Search Results (17)

Background: Spasticity is a common and disabling symptom of multiple sclerosis (MS), yet its assessment remains challenging. Clinical scales such as the Ashworth Scale (AS) evaluate resistance to passive movement, whereas neurophysiological measures (e.g., H-reflex, F-wave) provide objective indices of α-motoneuron excitability but correlate inconsistently with clinical severity. Real-time ultrasound elastography (RTE) enables semi-quantitative, in vivo assessment of muscle stiffness, while the recently introduced Muscle Elastography Multiple Sclerosis Score (MEMSs) aims to classify muscle spasticity in MS. Objective: To evaluate the utility of RTE using MEMSs for the objective assessment of muscle status in MS patients with spasticity, and to compare elastographic findings with clinical and neurophysiological measures. Methods: In this single-center study, 26 MS patients (diagnosed according to the 2017 McDonald criteria) and age- and sex-matched healthy controls (n = 27) were enrolled. Spasticity was graded using the AS. All participants underwent bilateral RTE of the gastrocnemius muscle, with images independently scored by two blinded neurologists using the 5-point MEMSs scale. Neurophysiological assessment included the soleus H-reflex, with calculation of H/M ratios. Correlations were analyzed using Pearson’s coefficient, and inter-observer reliability was assessed. Results: No consistent or statistically robust associations were found between clinical spasticity severity (AS scores) and either neurophysiological or elastographic parameters. Several MEMSs did not correlate reliably with AS grades, and neurophysiological measures showed limited discriminatory ability between MS patients and healthy controls. Correlations between neurophysiological and elastography parameters were weak to moderate (ρ ranging from −0.49 to 0.45). Inter-observer reliability of MEMSs scoring ranged from poor to moderate across the examined muscle groups, with Cohen’s κ values ranging from −0.02 to 0.54. Conclusions: RTE using MEMSs did not demonstrate sufficient validity or reproducibility for assessing muscle spasticity in MS, showing poor agreement with both clinical and neurophysiological measures. Full article

Parkinson’s disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, and key pathways such as neuroinflammation, oxidative stress, and autophagy are believed to significantly contribute to the mechanisms of neurodegeneration. Calpain activation plays a critical role in neuroinflammation and neurodegeneration, as demonstrated by its impact on microglial activation, reactive oxygen species (ROS) production, and neuronal survival. In this study, we investigated the effects of calpain inhibition using calpeptin (CP) and calpain-2-specific inhibitors in cellular and murine models of neuroinflammation and PD. In BV2 microglial cells, LPS-induced production of pro-inflammatory cytokines (TNF-α, IL-6) and chemokines (MCP-1, IP-10) were significantly reduced by CP treatment with a concomitant decrease in ROS generation. Similarly, in VSC-4.1 motoneuron cells, calpain inhibition attenuated IFN-γ-induced ROS production and improved cell viability, demonstrating its neuroprotective effects. Moreover, in a murine MPTP model of PD, calpain inhibition reduced astrogliosis, ROCK2 expression, and levels of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-7, and IL12p70) and chemokines (MCP-1 and IP-10) in the dorsal striatum and plasma. The specific role of calpain-2 in immune modulation was further highlighted in human microglia, SV-40 cells. With respect to immune modulation in these cells, siRNA-mediated knockdown of calpain-2, but not calpain-1, significantly reduced antigen presentation to CD4+ T cells. Thus, calpain-2 is likely involved in regulating antigen presentation and activation of inflammatory CD4+ T cells. These findings underscore the therapeutic potential of calpain-2 inhibition in mitigating neuroinflammation and neurodegeneration, particularly in PD, by targeting microglial activation, ROS production, and neuronal survival pathways. Full article

The muscle contraction during voluntary movement is controlled by activities of alpha- and gamma-motoneurons (αMNs and γMNs, respectively). In spite of the recent advances in research on molecular markers that can distinguish between αMNs and γMNs, electrophysiological membrane properties and firing patterns of γMNs have remained unknown, while those of αMNs have been clarified in detail. Because of the larger size of αMNs compared to γMNs, blindly or even visually recorded MNs were mostly αMNs, as demonstrated with molecular markers recently. Subsequently, the research on αMNs has made great progress in classifying their subtypes based on the molecular markers and electrophysiological membrane properties, whereas only a few studies demonstrated the electrophysiological membrane properties of γMNs. In this review article, we provide an overview of the recent advances in research on the classification of αMNs and γMNs based on molecular markers and electrophysiological membrane properties, and discuss their functional implication and significance in motor control. Full article

