Sex-specific behavioural effects of environmental enrichment in a transgenic mouse model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterised by motor neuron degeneration, muscle wasting and paralysis. While twin studies support a role for both genetic and environmental factors in ALS, the nature of environmental modifiers is unknown. We therefore compared onset and progression of disease symptoms in female and male transgenic ALS mice (expressing the human SOD1(G93A) gene mutation) and their wild-type littermates, housed in environmentally enriched versus standard conditions.

Leukemia inhibitory factor arrests oligodendrocyte death and demyelination in spinal cord injury.

As a consequence of secondary pathophysiological mechanisms elicited after spinal cord injury (SCI), oligodendrocytes die by waves of apoptosis. This ultimately results in demyelination of intact axons leading to a loss of their conducting properties. Preservation of as few as 5% to 10% of myelinated axons in individual tracts can confer locomotor recovery.

Induction of the unfolded protein response in familial amyotrophic lateral sclerosis and association of protein-disulfide isomerase with superoxide dismutase 1.

Mutations in Cu/Zn superoxide dismutase (SOD1) are linked to motor neuron death in familial amyotrophic lateral sclerosis (ALS) by an unclear mechanism, although misfolded SOD1 aggregates are commonly associated with disease. Proteomic analysis of the transgenic SOD1(G93A) ALS rat model revealed significant up-regulation of endoplasmic reticulum (ER)-resident protein-disulfide isomerase (PDI) family members in lumbar spinal cords. Expression of SOD1 mutants (mSOD1) led to an up-regulation of PDI in motor neuron-like NSC-34 cells but not other cell lines.

TNFalpha mediates Schwann cell death by upregulating p75NTR expression without sustained activation of NFkappaB.

Administration of tumour necrosis factor alpha (TNFalpha) to axotomised mouse neonatal sciatic nerves increased Schwann cell apoptosis in the distal nerve segments, 5-fold greater than axotomy alone. TNFalpha upregulated the low affinity neurotrophin receptor, p75NTR, indicative of phenotype reversion in Schwann cells. Furthermore, re-expression of p75NTR and downregulation of the pro-myelinating transcription factor, Oct 6, in Schwann cells occurred by treatment with TNFalpha, even after the maturation of these cells with brain derived neurotrophic factor (BDNF).

Properties of slow- and fast-twitch muscle fibres in a mouse model of amyotrophic lateral sclerosis.

This investigation was undertaken to determine if there are altered histological, pathological and contractile properties in presymptomatic or endstage diseased muscle fibres from representative slow-twitch and fast-twitch muscles of SOD1 G93A mice in comparison to wildtype mice. In presymptomatic SOD1 G93A mice, there was no detectable peripheral dysfunction, providing evidence that muscle pathology is secondary to motor neuronal dysfunction. At disease endstage however, single muscle fibre contractile analysis demonstrated that fast-twitch muscle fibres and neuromuscular junctions are preferentially affected by amyotrophic lateral sclerosis-induced denervation, being unable to produce the same levels of force when activated by calcium as muscle fibres from their age-matched controls.

Brain beta-amyloid accumulation in transgenic mice expressing mutant superoxide dismutase 1.

Oxidative stress is implicated in both the deposition and pathogenesis of beta-amyloid (Abeta) protein in Alzheimer's disease (AD). Accordingly, overexpression of the antioxidant enzyme superoxide dismutase 1 (SOD1) in neuronal cells and transgenic AD mice reduces Abeta toxicity and accumulation. In contrast, mutations in SOD1 associated with amyotrophic lateral sclerosis (ALS) confer enhanced pro-oxidative enzyme activities.

Loss of synaptophysin-positive boutons on lumbar motor neurons innervating the medial gastrocnemius muscle of the SOD1G93A G1H transgenic mouse model of ALS.

Amyotrophic lateral sclerosis (ALS) is a common form of motor neuron disease (MND) that involves both upper and lower nervous systems. In the SOD1G93A G1H transgenic mouse, a widely used animal model of human ALS, a significant pathology is linked to the degeneration of lower motor neurons in the lumbar spinal cord and brainstem. In the current study, the number of presynaptic boutons immunoreactive for synaptophysin was estimated on retrogradely labeled soma and proximal dendrites of alpha and gamma motor neurons innervating the medial gastrocnemius muscle.

Regulation of glutamate transporters in astrocytes: evidence for a relationship between transporter expression and astrocytic phenotype.

The astrocytic glutamate transporters, EAAT1 and EAAT2, remove released L-glutamate from the synaptic milieu thereby maintaining normal excitatory transmission. EAAT dysfunction during the excitotoxicity and oxidative stress of neurological insults may involve homoeostatic mechanisms associated with astrocytic function. We investigated aspects of EAAT function and expression in concert with astrocytic phenotype in primary cultures of cortical astrocytes and mixed cells of the spinal cord.

