Synergy of insulin-like growth factor-1 and exercise in amyotrophic lateral sclerosis

GHRH and its analogues in central nervous system diseases

Growth hormone-releasing hormone (GHRH) is primarily produced by the hypothalamus and stimulates the release of growth hormone (GH) in the anterior pituitary gland, which subsequently regulates the production of hepatic insulin-like growth factor-1 (IGF-1). GH and IGF-1 have potent effects on promoting cell proliferation, inhibiting cell apoptosis, as well as regulating cell metabolism. In central nerve system (CNS), GHRH/GH/IGF-1 promote brain development and growth, stimulate neuronal proliferation, and regulate neurotransmitter release, thereby participating in the regulation of various CNS physiological activities. In addition to hypothalamus-pituitary gland, GHRH and GHRH receptor (GHRH-R) are also expressed in other brain cells or tissues, such as endogenous neural stem cells (NSCs) and tumor cells. Alternations in GHRH/GH/IGF-1 axis are associated with various CNS diseases, for example, Alzheimer's disease, amyotrophic lateral sclerosis and emotional disorders manifest GHRH, GH or IGF-1 deficiency, and GH or IGF-1 supplementation exerts beneficial therapeutic effects on these diseases. CNS tumors, such as glioma, can express GHRH and GHRH-R, and activating this signaling pathway promotes tumor cell growth. The synthesized GHRH antagonists have shown to inhibit glioma cell growth and may hold promising as an adjuvant therapy for treating glioma. In addition, we have shown that GHRH agonist MR-409 can improve neurological sequelae after ischemic stroke by activating extrapituitary GHRH-R signaling and promoting endogenous NSCs-derived neuronal regeneration. This article reviews the involvement of GHRH/GH/IGF-1 in CNS diseases, and potential roles of GHRH agonists and antagonists in treating CNS diseases.

Skeletal muscle dysfunction in amyotrophic lateral sclerosis: a mitochondrial perspective and therapeutic approaches

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neuromuscular disease that results in the loss of motor neurons and severe skeletal muscle atrophy. The etiology of ALS is linked to skeletal muscle, which can activate a retrograde signaling cascade that destroys motor neurons. This is why satellite cells and mitochondria play a crucial role in the health and performance of skeletal muscles. This review presents current knowledge on the involvement of mitochondrial dysfunction, skeletal muscle atrophy, muscle satellite cells, and neuromuscular junction (NMJ) in ALS. It also discusses current therapeutic strategies, including exercise, drugs, stem cells, gene therapy, and the prospective use of mitochondrial transplantation as a viable therapeutic strategy.

Exercise training induces mild skeletal muscle adaptations without altering disease progression in a TDP-43 mouse model

Exercise training is considered a nonpharmacological therapeutic approach for many diseases. Mild-to-moderate endurance exercise training is suggested to improve the mental and physical state of people with amyotrophic lateral sclerosis (ALS). The aim of the present study was to determine the capacity of symptomatic rNLS8 mice, which develop ALS-reminiscent TAR DNA-binding protein 43 (TDP-43) pathology and motor dysfunction, to perform mild-to-moderate intensity treadmill exercise training and to evaluate the effects of this training on skeletal muscle health and disease progression. Symptomatic rNLS8 mice were able to complete 4 wk of mild-to-moderate treadmill running (30 min at 6-13 m/min, 3 days a week). Exercise training induced an increase in the percentage of type IIA fibers in the tibialis anterior muscle as well as minor adaptations in molecular markers of myogenic, mitochondrial, and neuromuscular junction health in some forelimb and hindlimb muscles. However, this exercise training protocol did not attenuate the loss in motor function or delay disease progression. Alternative exercise regimens need to be investigated to better understand the role exercise training may play in alleviating symptoms of ALS.NEW & NOTEWORTHY This is the first study to investigate the capacity of symptomatic rNLS8 mice, which develop ALS-reminiscent TDP-43 pathology and motor dysfunction, to perform exercise training. We demonstrate that despite the ALS-reminiscent aggressive disease progression characterizing the rNLS8 mouse model, rNLS8 mice are capable of performing mild-to-moderate endurance treadmill training for at least 3-4 wk. We demonstrate that exercise training induces several minor skeletal muscle adaptations without delaying disease progression in rNLS8 mice.

The role of macrophage plasticity in neurodegenerative diseases

Tissue-resident macrophages and recruited macrophages play pivotal roles in innate immunity and the maintenance of brain homeostasis. Investigating the involvement of these macrophage populations in eliciting pathological changes associated with neurodegenerative diseases has been a focal point of research. Dysregulated states of macrophages can compromise clearance mechanisms for pathological proteins such as amyloid-β (Aβ) in Alzheimer's disease (AD) and TDP-43 in Amyotrophic lateral sclerosis (ALS). Additionally, recent evidence suggests that abnormalities in the peripheral clearance of pathological proteins are implicated in the pathogenesis and progression of neurodegenerative diseases. Furthermore, numerous genome-wide association studies have linked genetic risk factors, which alter the functionality of various immune cells, to the accumulation of pathological proteins. This review aims to unravel the intricacies of macrophage biology in both homeostatic conditions and neurodegenerative disorders. To this end, we initially provide an overview of the modifications in receptor and gene expression observed in diverse macrophage subsets throughout development. Subsequently, we outlined the roles of resident macrophages and recruited macrophages in neurodegenerative diseases and the progress of targeted therapy. Finally, we describe the latest advances in macrophage imaging methods and measurement of inflammation, which may provide information and related treatment strategies that hold promise for informing the design of future investigations and therapeutic interventions.

Physical exercise in amyotrophic lateral sclerosis: a potential co-adjuvant therapeutic option to counteract disease progression

Amyotrophic lateral sclerosis (ALS) is a fatal disorder characterized by the selective degeneration of upper and lower motor neurons, leading to progressive muscle weakness and atrophy. The mean survival time is two to five years. Although the hunt for drugs has greatly advanced over the past decade, no cure is available for ALS yet. The role of intense physical activity in the etiology of ALS has been debated for several decades without reaching a clear conclusion. The benefits of organized physical activity on fitness and mental health have been widely described. Indeed, by acting on specific mechanisms, physical activity can influence the physiology of several chronic conditions. It was shown to improve skeletal muscle metabolism and regeneration, neurogenesis, mitochondrial biogenesis, and antioxidant defense. Interestingly, all these pathways are involved in ALS pathology. This review will provide a broad overview of the effect of different exercise protocols on the onset and progression of ALS, both in humans and in animal models. Furthermore, we will discuss challenges and opportunities to exploit physiological responses of imposed exercise training for therapeutic purposes.

Potential molecular mechanism of exercise reversing insulin resistance and improving neurodegenerative diseases

Neurodegenerative diseases are debilitating nervous system disorders attributed to various conditions such as body aging, gene mutations, genetic factors, and immune system disorders. Prominent neurodegenerative diseases include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. Insulin resistance refers to the inability of the peripheral and central tissues of the body to respond to insulin and effectively regulate blood sugar levels. Insulin resistance has been observed in various neurodegenerative diseases and has been suggested to induce the occurrence, development, and exacerbation of neurodegenerative diseases. Furthermore, an increasing number of studies have suggested that reversing insulin resistance may be a critical intervention for the treatment of neurodegenerative diseases. Among the numerous measures available to improve insulin sensitivity, exercise is a widely accepted strategy due to its convenience, affordability, and significant impact on increasing insulin sensitivity. This review examines the association between neurodegenerative diseases and insulin resistance and highlights the molecular mechanisms by which exercise can reverse insulin resistance under these conditions. The focus was on regulating insulin resistance through exercise and providing practical ideas and suggestions for future research focused on exercise-induced insulin sensitivity in the context of neurodegenerative diseases.

