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PubMed1994

Identification and characterization of pleural neurons that inhibit tail sensory neurons and motor neurons in Aplysia: correlation with FMRFamide immunoreactivity.

Neurons on the rostral edge of the ventral surface of the right pleural ganglion were identified as elements of the circuit mediating the defensive tail withdrawal reflex of Aplysia. These neurons produced IPSPs in tail sensory neurons and were classified into two groups, RPI4 and RPI5, according to their affinity for an antibody directed against FMRFamide. RPI4 was not FMRFamide immunoreactive, and RPI5 was. RPI4 and RPI5 were found to have different electrophysiological profiles. The summated IPSPs in sensory neurons produced by RPI4 developed more rapidly and had a shorter duration than those produced by RPI5. In addition, RPI4 produced IPSPs in the tail motor neurons, whereas RPI5 did not. Both RPI4 and RPI5 received excitatory synaptic inputs from stimulation of the pleural-abdominal connective as well as peripheral nerves P8 and P9, which innervate the tail and posterior part of the animal's body. These inputs were sufficient to elicit spikes. In RPI4, the excitatory synaptic inputs were followed by short and transient hyperpolarization, whereas in RPI5, the excitatory synaptic inputs were followed by slow and long-lasting hyperpolarization. Excitatory inputs elicited in RPI4 by stimulation of peripheral nerves appeared to be mediated, at least in part, by activation of tail sensory neurons. Intracellular stimulation of sensory neurons produced EPSPs in RPI4 that appeared to be monosynaptic. These results suggest that inhibitory interneurons underlying the circuit of the tail withdrawal reflex may play roles in mediating or modulating neuronal responses to tail stimulation. By inhibiting tail sensory and motor neurons, these interneurons may reduce the effectiveness of an animal's response to stimulation of the tail.

Animals↗
PubMed1990

Ultrastructure of swollen proximal axons of anterior horn neurons in motor neuron disease.

We have investigated ultrastructurally swellings of the proximal axons directly connected with the somata of anterior horn cells in a patient with motor neuron disease. In the distal portion of the initial segment, the swellings consisted predominantly of increased amounts of neurofilaments running nearly parallel to the longitudinal axis together with other cytoplasmic organelles. In the first internode of the myelinated axon, as the swellings became larger, the neurofilaments lost their parallel orientation and became intermingled. Most of the cell bodies connected with the swellings and their dendrites showed no particular changes. The abnormal neurofilamentous accumulations in the proximal axons suggest abnormal axonal transport, which may be pathogenetically associated with motor neuron disease.

Aged↗
PubMed1985

Auditory responses in avian vocal motor neurons: a motor theory for song perception in birds.

The hypoglossal motor neurons that innervate the vocal organ (syrinx) of the male zebra finch show a selective, long-latency (50-millisecond) response to sound. This response is eliminated by lesions to forebrain song-control nuclei. Different song syllables elicit a response from different syringeal motor neurons. Conspecific vocalizations may therefore be perceived as members of a set of vocal gestures and thus distinct from other environmental sounds. This hypothesis is an avian parallel to the motor theory of speech perception in humans.

Animals↗
PubMed1988

A filamentous inclusion body within anterior horn neurones in motor neurone disease defined by immunocytochemical localisation of ubiquitin.

Using an immunocytochemical method to localise antibodies to ubiquitin, filamentous inclusion bodies were seen in spinal anterior horn neurones in cases of motor neurone disease (MND) but not in any control cases. These inclusion bodies appeared to be closely associated with classical Bunina bodies and immuno-electron microscopy suggested that they were based on arrays of straight 10-15 nm filaments together with some granular material. These observations link the protein ubiquitin with a chronic neurodegenerative disease and extend previous observations of a close association between filamentous inclusion bodies and ubiquitin. Ubiquitin-filament inclusions should be regarded as a new hallmark in the histological diagnosis of MND.

Adult↗
PubMed2006

Concurrent administration of Neu2000 and lithium produces marked improvement of motor neuron survival, motor function, and mortality in a mouse model of amyotrophic lateral sclerosis.

The Fas pathway and oxidative stress mediate neuronal death in stroke and may contribute to neurodegenerative disease. We tested the hypothesis that these two factors synergistically produce spinal motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Levels of reactive oxygen species were increased in motor neurons from ALS mice compared with wild-type mice at age 10 weeks, before symptom onset. The proapoptotic proteins Fas, Fas-associated death domain, caspase 8, and caspase 3 were also elevated. Oral administration of 2-hydroxy-5-(2,3,5,6-tetrafluoro-4-trifluoromethyl-benzylamino)-benzoic acid (Neu2000), a potent antioxidant, blocked the increase in reactive oxygen species but only slightly reduced activation of proapoptotic proteins. Administration of lithium carbonate (Li(+)), a mood stabilizer that prevents apoptosis, blocked the apoptosis machinery without preventing oxidative stress. Neu2000 or Li(+) alone significantly enhanced survival time and motor function and together had an additive effect. These findings provide evidence that jointly targeting oxidative stress and Fas-mediated apoptosis can prevent neuronal loss and motor dysfunction in ALS.

