Dendritic synapses of anterior horn neurons in amyotrophic lateral sclerosis: an ultrastructural study

This ultrastructural study deals with the synapses of primary dendrites of the anterior horn neurons in the lower lumbar spinal cords of seven patients with amyotrophic lateral sclerosis (ALS) who had mild neuronal depletion. Specimens from seven age-matched, neurologically normal individuals served as controls. In each instance, the autopsy was performed within 6 h after death. Our results indicate a statistically significant increase in degenerative changes in the dendrite presynapses of normal-appearing neurons of the ALS patients. The alterations included aggregation of electron-dense synaptic vesicles and dark mitochondria with dense cristae, and bundles of neurofilaments. However, we found no significant difference between controls and patients with respect to cross-sectional area and length of the dendrites, number of synapses per dendrite, and lengths of individual synapses and their active zones in the normal-appearing neurons, even though the patients' neurons had a smaller cross-sectional area. In chromatolytic neurons, the number of synapses and the length of the active zone of the primary dendrites were significantly diminished. These findings suggest that despite degenerative changes of the presynapses, the synapses in the primary dendrites of the anterior horn neurons are preserved at the early stage of ALS. The preservation of these synapses may be due to their relative resistance to degenerative processes, or may represent a compensatory mechanism of the synapses for diminished synaptic function in distal dendrites. Received: 21 July 1995 / Accepted: 6 September 1995     

Postnatal development of lamina III/IV nonpyramidal neurons in rabbit auditory cortex: quantitative and spatial analyses of Golgi-impregnated material

We have studied the postnatal development of lamina III/IV spine-free nonpyramidal neurons in the auditory cortex of the New Zealand white rabbit. The morphology and dendritic branching pattern of single cells impregnated with a Golgi-Cox variant were analyzed with the aid of camera lucida drawings and three-dimensional reconstructions obtained with a computer microscope. Sample sizes of 20 neurons were obtained at birth (day 0), postnatal day (PD) 3, 6, 9, 12, 15, 21, and 30 days of age. Normative data were also available from PD-60 and young adult rabbits studied previously. At birth, lamina II-IV have not yet emerged from the cortical plate; immature nonpyramidal neurons at the bottom of the cortical plate (presumptive layer IV) are characterized by short, vertically oriented dendrites. Growth-cone-like structures are present along the shafts and at the tips of the dendrites. At birth, soma area and total dendritic length are, respectively, 34 and 10% of adult values. The cortical plate acquires a trilaminar appearance at PD-3. The six-layered cortex is present by PD-6. During the first postnatal week dendritic length increases fourfold and is accompanied by a significant increase in both terminal and preterminal dendritic growth cones. At the onset of hearing at PD-6, there is a significant proliferation of dendrites and branches to 144 and 200% of adult levels, respectively. These supernumerary dendrites are rapidly lost during the second postnatal week, at which time the somata and dendrites become covered with spines. The loss of higher-order dendrites occurs more gradually; the number of dendritic branches is still 116% of adult values at PD-30. Spine density peaks between days PD-12 and PD-15, and then gradually diminishes until the cells are sparsely spined or spine free by PD-30. Total dendritic length increases in a linear fashion up to PD-15, at which time it is 80% of adult values. An analysis of terminal and intermediate branches demonstrated that the increase in total dendritic length after PD-6 is due entirely to the growth of terminal dendrites. Total dendritic length attains adult levels by PD-30. Spatial analyses revealed that a vertical orientation of dendrites is present at birth. Associated with the onset of hearing at PD-6, there is an explosive elaboration of dendrites toward the pial surface.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-lasting structural changes in CA3 hippocampal and layer V motor cortical pyramidal neurons associated with self-stimulation rewarding experience: a quantitative Golgi study

