galactocerebroside and Demyelinating-Diseases

Remyelination is the regenerative process by which demyelinated axons are reinvested with new myelin sheaths. It is associated with functional recovery and maintenance of axonal health. It occurs as a spontaneous regenerative response following demyelination in a range of pathologies including traumatic injury as well as primary demyelinating disease such as multiple sclerosis (MS). Experimental models of demyelination based on the use of toxins, while not attempting to accurately mimic a disease with complex etiology and pathogenesis such as MS, have nevertheless proven extremely useful for studying the biology of remyelination. In this chapter, we review the main toxin models of demyelination, drawing attention to their differences and how they can be used to study different aspects of remyelination. We also describe the optimal use of these models, highlighting potential pitfalls in interpretation, and how remyelination can be unequivocally recognized. Finally, we discuss the role of toxin models alongside viral and immune-mediated models of demyelination.

Topics: Animals; Antibodies; Cats; Demyelinating Diseases; Disease Models, Animal; Ethidium; Galactosylceramides; Humans; Lysophosphatidylcholines; Mice; Mice, Inbred C57BL; Myelin Sheath; Nerve Regeneration; Rabbits; Rats; Spinal Cord

During postnatal development of the higher vertebrate CNS, large populations of oligodendroglia are generated from precursor cells in a very dependable way. In adult lesioned CNS tissues, local populations of oligodendroglia are replenished by proliferation of this replenishment varies from one species to another and also from one lesion type another. Studies on the developmental generation of oligodendroglia are reviewed here, delineating what is known of the early relationships between the CNS glial lineages and of what regulates this development. Contributions from recent cell biological work are considered against the background of morphological and radioautographic results. The quiescent condition of extremely slow turnover in the normal adult CNS is noted, and the dramatic effects of lesions on the neural cell environment are considered. Lesions can trigger proliferation at a much greater rate in the mature oligodendroglial population, as observed both in situ and in tissue culture; in addition to persisting stem cells, the mature cells participate in replenishing the local oligodendroglial population. This regeneration from cells already committed to the oligodendroglial lineage may minimise such disturbing effects of the lesion environment as might distort replenishment of the population from precursor cells.

Topics: Animals; Blood-Brain Barrier; Cell Differentiation; Cell Separation; Cell Survival; Cells, Cultured; Central Nervous System; Demyelinating Diseases; Galactosylceramides; Glial Fibrillary Acidic Protein; Glucose; Humans; Insulin; Mice; Mice, Neurologic Mutants; Mitosis; Myelin Basic Protein; Myelin Proteins; Myelin Sheath; Neuroglia; Oligodendroglia; Rats

Several cell populations have been shown to provide a permissive environment for axonal extension following transplantation to injury sites. The limited spread of transplanted cells from implantation sites in the mature CNS, and the superior substrate and trophic environment that they provide, likely contribute to the fact that few transplantation-based therapies have elicited axonal extension beyond the transplant. The aim of this study was to determine whether (1) regions of demyelination cranial and caudal to a spinal cord injury site would improve the spread of Schwann cells transplanted into the site of injury, and (2) whether this combination therapy was associated with improved anatomical regeneration. Three days following contusion injury, anti-galactocerebroside antibodies plus complement proteins were injected into the dorsal column cranial and caudal to the injury site, resulting in complete and well defined regions of demyelination that extended 8 mm either side of the injury site. One day later, naïve Schwann cells in suspension were injected into the contusion site. Transplanted Schwann cells homogeneously redistributed throughout the contusion site and the adjacent regions of demyelination cranial and caudal to the contusion site, providing a long-distance prospective path for repair that was free of myelin and contained transplanted cells. Animals that received demyelination plus transplantation therapy, but not untreated or single-treatment groups, exhibited robust axonal regeneration beyond the contusion site within the treated dorsal column. Axonal regeneration in these animals was not associated with an improvement in locomotor ability. These findings suggest that this combination therapy may overcome a central limitation of transplant strategies in which the permissive environment provided remains at the implantation site.