Testosterone Reduces Myelin Abnormalities in the Wobbler Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal motoneuron degenerative disease that is associated with demyelination. The Wobbler (WR) mouse exhibits motoneuron degeneration, gliosis and myelin deterioration in the cervical spinal cord. Since male WRs display low testosterone (T) levels in the nervous system, we investigated if T modified myelin-relative parameters in WRs in the absence or presence of the aromatase inhibitor, anastrozole (A). We studied myelin by using luxol-fast-blue (LFB) staining, semithin sections, electron microscopy and myelin protein expression, density of IBA1+ microglia and mRNA expression of inflammatory factors, and the glutamatergic parameters glutamine synthetase (GS) and the transporter GLT1. Controls and WR + T showed higher LFB, MBP and PLP staining, lower g-ratios and compact myelin than WRs and WR + T + A, and groups showing the rupture of myelin lamellae. WRs showed increased IBA1+ cells and mRNA for CD11b and inflammatory factors (IL-18, TLR4, TNFαR1 and P2Y12R) vs. controls or WR + T. IBA1+ cells, and CD11b were not reduced in WR + T + A, but inflammatory factors' mRNA remained low. A reduction of GS+ cells and GLT-1 immunoreactivity was observed in WRs and WR + T + A vs. controls and WR + T. Clinically, WR + T but not WR + T + A showed enhanced muscle mass, grip strength and reduced paw abnormalities. Therefore, T effects involve myelin protection, a finding of potential clinical translation.

Targeting mitochondrial Ca2+ uptake for the treatment of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rare adult-onset neurodegenerative disease characterized by progressive motor neuron (MN) loss, muscle denervation and paralysis. Over the past several decades, researchers have made tremendous efforts to understand the pathogenic mechanisms underpinning ALS, with much yet to be resolved. ALS is described as a non-cell autonomous condition with pathology detected in both MNs and non-neuronal cells, such as glial cells and skeletal muscle. Studies in ALS patient and animal models reveal ubiquitous abnormalities in mitochondrial structure and function, and disturbance of intracellular calcium homeostasis in various tissue types, suggesting a pivotal role of aberrant mitochondrial calcium uptake and dysfunctional calcium signalling cascades in ALS pathogenesis. Calcium signalling and mitochondrial dysfunction are intricately related to the manifestation of cell death contributing to MN loss and skeletal muscle dysfunction. In this review, we discuss the potential contribution of intracellular calcium signalling, particularly mitochondrial calcium uptake, in ALS pathogenesis. Functional consequences of excessive mitochondrial calcium uptake and possible therapeutic strategies targeting mitochondrial calcium uptake or the mitochondrial calcium uniporter, the main channel mediating mitochondrial calcium influx, are also discussed.

Muscle Involvement in Amyotrophic Lateral Sclerosis: Understanding the Pathogenesis and Advancing Therapeutics

Amyotrophic lateral sclerosis (ALS) is a fatal condition characterized by the selective loss of motor neurons in the motor cortex, brainstem, and spinal cord. Muscle involvement, muscle atrophy, and subsequent paralysis are among the main features of this disease, which is defined as a neuromuscular disorder. ALS is a persistently progressive disease, and as motor neurons continue to degenerate, individuals with ALS experience a gradual decline in their ability to perform daily activities. Ultimately, muscle function loss may result in paralysis, presenting significant challenges in mobility, communication, and self-care. While the majority of ALS research has traditionally focused on pathogenic pathways in the central nervous system, there has been a great interest in muscle research. These studies were carried out on patients and animal models in order to better understand the molecular mechanisms involved and to develop therapies aimed at improving muscle function. This review summarizes the features of ALS and discusses the role of muscle, as well as examines recent studies in the development of treatments.

One episode of low intensity aerobic exercise prior to systemic AAV9 administration augments transgene delivery to the heart and skeletal muscle

INTRODUCTION

The promising potential of adeno-associated virus (AAV) gene delivery strategies to treat genetic disorders continues to grow with an additional three AAV-based therapies recently approved by the Food and Drug Administration and dozens of others currently under evaluation in clinical trials. With these developments, it has become increasingly apparent that the high doses currently needed for efficacy carry risks of toxicity and entail enormous manufacturing costs, especially for clinical grade products. Strategies to increase the therapeutic efficacy of AAV-mediated gene delivery and reduce the minimal effective dose would have a substantial impact on this field. We hypothesized that an exercise-induced redistribution of tissue perfusion in the body to favor specific target organs via acute aerobic exercise prior to systemic intravenous (IV) AAV administration could increase efficacy.

BACKGROUND

Aerobic exercise triggers an array of downstream physiological effects including increased perfusion of heart and skeletal muscle, which we expected could enhance AAV transduction. Prior preclinical studies have shown promising results for a gene therapy approach to treat Barth syndrome (BTHS), a rare monogenic cardioskeletal myopathy, and clinical studies have shown the benefit of low intensity exercise in these patients, making this a suitable disease in which to test the ability of aerobic exercise to enhance AAV transduction.

METHODS

Wild-type (WT) and BTHS mice were either systemically administered AAV9 or completed one episode of low intensity treadmill exercise immediately prior to systemic administration of AAV9.

RESULTS

We demonstrate that a single episode of acute low intensity aerobic exercise immediately prior to IV AAV9 administration improves marker transgene delivery in WT mice as compared to mice injected without the exercise pre-treatment. In BTHS mice, prior exercise improved transgene delivery and additionally increased improvement in mitochondrial gene transcription levels and mitochondrial function in the heart and gastrocnemius muscles as compared to mice treated without exercise.

CONCLUSIONS

Our findings suggest that one episode of acute low intensity aerobic exercise improves AAV9 transduction of heart and skeletal muscle. This low-risk, cost effective intervention could be implemented in clinical trials of individuals with inherited cardioskeletal disease as a potential means of improving patient safety for human gene therapy.

Forelimb Resistance Exercise Protects Against Neuromuscular Junction Denervation in the SOD1-G93A Rat Model of ALS

INTRODUCTION

The symptoms of Amyotrophic Lateral Sclerosis (ALS) include muscle weakness and eventual paralysis. These symptoms result from denervation of the neuromuscular junction (NMJ) and motor neuron cell death in the brain and spinal cord. Due to the "dying back" pattern of motor neuron degeneration, protecting NMJs should be a therapeutic priority. Although exercise has the potential to protect against NMJ denervation, its use in ALS has been controversial. Most preclinical studies have focused on aerobic exercise, which report that exercise can be beneficial at moderate intensities. The effects of resistance exercise on NMJ preservation in limb muscles have not been explored.

METHODS

We trained male SOD1-G93A rats, which model ALS, to perform a unilateral isometric forelimb resistance exercise task. This task allows within-animal comparisons of trained and untrained forelimbs. We then determined the effects of isometric resistance exercise on NMJ denervation and AMP kinase (AMPK) activation in forelimb muscles.