Amyotrophic Lateral Sclerosis↗
PubMed2001

A comparison of bowel care patterns in patients with spinal cord injury: upper motor neuron bowel vs lower motor neuron bowel.

STUDY DESIGN: A face-to-face interview survey. OBJECTIVE: To compare bowel care patterns in spinal cord injury (SCI) patients based on type of neurogenic bowel. SETTING: Department of Physical Medicine and Rehabilitation of a tertiary university hospital in Suwon, Korea. METHODS: Among chronic SCI patients, 22 patients with upper motor neuron bowel (UMNB) and 20 patients with lower motor neuron bowel (LMNB) participated in an interview survey for the evaluation of bowel care patterns. RESULTS: The patients with LMNB demonstrated increased frequency of defecation, increased frequency of fecal incontinence, increased use of oral medications for bowel care, increased required time for defecation and more diet modification than those with UMNB (P < 0.05). However, there was no significant difference in the subjective difficulty of bowel care. Among several available bowel care methods, suppositories were used most frequently by the UMNB group, whereas the Valsalva maneuver was the most frequently used method by the LMNB group. CONCLUSIONS: Patients with LMNB tend to suffer more difficulties in management of their neurogenic bowel than those with UMNB. Therefore, more intensive and aggressive bowel care programs should be provided for SCI patients with LMNB.

Activities of Daily Living↗
PubMed2002

Reduced neuronal nitric oxide synthase (NOS1) antigen in sacral motor neurones in motor neurone disease.

Immunocytochemistry and microdensitometry applied under standardised conditions were used to evaluate neuronal nitric oxide synthase (NOS1) antigen in segmental motor neurones (MN) of six subjects without neurological disease, nine subjects with sporadic motor neurone disease (MND) and five with neurological disease unrelated to MND. No significant segmental differences in levels of NOS1 immunoreactivity occurred between the two control groups, and differences between cervical, thoracic and lumbar MN of the three subject groups were not significant. However, MND patients showed a significantly reduced level of NOS1 immunoreactivity in the Onuf's nucleus (ON); this is discussed in relation to neuroprotection and the relative sparing of ON in MND.

Adolescent↗
PubMed1998

Quantitative assessment of motor neuron loss in equine motor neuron disease (EMND).

The mean number of motor neurons was assessed in the C7 spinal cord segment of 5 EMND and 5 control horses. Mean number per section in EMND horses was reduced significantly (P<0.001). The mean neuronal loss was estimated at 31%. Each of the 5 affected horses had a mean neuronal count below the 95% confidence interval for control horses. The statistically significant difference between the 2 groups was consistent in the cranial, middle and caudal thirds of the C7 segment (P<0.001). The results of regression analysis indicated an association between neuronal reduction in EMND horses and the duration of the disease when adjusted for age (P<0.001). This is the first quantitation of the neurodegenerative loss in EMND and it provides a clearer explanation for residual deficits in horses that survive EMND.

Animals↗
PubMed1994

Detection of cortical neuron loss in motor neuron disease by proton magnetic resonance spectroscopic imaging in vivo.

We performed proton magnetic resonance spectroscopic imaging (1H-MRSI) in patients with motor neuron disease (MND) to evaluate the distribution and extent of cortical neuron damage or loss as reflected by decreased N-acetyl (NA) to creatine (Cr) resonance intensity ratios. We examined premotor (superior frontal gyrus), primary motor (precentral gyrus), primary sensory (postcentral gyrus), and parietal (superior parietal gyrus/precuneus) neocortical regions of 12 patients with MND and six normal control subjects. Patients with MND were representative of three syndromes: amyotrophic lateral sclerosis (ALS) with definite lower motor neuron and upper motor neuron signs, MND with probable upper motor neuron signs (PUMNS), and progressive spinal muscular atrophy (PSMA) with lower motor neuron signs only. Compared with healthy controls, ALS patients had a significant decrease in NA/Cr resonance intensity ratios, most prominently in the primary motor cortex (p < 0.001) but also, to varying degrees, in primary sensory (p < 0.01), posterior premotor, and parietal (p < 0.05) regions. Patients classified as ALS-PUMNS showed less prominent reduction in NA/Cr ratios in the same regions; patients with PSMA had normal cortical NA/Cr ratios. Sequential studies in one patient suggested that 1H-MRSI could document progression of the NA/Cr abnormality. Decreased NA/Cr ratios on 1H-MRSI provide an index of cortical motor neuron loss and/or dysfunction in MND patients. Clinical applications of 1H-MRSI could include documenting the extent of upper motor neuron involvement, aiding diagnosis of syndromes presenting with an ALS-like picture, and monitoring disease progression.