Topics: Animals; Antibodies; Axons; Cell Movement; Demyelinating Diseases; Female; Galactosylceramides; Myelin Sheath; Nerve Regeneration; Rats; Rats, Sprague-Dawley; Schwann Cells; Spinal Cord Injuries

The pigmentary type of orthochromatic leukodystrophy (van Bogaert-Nyssen disease) is a hardly known neurological disorder usually with late onset that is very difficult to diagnose in vivo. Neuropathologically, the disorder features noninflammatory demyelination and the presence of pigmented macrophages and astrocytes that may contain iron. Clinically, van Bogaert-Nyssen disease can lead to death within a few years and is characterized by dementia, psychiatric abnormalities, epileptic seizures, spastic pareses, and occasionally extrapyramidal motor symptoms. This report presents a typical case and an overview of the literature. Furthermore, galactocerebroside could be documented in remaining macrophages and astrocytes by immunohistochemistry. This possibly indicates a dysfunction in sphingolipid breakdown and could relate the pigmented form of orthochromatic leukodystrophy to the genetically defined globoid cell leukodystrophy (Krabbe's disease). Thus, the rather heterogeneous pool of orthochromatic leukodystrophies could be further narrowed.

Topics: Adult; Astrocytes; Brain; Brain Diseases, Metabolic, Inborn; Demyelinating Diseases; Diagnosis, Differential; Fatal Outcome; Female; Galactosylceramides; Humans; Inclusion Bodies; Iron; Leukodystrophy, Globoid Cell; Lipofuscin; Macrophages; Microscopy, Electron; Myelin Sheath; Peripheral Nerves; Sphingolipidoses

Neurological deficit in experimental allergic encephalomyelitis (EAE) and multiple sclerosis (MS) is probably a consequence of synergy between T and B cell responses to CNS antigens. During the demyelinating phase of chronic relapsing EAE in ABH mice, anti-myelin oligodendrocyte glycoprotein (MOG) responses were increased compared to the inflammatory acute phase, but such levels did not correlate with the severity of clinical disease. The pathogenicity of antibodies (Ab) to MOG, myelin basic protein (MBP), proteolipid protein (PLP) and galactocerebroside (GalC) was investigated in vivo following injection at the onset of EAE. An IgG2a monoclonal Ab (mAb), clone Z12, directed to MOG augmented clinical disease and demyelination in ABH and C57BL/6 mice, but not MOG knock-out mice. No effect was observed with F(ab(2))' fragments of Z12 or with the anti-MOG IgG1 mAbs, clones Y10 or 8-18C5. Cobra venom factor partially reduced the augmenting effect of mAb Z12 suggesting a role for complement. The pathogenic effect of anti-myelin Abs was not restricted to MOG since an anti-GalC mAb exacerbated inflammation in the CNS while an MBP mAb (clone 22) reduced clinical disease. Taken together, these data provide further evidence that myelin-reactive Abs generated during autoimmune neurological disease may play an important role not only in the pathogenesis of disease but also the regulation of myelin-targeted autoimmune disease.

Topics: Animals; Autoantibodies; Complement System Proteins; Demyelinating Diseases; Disease Models, Animal; Elapid Venoms; Encephalomyelitis, Autoimmune, Experimental; Female; Galactosylceramides; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myelin Basic Protein; Myelin Proteins; Myelin Proteolipid Protein; Myelin-Associated Glycoprotein; Myelin-Oligodendrocyte Glycoprotein; Recurrence; Spinal Cord