RESULTS

Our results revealed that SOD1-G93A rats were able to learn and perform the task similarly to wildtype rats, even after loss of body weight. SOD1-G93A rats exhibited significantly greater NMJ innervation in their trained vs their untrained forelimb biceps muscles. Measures of activated (phosphorylated) AMPK (pAMPK) were also greater in the trained vs untrained forelimb triceps muscles.

DISCUSSION

These results demonstrate that isometric resistance exercise may protect against NMJ denervation in ALS. Future studies are required to determine the extent to which our findings generalize to female SOD1-G93A rats and to other subtypes of ALS.

The protective role of exercise against age-related neurodegeneration

Endurance exercise is a widely accessible, low-cost intervention with a variety of benefits to multiple organ systems. Exercise improves multiple indices of physical performance and stimulates pronounced health benefits reducing a range of pathologies including metabolic, cardiovascular, and neurodegenerative disorders. Endurance exercise delays brain aging, preserves memory and cognition, and improves symptoms of neurodegenerative pathologies like Amyotrophic Lateral Sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and various ataxias. Potential mechanisms underlying the beneficial effects of exercise include neuronal survival and plasticity, neurogenesis, epigenetic modifications, angiogenesis, autophagy, and the synthesis and release of neurotrophins and cytokines. In this review, we discuss shared benefits and molecular pathways driving the protective effects of endurance exercise on various neurodegenerative diseases in animal models and in humans.

Swim training affects Akt signaling and ameliorates loss of skeletal muscle mass in a mouse model of amyotrophic lateral sclerosis

We tested the hypothesis that swim training reverses the impairment of Akt/FOXO3a signaling, ameliorating muscle atrophy in ALS mice. Transgenic male mice B6SJL-Tg (SOD1^G93A) 1Gur/J were used as the ALS model (n = 35), with wild-type B6SJL (WT) mice as controls (n = 7). ALS mice were analyzed before ALS onset, at ALS onset, and at terminal ALS. Levels of insulin/Akt signaling pathway proteins were determined, and the body and tibialis anterior muscle mass and plasma creatine kinase. Significantly increased levels of FOXO3a in ALS groups (from about 13 to 21-fold) compared to WT mice were observed. MuRF1 levels in the ONSET untrained group (12.0 ± 1.7 AU) were significantly higher than in WT mice (1.12 ± 0.2 AU) and in the BEFORE ALS group (3.7 ± 0.9 AU). This was associated with body mass and skeletal muscle mass reduction. Swim training significantly ameliorated the reduction of skeletal muscle mass in both TERMINAL groups (p < 0.001) and partially reversed changes in the levels of Akt signaling pathway proteins. These findings shed light on the swimming-induced attenuation of skeletal muscle atrophy in ALS with possible practical implications for anti-cachexia approaches.

Skeletal Muscle Metabolism: Origin or Prognostic Factor for Amyotrophic Lateral Sclerosis (ALS) Development?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive and selective loss of motor neurons, amyotrophy and skeletal muscle paralysis usually leading to death due to respiratory failure. While generally considered an intrinsic motor neuron disease, data obtained in recent years, including our own, suggest that motor neuron protection is not sufficient to counter the disease. The dismantling of the neuromuscular junction is closely linked to chronic energy deficit found throughout the body. Metabolic (hypermetabolism and dyslipidemia) and mitochondrial alterations described in patients and murine models of ALS are associated with the development and progression of disease pathology and they appear long before motor neurons die. It is clear that these metabolic changes participate in the pathology of the disease. In this review, we summarize these changes seen throughout the course of the disease, and the subsequent impact of glucose–fatty acid oxidation imbalance on disease progression. We also highlight studies that show that correcting this loss of metabolic flexibility should now be considered a major goal for the treatment of ALS.

Skeletal Muscle in ALS: An Unappreciated Therapeutic Opportunity?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the selective degeneration of upper and lower motor neurons and by the progressive weakness and paralysis of voluntary muscles. Despite intense research efforts and numerous clinical trials, it is still an incurable disease. ALS had long been considered a pure motor neuron disease; however, recent studies have shown that motor neuron protection is not sufficient to prevent the course of the disease since the dismantlement of neuromuscular junctions occurs before motor neuron degeneration. Skeletal muscle alterations have been described in the early stages of the disease, and they seem to be mainly involved in the "dying back" phenomenon of motor neurons and metabolic dysfunctions. In recent years, skeletal muscles have been considered crucial not only for the etiology of ALS but also for its treatment. Here, we review clinical and preclinical studies that targeted skeletal muscles and discuss the different approaches, including pharmacological interventions, supplements or diets, genetic modifications, and training programs.

Androgen Therapy in Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer disease (AD), Parkinson disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington disease, are characterized by the loss of neurons as well as neuronal function in multiple regions of the central and peripheral nervous systems. Several studies in animal models have shown that androgens have neuroprotective effects in the brain and stimulate axonal regeneration. The presence of neuronal androgen receptors in the peripheral and central nervous system suggests that androgen therapy might be useful in the treatment of neurodegenerative diseases. To illustrate, androgen therapy reduced inflammation, amyloid-β deposition, and cognitive impairment in patients with AD. As well, improvements in remyelination in MS have been reported; by comparison, only variable results are observed in androgen treatment of PD. In ALS, androgen administration stimulated motoneuron recovery from progressive damage and regenerated both axons and dendrites. Only a few clinical studies are available in human individuals despite the safety and low cost of androgen therapy. Clinical evaluations of the effects of androgen therapy on these devastating diseases using large populations of patients are strongly needed.

Running and swimming prevent the deregulation of the BDNF/TrkB neurotrophic signalling at the neuromuscular junction in mice with amyotrophic lateral sclerosis

Nerve-induced muscle contraction regulates the BDNF/TrkB neurotrophic signalling to retrogradely modulate neurotransmission and protect the neuromuscular junctions and motoneurons. In muscles with amyotrophic lateral sclerosis, this pathway is strongly misbalanced and neuromuscular junctions are destabilized, which may directly cause the motoneuron degeneration and muscular atrophy observed in this disease. Here, we sought to demonstrate (1) that physical exercise, whose recommendation has been controversial in amyotrophic lateral sclerosis, would be a good option for its therapy, because it normalizes and improves the altered neurotrophin pathway and (2) a plausible molecular mechanism underlying its positive effect. SOD1-G93A mice were trained following either running or swimming-based protocols since the beginning of the symptomatic phase (day 70 of age) until day 115. Next, the full BDNF pathway, including receptors, downstream kinases and proteins related with neurotransmission, was characterized and motoneuron survival was analysed. The results establish that amyotrophic lateral sclerosis-induced damaging molecular changes in the BDNF/TrkB pathway are reduced, prevented or even overcompensated by precisely defined exercise protocols that modulate TrkB isoforms and neurotransmission regulatory proteins and reduce motoneuron death. Altogether, the maintenance of the BDNF/TrkB signalling and the downstream pathway, particularly after the swimming protocol, adds new molecular evidence of the benefits of physical exercise to reduce the impact of amyotrophic lateral sclerosis. These results are encouraging since they reveal an improvement even starting the therapy after the onset of the disease.