Adult↗
PubMed2003

Pathological involvement of the motor neuron system and hippocampal formation in motor neuron disease-inclusion dementia.

We report two patients with motor neuron disease-inclusion dementia, with special reference to the pathology of the motor neuron system and hippocampal formation. The ages of the patients at death were 55 and 62 years, and the disease durations were 8 and 3 years, respectively. The two patients exhibited progressive frontotemporal dementia in the absence of motor neuron signs. At autopsy, both cases exhibited frontotemporal lobar atrophy with ubiquitin-positive, and tau- and alpha-synuclein-negative neuronal inclusions. As expected from the clinical signs, in both cases, the upper and lower motor neuron systems were well preserved: no Bunina bodies or ubiquitinated inclusions were detected in the motor neurons. However, of great importance was that when visualized immunohistochemically, the Golgi apparatus and trans-Golgi network often exhibited fragmentation in the lower motor neurons (the spinal anterior horn cells). In one of the cases, a decrease in the amount of Golgi apparatus was also a frequent feature in the upper motor neurons (Betz cells in the motor cortex). Moreover, in both cases, circumscribed degeneration affecting the CA1-subiculum border zone was evident in the hippocampal formation. These findings further strengthen the idea that, pathologically, motor neuron disease-inclusion dementia is a rare phenotype of amyotrophic lateral sclerosis.

Crystallins↗
PubMed2006

Neuronal-specific roles of the survival motor neuron protein: evidence from survival motor neuron expression patterns in the developing human central nervous system.

Despite recent data on the cellular function of the survival motor neuron (SMN) gene, the spinal muscular atrophy (SMA) disease gene, the role of the SMN protein in motor neurons and hence in the pathogenesis of SMA is still unclear. The spatial and temporal expression of SMN in neurons, particularly during development, could help in verifying the hypotheses on the SMN protein functions so far proposed. We have therefore investigated the expression and subcellular localization of the SMN protein in the human central nervous system (CNS) during ontogenesis with immunocytochemical, confocal immunofluorescence, and Western blot experiments using a panel of anti-SMN antibodies recognizing the full-length SMN protein. The experiments not only revealed the early SMN expression in all neurons, but also demonstrated the progressive shift in SMN subcellular localization from mainly nuclear to cytoplasmic and then to axons during CNS maturation. This finding was present in selected neuronal cell populations and it was particularly conspicuous in motor neurons. Our data support the idea of a specific role for SMN in axons, which becomes predominant in the ontogenetic period encompassing axonogenesis and axonal sprouting. In addition, the asymmetric SMN staining demonstrated in the germinative neuroepithelium suggests a possible role for SMN in neuronal migration and/or differentiation.

Adult↗
PubMed1999

Classification and clinical features of motor neurone diseases and motor neuropathies in adults.

The term motor neurone disease encompasses combined upper and lower motor neurone disorders (amyotrophic lateral sclerosis), pure lower motor neurone disorders (spinal muscular atrophies, multifocal motor neuropathies, post irradiation lumbosacral radiculopathy, post-polio syndrome, hereditary bulbar palsy) and pure upper motor neurone disorders (primary lateral sclerosis, hereditary spastic paraplegia, neurolathyrism, Konzo). The chief clinical and electrophysiological criteria for these different disorders are discussed, with particular attention to diagnostically distinctive characteristics of each. Age of onset, and inheritance are considered as additional diagnostic features.

Adult↗
PubMed2006

Loss of nitric oxide-mediated down-regulation of NMDA receptors in neurofilament aggregate-bearing motor neurons in vitro: implications for motor neuron disease.

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disorder in which excitotoxicity has been implicated as a cause for cell death. To examine neurofilament (NF) aggregate-mediated sensitization of motor neurons to NMDA excitotoxicity, we examined NMDA receptor expression and the impact of NO donors (NOC12 or NOC5) or sodium cyanide (NaCN) on calcium influx and viability in dissociated motor neurons derived from wt and hNFL+/+ (NF aggregate-forming) mice. Alterations in intracellular calcium were assayed using Oregon Green calcium dye and the extent of apoptosis using active caspase-3 immunoreactivity. Although NF aggregate-bearing neurons demonstrated increased intracellular calcium levels and enhanced cell death in response to NMDA receptor activation, this was not associated with increased NMDA receptor expression. The down-regulation of the NMDA receptor using NO donors decreased calcium influx and caspase-3 activation in aggregate-bearing neurons, but had no effect on wt cultures. The converse was observed with NaCN in which intracellular calcium levels increased significantly in wt cultures in association with increased cell death. No effect was observed in aggregate-bearing neurons. These findings suggest that the presence of NF aggregates renders motor neurons more susceptible to NMDA-mediated excitotoxicity, and that this can be reversed by NO.