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a fatal childhood motoneuron disease caused by mutations in the IGHMBP2 gene. It is characterized by muscle weakness, initially affecting the distal extremities due to the degeneration of spinal α-motoneurons, and respiratory distress, due to the paralysis of the diaphragm. Infantile forms with a severe course of the disease can be distinguished from juvenile forms with a milder course. Mutations in the IGHMBP2 gene have also been found in patients with peripheral neuropathy Charcot–Marie–Tooth type 2S (CMT2S). IGHMBP2 is an ATP-dependent 5′→3′ RNA helicase thought to be involved in translational mechanisms. In recent years, several animal models representing both SMARD1 forms and CMT2S have been generated to initially study disease mechanisms. Later, the models showed very well that both stem cell therapies and the delivery of the human IGHMBP2 cDNA by AAV9 approaches (AAV9-IGHMBP2) can lead to significant improvements in disease symptoms. Therefore, the SMARD1 animal models, in addition to the cellular models, provide an inexhaustible source for obtaining knowledge of disease mechanisms, disease progression at the cellular level, and deeper insights into the development of therapies against SMARD1. Full article

The importance of spinal reflexes is connected to the rehabilitation processes in neural prostheses and to the neuromuscular junction. In order to model neuron networks as electronic circuits, a simulation environment like LTSpice XVII or PSpice can be used to create a complete electronic description. There are four types of neurons employed in spinal reflexes: α-motoneurons, sensitive neurons, excitatory interneurons, and inhibitory interneurons. Many proposals have been made regarding methods that can be used for assimilating neurons using electronic circuits. In this paper, only a single internal model of a neuron is considered enough to simulate all four types of neurons implicated in the control loops. The main contribution of this paper is to propose the modeling of neurons using some electronic circuits designed either with a bipolar transistor or with CMOS transistors for the input and output of circuits stages. In this way, it is possible to mimic the neural pulses’ circulation along the loops of the spinal reflexes and to prove the accuracy of the simulation results with respect to the biological signals collected from the bibliographic materials. Full article

The interaction of the activating transcription factor 6 (ATF6), a key effector of the unfolded protein response (UPR) in the endoplasmic reticulum, with the neuronal calcium sensor Downstream Regulatory Element Antagonist Modulator (DREAM) is a potential therapeutic target in neurodegeneration. Modulation of the ATF6–DREAM interaction with repaglinide (RP) induced neuroprotection in a model of Huntington’s disease. Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder with no cure, characterized by the progressive loss of motoneurons resulting in muscle denervation, atrophy, paralysis, and death. The aim of this work was to investigate the potential therapeutic significance of DREAM as a target for intervention in ALS. We found that the expression of the DREAM protein was reduced in the spinal cord of SOD1G93A mice compared to wild-type littermates. RP treatment improved motor strength and reduced the expression of the ALS progression marker collagen type XIXα1 (Col19α1 mRNA) in the quadriceps muscle in SOD1G93A mice. Moreover, treated SOD1G93A mice showed reduced motoneuron loss and glial activation and increased ATF6 processing in the spinal cord. These results indicate that the modulation of the DREAM–ATF6 interaction ameliorates ALS symptoms in SOD1G93A mice. Full article

Liposomes modified with tetradecyltriphenylphosphonium bromide with dual loading of α-tocopherol and donepezil hydrochloride were successfully designed for intranasal administration. Physicochemical characteristics of cationic liposomes such as the hydrodynamic diameter, zeta potential, and polydispersity index were within the range from 105 to 115 nm, from +10 to +23 mV, and from 0.1 to 0.2, respectively. In vitro release curves of donepezil hydrochloride were analyzed using the Korsmeyer–Peppas, Higuchi, First-Order, and Zero-Order kinetic models. Nanocontainers modified with cationic surfactant statistically better penetrate into the mitochondria of rat motoneurons. Imaging of rat brain slices revealed the penetration of nanocarriers into the brain. Experiments on transgenic mice with an Alzheimer’s disease model (APP/PS1) demonstrated that the intranasal administration of liposomes within 21 days resulted in enhanced learning abilities and a reduction in the formation rate of Aβ plaques in the entorhinal cortex and hippocampus of the brain. Full article

Fast Blue (FB) and Cholera Toxin-B (CTB) are two retrograde tracers extensively used to label alpha-motoneurons (α-MNs). The overall goals of the present study were to (1) assess the effectiveness of different FB and CTB protocols in labeling α-MNs, (2) compare the labeling quality of these tracers at standard concentrations reported in the literature (FB 2% and CTB 0.1%) versus lower concentrations to overcome tracer leakage, and (3) determine an optimal protocol for labeling α-MNs in young B6SJL and aged C57Bl/J mice (when axonal transport is disrupted by aging). Hindlimb muscles of young B6SJL and aged C57Bl/J mice were intramuscularly injected with different FB or CTB concentrations and then euthanized at either 3 or 5 days after injection. Measurements were performed to assess labeling quality via seven different parameters. Our results show that tracer protocols of lower concentration and shorter labeling durations were generally better in labeling young α-MNs, whereas tracer protocols of higher tracer concentration and longer labeling durations were generally better in labeling aged α-MNs. A 0.2%, 3-day FB protocol provided optimal labeling of young α-MNs without tracer leakage, whereas a 2%, 5-day FB protocol or 0.1% CTB protocol provided optimal labeling of aged α-MNs. These results inform future studies on the selection of optimal FB and CTB protocols for α-MNs labeling in normal, aging, and neurodegenerative disease conditions. Full article