Impaired extracellular secretion of mutant superoxide dismutase 1 associates with neurotoxicity in familial amyotrophic lateral sclerosis.

Mutations in the intracellular metalloenzyme superoxide dismutase 1 (SOD1) are linked to neurotoxicity in familial amyotrophic lateral sclerosis (ALS) by an unclear mechanism. Golgi fragmentation and endoplasmic reticulum stress are early hallmarks of spinal motor neuron pathology in transgenic mice overexpressing mutant SOD1, suggesting that dysfunction of the neuronal secretory pathway may contribute to ALS pathogenesis. We therefore proposed that mutant SOD1 directly engages and modulates the secretory pathway based on recent evidence of SOD1 secretion in diverse human cell lines.

Magnetic resonance imaging reveals neuronal degeneration in the brainstem of the superoxide dismutase 1 transgenic mouse model of amyotrophic lateral sclerosis.

Magnetic resonance imaging (MRI) is becoming the preferred neuroimaging modality for the diagnosis of human amyotrophic lateral sclerosis (ALS). A useful animal model of ALS is the superoxide dismutase 1G93A G1H transgenic mouse, which shows many of the clinico-pathological features of the human condition. We have employed a 4.

Effect of p75 neurotrophin receptor antagonist on disease progression in transgenic amyotrophic lateral sclerosis mice.

Neurotrophin level imbalances and altered p75 neurotrophin receptor (p75(NTR)) expression are implicated in spinal motor neuron degeneration in human and mouse models of amyotrophic lateral sclerosis (ALS). Recently, elevated reactive astrocyte-derived nerve growth factor (NGF) was linked to p75(NTR)-expressing motor neuron death in adult transgenic ALS mice. To test the role of NGF-dependent p75(NTR)-mediated signalling in ALS, we examined the effects of a cyclic decapeptide antagonist of p75(NTR) ligand binding by using neurotrophin-stimulated cell death assays and transgenic ALS mice.

Expression of the low-affinity neurotrophin receptor, p75(NTR), is upregulated by oligodendroglial progenitors adjacent to the subventricular zone in response to demyelination.

Precursor cells have the capacity to repopulate the demyelinated brain, but the molecular mechanisms that facilitate their recruitment are largely unknown. The low-affinity neurotrophin receptor, p75(NTR), may be one of these regulators; however, its expression profile by oligodendroglia within the multiple sclerosis (MS) brain remains uncertain. We therefore assessed the expression profile of this receptor within 8 MS and 4 control brains.

Antisense peptide nucleic acid targeting GluR3 delays disease onset and progression in the SOD1 G93A mouse model of familial ALS.

Glutamate excitotoxicity is strongly implicated as a major contributing factor in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Excitotoxicity results from elevated intracellular calcium ion (Ca(2+)) levels, which in turn recruit cell death signaling pathways. Recent evidence suggests that alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit (GluR) stoichiometry is a dominant factor leading to excess Ca(2+) loading in neurodegeneration.

Human BAC-mediated rescue of the Friedreich ataxia knockout mutation in transgenic mice.

Three independent transgenic mouse lines were generated with the human Friedreich ataxia gene, FRDA, in an 188-kb bacterial artificial chromosome (BAC) genomic sequence. Three copies of the transgene per diploid mouse genome were integrated in a single site in each mouse line. Transgenic mice were mated with mice heterozygous for a knockout mutation of the murine Frda gene, to generate mice homozygous for the Frda knockout mutation and hemizygous or homozygous for the human transgene.

Degenerative and regenerative mechanisms governing spinal cord injury.

Spinal cord injury (SCI) is a major cause of disability, and at present, there is no universally accepted treatment. The functional decline following SCI is contributed to both direct mechanical injury and secondary pathophysiological mechanisms that are induced by the initial trauma. These mechanisms initially involve widespread haemorrhage at the site of injury and necrosis of central nervous system (CNS) cellular components.

Inducible superoxide dismutase 1 aggregation in transgenic amyotrophic lateral sclerosis mouse fibroblasts.

High molecular weight detergent-insoluble complexes of superoxide dismutase 1 (SOD1) enzyme are a biochemical abnormality associated with mutant SOD1-linked familial amyotrophic lateral sclerosis (FALS). In the present study, SOD1 protein from spinal cords of transgenic FALS mice was fractionated according to solubility in saline, zwitterionic, non-ionic or anionic detergents. Both endogenous mouse SOD1 and mutant human SOD1 were least soluble in SDS, followed by NP-40 and CHAPS, with an eight-fold greater detergent resistance of mutant protein overall.