Insulin-like growth factor 1 signaling in motor neuron and polyglutamine diseases: From molecular pathogenesis to therapeutic perspectives

The pleiotropic peptide insulin-like growth factor 1 (IGF-I) regulates human body homeostasis and cell growth. IGF-I activates two major signaling pathways, namely phosphoinositide-3-kinase (PI3K)/protein kinase B (PKB/Akt) and Ras/extracellular signal-regulated kinase (ERK), which contribute to brain development, metabolism and function as well as to neuronal maintenance and survival. In this review, we discuss the general and tissue-specific effects of the IGF-I pathways. In addition, we present a comprehensive overview examining the role of IGF-I in neurodegenerative diseases, such as spinal and muscular atrophy, amyotrophic lateral sclerosis, and polyglutamine diseases. In each disease, we analyze the disturbances of the IGF-I pathway, the modification of the disease protein by IGF-I signaling, and the therapeutic strategies based on the use of IGF-I developed to date. Lastly, we highlight present and future considerations in the use of IGF-I for the treatment of these disorders.

The role of serum growth hormone and insulin-like growth factor-1 in adult humans brain morphology

Growth hormone (GH) and its anabolic mediator, insulin-like growth factor-1 (IGF-1), have a critical role in the central nervous system. However, their detailed roles in the adult human brain are not clear. In this study, structural MRIs of 48 patients with GH-secreting pituitary adenoma (GH-PA), 48 sex- and age-matched clinical Non-Functional pituitary adenoma patients (NonFun-PA) and healthy controls (HCs) were assessed using voxel-based morphometry (VBM) and region-based morphometry (RBM). Correlation analyses helped determine the relationships between serum hormone levels and brain structure. The whole-brain gray matter volume (GMV) and white matter volume (WMV) significantly increased at the expense of cerebrospinal fluid volume (CSFV) in GH-PA (Bonferroni corrected, p<0.01). The increase in GMV and reduction in CSFV were significantly correlated with serum GH/IGF-1 levels (p<0.05). VBM showed significant correlations of the GMV/WMV alteration pattern between GH-PA vs HCs and GH-PA vs NonFun-PA and widespread bilateral clusters of significantly increased GMV and WMV in GH-PA (pFDR<0.05). RBM showed obviously increased GMV/WMV in 54 of 68 brain regions (p<0.05) in GH-PA compared to HCs. Our results provide imaging evidence that serum GH/IGF-1 contributes to brain growth, which may be a potential treatment option for neurodegenerative disorders and brain injury in humans.

The influence of metallothionein treatment and treadmill running exercise on disease onset and survival in SOD1G93A amyotrophic lateral sclerosis mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, characterised by the degeneration of motor neurons innervating skeletal muscle. The mechanisms underlying neurodegeneration in ALS are not yet fully elucidated, and with current therapeutics only able to extend lifespan by a matter of months there is a clear need for novel therapies to increase lifespan and patient quality of life. Here, we evaluated whether moderate-intensity treadmill exercise and/or treatment with metallothionein-2 (MT2), a neuroprotective protein, could improve survival, behavioural or neuropathological outcomes in SOD1^G93A familial ALS mice. Six-week-old female SOD1^G93A mice were allocated to one of four treatment groups: MT2 injection, i.m.; moderate treadmill exercise; neither MT2 nor exercise; or both MT2 and exercise. MT2-treated mice survived around 3% longer than vehicle-treated mice, with this mild effect reaching statistical significance in Cox proportional hazards analysis once adjusted for potential confounders. Mixed model body weight trajectories over time indicated that MT2-treated mice, with or without exercise, reached maximum body weight at a later age, suggesting a delay in disease onset of around 4% compared to saline-treated mice. Exercise alone did not significantly increase survival or delay disease onset, and neither exercise nor MT2 substantially ameliorated gait abnormalities or muscle strength loss. We conclude that neither exercise nor MT2 treatment was detrimental in female SOD1^G93A mice, and further study could determine whether the mild effect of peripheral MT2 administration on disease onset and survival could be improved via direct administration of MT2 to the central nervous system.

The Impact of Kinases in Amyotrophic Lateral Sclerosis at the Neuromuscular Synapse: Insights into BDNF/TrkB and PKC Signaling

Brain-derived neurotrophic factor (BDNF) promotes neuron survival in adulthood in the central nervous system. In the peripheral nervous system, BDNF is a contraction-inducible protein that, through its binding to tropomyosin-related kinase B receptor (TrkB), contributes to the retrograde neuroprotective control done by muscles, which is necessary for motor neuron function. BDNF/TrkB triggers downstream presynaptic pathways, involving protein kinase C, essential for synaptic function and maintenance. Undeniably, this reciprocally regulated system exemplifies the tight communication between nerve terminals and myocytes to promote synaptic function and reveals a new view about the complementary and essential role of pre and postsynaptic interplay in keeping the synapse healthy and strong. This signaling at the neuromuscular junction (NMJ) could establish new intervention targets across neuromuscular diseases characterized by deficits in presynaptic activity and muscle contractility and by the interruption of the connection between nervous and muscular tissues, such as amyotrophic lateral sclerosis (ALS). Indeed, exercise and other therapies that modulate kinases are effective at delaying ALS progression, preserving NMJs and maintaining motor function to increase the life quality of patients. Altogether, we review synaptic activity modulation of the BDNF/TrkB/PKC signaling to sustain NMJ function, its and other kinases’ disturbances in ALS and physical and molecular mechanisms to delay disease progression.

The Role of Exercise as a Non-pharmacological Therapeutic Approach for Amyotrophic Lateral Sclerosis: Beneficial or Detrimental?

Amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, involves the rapid deterioration of motor neurons resulting in severe muscle atrophy and respiratory insufficiency. It is considered a "multisystemic" disease with many potential mechanisms responsible for its pathology. Currently, there is no cure for ALS. Exercise training is suggested as a potential approach to reduce ALS pathology, but its beneficial role remains controversial. This review provides an overview of the effects of exercise training in ALS-affected mice and patients. It will compare the intensity, duration, and type of exercise on the health of SOD1^G93A mice, a mouse model of familial ALS, and review clinical studies involving ALS patients undergoing both endurance and resistance training. In summary, mild-to-moderate swimming-based endurance training appears the most advantageous mode of exercise in SOD1^G93A mice, improving animal survival, and delaying the onset and progression of disease. Furthermore, clinical studies show that both endurance and resistance training have an advantageous impact on the quality of life of ALS patients without extending life expectancy. However, small sample sizes, non-representative control populations, heterogeneous disease stage of patients, and the presence of confounders often exist in the exercise studies conducted with ALS patients. This raises concerns about the interpretation of these findings and, therefore, these results should be considered with caution. While promising, more pre-clinical and clinical studies with improved experimental design and fewer limitations are still necessary to confirm the impact of exercise training on the health of ALS patients.

Recumbent stepping aerobic exercise in amyotrophic lateral sclerosis: a pilot study

OBJECTIVES

Aerobic exercise can promote neuroplastic responses in the healthy and injured brain. Although the role of exercise in amyotrophic lateral sclerosis (ALS) is debated, new evidence suggests that exercise may reduce disease progression. While common exercise modalities such as the treadmill and cycle ergometer have been explored in ALS, the safety and feasibility of a total body recumbent stepper have not been investigated. Additionally, the functional and neurophysiological effects of recumbent stepping in ALS are still unknown. Here, we investigated the safety and feasibility of a 4-week recumbent stepping program to slow disease progression in ALS and possibly facilitate neuroplasticity.

