Heparan sulfate-like immunoreactivity in the spinal cord in motor neuron disease

Summary The spinal cords from eight autopsy cases of sporadic motor neuron disease (MND) and two control cases were immunohistochemically examined using anti-bodies directed to neurofilament proteins (anti-Nf) and to heparan sulfate (HepSS-1). Variable numbers of spheroids were observed in the anterior horns in the MND cases. In one case of MND, one third to half of the remaining anterior horn cells contained conglomerate inclusions in their perikarya. These pathological structures were not encountered in the control cases. The immunohistochemical study revealed that both anti-Nf and HepSS-1 intensely labelled all spheroids and conglomerate inclusions in the MND cases. The colocalization of heparan sulfate with neurofilamentous accumulation suggests that heparan sulfate is required for the aggregation of neurofilaments, resulting in the formation of spheroids and conglomerate inclusions in MND.Supported in part by the Amyotrophic Lateral Sclerosis Association (USA)     

Trace elements in the spinal cord and other tissues in motor neuron disease.

Trace elements were estimated in the spinal cord, liver and bone of five patients dying of motor neuron disease and five control subjects dying of non-neurological disease. The content of selenium in cord and liver and the cord manganese level were significantly increased in the motor neuron disease patients. These findings are discussed in terms of the possible aetiology of motor neuron disease.     

Oxidative damage to protein in sporadic motor neuron disease spinal cord

The recent discovery that defects in the gene encoding copper-zinc superoxide dismutase (SOD1) are associated with some cases of familial motor neuron disease has heightened interest in the possibility that free radical mechanisms may contribute to selective motor neuron injury. Sporadic and familial motor neuron diseases are clinically and pathologically very similar and may share common pathophysiological mechanisms. Thus the role of free radical mechanisms as a contributory factor to motor neuron injury in the common sporadic form of motor neuron disease requires urgent exploration, particularly as this may provide an avenue for therapy aimed at retarding pathological progression. We investigated oxidative damage to proteins in the lumbar spinal cord by quantifying the protein carbonyl level from 19 patients with sporadic motor neuron disease, 8 neurologically normal control subjects, and 11 neurological disease control subjects, most of whom had slowly progressive neurodegenerative disease. In sporadic motor neuron disease the mean protein carbonyl level in the spinal cord was increased by 119% (p < 0.02) compared to normal control subjects and by 88% (p < 0.04) compared to the neurological disease control subjects. These data contribute to the emerging evidence that oxidative damage may play a contributory role in the neuronal death in sporadic motor neuron disease. This mechanism may be particularly important in a subset of patients with motor neuron disease.     

Embryonic mouse spinal cord motor neuron hybrid cells.

Studies of motor neurons are difficult because of limitations in their isolation and culture. One solution is to produce clonal neural hybrid cells that can express motor neuron characteristics; we fused an aminopterin-sensitive and neomycin-resistant mouse neuroblastoma cell line to isolated embryonic mouse spinal cord motor neurons. Several hybrid neuron cell lines expressing high levels of choline acetyltransferase (CHAT) enzyme activity were found. These were cloned and clones with high CHAT activity isolated. The hybrid nature of cloned cells was confirmed by karyotyping and determining glucose phosphate isomerase allozymes. The availability of these embryonic clonal hybrid cells will enable molecular, physiological, and biochemical studies to define motor neuron-specific properties.     

Metals in spinal cord tissue of patients dying of motor neuron disease

To evaluate the role of toxic metals in causing motor neuron disease (MND), we used a photon-excited, energy-dispersive x-ray analytical system to measure the metal content of spinal ventral horn tissue. Specimens were taken from the cervical and lumbar enlargements of 7 patients who died of MND and the results compared with those found in 12 control patients. Anterior horn lead levels were elevated in MND patients compared to controls (mean, 40.7 micrograms/gm versus 14.6 micrograms/gm; p less than 0.05) and lead levels correlated with the duration of illness (r = +0.84, p less than 0.05). Only 2 MND patients had detectable manganese levels (72.3 and 132.2 micrograms/gm) whereas 1 control had detectable manganese (14.3 micrograms/gm). One MND patient had 244 micrograms/gm selenium, but 3 controls had levels of 180, 58, and 62. Patients with the histories of greatest environmental exposure to metals during life exhibited the highest tissue levels of metals after death; despite chelation therapy for about a year, high lead levels remained in their tissue.     