Self-stimulation (SS) rewarding experience induced structural changes in CA3 hippocampal and layer V motor cortical pyramidal neurons in adult male Wistar rats has been demonstrated. In the present study, whether these structural changes are transient or of a permanent nature was evaluated. Self-stimulation experience was provided for 1 h daily over a period of 10 days through bilaterally implanted bipolar electrodes in the lateral hypothalamus and the substantia nigra-ventral tegmental area. Following 10 days of SS experience, the rats were sacrificed after an interval of 30 and 60 days for the quantitative analysis of the dendritic morphology in Golgi stained CA3 hippocampal and layer V motor cortical pyramidal neurons. The results revealed a significant increase in the dendritic branching points and intersections in apical and basal dendrites in both types of neurons in 30 days post-SS group compared to sham control. The total number of apical and basal dendrites were significantly increased in both 30 and 60 days post-SS groups of rats. This study suggests that SS experience induced structural changes are sustainable, even in the absence of rewarding experience.     

Postnatal development of neurons and synapses in the visual and motor cortex of rabbits: a quantitative light and electron microscopic study

Introductory to a morphological investigation on the effects of early visual deprivation and on the critical periods in early postnatal life we have studied quantitatively the normal postnatal growth of neurons and synapses in the visual and motor cortex of rabbits. The major results of this analytical study are: (1) rapid decrease in neuron density and a rapid increase in neuronal volume are observed. They are almost completed at postnatal Day 10, i.e., before natural eye opening. The drop in neuron density is caused to a very large extent by an increase in cortical volume and not by a considerable disappearance of neurons; (2) the formation of synaptic contact zones starts at Day 6 to 7 and is most pronounced between Day 10 and Day 21, i.e., after natural eye opening. At Day 27 synaptic density has reached adult levels in the visual cortex and is in excess of the adult level in the motor cortex. In visual area I and in the motor cortex a significant difference in synaptic increase is observed between the left and right hemisphere, resulting in a lower synaptic density in the left counterparts at Day 27 and in adult animals [56,57]. In the visual cortex a small but highly correlated increase in synaptic vesicle density is observed. In the motor cortex no correlated relation between age and vesicle density is observed. In both cortical areas synaptic vesicle density has reached about 70 percent of the adult level at Day 27; and (3) in newborn and young rabbits the motor cortex seems to be more mature than the visual cortex.     

Transplantation of embryonic noradrenergic neurons in two models of adult rat spinal cord injury: ultrastructural immunocytochemical study

The synaptic connections established by grafted noradrenergic (NA) neurons into the lesioned adult rat spinal cord were analysed using immunocytochemistry at the electron microscopic level. An embryonic cell suspension of the locus coeruleus region from E-13 rat embryos was transplanted into the spinal cord following either: (1) spinal cord transection or (2), partial selective denervation by 6-hydroxy dopamine (6-OH DA). One month after grafting, the NA-neurons established, in the two models, an innervation pattern similar to that found in the intact spinal cord. In both models, the transplanted NA-immunoreactive neurons formed extensive synaptic contacts with dendrites, spines and perikarya. The proportion of axodendritic and axospinous contacts was inverse in the two models. The first model thus reproduced more closely the normal synaptic pattern prefering dendritic targets, which could correspond to a better integration of the graft. In the second model, a partially NA-denervated spinal cord, there existed a competition between residual intrinsic and grafted neuron-derived fibres, which presumably affects synaptogenesis. In conclusion, the present study illustrate the complexity of cell interations conducting to the formation of a specific circuitry. Recognition phenomenon are likely modulated by space constraints, which ultimately shape-up the geometry of synaptic contacts.     