METHOD

Nine individuals with ALS performed moderate intensity recumbent stepping for four weeks. Outcomes included participation satisfaction questionnaire, ALS Functional Rating Scale Revised (ALSFRS-R), clinical tests of walking and endurance, fatigue severity scale, Beck depression inventory, SF-12, and transcranial magnetic stimulation-induced motor evoked potentials (MEPs). All measurements were collected at baseline, post-intervention, and at the 1-month follow-up.

RESULTS

Eight participants completed the study without any adverse events. The ALSFRS-R scores were similar at the end of the study and at follow-up. No significant differences were noted for any of the clinical outcomes. MEPs were present only in two participants and changes in corticomotor excitability after exercise were minimal.

CONCLUSIONS

Results from this preliminary study support the safety and feasibility of 12 sessions of total body recumbent stepping in individuals with ALS.

Astrocyte-Mediated Neuromodulatory Regulation in Preclinical ALS: A Metadata Analysis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease characterized by progressive degradation of motoneurons in the central nervous system (CNS). Astrocytes are key regulators for inflammation and neuromodulatory signaling, both of which contribute to ALS. The study goal was to ascertain potential temporal changes in astrocyte-mediated neuromodulatory regulation with transgenic ALS model progression: glutamate, GTL-1, GluR1, GluR2, GABA, ChAT activity, VGF, TNFα, aspartate, and IGF-1. We examine neuromodulatory changes in data aggregates from 42 peer-reviewed studies derived from transgenic ALS mixed cell cultures (neurons + astrocytes). For each corresponding experimental time point, the ratio of transgenic to wild type (WT) was found for each compound. ANOVA and a student's t-test were performed to compare disease stages (early, post-onset, and end stage). Glutamate in transgenic SOD1-G93A mixed cell cultures does not change over time (p > 0.05). GLT-1 levels were found to be decreased 23% over WT but only at end-stage (p < 0.05). Glutamate receptors (GluR1, GluR2) in SOD1-G93A were not substantially different from WT, although SOD1-G93A GluR1 decreased by 21% from post-onset to end-stage (p < 0.05). ChAT activity was insignificantly decreased. VGF is decreased throughout ALS (p < 0.05). Aspartate is elevated by 25% in SOD1-G93A but only during end-stage (p < 0.05). TNFα is increased by a dramatic 362% (p < 0.05). Furthermore, principal component analysis identified TNFα as contributing to 55% of the data variance in the first component. Thus, TNFα, which modulates astrocyte regulation via multiple pathways, could be a strategic treatment target. Overall results suggest changes in neuromodulator levels are subtle in SOD1-G93A ALS mixed cell cultures. If excitotoxicity is present as is often presumed, it could be due to ALS cells being more sensitive to small changes in neuromodulation. Hence, seemingly unsubstantial or oscillatory changes in neuromodulators could wreak havoc in ALS cells, resulting in failed microenvironment homeostasis whereby both hyperexcitability and hypoexcitability can coexist. Future work is needed to examine local, spatiotemporal neuromodulatory homeostasis and assess its functional impact in ALS.

Prolonged Voluntary Running Negatively Affects Survival and Disease Prognosis of Male SOD1G93A Low-Copy Transgenic Mice

Amyotrophic Lateral Sclerosis (ALS) is a disease in which physical activity plays a controversial role. Epidemiological studies indicate an association between intense exercise and risk of developing ALS. To study the impact of physical activity on ALS, mouse models rely mostly on forced exercise. In this study we hypothesized that voluntary wheel running could represent a better model of the influence of exercise in the pathogenesis of ALS. We used an automated home-cage running-wheel system that enables individual monitoring of performance. To verify the effect of voluntary running on disease progression, prognosis and survival as well as motor functions, we challenged SOD1G93A low-copy male and female mice on one (1 RW, at age 24 weeks) or multiple (3 RW) running sessions at age 13, 18, and 24 weeks. In parallel we measured performance on Rotarod and Grip strength tests at different ages. Several parameters were analyzed through Principal Component Analysis in order to detect what indices correlate and may be useful for deeper understanding of the relation between exercise and disease development. We found mutant male mice more negatively affected than females by prolonged and repeated exercise. SOD1G93A low-copy male mice showed shorter survival, increased body weight loss and poorer disease prognosis when exposed to multiple running sessions. These findings could encourage the investigation of the pathogenetic mechanisms underlying the supposedly increased risk to develop ALS in humans engaged in specific and intense exercise activities.

Defective daily temperature regulation in a mouse model of amyotrophic lateral sclerosis

Current understanding of the pathogenesis of the familial form of amyotrophic lateral sclerosis has been aided by the study of transgenic mice that over-express mutated forms of the human CuZn-superoxide dismutase (SOD1) gene. While mutant SOD1 in motor neurons determines disease onset, other non-cell autonomous factors are critical for disease progression, and altered energy metabolism has been implicated as a contributing factor. Since most energy expended by laboratory mice is utilized to defend body temperature (T_b), we analyzed thermoregulation in transgenic mice carrying the G93A mutation of the human SOD1 gene, using implantable temperature data loggers to continuously record T_b for up to 85 days. At room (22 °C) ambient temperature, G93A mice exhibited a diminished amplitude of the daily T_b rhythm compared to C57BL/6J controls, secondary to decreased T_b values during the dark (behaviorally active) phase of the light-dark cycle. The defect arose at 85-99 days of age, around the age of symptom onset (as assessed by grip strength), well before observable weakness and weight loss, and could not be accounted for by decreased levels of locomotor activity or food consumption. Housing under thermoneutral (29 °C) ambient temperature partially rescued the defect, but age-dependently (only in animals >100 days of age), suggesting that the deficit in older mice was due in part to inadequate thermogenesis by "peripheral" thermogenic organs as the disease progressed. In younger mice, we found that cold-induced thermogenesis and energy expenditure were intact, hinting that an initial "central" defect might localize to the subparaventricular zone, involving neural output pathways from the circadian clock in the hypothalamic suprachiasmatic nucleus to forebrain thermoregulatory circuitry.

New Therapeutics to Modulate Mitochondrial Function in Neurodegenerative Disorders

BACKGROUND

Mitochondrial function and energy metabolism are impaired in neurodegenerative diseases. There is evidence for these functional declines both within the brain and systemically in Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis. Due to these observations, therapeutics targeted to alter mitochondrial function and energy pathways are increasingly studied in pre-clinical and clinical settings.

METHODS

The goal of this article was to review therapies with specific implications on mitochondrial energy metabolism published through May 2016 that have been tested for treatment of neurodegenerative diseases.

RESULTS

We discuss implications for mitochondrial dysfunction in neurodegenerative diseases and how this drives new therapeutic initiatives.

CONCLUSION

Thus far, treatments have achieved varying degrees of success. Further investigation into the mechanisms driving mitochondrial dysfunction and bioenergetic failure in neurodegenerative diseases is warranted.