Animals↗
PubMed1996

Synaptic loss in anterior horn neurons in lower motor neuron disease.

This report concerns an ultrastructural investigation of the synapses of anterior horn neurons in the lumbar spinal cord of four patients with lower motor neuron disease (LMND) who had no upper motor neuron and corticospinal tract involvement. Anterior horn neurons of five normal individuals served as controls. The cell body area and the number of synapses of the normal-appearing neurons of the LMND patients were significantly reduced (P < 0.0001). These findings suggest that synaptic changes of anterior horn neurons could be ascribed to the degeneration of lower motor neurons rather than to the influence of upper motor neuron system degeneration. On the other hand, the lengths of individual synapses (P < 0.0001) and of their active zones (P < 0.05) were significantly increased in the patients. These increases would indicate that synapses on anterior horn neurons of individuals with LMND appear to have the capacity to react to progressive degeneration and loss of other synapses by means of a compensatory response or plasticity that enhances their efficiency.

Adult↗
PubMed1993

Amyotrophic lateral sclerosis: lower motor neuron disease spreading to upper motor neurons.

Contrary to the recently reemphasized notion that the primary neuron involved in amyotrophic lateral sclerosis (ALS) is the cortical (upper) motor neuron (UMN), we believe that the lower motor neuron (LMN) is primarily involved by the retrograde transport of pathogens from neuromuscular junctions, and the disease process spreads monosynaptically to the UMN. Pathologically and epidemiologically, the LMN hypothesis is more logical than the UMN in light of the recent understanding of neuroaxonal transport systems, particularly in regard to anterograde cytoskeleton transport and the kinetics of the force promoting slow axonal transport. By correlating the early pathologic findings, i.e., the swelling of the initial axons and formation of intracytoplasmic inclusions in the LMN, ALS may be regarded as a disease of axonal transport, especially its slow component (SCa). Therapeutic intervention to facilitate SCa should be attempted in ALS.

Amyotrophic Lateral Sclerosis↗
PubMed2006

Multiprotein complexes of the survival of motor neuron protein SMN with Gemins traffic to neuronal processes and growth cones of motor neurons.

Spinal muscular atrophy (SMA), a progressive neurodegenerative disease affecting motor neurons, is caused by mutations or deletions of the SMN1 gene encoding the survival of motor neuron (SMN) protein. In immortalized non-neuronal cell lines, SMN has been shown to form a ribonucleoprotein (RNP) complex with Gemin proteins, which is essential for the assembly of small nuclear RNPs (snRNPs). An additional function of SMN in neurons has been hypothesized to facilitate assembly of localized messenger RNP complexes. We have shown that SMN is localized in granules that are actively transported into neuronal processes and growth cones. In cultured motor neurons, SMN granules colocalized with ribonucleoprotein Gemin proteins but not spliceosomal Sm proteins needed for snRNP assembly. Quantitative analysis of endogenous protein colocalization in growth cones after three-dimensional reconstructions revealed a statistically nonrandom association of SMN with Gemin2 (40%) and Gemin3 (48%). SMN and Gemin containing granules distributed to both axons and dendrites of differentiated motor neurons. A direct interaction between SMN and Gemin2 within single granules was indicated by fluorescence resonance energy transfer analysis of fluorescently tagged and overexpressed proteins. High-speed dual-channel imaging of live neurons depicted the rapid and bidirectional transport of the SMN-Gemin complex. The N terminus of SMN was required for the recruitment of Gemin2 into cytoplasmic granules and enhanced Gemin2 stability. These findings provide new insight into the molecular composition of distinct SMN multiprotein complexes in neurons and motivation to investigate deficiencies of localized RNPs in SMA.

Animals↗
PubMed1981

Development of the topographical projection of motor neurons to amphibian muscle accompanies motor neuron death.

The topographical projection of segmental nerves 8 and 9 to the glutaeus muscle of developing frogs was determined during the motor neuron death period (stages 54 to 59). Electrophysiological techniques showed that at stage 54 the entire glutaeus muscle received an innervation from both nerves 8 and 9. By stage 59 the muscle received an innervation from nerve 8 only on one side and by nerve 9 only on the opposite side. The emergence of this mature innervation pattern is accompanied by motor neuron death, with which it may be causally related.

Amphibians↗