Postnatal development of dendrites of relay neurons in the lateral geniculate nucleus of the marmoset (Callithrix jacchus): a quantitative Golgi study

Dendrites of multipolar relay neurons in the lateral geniculate nucleus of the marmoset (Callithrix jacchus), at various ages from birth to adulthood, were studied in rapid Golgi preparations. The dendrites were analyzed by means of three-dimensional computer reconstructions and decomposed into intermediate and terminal segments, both of which were further classified according to their centrifugal order. Measurements were made of the number of segments per dendrite, the total length of dendrites, and the mean length of intermediate and terminal segments. In adult marmosets, there are four stem dendrites on average per neuron, and each dendrite divides into a mean of 14 segments. Between birth and 6 weeks of age, the mean dendritic length doubles, mainly because of changes in terminal segments. There is a significant decrease in dendritic length into adulthood. The total number of stem dendrites does not change after birth, but during the first postnatal week dendrites lose distal segments, after which there is a significant increase in the number of segments of orders 3 to 7. The mean length of intermediate segments does not change with age, nor with order, whereas the length of terminal segments increases from 50 to 120 microns from birth to 6 weeks of age, and then decreases to the adult value of 80 microns. In conclusion, during the period of most rapid visual development, important morphological changes occur in geniculate relay-cell dendrites, involving essentially terminal segments. These observations correlate well with changes of geniculate volume and neuronal density.     

A quantitative study of retrograde axonal transport in motor and sensory neurons

We used 3H N-succinimidyl propionate to covalently label in vivo proteins of the rat sciatic nerve, and studied the accumulation of radioactively labeled proteins in the cell bodies of the ipsilateral dorsal root ganglion and ventral horn of spinal cord to assess retrograde axonal transport in sensory and motor neurons respectively. In each case the early accumulation of a small amount of radioactively labeled protein is followed by the later accumulation of a larger amount, which subsequently declines to lower levels. The differences between accumulation in the motor neuron and sensory neuron are discussed. Quantitative assessment of retrograde axonal transport will allow future determination of alterations in that transport after nerve injury and in toxic states, which will help elucidate the role of retrogradely transported proteins in neuronal cell biology.     

Dendritic properties of hippocampal CA1 pyramidal neurons in the rat: Intracellular staining in vivo and in vitro

Dendritic morphology and passive cable properties determine many aspects of synaptic integration in complex neurons, together with voltage-dependent membrane conductances. We investigated dendritic properties of CA1 pyramidal neurons intracellularly labeled during in vivo and in vitro physiologic recordings, by using similar intracellular staining and three-dimensional reconstruction techniques. Total dendritic length of the in vivo neurons was similar to that of the in vitro cells. After correction for shrinkage, cell extent in three-dimensional representation was not different between the two groups. Both in vivo and in vitro neurons demonstrated a variable degree of symmetry, with some neurons showing more cylindrical symmetry around the main apical axis, whereas other neurons were more elliptical, with the variation likely due to preparation and preservation conditions. Branch order analysis revealed no difference in the number of branch orders or dendritic complexity. Passive conduction of dendritic signals to the soma in these neurons shows considerable attenuation, particularly with higher frequency signals (such as synaptic potentials compared with steady-state signals), despite a relatively short electrotonic length. Essential aspects of morphometric appearance and complex dendritic integration critical to CA1 pyramidal cell functioning are preserved across neurons defined from the two different hippocampal preparations used in this study. J. Comp. Neurol. 391:335–352, 1998. © 1998 Wiley-Liss, Inc.     

Morphological development of microglia in the postnatal rat brain: A quantitative study

Morphological transformation of lectin-positive microglia/macrophages in the developing rat cerebral hemisphere was analysed using quantitative methods. During the first postnatal month, the cells showed increases in their size and fractal dimension accompanied by a simultaneous decrease in their solidity. Regional variations in dynamics of the process indicated the existence of spatio-temporal developmental gradients within the cerebral hemisphere wall which might correspond with regional patterns of neuronal differentiation. Results of the present study prove that the quantitative methods can be the source of reliable data replacing subjective cell typologies.     

Dendritic development of cortical neurons of mice subjected to total asphyxia: A Golgi-Cox study

Summary The effect of total asphyxia on dendritic development of the pyramidal cells in the mouse cerebrum was investigated using the Golgi-Cox method. Although neonatal asphyxia did not alter the number of basal dendrites arising from the cell bodies, the dendrites in the 20-day-old treated animals were significantly shorter than those in the controls. Even at 60 days, the number of longer dendrites in the treated mice was significantly less than that in the controls.Supported in part by Grant No. 85-15 from the National Center for Nervous, Mental and Muscular Disorders (NCNMMD) of the Ministry of Health and Welfare, Japan     

Embryonic development of choline acetyltransferase in thoracic spinal motor neurons: somatic and autonomic neurons may be derived from a common cellular group.