Effects of combined endurance and resistance training in Amyotrophic Lateral Sclerosis: A pilot, randomized, controlled study

Based on available evidence, muscle strengthening and cardiovascular exercises can help maintain function and not adversely affect the progression of disease in patients with ALS. However, this evidence is not sufficiently detailed to recommend a specific exercise prescription. The purpose of this project was to assess clinical outcomes of a combined exercise programme to increase knowledge of rehabilitation in ALS patients. 38 ALS patients were assigned randomly to two groups: one group underwent a specific exercise programme (ALS-EP) based on a moderate aerobic workout and isometric contractions, and the second group followed a standard neuromotor rehabilitation treatment. Objective evaluation consisted of cardiovascular measures, muscle strength and fatigue. Some positive effects of physical activity on ALS patients were found. Among the benefits, an overall improvement of functional independence in all patients, independently of the type of exercise conducted was seen. In addition, improvements in muscle power, oxygen consumption and fatigue were specifically observed in the ALS-EP group, all hallmarks of a training effect for the specific exercises. In conclusion, moderate intensity exercise is beneficial in ALS, helping in avoiding deconditioning and muscle atrophy resulting from progressive inactivity.

A randomized controlled trial of resistance and endurance exercise in amyotrophic lateral sclerosis

OBJECTIVE

Evaluate the safety and tolerability of resistance and endurance exercise in ALS participants as measured by their ability to complete this six-month study.

METHODS

Participants were randomized to Resistance, Endurance, or Stretching/Range of Motion (SROM the exercise regimen prescribed for most ALS patients) exercises. All exercises were performed at home with an individualized regimen designed by a physical therapist trained in ALS management. Primary outcome measures were tolerability of the exercises at 24 weeks defined by 50% of participants completing at least 50% of the prescribed exercise regimen. Secondary outcome measures included the ALSFRS-R, pulmonary FVC, and other measures of ALS function.

RESULTS

At 12 and 24 weeks, all three exercise regimens were tolerated according to our pre-specified criteria. Compliance to the prescribed exercise regimen was the highest in the resistance and SROM arms of the study. All three forms of exercise were considered safe as there were no differences in the rates of disease progression among groups. There were no differences in the secondary outcome measures and feasibility for evaluating these measures was successful. In a post-hoc analysis, there was a trend towards fewer falls in the Resistance and Endurance groups.

CONCLUSIONS

This study demonstrates that SROM, resistance, and endurance exercise are all safe to be performed with the specified regimen without any worsening of outcomes as related to ALS function. All three forms of exercise were tolerated with resistance and SROM exercises showing the highest compliance over the 24 week-period.

Neurotrophic and Neuroregenerative Effects of GH/IGF1

Introduction. Human neurodegenerative diseases increase progressively with age and present a high social and economic burden. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are both growth factors exerting trophic effects on neuronal regeneration in the central nervous system (CNS) and peripheral nervous system (PNS). GH and IGF-1 stimulate protein synthesis in neurons, glia, oligodendrocytes, and Schwann cells, and favor neuronal survival, inhibiting apoptosis. This study aims to evaluate the effect of GH and IGF-1 on neurons, and their possible therapeutic clinical applications on neuron regeneration in human subjects. Methods. In the literature, we searched the clinical trials and followed up studies in humans, which have evaluated the effect of GH/IGF-1 on CNS and PNS. The following keywords have been used: “GH/IGF-1” associated with “neuroregeneration”, “amyotrophic lateral sclerosis”, “Alzheimer disease”, “Parkinson’s disease”, “brain”, and “neuron”. Results. Of the retrieved articles, we found nine articles about the effect of GH in healthy patients who suffered from traumatic brain injury (TBI), and six studies (four using IGF-1 and two GH therapy) in patients with amyotrophic lateral sclerosis (ALS). The administration of GH in patients after TBI showed a significantly positive recovery of brain and mental function. Treatment with GH and IGF-1 therapy in ALS produced contradictory results. Conclusions. Although strong findings have shown the positive effects of GH/IGF-1 administration on neuroregeneration in animal models, a very limited number of clinical studies have been conducted in humans. GH/IGF-1 therapy had different effects in patients with TBI, evidencing a high recovery of neurons and clinical outcome, while in ALS patients, the results are contradictory. More complex clinical protocols are necessary to evaluate the effect of GH/IGF-1 efficacy in neurodegenerative diseases. It seems evident that GH and IGF-1 therapy favors the optimal recovery of neurons when a consistent residual activity is still present. Furthermore, the effect of GH/IGF-1 could be mediated by, or be overlapped with that of other hormones, such as estradiol and testosterone.

Neurturin is a PGC-1α1-controlled myokine that promotes motor neuron recruitment and neuromuscular junction formation

OBJECTIVE

We examined whether skeletal muscle overexpression of PGC-1α1 or PGC-1α4 affected myokine secretion and neuromuscular junction (NMJ) formation.

METHODS

A microfluidic device was used to model endocrine signaling and NMJ formation between primary mouse myoblast-derived myotubes and embryonic stem cell-derived motor neurons. Differences in hydrostatic pressure allowed for fluidic isolation of either cell type or unidirectional signaling in the fluid phase. Myotubes were transduced to overexpress PGC-1α1 or PGC-1α4, and myokine secretion was quantified using a proximity extension assay. Morphological and functional changes in NMJs were measured by fluorescent microscopy and by monitoring muscle contraction upon motor neuron stimulation.

RESULTS

Skeletal muscle transduction with PGC-1α1, but not PGC-1α4, increased NMJ formation and size. PGC-1α1 increased muscle secretion of neurturin, which was sufficient and necessary for the effects of muscle PGC-1α1 on NMJ formation.

CONCLUSIONS

Our findings indicate that neurturin is a mediator of PGC-1α1-dependent retrograde signaling from muscle to motor neurons.

Specific Physical Exercise Improves Energetic Metabolism in the Skeletal Muscle of Amyotrophic-Lateral- Sclerosis Mice

Amyotrophic Lateral Sclerosis is an adult-onset neurodegenerative disease characterized by the specific loss of motor neurons, leading to muscle paralysis and death. Although the cellular mechanisms underlying amyotrophic lateral sclerosis (ALS)-induced toxicity for motor neurons remain poorly understood, growing evidence suggest a defective energetic metabolism in skeletal muscles participating in ALS-induced motor neuron death ultimately destabilizing neuromuscular junctions. In the present study, we report that a specific exercise paradigm, based on a high intensity and amplitude swimming exercise, significantly improves glucose metabolism in ALS mice. Using physiological tests and a biophysics approach based on nuclear magnetic resonance (NMR), we unexpectedly found that SOD1(G93A) ALS mice suffered from severe glucose intolerance, which was counteracted by high intensity swimming but not moderate intensity running exercise. Furthermore, swimming exercise restored the highly ALS-sensitive tibialis muscle through an autophagy-linked mechanism involving the expression of key glucose transporters and metabolic enzymes, including GLUT4 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Importantly, GLUT4 and GAPDH expression defects were also found in muscles from ALS patients. Moreover, we report that swimming exercise induced a triglyceride accumulation in ALS tibialis, likely resulting from an increase in the expression levels of lipid transporters and biosynthesis enzymes, notably DGAT1 and related proteins. All these data provide the first molecular basis for the differential effects of specific exercise type and intensity in ALS, calling for the use of physical exercise as an appropriate intervention to alleviate symptoms in this debilitating disease.