Spasticity impacts the quality of life of patients suffering spinal cord injury and impedes the recovery of locomotion. At the cellular level, spasticity is considered to be primarily caused by the hyperexcitability of spinal α-motoneurons (MNs) within the spinal stretch reflex circuit. Here, we hypothesized that after a complete spinal cord transection in rats, fast adaptive molecular responses of lumbar MNs develop in return for the loss of inputs. We assumed that early loss of glutamatergic afferents changes the expression of glutamatergic AMPA and NMDA receptor subunits, which may be the forerunners of the developing spasticity of hindlimb muscles. To better understand its molecular underpinnings, concomitant expression of GABA and Glycinergic receptors and serotoninergic and noradrenergic receptors, which regulate the persistent inward currents crucial for sustained discharges in MNs, were examined together with voltage-gated ion channels and cation-chloride cotransporters. Using quantitative real-time PCR, we showed in the tracer-identified MNs innervating extensor and flexor muscles of the ankle joint multiple increases in transcripts coding for AMPAR and 5-HTR subunits, along with a profound decrease in GABA_AR, GlyR subunits, and KCC2. Our study demonstrated that both MNs groups similarly adapt to a more excitable state, which may increase the occurrence of extensor and flexor muscle spasms. Full article

Mice with transgenic expression of human SOD1^G93A are a widely used model of ALS, with a caudal–rostral progression of motor impairment. Previous studies have quantified the progression of motoneuron (MN) degeneration based on size, even though alpha (α-) and gamma (γ-) MNs overlap in size. Therefore, using molecular markers and synaptic inputs, we quantified the survival of α-MNs and γ-MNs at the lumbar and cervical spinal segments of 3- and 4-month SOD1^G93A mice, to investigate whether there is a caudal–rostral progression of MN death. By 3 months, in the cervical and lumbar spinal cord, there was α-MN degeneration with complete γ-MN sparing. At 3 months, the cervical spinal cord had more α-MNs per ventral horn than the lumbar spinal cord in SOD1^G93A mice. A similar spatial trend of degeneration was observed in the corticospinal tract, which remained intact in the cervical spinal cord at 3- and 4- months of age. These findings agree with the corticofugal synaptopathy model that α-MNs and CST of the lumbar spinal cord are more susceptible to degeneration in SOD1^G93A mice. Hence, there is a spatial and temporal caudal–rostral progression of α-MN and CST degeneration in SOD1^G93A mice. Full article

The peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a well-known transcriptional coactivator involved in mitochondrial biogenesis. PGC-1α is implicated in the pathophysiology of many neurodegenerative disorders; therefore, a deep understanding of its functioning in the nervous system may lead to the development of new therapeutic strategies. The central nervous system (CNS)-specific isoforms of PGC-1α have been recently identified, and many functions of PGC-1α are assigned to the particular cell types of the central nervous system. In the mice CNS, deficiency of PGC-1α disturbed viability and functioning of interneurons and dopaminergic neurons, followed by alterations in inhibitory signaling and behavioral dysfunction. Furthermore, in the ALS rodent model, PGC-1α protects upper motoneurons from neurodegeneration. PGC-1α is engaged in the generation of neuromuscular junctions by lower motoneurons, protection of photoreceptors, and reduction in oxidative stress in sensory neurons. Furthermore, in the glial cells, PGC-1α is essential for the maturation and proliferation of astrocytes, myelination by oligodendrocytes, and mitophagy and autophagy of microglia. PGC-1α is also necessary for synaptogenesis in the developing brain and the generation and maintenance of synapses in postnatal life. This review provides an outlook of recent studies on the role of PGC-1α in various cells in the central nervous system. Full article