This investigation focused on the relationship between neurotransmitter phenotype expression and rat motor neuron development, as studied with choline acetyltransferase (ChAT) immunocytochemical techniques. The development of two subclasses of motor neurons, somatic and autonomic efferents, was examined in the upper thoracic spinal cord. ChAT was first detected in a few neurons on embryonic day 12 1/2 (E12 1/2), and in numerous cells located in a single, ventrolaterally located column in the intermediate zone on E13. By E14, this group of ChAT-positive neurons was more intensely immunoreactive, and their axons could be traced to appropriate targets in developing somatic muscle and paravertebral sympathetic ganglia. During the E15-16 period, somatic and autonomic motor neurons separated into two distinct subgroups, with the latter cells being observed to translocate dorsally. By E17, these autonomic motor neurons reached their final positions in the midportion of the intermediate zone. The autonomic motor neurons were observed to extend transverse dendritic bundles across the spinal cord between E15-16, but evidence of the longitudinal bundles of sympathetic preganglionic dendrites was not observed until after birth. A recent study of cholinergic thoracic motor neurons found that both somatic and autonomic cells were generated synchronously during the E11-12 period (Barber et al., Soc Neurosci Abstr 15:588, 1989). In combination with the present results, these data indicate that no more than 1 1/2 days are necessary after motor neuron genesis before a few cells begin to express detectable levels of ChAT, and that no more than 2 days are required before large numbers express this marker of the cholinergic phenotype. Further comparisons of the present findings with those of previous investigations of the development of both somatic and autonomic motor neurons (Dennis et al., Dev Biol 81:266, 1981; Rubin, J Neurosci 5:685, 697, 1985) indicate that these cells contain ChAT at the time their axons are growing toward their respective peripheral targets 1 day before the time when physiological evidence of function is manifest. Furthermore, the present results suggest that both subclasses of motor neurons initially migrate together from the ventricular zone into a single motor column within the ventral intermediate zone, and that the autonomic neurons subsequently translocate dorsally. Thus, autonomic motor neurons appear to be an exception to the generalization that postmitotic neurons migrate directly from the germinal zone to their final positions within the central nervous system.     

Motor neurons and motor columns of the anterior spinal cord of salamanders: posthatching development and phylogenetic distribution

The posthatching development of rostral (1st-4th) spinal motor neurons was studied in ten species of salamanders, using horseradish peroxidase and cobaltic lysine tracing techniques. Development of spinal motor neurons differs among species in association with differences in life history and general developmental patterns (i.e., between species with aquatic larvae versus those with direct development, with or without ontogenetic repatterning). In the plesiomorphic state, represented by species with aquatic larvae, five types of motor neurons are present: (1) large, multipolar neurons, believed to be primary motor neurons; (2) medial, pear-shaped neurons; (3) larger, spindle-shaped neurons, which increase in number during posthatching development; (4) cone-shaped neurons, and (5) bilaterally arborizing neurons (found only at the rostral pole of the first spinal nucleus). Direct-developing desmognathine salamanders have the plesiomorphic set of motor neurons, but appear to lack Mauthner neurons. Direct-developing plethodontine salamanders have cone-shaped, pear-shaped, and spindle-shaped neurons, but lack primary motor neurons and Mauthner neurons. Direct-developing bolitoglossine salamanders, which exhibit both pedomorphosis and ontogenetic repatterning, have only medial, pear-shaped neurons, and lack primary motor neurons, spindle-shaped neurons, cone-shaped and bilaterally arborizing neurons. At all developmental stages in all species studied, pear-shaped neurons are always found in medial positions and spindle-shaped neurons are always found in lateral positions. Spindle-shaped neurons are found more laterally as development proceeds. The medial and lateral motor columns of salamanders and amniotes differ in their connections with peripheral targets (i.e., axial muscles vs. limbs). This implies a lack of homology of neuron types in salamanders and amniotes, which has been obscured by the current terminology.     