运动神经元疾病患者颈髓弥散张量成像研究

目的 研究运动神经元疾病颈髓弥散张量成像(DTI)特点,探讨DTI在运动神经元疾病中的诊断价值.方法 选取临床诊断为肌萎缩侧索硬化(ALS)患者16例、肯尼迪病(KD)患者12例及健康志愿者15名.分别行颈髓常规MRI及横断面DTI检查,测定各组C3、C5椎体水平层面颈髓前索区、后索区及舣侧皮质脊髓侧束区4个区域内感兴趣区(ROI)的表观弥散系数(apparent diffusion coefficient,ADC)和部分各向异性比值(fractional anisotropy,FA),并分析影像学参数与其病程、ALSFRS-R评分、肺功能等之间的关系.结果 ALS 组患者在C3与C5水平,前索、双侧皮质脊髓侧束的FA值较KD组、健康对照组显著降低(P<0.05),而KD组与健康对照组之间差异无统计学意义(P>0.05).3组在各不同位置的ADC值之间差异无统计学意义(P>0.05).ALS组在C3水平右侧皮质脊髓束FA值与患者ALSFRS-R评分呈正相关(r=0.52,P=0.041);各水平前索、双侧皮质脊髓束的FA值、ADC值与患者病程、肺功能之间无相关性.结论 FA值可反映颈髓皮质脊髓束的功能异常,可用于评估ALS患者上运动神经元的损伤程度,有利于运动神经元疾病的鉴别诊断.     

Cultured rat spinal cord neurons: interaction with motor neuron disease immunoglobulins

Conditions have been developed for the culture of rat spinal cord neurons in serum-free media supplemented with hormones and growth factors. Neurons were identified by immunofluorescence-labeled anti-neurofilament antibody, and their growth was monitored by assay of choline acetyltransferase and cholinesterase activities. Activities of these enzymes were considerably higher than those of comparable cultures in serum supplemented media in which there were visibly many more nonneuronal cells. Serum immunoglobulins from patients with motor neuron disease showed enhanced binding to rat spinal cord cells maintained in both serum-supplemented and serum-free media, as compared with those from normal healthy individuals. Enhanced binding was more marked with the latter cells, presumably because of the higher proportion of neuronal cells in these cultures. Serum immunoglobulins from patients with other neurologic disorders showed a similar binding to that of the normal controls. The results demonstrate the presence of an immune response to spinal cord cell membrane components in patients with motor neuron disease, although whether the response is primary or secondary in the disease process remains unclear.     

FKBP12 immunoreactivity in the human spinal cord of motor neuron disease patients

We investigated the FKBP12 immunoreactivity in the spinal cord of neurological controls and motor neuron disease (MND) patients. In the neurological controls, the spinal neurons were markedly stained with antihuman FKBP12 (N‐19 and C‐19) antibodies. FKBP12 immunoreactivity was associated with lipofuscin in formalin‐fixed paraffin‐embedded samples. In an electron microscopic view, the 10‐nm colloidal gold particles labeled by the anti‐FKBP12 (N‐19) antibody were present on the lipofuscin of the spinal anterior horn neurons. In the MND cases, atrophic neurons with an abundance of lipofuscin granules in the anterior horns of the spinal cord were mildly stained with the anti‐FKBP12 (N‐19 and C‐19) antibodies. Normal‐appearing neurons, inclusion‐laden neurons and chromatolytic neurons of MND cases were weak or negatively stained with anti‐FKBP12 (N‐19) antibodies. These findings suggest that FKBP12 (N‐19) may decrease in the early stages of degeneration in MND. Complexes of FKBP12 and ligands were reported to have neuroprotective and/or neuroregenerative properties. It is speculated that the decrease in FKBP12 (N‐19) plays some causative role in the development of neurodegeneration in MND. Further investigation of FKBP12 and ligands may help elucidate the pathogenesis of MND.     

