the role of caspase-dependent and -independent routes in MPP+-induced apoptosis in rat cerebellar granule neurons (CGNs).

Implication of the transcription factor E2F-1 in the modulation of neuronal apoptosis.

Neurodegenerative diseases as Alzheimer's disease, Parkinson's disease and other neurological disorders remain major problem worldwide since is currently no effective treatment. Thus, studying the mechanisms involved in neuronal apoptotic pathways is imperative if drugs that might stop or delay these disease processes are to be synthesized. In recent years it has become evident that mitochondria are key component of the neuronal apoptotic route.

The role of CDK5/P25 formation/inhibition in neurodegeneration.

Cdk5 is an atypical cyclin-dependent kinase localized in the brain, and its activity is dependent upon binding to p35/p39. In addition, while cdk5 has important physiological functions related to brain development, the breakdown of cdk5/p35 into cdk5/p25 increases its kinase activity and neurotoxicity. Interestingly, in recent years increased cdk5/p25 expression has been demonstrated in the brains of patients with Alzheimer's and Parkinson's diseases.