Experimentally induced demyelination due to the direct injection of gliotoxic agents has provided powerful models for studying the biology of remyelination. For the most part, these models have involved injection into white matter tracts of the spinal cord. However, the spinal cord has a number of limitations, such as the size of lesions that it is possible to make and its unsuitability for long-term direct cannulation for the delivery of putative remyelination-enhancing agents. In this study, we describe the natural history of three new models of demyelination/remyelination based on the stereotaxic injection of three gliotoxins: lysolecithin, ethidium bromide, and a combination of anti-galactocerebroside antibody and complement (GalC-ab/comp) into the caudal cerebellar peduncle of adult rats. All three agents produced large areas of demyelination with minimal axonal damage, which undergo extensive remyelination. Ethidium bromide- and GalC-ab/comp-induced lesions remyelinated more slowly than those induced by lysolecithin. The contribution to the remyelination of the lesion by Schwann cells reflects the degree of astrocyte damage incurred within the demyelinated area and is greatest for ethidium bromide-induced demyelination. These new models not only provide further insights into the mechanisms of CNS remyelination but also provide a valuable new resource for addressing a series of key issues relevant to current efforts to promote CNS remyelination either by the enhancement of intrinsic processes or by the transplantation of myelinogenic cells.

Topics: Animals; Cerebellum; Complement System Proteins; Demyelinating Diseases; Ethidium; Female; Galactosylceramides; Glial Fibrillary Acidic Protein; Gliotoxin; Lysophosphatidylcholines; Myelin Sheath; Oligodendroglia; Rats; Rats, Sprague-Dawley; Schwann Cells

We have treated spinal cord injured rats with demyelination plus Schwann cell transplantation and assessed neurite outgrowth in a quantifiable model of axonal regeneration. Axonal injuries of differing severity were induced in the dorsal funiculus of adult rats using a micromanipulator-controlled Scouten knife. Demyelinated regions were produced so as to overlap with the injury site by the injection of galactocerebroside antibodies plus complement one segment cranial to the axonal injury site. Schwann cells were isolated from the sciatic nerve, expanded in vitro, and transplanted into the injury site 1 day later. Animals were killed after an additional 7 days. Schwann cells were evenly distributed throughout the region of demyelination, which extended 6-7 mm cranial to the axonal injury site. The severity of axonal injury was quantified by counting degenerate axons in transverse resin sections. The degree of axonal regeneration was assessed by an electron microscopic analysis of growth cone frequency and distribution relative to the site of axonal injury. Quantification of growth cones at a distance from the site of axonal injury indicated a strong linear relationship (P < 0.001) between the number of growth cones and the number of severed axons; the ratio of growth cones to severed axons was increased by 26.5% in demyelinated plus transplanted animals compared to demyelinated animals without a transplant. Furthermore, only the demyelinated plus transplanted animals contained growth cones associated with myelin in white matter immediately outside of the region of complete demyelination. Growth cones were absent in transplanted-only animals at a distance from the site of axonal injury. These findings indicate that combined demyelination plus Schwann cell transplantation therapy enhances axonal regeneration following injury and suggests that growth cones are able to overcome myelin-associated inhibitors of neurite outgrowth in the presence of trophic support.

Topics: Age Factors; Animals; Antibodies; Axons; Axotomy; Complement System Proteins; Demyelinating Diseases; Female; Galactosylceramides; Growth Cones; Microscopy, Electron; Myelin Sheath; Nerve Regeneration; Oligodendroglia; Rats; Rats, Sprague-Dawley; Schwann Cells; Spinal Cord; Spinal Cord Injuries

Strategies to increase the extent of axonal regeneration in the adult CNS must address an array of intrinsic and environmental factors which influence neuritic outgrowth. In order to develop an in vivo model of axonal regeneration in which potential therapies may be assessed, we have quantified growth cones within demyelinated regions in the dorsal funiculus of the spinal cord, following a discrete axotomy. Demyelinated lesions were produced by the intraspinal injection of galactocerebroside antibodies plus serum complement proteins. Axonal integrity was not compromised by the demyelination protocol. Axonal injury was induced at the caudal extent of the demyelinated region using a micromanipulator-controlled Scouten knife. The severity of axonal injury was varied in different animals at the time of surgery and was quantified 8 days later by counting degenerate axons in transverse 1-microm resin sections. Evidence of axonal regeneration within these animals was assessed by an electron microscopic analysis of growth cone frequency and position relative to the site of axotomy. Growth cones were identified within the region of demyelination only; no growth cones were identified within the dorsal column white matter adjacent to the demyelinated region, or rostral or caudal to the region of demyelination, or in animals with an injury but no demyelination. Quantification of growth cones within regions of demyelination indicated a strong linear relationship (P < 0.001) between the number of growth cones and the number of axons severed. These findings indicate that demyelination facilitates axonal regeneration in the adult rat CNS and illustrate a quantifiable method of assessing axonal regeneration.