免疫介导的脊髓前角运动神经元损伤过程中神经丝异常的观察

目的 研究免疫介导的脊髓前角运动神经元损伤过程中神经丝(NF)磷酸化及超微结构的特征,探讨免疫与肌萎缩侧索硬化发病之间的关系.方法 通过透射电镜技术及免疫组化方法,对免疫介导的脊髓前角运动神经元损伤过程中NF异常聚集的超微结构特征及异常磷酸化状态进行研究.结果 电镜观察发现免疫后动物脊髓前角运动神经元胞质及轴索近端有神经丝异常聚集;免疫组化证实抗非磷酸化神经丝(SMI-32)抗体阳性的脊髓前角运动神经元(个/张脊髓切片)数量(12.00±1.05)与对照组(18.00±1.83)相比,明显减少(P＜0.05),而抗磷酸化NF抗体(SMI-31)阳性的脊髓前角运动神经元数量(13.00±1.60)与对照相比(3.23±1.33)明显增加(P＜0.01).结论 在免疫介导的运动神经元损伤过程中存在类似于肌萎缩侧索硬化的神经丝结构及代谢异常特征,两者之间可能存在共同的发病机制.     

Brain MRI shows white matter sparing in Kennedy's disease and slow‐progressing lower motor neuron disease

The extent of central nervous system involvement in Kennedy's disease (KD) relative to other motor neuron disease (MND) phenotypes still needs to be clarified. In this study, we investigated cortical and white matter (WM) MRI alterations in 25 patients with KD, compared with 24 healthy subjects, 25 patients with sporadic amyotrophic lateral sclerosis (ALS), and 35 cases with lower motor neuron‐predominant disease (LMND). LMND patients were clinically differentiated into 24 fast and 11 slow progressors. Whole‐brain cortical thickness, WM tract‐based spatial statistics and corticospinal tract (CST) tractography analyses were performed. No significant difference in terms of cortical thickness was found between groups. ALS patients showed widespread decreased fractional anisotropy and increased mean (MD) and radial diffusivity (radD) in the CST, corpus callosum and fronto‐temporal extra‐motor tracts, compared with healthy controls and other patient groups. CST tractography showed significant alterations of DT MRI metrics in ALS and LMND‐fast patients whereas KD and LMND‐slow patients were comparable with healthy controls. Our study demonstrated the absence of WM abnormalities in patients with KD and LMND‐slow, in contrast with diffuse WM damage in ALS and focal CST degeneration in LMND‐fast, supporting the use of DT MRI measures as powerful tools to differentiate fast‐ and slow‐progressing MND syndromes, including KD.     

Neurochemical changes in the spinal cord in degenerative motor neuron diseases

Human amyotrophic lateral sclerosis (ALS), a typical motor neuron disease, is characterized pathologically by selective degenerative loss of motoneurons in the CNS. We have demonstrated significant reductions of neurotransmitter-related factors, such as acetylcholine-(ACh)-synthesizing enzyme activity and glutamate and aspartate contents in the ALS, compared to the non-ALS spinal cord obtained at autopsy. We have also shown considerable reductions in activities of cytochrome-c oxidase (CO), an enzyme contributing to aerobic energy production, and transglutaminase (TG), a Ca²⁺-dependent marker enzyme for tissue degeneration, in the ALS spinal cord. We found marked increases in fragmented glial fibrillary acidic protein (GFAP), a filamentous protein specifically associated with reactive astrocytes, in the ALS spinal cord relative to non-ALS tissue. These biochemical results corresponded well to pathomor-phological neuronal degenerative loss and reactive proliferation of astroglial components in the ALS spinal cord tissue. However, these results only indicate the final pathological and biochemical outcomes of ALS, and it is difficult to follow up cause and process in the ALS spinal cord during progression of the disease. Therefore, we used an animal model closely resembling human ALS, motor neuron degeneration (Mnd) mutant mice, a subline of C57BL/6 that shows late-onset progressive degeneration of lower motor neurons with paralytic gait beginning around 6.5 mo of age, to follow the biochemical and pathological alterations during postnatal development. We detected significant decreases in CO activity during early development and in activity of superoxide dismutase (SOD), an antioxidant enzyme, in later stages inMnd mutant spinal cord tissue. TG activity in theMnd spinal cord showed gradual increases during early development reaching a maximum at 5 mo, and then tending to decrease thereafter. Amounts of fragmented GFAPs increased continuously during postnatal development inMnd spinal cord. These biochemical changes were observed prior to the appearance of clinical motor dysfunctions in theMnd mutant mice. Such biochemical analyses using appropriate animal models will be useful for inferring the origin and progression of human ALS.     