Neuromuscular Junction Dismantling in Amyotrophic Lateral Sclerosis

Neuromuscular junction assembly and plasticity during embryonic, postnatal, and adult life are tightly regulated by the continuous cross-talk among motor nerve endings, muscle fibers, and glial cells. Altered communications among these components is thought to be responsible for the physiological age-related changes at this synapse and possibly for its destruction in pathological states. Neuromuscular junction dismantling plays a crucial role in the onset of Amyotrophic Lateral Sclerosis (ALS). ALS is characterized by the degeneration and death of motor neurons leading to skeletal muscle denervation, atrophy and, most often, death of the patient within five years from diagnosis. ALS is a non-cell autonomous disease as, besides motor neuron degeneration, glial cells, and possibly muscle fibers, play a role in its onset and progression. Here, we will review the recent literature regarding the mechanisms leading to neuromuscular junction disassembly and muscle denervation focusing on the role of the three players of this peripheral tripartite synapse.

Effect of physical exercise and anabolic steroid treatment on spinal motoneurons and surrounding glia of wild-type and ALS mice

Motoneuron degeneration is the hallmark of amyotrophic lateral sclerosis (ALS). The cause and predisposing factors for sporadic ALS are still unknown. Exposure to a specific environmental risk factors in subjects with a susceptibility genotype may increase the risk of the disease. The role of physical activity and the use of anabolic steroids are still debated in epidemiological studies on patients and murine models of ALS. To assess at the cellular level the role (beneficial or detrimental) of physical exercise and the use of anabolic steroid, we here investigated, in SOD1(G93A) (mSOD1) mice and wild-type littermates, changes in the ventral horn after regular exercise, treatment with the anabolic androgenic steroid 19-nortestosterone (nandrolone), and their combination, compared with matched control sedentary mice. The experiments were pursued for several weeks until symptom onset in mSOD1 mice. Lumbar motoneurons, astrocytes and microglia were analyzed. In wild-type mice, cytological alterations of motoneurons were observed especially after nandrolone treatment. The following main findings were observed in treated mSOD1 mice versus untreated ones: i) nandrolone treatment markedly enhanced motoneuron loss; this detrimental effect was reverted by the combination with exercise, resulting in increased motoneuron survival; ii) astrocytic activation was most marked after nandrolone treatment when motoneuron damage was most severe; iii) microglia activation was most marked after physical exercise when motoneuron damage was less severe. The results indicate a vulnerability of mSOD1 motoneurons to nandrolone treatment, a potential neuroprotective effect of physical exercise, and a modulation by glial cells in the ALS murine model in the examined paradigms.

Impact of expiratory strength training in amyotrophic lateral sclerosis

INTRODUCTION

We evaluated the feasibility and impact of expiratory muscle strength training (EMST) on respiratory and bulbar function in persons with amyotrophic lateral sclerosis (ALS).

METHODS

Twenty-five ALS patients participated in this delayed intervention open-label clinical trial. Following a lead-in period, patients completed a 5-week EMST protocol. Outcome measures included: maximum expiratory pressure (MEP); physiologic measures of swallow and cough; and penetration-aspiration scale (PAS) scores.

RESULTS

Of participants who entered the active phase of the study (n = 15), EMST was well tolerated and led to significant increases in MEPs and maximum hyoid displacement during swallowing post-EMST (P < 0.05). No significant differences were observed for PAS scores or cough spirometry measures.

CONCLUSIONS

EMST was feasible and well tolerated in this small cohort of ALS patients and led to improvements in expiratory force-generating pressures and swallow kinematics. Further investigation is warranted to confirm these preliminary findings. Muscle Nerve 54: 48-53, 2016.

Control of the Cell Cycle in Adult Neurogenesis and its Relation with Physical Exercise

In the adult brain the neurogenesis is mainly restricted to two neurogenic regions: newly generated neurons arise at the subventricular zone (SVZ) of the lateral ventricle and at the subgranular zone of the hippocampal subregion named the dentate gyrus. The hippocampus is involved in learning and memory paradigms and the generation of new hippocampal neurons has been hypothesized to be a pivotal form of plasticity involved in the process. Moreover the dysregulation of hippocampal adult neurogenesis has been recognized and could anticipate several varieties of brain disease such as Alzheimer disease, epilepsy and depression. Over the last few decades numerous intrinsic, epigenetic and environmental factors have been revealed to deeply influence the process of adult neurogenesis, although the underlying mechanisms remain largely unknown. Growing evidence indicates that physical exercise represents one of the main extrinsic factor able to profoundly increase hippocampal adult neurogenesis, by altering neurochemistry and function of newly generated neurons. The present review surveys how neurogenesis can be modulated by cell cycle kinetics and highlights the putative role of the cell cycle length as a key component of the beneficial effect of running for hippocampal adult neurogenesis, both in physiological conditions and in the presence of defective neurogenesis.

Mechanisms of Muscle Denervation in Aging: Insights from a Mouse Model of Amyotrophic Lateral Sclerosis

Muscle denervation at the neuromuscular junction (NMJ) is thought to be a contributing factor in age-related muscle weakness. Therefore, understanding the mechanisms that modulate NMJ innervation is a key to developing therapies to combat age-related muscle weakness affecting the elderly. Two mouse models, one lacking the Cu/Zn superoxide dismutase (SOD1) gene and another harboring the transgenic mutant human SOD1 gene, display progressive changes at the NMJ, including muscle endplate fragmentation, nerve terminal sprouting, and denervation. These changes at the NMJ share many of the common features observed in the NMJs of aged mice. In this review, research findings demonstrating the effects of PGC-1α, IGF-1, GDNF, MyoD, myogenin, and miR-206 on NMJ innervation patterns in the G93A SOD1 mice will be highlighted in the context of age-related muscle denervation.

Is There a Role for Exercise in the Management of Bulbar Dysfunction in Amyotrophic Lateral Sclerosis?

PURPOSE

The role of exercise in the management of people with amyotrophic lateral sclerosis (PALS) is controversial and currently unclear. The purpose of this review article is to review literature examining the impact of limb, respiratory, and oral motor exercise on function, disease progression, and survival in PALS and the transgenic ALS animal model.

METHOD

A literature review was conducted to examine relevant studies published in peer-reviewed journals between 1960 and 2014. All studies were appraised for quality of research and were assigned a level of evidence, and treatment outcomes were classified as either positive, negative, or neutral.

RESULTS

A total of 18 exercise-based intervention studies on limb (13), respiratory (3), or speech (2) function were identified. Of the human clinical trials, 6 were experimental and 4 were exploratory. No experimental studies were identified examining the impact of targeted exercise on speech or swallowing function. Mild to moderate intensity limb or respiratory exercise, applied early in the disease, was noted to have a beneficial impact on motor function and survival.

CONCLUSION

Insufficient data exist to support or refute the role of exercise in the management of bulbar dysfunction in PALS. This represents a critical area of future investigation.

Characterization of the Contribution of Genetic Background and Gender to Disease Progression in the SOD1 G93A Mouse Model of Amyotrophic Lateral Sclerosis: A Meta-Analysis

Background: The SOD1 G93A mouse model of amyotrophic lateral sclerosis (ALS) is the most frequently used model to examine ALS pathophysiology. There is a lack of homogeneity in usage of the SOD1 G93A mouse, including differences in genetic background and gender, which could confound the field’s results.