Topics: Age Factors; Animals; Axons; Axotomy; Demyelinating Diseases; Female; Galactosylceramides; Laminectomy; Microscopy, Electron; Myelin Proteins; Nerve Regeneration; Neurites; Oligodendroglia; Rats; Rats, Sprague-Dawley; Spinal Cord

Vertebrate myelin is enriched in the lipid galactocerebroside (GalC) and its sulfated derivated sulfatide. To understand the in vivo function of these lipids, we analyzed myelination in mice that contain a null mutation in the gene encoding UDP-galactose:ceramide galactosyltransferase, the enzyme responsible for catalyzing the final step in GalC synthesis. Galactolipid-deficient myelin is regionally unstable and progressively degenerates. At postnatal day 30, demyelination is restricted to the midbrain and hindbrain, but by postnatal day 90, it spreads throughout the central nervous system. Activated microglial cells and reactive astrocytes appear with the loss of myelin in older animals. Nonetheless, major myelin protein gene mRNA levels are normal throughout the life of these animals, suggesting that widespread oligodendrocyte death is not the primary cause of demyelination. The developmental switch in myelin-associated glycoprotein isoform expression, however, does not occur normally in these mice, suggesting an alteration in oligodendrocyte maturation. Taken together, these findings indicate that GalC and sulfatide are required for the long-term maintenance of myelin and that their absence may have subtle effects on the development of oligodendrocytes.

Topics: Animals; Brain; Demyelinating Diseases; Galactosylceramides; Galactosyltransferases; Ganglioside Galactosyltransferase; Gene Expression Regulation, Developmental; Mice; Mice, Knockout; Mice, Neurologic Mutants; Myelin Proteins; Myelin Sheath; Myelin-Associated Glycoprotein; Nerve Tissue Proteins; Oligodendroglia; Protein Isoforms; RNA, Messenger; Sulfoglycosphingolipids

We previously observed that the transient developmental suppression of myelination or disruption of mature myelin, by local intraspinal infusion of serum complement proteins along with a complement-fixing, myelin-specific antibody (e.g., anti-Galactocerebroside), facilitated avian brainstem-spinal axonal regeneration after spinal transection. We now report the effects of similar immunological protocols on axonal regeneration in the injured adult rat spinal cord. After a lateral hemisection injury of the T10 spinal cord, infusion of the above reagents, over 14 days at T11, facilitated the regeneration of some brainstem-spinal axons. The hemisection lesion enabled comparisons between the retrograde labeling within an injured brainstem-spinal nucleus and the uninjured contralateral homologue. The brainstem-spinal nucleus examined in detail was the red nucleus (RN), chosen for its relatively compact descending pathway within the dorsolateral cord. Comparing the number of labeled neurons within each RN, of an experimentally myelin suppressed animal, indicated that approximately 32% of injured rubrospinal projections had regenerated into the caudal lumbar cord. In contrast, control-treated animals (e.g., PBS vehicle alone, GalC antibody alone, or serum complement alone) showed little or no axonal regeneration. We also examined the ultrastructural appearance of the treated cords. We noted demyelination over 1-2 segments surrounding the infusion site (T11) and a further two segments of myelin disruption (delamination) on either side of the demyelinated zone. The demyelination is an active process (< 3 days) with microglia and/or macrophages engulfing myelin. Thus, the facilitation of axonal regeneration through the transient suppression of CNS myelin may be fundamental to all higher vertebrates.