Progesterone neuroprotection in the Wobbler mouse,a genetic model of spinal cord motor neuron disease

Motor neuron degeneration characterizes the spinal cord of patients with amyotrophic lateral sclerosis and the Wobbler mouse mutant. Considering that progesterone (PROG) provides neuroprotection in experimental ischemia and injury, its potential role in neurodegeneration was studied in the murine model. Two-month-old symptomatic Wobbler mice were left untreated or received sc a 20-mg PROG implant for 15 days. Both light and electron microscopy of Wobbler mice spinal cord showed severely affected motor neurons with profuse cytoplasmic vacuolation of the endoplasmic reticulum and/or Golgi apparatus and ruptured mitochondria with damaged cristae, a profile indicative of a type II cytoplasmic form of cell death. In contrast to untreated mice, neuropathology was less severe in Wobbler mice receiving PROG; including a reduction of vacuolation and of the number of vacuolated cells and better conservation of the mitochondrial ultrastructure. In biochemical studies, we determined the mRNA for the alpha3 subunit of Na,K-ATPase, a neuronal enzyme controlling ion fluxes, neurotransmission, membrane potential, and nutrient uptake. In untreated Wobbler mice, mRNA levels in motor neurons were reduced by half compared to controls, whereas PROG treatment of Wobbler mice restored the expression of alpha3 subunit Na,K-ATPase mRNA. Therefore, PROG was able to rescue motor neurons from degeneration, based on recovery of histopathological abnormalities and of mRNA levels of the sodium pump. However, because the gene mutation in Wobbler mice is still unknown, further studies are needed to unveil the action of PROG and the mechanism of neuronal death in this genetic model of neurodegeneration.     

Peripherin and neurofilament protein coexist in spinal spheroids of motor neuron disease.

We have compared the immunolocalization of neurofilament protein (NF) with two other neuronal-specific intermediate filament proteins in large spinal axonal swellings (spheroids) of motor neuron disease and controls. All spheroids labeled each of the three different subunits of NF, the low, middle, and high molecular weight polypeptides. In doublelabel immunofluorescence, 300 axonal swellings were immunostained for NF, and 87% of them contained the intermediate protein peripherin. The pattern of immunostaining of NF and peripherin was indistinguishable at a high resolution viewed in 1 microns optical sections by confocal microscopy. A minority of the spheroids contained alpha-internexin, another intermediate protein, but it was weakly immunoreactive. The immunostaining of axonal swellings was similar for all epitopes tested in motor neuron disease and control subjects. The findings suggest that peripherin as well as neurofilament protein are major components of the proliferated intermediate filaments in spheroids.     

Ocular motor function in motor neuron disease.

We studied ocular motor function in 34 patients with motor neuron disease (MND) and in 18 age-matched controls. This included the latency, accuracy, and amplitude-velocity relationships of saccades. We also examined ocular pursuit, the slow phases of optokinetic nystagmus, and the ability to suppress the vestibulo-ocular reflex (VOR) with visual fixation of a head-mounted target. Five of the subjects with MND had pronounced parkinsonian features on neurologic examination. The nonparkinsonian MND subjects had normal ocular motor function for all measures. Most subjects suppressed the VOR completely. The parkinsonian-MND patients had impairment of both saccadic and pursuit eye movements, and one parkinsonian-MND patient with poor pursuit was unable to suppress the VOR. We conclude that ocular motor function is generally spared in MND. The occasional appearance of ocular motor dysfunction probably reflects the incidence of secondary abnormalities such as parkinsonism.     