Influence of acetylcholinesterase on embryonic spinal rat motoneurones growth in culture: a quantitative morphometric study

Rat spinal motoneurones sampled at day embryonic 15 were purified using a Nycodenz gradient and cultured in defined medium, during 7 days, on glass coverslips coated with poly-l -lysine and laminine. Purified acetylcholinesterase (AChE), ecothiopate, BW 284C51 and fasciculin II, inhibitors of either the catalytic or peripheral site of AChE, were added to the defined medium. Morphological changes of spinal motoneurones were measured using a statistical quantitative morphometric method, allowing the determination of various parameters such as the number of neurites and bifurcations, the length of neurites, the surface and spreading index. Presence of AChE in the medium (4 units/mL) increases the surface and the total length of neurites and axons without any change in the spreading index. When spinal motoneurones were cultured on AChE coated substrate, neurones rapidly migrate and form clusters. Addition of ecothiopate (10^–6m ) in the medium, which selectively blocks the catalytic site of AChE, leads to a slight increase in the number of primary neurite and a decrease of the spreading index during the three first days in culture. BW 284C51 (10^–5m ) which blocks the catalytic site but also affect the peripheral one, significantly reduces the number of primary neurites and increases the number of bifurcations. Fasciculin II, a potent blocker (10^–9m ) of the AChE peripheral site induces a decrease of both primary neurites and bifurcations with a significant increase of the length and growth velocity of the axon, giving a drastic enhancement of the spreading index. These phenomena are discussed in terms of catalytic and non-catalytic function of AChE, including the involvement of the enzyme in adhesive processes, occurring during growth and differentiation of spinal motoneurones.     

Region-specific cell grafting into cervical and lumbar spinal cord in rat: a qualitative and quantitative stereological study

In the present study, we have characterized an atraumatic grafting technique which permits multiple, segmental, and lamina-specific injections into cervical or lumbar spinal cord. Cell injections were performed in spinally mounted rats of different ages and spinal cord size, using a micromanipulator and glass microcapillary connected to a digital microinjector. For grafting, we used human neuroteratoma (hNT) cells, BrdU-labeled rat spinal precursors or primary embryonic spinal cord neurons isolated from E14 spinal cord of the eGFP+ rat. Systematic quantification of grafted cells was performed using stereological principles of systematic random sampling and semi-automated optical Disector software. Volume reconstruction was performed using serial sections from grafted areas and custom-developed software (Ellipse) which permits "two reference points" semi-automated alignment of images, as well as volume reconstruction and calculation. By coupling these techniques, it is possible to achieve a relatively precise and atraumatic cell delivery into multiple spinal cord segments and specific spinal laminae. Consistency of the multiple grafts position in the targeted laminar areas was verified by a systematic volume reconstruction. Good survival of implanted cells for the three different cell lines used indicate that this grafting technique coupled with a systematic analysis of the individual grafting sites can represent a valuable implantation-analytical system.     

Dendritic changes in the hippocampal formation of AIDS patients: a quantitative Golgi study