Topics: Animals; Antibodies; Axotomy; Brain Stem; Complement System Proteins; Demyelinating Diseases; Female; Fluorescent Dyes; Galactosylceramides; Histocytochemistry; Myelin Sheath; Nerve Regeneration; Rats; Rats, Sprague-Dawley; Red Nucleus; Spinal Cord; Stilbamidines

In order to investigate the remyelinating potential of mature oligodendrocytes in vivo, we have developed a model of demyelination in the adult rat spinal cord in which some oligodendrocytes survive demyelination. A single intraspinal injection of complement proteins plus antibodies to galactocerebroside (the major myelin sphingolipid) resulted in demyelination followed by oligodendrocyte remyelination. Remyelination was absent when the spinal cord was exposed to 40 Grays of x-irradiation prior to demyelination, a procedure that kills dividing cells. Quantitative Rip immunohistochemical analysis revealed a similar density of surviving oligodendrocytes in x-irradiated and nonirradiated lesions 3 days after demyelination. Rip and bromodeoxyuridine double immunohistochemical analysis of demyelinated lesions indicated that Rip+ oligodendrocytes did not divide as an acute response to demyelination. Oligodendrocytes were also identified by Rip immunostaining and electron microscopy at late time points (3 weeks) within x-irradiated areas of demyelination. These oligodendrocytes extended processes that engaged axons, and on occasion formed myelin membranes, but did not lay down new myelin sheaths. These studies demonstrate that (a) oligodendrocytes that survive within a region of demyelination are not induced to divide in the presence of demyelinated axons, and (b) fully-differentiated oligodendrocytes are therefore postmitotic and do not contribute to remyelination in the adult CNS.

Topics: Animals; Antibodies; Cell Differentiation; Cell Division; Cell Survival; Complement System Proteins; Demyelinating Diseases; Female; Galactosylceramides; Immunohistochemistry; Microscopy, Electron; Mitosis; Myelin Sheath; Oligodendroglia; Rats; Rats, Sprague-Dawley; Spinal Cord; X-Rays

Myelin basic protein (MBP), a major protein of myelin, is thought to play an important role in myelination, which occurs postnatally in mouse. Here we report that the MBP gene is expressed from the 12th embryonic day in mouse brain and that most of the predominant embryonic isoforms are not those reported previously. These isoforms have a deletion of a sequence encoded by exon 5 from the well-known isoforms. These isoforms show a unique developmental profile, i.e., they peak in the embryonic stage and decrease thereafter. In jimpy, a dysmyelinating mutant, the level of these isoforms remains high even in the older ages. These results suggest that MBPs have heretofore unknown functions unrelated to myelination before myelinogenesis begins. The possible presence of 18 isoforms of MBP mRNA, which are classified into at least three groups with different developmental profiles, is also reported here.

Topics: Animals; Base Sequence; Brain; Cloning, Molecular; Demyelinating Diseases; Exons; Galactosylceramides; Gene Expression; Male; Mice; Mice, Inbred ICR; Mice, Neurologic Mutants; Molecular Sequence Data; Mutation; Myelin Basic Protein; Nucleic Acid Hybridization; Oligodendroglia; Polymerase Chain Reaction; Promoter Regions, Genetic; RNA, Messenger

There is suggestive but inconclusive evidence for a contribution of T cells and antimyelin antibodies to the pathogenesis of the Guillain-Barré polyneuropathy. We have studied the potential synergism of cellular and humoral immunity in the adoptive transfer model of EAN. EAN was induced in Lewis rats by injecting varying doses of P2 peptide (SP26)-sensitized T lymphocytes. Disease severity was dose-dependent. The addition of intravenous GC-AB to a subclinical dose of SP26-sensitized T cells resulted in overt clinical disease and markedly enhanced demyelination. Intravenous injection of antibody alone had no effect. We conclude that activated neuritogenic T cells, while entering into peripheral nerves, alter the blood-nerve barrier, which gives circulating demyelinating antibodies access to the endoneurium. The observations support the concept of a synergistic role of T-cell autoimmunity and humoral responses in the inflammatory demyelination of Lewis rat EAN.