Akt/Bad signaling and motor neuron survival after spinal cord injury

The serine-threonine kinase Akt is a cell survival signaling pathway that inactivates the proapoptotic BCL-2 family protein Bad and promotes cell survival in cerebral ischemia. Involvement of the Akt/Bad signaling pathway after spinal cord injury (SCI) is, however, uncertain. Our results showed that phospho-Akt (serine-473) and phospho-Bad (serine-136) were significantly upregulated at 1 day after SCI. In addition, phospho-Akt and phospho-Bad were colocalized in motor neurons that survived SCI and inhibition of PI3-K reduced expression of phospho-Akt and phospho-Bad. Dimerization of Bad with 14-3-3 in the cytosol was increased whereas Bad/Bcl-XL binding in the mitochondria was decreased after SCI. We further found that reduced oxidative stress by SOD1 overexpression in rats enhanced the expression of phospho-Akt, phospho-Bad, Bad/14-3-3 binding and reduced Bad/Bcl-XL binding after SCI, as compared to wild-type rats. We conclude that oxidative stress may play a role in modulating Akt/Bad signaling and subsequent motor neuron survival after SCI.     

Spinal cord metabolic changes in murine retrovirus-induced motor neuron disease

Decreased cerebrospinal fluid concentrations of cyclic nucleotides in human motor neuron disease and decreased spinal cord concentrations of cyclic nucleotides in murine (Wobbler) motor neuron disease suggest that an abnormality in cyclic nucleotide metabolism may play a role in motor neuron degeneration. Retroviruses cause decreased cellular levels of cyclic nucleotides in infected cells. We induced a motor neuron degeneration with a neurotropic retrovirus, but not with a non-neurotropic retrovirus. In paralyzed mice, mean cAMP was decreased 21% in posterior horn segments and 34% in anterior horn segments compared to controls. The proportion of spinal cord phosphorylase a decreased 24% in paralyzed mice compared to controls. The content of cGMP decreased 48% in the cerebellum and 25% in both anterior and posterior horn segments of the spinal cords of paralyzed mice compared to controls. White matter content of these chemicals did not decrease in the posterior column of affected animals. Spinal cord content of ATP increased 20-22% in all three compartments, but the spinal cord content of phosphocreatine increased dramatically in white matter (46%), posterior horn gray matter (69%), and anterior horn gray matter (103%) compared to controls. Changes in high-energy phosphate intermediate and cyclic nucleotide metabolites occurred only in topographical regions showing neuronal and astrocyte pathological changes, but did not occur in the cerebral cortex.     

MR-pathologic comparison of the upper spinal cord in different motor neuron diseases

This MRI study was performed to evaluate in vivo alterations of the spinal cord in defined subgroups of motor neuron diseases. Standard MRI examinations of the cervical and thoracic spinal cord in sporadic amyotrophic lateral sclerosis (ALS; n = 39), sporadic lower motor neuron disease (LMND; n = 19), Kennedy's disease (KD; n = 19) and a control group (n = 96) were analyzed with respect to spinal cord signal changes and the thickness of the spinal cord. No significant changes in thickness or signal alterations were observed when comparing ALS, LMND and control groups with one another. However, in KD patients significant upper spinal cord atrophy was detected at the cervical level as compared with all other groups. At the thoracic level, KD patients had significant upper cord atrophy as compared with controls and LMND. Marked atrophy of the upper spinal cord seems to be a feature of the KD-associated central-peripheral distal axonopathy.     

Osteopontin is an alpha motor neuron marker in the mouse spinal cord

Motor neurons (MNs) are designated as alpha/gamma and fast/slow based on their target sites and the types of muscle fibers innervated; however, few molecular markers that distinguish between these subtypes are available. Here we report that osteopontin (OPN) is a selective marker of alpha MNs in the mouse spinal cord. OPN was detected in approximately 70% of postnatal choline acetyltransferase (ChAT)-positive MNs with relatively large somas, but not in those with smaller somas. OPN+/ChAT+ MNs were also positive for NeuN, an alpha MN marker, but were negative for Err3, a gamma MN marker. The size distribution of OPN+/ChAT+ cells was nearly identical to that of NeuN+/ChAT+ alpha MNs. Group Ia proprioceptive terminals immunoreactive for vesicular glutamate transporter-1 were selectively detected on the OPN+/ChAT+ cells. OPN staining was also detected at motor axon terminals at neuromuscular junctions, where the OPN+ terminals were positive or negative for SV2A, a marker distinguishing fast/slow motor endplates. Finally, retrograde labeling following intramuscular injection of fast blue indicated that OPN is expressed in both fast and slow MNs. Collectively, our findings show that OPN is an alpha MN marker present in both the soma and the endplates of alpha MNs in the postnatal mouse spinal cord.