We have previously shown that in the hippocampal formation of patients with acquired immunodeficiency syndrome (AIDS) there is neuronal atrophy, without cell loss. Because reductions in neuronal size are suggestive of associated neuritic alterations, we decided to study the dendritic trees of the main neuronal populations in the hippocampal formation. Material was obtained in five male AIDS patients and five male controls. After Golgi impregnation, the dendritic arborizations of dentate granule and hilar basket cells, and of CA3 and CA1 pyramidal cells, were hand traced, and their segments classified, counted and measured. We found an impoverishment of the dendritic trees in all neuronal populations in the AIDS group, which was more striking in the hilus and CA3 field. Specifically, hilar neurons had fewer dendritic segments, and reduced branching density and dendritic extent; in CA3 pyramids there was a decrease in the number of terminal segments in the basal trees, and a reduction in the total number of segments, number of medium order terminals, dendritic branching density and dendritic extent in the apical trees. In CA1 pyramids, the terminals were shorter in the apical trees and the dendritic spine density decreased in the basal trees, whereas in granule cells only the dendritic spine density was reduced in AIDS patients. Subtle signs suggestive of dendritic reorganization were observed. These results point to a regional vulnerability of the hippocampal formation to HIV infection, and might contribute to explaining the occurrence of dementia, as a consequence of overall reduction in the hippocampal neuronal receptive surface.     

Generation of spinal motor neurons from human fetal brain-derived neural stem cells: role of basic fibroblast growth factor

Neural stem cells (NSCs) have some specified properties but are generally uncommitted and so can change their fate after exposure to environmental cues. It is unclear to what extent this NSC plasticity can be modulated by extrinsic cues and what are the molecular mechanisms underlying neuronal fate determination. Basic fibroblast growth factor (bFGF) is a well-known mitogen for proliferating NSCs. However, its role in guiding stem cells for neuronal subtype specification is undefined. Here we report that in-vitro-expanded human fetal forebrain-derived NSCs can generate cholinergic neurons with spinal motor neuron properties when treated with bFGF within a specific time window. bFGF induces NSCs to express the motor neuron marker Hb9, which is blocked by specific FGF receptor inhibitors and bFGF neutralizing antibodies. This development of spinal motor neuron properties is independent of selective proliferation or survival and does not require high levels of MAPK activation. Thus our study indicates that bFGF can play an important role in modulating plasticity and neuronal fate of human NSCs and presumably has implications for exploring the full potential of brain NSCs for clinical applications, particularly in spinal motor neuron regeneration.     

GABA-immunoreactive neurons in the rat cerebellum: a light and electron microscope study

An antibody raised against gamma - amino-butyric acid (GABA) coupled to bovine serum albumin with glutaraldehyde (Hodgson et al: J. Histochem. Cytochem. 33:229-239, '85) was used to localise immunocytochemically the presumptive GABAergic neuronal elements in the cerebellar cortex of the adult rat. employing the unlabelled antibody enzyme method with pre- and post-embedding immunocytochemical procedures, the following cellular structures were observed to be GABA-immunopositive in both the light and electron microscopes: the somata, dendrites, and axonal processes (including axon terminals) of stellate, basket, and Golgi neurons. In immunopositive neuronal somata and dendrites, the reaction product was found to be associated with all intracellular organelles and with the postsynaptic densities of synaptic junctions. Specific GABA-like immunoreactivity was also seen around outer mitochondrial membranes, microtubules, and neurofilaments, and coating synaptic vesicles in presynaptic axon terminals. In the pre-embedding procedure with dilutions of the antiserum between 1:1,000 and 1:2,000, the perikarya and dendrites of Purkinje cells were GABA-immunonegative, whereas at an antiserum dilution of 1:500 the somata of Purkinje cells were mildly GABA-immunoreactive. Purkinje cell axon terminals in the infra- and supraganglionic plexuses and in the deep cerebellar nuclei were always strongly immunopositive. Neuroglia were invariably GABA-immunonegative, as were the dendrites, axons (parallel fibres), and somata of granule cells. Mossy fibre and climbing fibre afferents were also immunonegative. The pattern of immunoreactivity obtained with this antiserum directed against the inhibitory neurotransmitter GABA was found to resemble closely the immunocytochemical distribution of GABA and of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD) as reported previously in other immunocytochemical investigations (Oertel et al. and Wu et al: Cytochemical Methods in Neuroanatomy. New York: A. R. Liss, '82; Seguela et al: Neuroscience 16:865-874, '85; Mugnaini and Oertel: GABA and Neuropeptides in the CNS. Handbook of Chemical Neuroanatomy, Vol. 4, Part I. Amsterdam: Elsevier, '85.     