Objective: In an analysis of 97 studies, we characterized the ALS progression for the high transgene copy control SOD1 G93A mouse on the basis of disease onset, overall lifespan, and disease duration for male and female mice on the B6SJL and C57BL/6J genetic backgrounds and quantified magnitudes of differences between groups.

Methods: Mean age at onset, onset assessment measure, disease duration, and overall lifespan data from each study were extracted and statistically modeled as the response of linear regression with the sex and genetic background factored as predictors. Additional examination was performed on differing experimental onset and endpoint assessment measures.

Results: C57BL/6 background mice show delayed onset of symptoms, increased lifespan, and an extended disease duration compared to their sex-matched B6SJL counterparts. Female B6SJL generally experience extended lifespan and delayed onset compared to their male counterparts, while female mice on the C57BL/6 background show delayed onset but no difference in survival compared to their male counterparts. Finally, different experimental protocols (tremor, rotarod, etc.) for onset determination result in notably different onset means.

Conclusions: Overall, the observed effect of sex on disease endpoints was smaller than that which can be attributed to the genetic background. The often-reported increase in lifespan for female mice was observed only for mice on the B6SJL background, implicating a strain-dependent effect of sex on disease progression that manifests despite identical mutant SOD1 expression.

Potential therapeutic drugs and methods for the treatment of amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder caused by damage of motoneurons leading to paralysis state and long term disability. Riluzole is currently the only FDA-approved drug for the treatment of ALS. The proposed mechanisms of ALS include glutamate excitotoxicity, oxidative stress, mitochondrial dysfunction, protein aggregation, SOD1 accumulations, and neuronal death. In this review, we discuss potential biomarkers for the identification of patients with ALS. We further emphasize potential therapy involving the uses of neurotrophic factors such as IGFI, GDNF, VEGF, ADNF-9, colivelin and angiogenin in the treatment of ALS. Moreover, we described several existing drugs such as talampanel, ceftriaxone, pramipexole, dexpramipexole and arimoclomol potential compounds for the treatment of ALS. Interestingly, the uses of stem cell therapy and immunotherapy are promising for the treatment of ALS.

Aerobic fitness and body mass index in individuals with schizophrenia: Implications for neurocognition and daily functioning

Previous reports indicate that among healthy individuals low aerobic fitness (AF) and high body-mass index (BMI) predict poor neurocognition and daily-functioning. It is unknown whether these associations extend to disorders characterized by poor neurocognition, such as schizophrenia. Therefore, we compared AF and BMI in individuals with schizophrenia and non-clinical controls, and then within the schizophrenia group we examined the links between AF, BMI, neurocognition and daily-functioning. Thirty-two individuals with schizophrenia and 64 gender- and age-matched controls completed assessments of AF (indexed by VO2max) and BMI. The former also completed measures of neurocognition, daily-functioning and physical activity. The schizophrenia group displayed significantly lower AF and higher BMI. In the schizophrenia group, AF was significantly correlated with overall neurocognition (r=0.57), along with executive functioning, working memory, social cognition, and processing speed. A hierarchical regression analysis indicated that AF accounted for 22% of the neurocognition variance. Furthermore, AF was significantly correlated with overall daily-functioning (r=0.46). In contrast, BMI displayed significant inverse correlations with neurocognition, but no associations to daily-functioning. AF was significantly correlated physical activity. The authors discuss the potential use of AF-enhancing interventions to improve neurocognitive and daily-functioning in schizophrenia, along with putative neurobiological mechanisms underlying these links, including Brain-Derived Neurotrophic Factor.

ALS-related misfolded protein management in motor neurons and muscle cells

Amyotrophic Lateral Sclerosis (ALS) is the most common form of adult-onset motor neuron disease. It is now considered a multi-factorial and multi-systemic disorder in which alterations of the crosstalk between neuronal and non-neuronal cell types might influence the course of the disease. In this review, we will provide evidence that dysfunctions of affected muscle cells are not only a marginal consequence of denervation associated to motor neurons loss, but a direct consequence of cell muscle toxicity of mutant SOD1. In muscle, the misfolded state of mutant SOD1 protein, unlike in motor neurons, does not appear to have direct effects on protein aggregation and mitochondrial functionality. Muscle cells are, in fact, more capable than motor neurons to handle misfolded proteins, suggesting that mutant SOD1 toxicity in muscle is not mediated by classical mechanisms of intracellular misfolded proteins accumulation. Several recent works indicate that a higher activation of molecular chaperones and degradative systems is present in muscle cells, which for this reason are possibly able to better manage misfolded mutant SOD1. However, several alterations in gene expression and regenerative potential of skeletal muscles have also been reported as a consequence of the expression of mutant SOD1 in muscle. Whether these changes in muscle cells are causative of ALS or a consequence of motor neuron alterations is not yet clear, but their elucidation is very important, since the understanding of the mechanisms involved in mutant SOD1 toxicity in muscle may facilitate the design of treatments directed toward this specific tissue to treat ALS or at least to delay disease progression.

Breathing new life into treatment advances for respiratory failure in amyotrophic lateral sclerosis patients

SUMMARY In the last three decades, improvements in respiratory management are responsible for increasing survival and improving quality of life for amyotrophic lateral sclerosis (ALS) patients. Nowadays, ALS patients with respiratory involvement are offered a support treatment other than the traditional respiratory palliative care. Knowledge about available respiratory support potentialities is essential for appropriate, customized and effective treatment of ALS, which should probably be started sooner than the conventional approach. There is evidence supporting that respiratory support has a larger impact than riluzole on survival. Noninvasive ventilation is essential in the treatment of ALS patients with respiratory involvement. In this article methods to determine respiratory failure in ALS, mechanical invasive and noninvasive ventilation, telemetry, diaphragm pacing, cough aids and respiratory exercise are reviewed, after a brief overlook of respiratory insufficiency in ALS.

More than a bystander: the contributions of intrinsic skeletal muscle defects in motor neuron diseases

Spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and spinal-bulbar muscular atrophy (SBMA) are devastating diseases characterized by the degeneration of motor neurons. Although the molecular causes underlying these diseases differ, recent findings have highlighted the contribution of intrinsic skeletal muscle defects in motor neuron diseases. The use of cell culture and animal models has led to the important finding that muscle defects occur prior to and independently of motor neuron degeneration in motor neuron diseases. In SMA for instance, the muscle specific requirements of the SMA disease-causing gene have been demonstrated by a series of genetic rescue experiments in SMA models. Conditional ALS mouse models expressing a muscle specific mutant SOD1 gene develop atrophy and muscle degeneration in the absence of motor neuron pathology. Treating SBMA mice by over-expressing IGF-1 in a skeletal muscle-specific manner attenuates disease severity and improves motor neuron pathology. In the present review, we provide an in depth description of muscle intrinsic defects, and discuss how they impact muscle function in these diseases. Furthermore, we discuss muscle-specific therapeutic strategies used to treat animal models of SMA, ALS, and SBMA. The study of intrinsic skeletal muscle defects is crucial for the understanding of the pathophysiology of these diseases and will open new therapeutic options for the treatment of motor neuron diseases.