Isolation and culture of motor neurons from the newborn mouse spinal cord.

A protocol for the isolation and culture of motor neurons from postnatal day 1 mouse spinal cord is described. After 72 h in culture, phase contrast microscopy reveals healthy cells with motor neuronal morphology and extensive neuritic processes. These neurons express the 75-kDa low-affinity neurotrophin receptor (p75NTR) and choline acetyltransferase (ChAT), both proteins are specifically expressed by neonatal and embryonic motor neurons in vivo.

Leukemia inhibitory factor promotes recovery of locomotor function following spinal cord injury in the mouse.

We describe an easy, minimal, rapid, and reproducible model of mouse spinal cord injury (SCI) that results in permanent paralysis involving one hind limb. We used this model to evaluate whether the paralysis can be prevented using two known neuroprotective drugs, namely leukemia inhibitory factor (LIF) and minocycline (MIN). Mice in the control vehicle (VEH) and MIN groups with SCI had negligible recovery of locomotor behavior.

Magnesium supplementation does not delay disease onset or increase survival in a mouse model of familial ALS.

Treatment of amyotrophic lateral sclerosis (ALS) with anti-glutamate agents has had some success, but the search continues for more effective glutamate blockers. Magnesium (Mg) ions inhibit the opening of some glutamate receptors, so we increased dietary Mg in a mouse model of ALS in an attempt to modify the course of the disease. From the age of 6 weeks, mutant superoxide dismutase 1 (SOD1) transgenic mice and wild-type controls had either 0, 21.

Antisense peptide nucleic acid-mediated knockdown of the p75 neurotrophin receptor delays motor neuron disease in mutant SOD1 transgenic mice.

Re-expression of the death-signalling p75 neurotrophin receptor (p75NTR) is associated with injury and neurodegeneration in the adult nervous system. The induction of p75NTR expression in mature degenerating spinal motor neurons of humans and transgenic mice with amyotrophic lateral sclerosis (ALS) suggests a role of p75NTR in the progression of motor neuron disease (MND). In this study, we designed, synthesized and evaluated novel antisense peptide nucleic acid (PNA) constructs targeting p75NTR as a potential gene knockdown therapeutic strategy for ALS.

Neuromuscular accumulation of mutant superoxide dismutase 1 aggregates in a transgenic mouse model of familial amyotrophic lateral sclerosis.

Superoxide dismutase 1 (SOD1) aggregates are a histological and biochemical correlate of disease progression in neural tissues from mutant SOD1-linked forms of familial amyotrophic lateral sclerosis (FALS). In the present study, we assayed the monomeric and high molecular weight mutant SOD1 content of nervous, muscle and visceral tissues from transgenic SOD1(G93A) mice using immunoblotting and zymograms. A progressive age-dependent increase in mutant SOD1 level, aggregation and stabilisation by cross-species heterodimers was determined in lumbar spinal cord, sciatic nerve and gastrocnemius muscle.

Behavioural and anatomical effects of systemically administered leukemia inhibitory factor in the SOD1(G93A G1H) mouse model of familial amyotrophic lateral sclerosis.

We investigated the anatomical and behavioural effects of daily intraperitoneal injection of 25 microg/kg of LIF in the SOD1(G93A G1H) mouse model of familial ALS. We found some subtle beneficial behavioural changes in LIF treated mice. These included later onset of clinical disease in females as determined by clinical scoring; better grip strength in males; and delayed development of motor impairment in males as determined by the rotarod test.

Design and application of a peptide nucleic acid sequence targeting the p75 neurotrophin receptor.

Novel antisense peptide nucleic acid (PNA) constructs targeting p75NTR as a potential therapeutic strategy for amyotrophic lateral sclerosis (ALS) were designed, synthesised and evaluated against phosphorothioate oligonucleotide sequences (PS-ODN). An 11-mer antisense PNA directed at the initiation codon dose-dependently inhibited p75NTR expression and death signalling by nerve growth factor in Schwann cell cultures. Inhibition of p75NTR production was not detected in cultures treated with the nonsense PNA or antisense PNA directed at the 3'-terminus sequence.

Schwann cell apoptosis in the postnatal axotomized sciatic nerve is mediated via NGF through the low-affinity neurotrophin receptor.

Schwann cell death is a developmentally regulated phenomenon and is also induced after peripheral nerve axotomy in neonatal rodents. In this study, we explored whether ligand-induced activation of the low-affinity neurotrophin receptor (p75(NTR)) is responsible for inducing Schwann cell death in vivo. Administration of exogenous nerve growth factor (NGF) to the axotomized nerve site in wild-type animals resulted in a 2.