Postnatal development of neurons containing choline acetyltransferase in rat spinal cord: an immunocytochemical study

A monoclonal antibody to choline acetyltransferase (ChAT) has been used in an immunocytochemical study of the postnatal development of ChAT-containing neurons in cervical and thoracic spinal cord. Specimens from rat pups ranging in age from 1 to 28 days postnatal (dpn) were studied and compared with adult specimens (Barber et al., '84). The development of established cholinergic neurons, the somatic motoneurons and sympathetic preganglionic cells, has been described as has that of previously unidentified ChAT-positive neurons in the dorsal, intermediate, and central gray matter. Cell bodies of somatic and visceral motoneurons contained moderate amounts of ChAT-positive reaction product at birth that gradually increased in intensity until 14-21 dpn. The most intensely stained ChAT-positive neurons in 1-5-dpn specimens were named partition cells because this cell group extended from the central gray to an area dorsal to the lateral motoneurons, and thereby divided the spinal cord into dorsal and ventral halves. Partition cells were medium to large in size with 5-7 primary dendrites, and axons that, in fortuitous sections, could be traced into the ventrolateral motoneuron pools, the ventral funiculi, or the ventral commissure. Small ChAT-positive cells clustered around the central canal and scattered in laminae III-VI of the dorsal horn were detectable at birth. These neurons were moderately immunoreactive at 11-14 dpn and intensely ChAT positive by 21 dpn. The band of ChAT-positive terminal-like structures demonstrated in lamina III of adult specimens (Barber et al., '84) was first visible in 11-14-dpn specimens. By 28 dpn, both laminae I and III contained punctate bands that approximated the density of those observed in adult spinal cord. This investigation has demonstrated ChAT within individual neurons of developing spinal cord, and has identified a group of neurons, the partition cells, that exhibit intense ChAT-positive immunoreactivity earlier than any other putative cholinergic cells in spinal cord, including motoneurons. Another important observation has been that each ChAT-positive neuronal type achieves adult levels of staining intensity at different times during development. A likely explanation for this differential staining is that various groups of neurons acquire their mature concentration of ChAT molecules at different developmental stages. In turn, this may correlate with the maturation of cholinergic synaptic activity manifest by individual cells or groups of neurons.     

Large motor neuron involvement in Stiff-man syndrome: a qualitative and quantitative study

Stiff-man syndrome (SMS) is characterized by fluctuating muscular rigidity and spasm. Recently, antibodies against glutamic acid decarboxylase (GAD), the enzyme catalyzing the synthesis of γ-amino butyric acid (GABA), have been detected in SMS patients. An autoimmune mechanism against GAD was thus proposed for the suppression of GABAergic inhibitory interneurons, resulting in rigidity and spasm. We conducted quantitative investigations on the ventral horn of the spinal cord and its GAD immunoreactivity, post mortem, in a SMS patient and four controls. In the spinal cord of the SMS patient, we found a 70%, 33% and 27% reduction (P < 0.05) in the density of neurons with somal areas of 1000–1500 μm², 500–1000 μm², and 0–500 μm², respectively. The density of neurons with a somal area greater than 1500 μm² was not reduced, although some neurons in this class showed central chromatolytic changes. The affected muscles exhibited neurogenic atrophy. GAD-like immunoreactivity in the spinal gray matter was not significantly decreased. The density of Purkinje cells, known to contain high amounts of GAD, was not significantly reduced. While the co-occurrence of elevation of anti-GAD antibody in the serum and reduction in the density of small spinal neurons was confirmed, that of smaller α-motor neurons and γ-motor neurons, the qualitative changes in larger α-motor neurons, and the preservation of spinal GAD-like immunoreactivity and non-spinal GAD-containing neurons suggest the involvement of factors other than autoimmune mechanisms through anti-GAD antibodies. More diverse mechanisms may be associated in the pathogenesis of SMS. Received: 2 April 1998 / Revised, accepted: 17 July 1998