Epidural electrical stimulation (ES) of the lumbar spinal cord combined with daily locomotor training has been demonstrated to enhance stepping ability after complete spinal transection in rodents and clinically complete spinal injuries in humans. Although functional gain is observed, plasticity mechanisms associated with such recovery remain mostly unclear. Here, we investigated how ES and locomotor training affected expression of chondroitin sulfate proteoglycans (CSPG), perineuronal nets (PNN), and synaptic plasticity on spinal motoneurons. To test this, adult rats received a complete spinal transection (T9–T10) followed by daily locomotor training performed under ES with administration of quipazine (a serotonin (5-HT) agonist) starting 7 days post-injury (dpi). Excitatory and inhibitory synaptic changes were examined at 7, 21, and 67 dpi in addition to PNN and CSPG expression. The total amount of CSPG expression significantly increased with time after injury, with no effect of training. An interesting finding was that γ-motoneurons did not express PNNs, whereas α-motoneurons demonstrated well-defined PNNs. This remarkable difference is reflected in the greater extent of synaptic changes observed in γ-motoneurons compared to α-motoneurons. A medium negative correlation between CSPG expression and changes in putative synapses around α-motoneurons was found, but no correlation was identified for γ-motoneurons. These results suggest that modulation of γ-motoneuron activity is an important mechanism associated with functional recovery induced by locomotor training under ES after a complete spinal transection. Full article

The neurosteroid allopregnanolone (ALLO) causes unconsciousness by allosteric modulation of γ-aminobutyric acid type A (GABA_A) receptors, but its actions on the spinal motor networks are unknown. We are therefore testing the hypothesis that ALLO attenuates the action potential firing of spinal interneurons and motoneurons predominantly via enhancing tonic, but not synaptic GABAergic inhibition. We used video microscopy to assess motoneuron-evoked muscle activity in organotypic slice cultures prepared from the spinal cord and muscle tissue. Furthermore, we monitored GABA_A receptor-mediated currents by performing whole-cell voltage-clamp recordings. We found that ALLO (100 nM) reduced the action potential firing of spinal interneurons by 27% and that of α-motoneurons by 33%. The inhibitory effects of the combination of propofol (1 µM) and ALLO on motoneuron-induced muscle contractions were additive. Moreover, ALLO evoked a tonic, GABA_A receptor-mediated current (amplitude: 41 pA), without increasing phasic GABAergic transmission. Since we previously showed that at a clinically relevant concentration of 1 µM propofol enhanced phasic, but not tonic GABAergic inhibition, we conclude that ALLO and propofol target distinct subpopulations of GABA_A receptors. These findings provide first evidence that the combined application of ALLO and propofol may help to reduce intraoperative movements and undesired side effects that are frequently observed under total intravenous anesthesia. Full article

Background and Objectives: Neuroinflammation is associated with many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). In this study, we investigate the anti-inflammatory, anti-oxidant, and anti-apoptotic properties of two non-psychoactive phytocannabinoids, cannabigerol (CBG) and cannabidiol (CBD). Materials and Methods: The motoneuron-like cell line NSC-34 differentiated by serum deprivation and with the additional treatment of all-trans retinoic acid (RA) is a valid model to investigate molecular events linked to neurodegeneration in ALS. Results: Pre-treatment with CBG (at 2.5 and 5 µM doses) alone and in combination with CBD (at 2.5 and 5 µM doses) was able to reduce neuroinflammation induced by a culture medium of LPS-stimulated macrophages. In particular, the pre-treatment with CBD at a 5 µM dose decreased TNF-α levels and increased IL10 and IL-37 expression. CBG–CBD association at a 5 µM dose also reduced NF-kB nuclear factor activation with low degradation of the inhibitor of kappaB alpha (IkBα). CBG and CBD co-administered at a 5 µM dose decreased iNOS expression and increased Nrf2 levels. Furthermore, the pre-treatment with the association of two non-psychoactive cannabinoids downregulated Bax protein expression and upregulated Bcl-2 expression. Our data show the anti-inflammatory, anti-oxidant, and anti-apoptotic effects PPARγ-mediated. Conclusions: Our results provide preliminary support on the potential therapeutic application of a CBG–CBD combination for further preclinical studies. Full article

Complete restoring of functional connectivity between neurons or target tissue after traumatic lesions is still an unmet medical need. Using models of nerve axotomy and compression, we investigated the effect of autophagy induction by genetic and pharmacological manipulation on motor nerve regeneration. ATG5 or NAD⁺-dependent deacetylase sirtuin-1 (SIRT1) overexpression on spinal motoneurons stimulates mTOR-independent autophagy and facilitates a growth-competent state improving motor axonal regeneration with better electromyographic records after nerve transection and suture. In agreement with this, using organotypic spinal cord cultures and the human cell line SH-SY5Y, we observed that the activation of SIRT1 and autophagy by NeuroHeal increased neurite outgrowth and length extension and that this was mediated by downstream HIF1a. To conclude, SIRT1/Hifα-dependent autophagy confers a more pro-regenerative phenotype to motoneurons after peripheral nerve injury. Altogether, we provide evidence showing that autophagy induction by SIRT1/Hifα activation or NeuroHeal treatment is a novel therapeutic option for improving motor nerve regeneration and functional recovery after injury. Full article