Topics: Animals; Antibodies; Axons; Demyelinating Diseases; Edema; Female; Galactosylceramides; Ganglia, Spinal; Immunization, Passive; Lymphocyte Activation; Macrophages; Male; Motor Neurons; Myelin Basic Protein; Myelin P2 Protein; Nerve Degeneration; Neurilemma; Neuritis, Autoimmune, Experimental; Neurons, Afferent; Rabbits; Rats; Rats, Inbred Lew; Sciatic Nerve; Spinal Cord; Spinal Nerve Roots; T-Lymphocytes

The effects of psychosine on the metabolism of myelin associated glycolipids such as galactocerebroside and sulfatide in mouse brain cell cultures were investigated in order to clarify the mechanism of demyelination in globoid cell leukodystrophy (Krabbe's disease). The incorporation of 3H-galactose into cerebroside and sulfatide was studied in the presence of psychosine (1-3 micrograms/ml medium). These data indicated that psychosine inhibited the incorporation of 3H-galactose into cerebroside and sulfatide not in astroglial cell culture but in oligodendroglial cell culture. Oligodendrocytes produce myelin in the central nervous system, and cerebroside and sulfatide are major components of myelin. These results suggest that psychosine influences the lipid metabolisms of myelin and subsequently leads to the demyelination in Krabbe's disease.

Topics: Animals; Cells, Cultured; Demyelinating Diseases; Galactosylceramides; Leukodystrophy, Globoid Cell; Mice; Oligodendroglia; Psychosine; Sphingosine; Sulfoglycosphingolipids

Myelin in PNS is multi-layered membranes formed by Schwann cells, and surrounds axon. Destruction of myelin sheath results in demyelination and disturbance of nerve conduction. In PNS, Charcot-Marie-Tooth disease, certain lipidoses, Guillain-Barré syndrome, lead poisoning, compression and some metabolic neuropathies can produce demyelination. In these diseases, GBS is thought to be resulted from abnormalities of immune mechanism. Recently, autoantibodies against Gal-C, P2 and GM1, and complement fixing antibodies against PNS myelin are found in some of GBS patient sera. Here, I present studies on effector mechanism of PNS demyelination using models produced by application of Galactocerebroside (Gal-C) antibodies to PNS. Mainly, three types of effector mechanisms are involved in Gal-C antibody-induced demyelination. In abundance of antibodies, complement-mediated demyelination is at work. When complements are absent, antibody dependent macrophage-mediated demyelination can be involved. Thirdly, myelin once damaged by oxidants and etc can be opsonized by antibodies and C3b, and phagocytized by macrophages. These processes may be operating in such diseases like GBS and CIDP.

Topics: Animals; Antibodies; Complement System Proteins; Demyelinating Diseases; Galactosylceramides; Haplorhini; Macrophages; Myelin Proteins; Phagocytosis; Polyradiculoneuropathy; Rabbits

The cytotropism of two strains, GDVII and DA, of Theiler's murine encephalomyelitis viruses (TMEV) was studied in the oligodendrocyte-enriched murine neural cell cultures. Both GDVII and DA caused cytopathic effects in the neural cell cultures, and double immunostaining for galactocerebroside (Gal-Cer), a marker molecule for oligodendrocyte, and viral antigens disclosed a dual expression of Gal-Cer and viral antigens in over 80% of cells in both cultures 24 h after infection with either GDVII or DA. The kinetics of cell-free and cell-associated infectivity were not significantly different between two cultures. These in vitro observations suggest that neither replication in oligodendrocyte nor cell-associated infectivity is a sole factor in discriminating those two subgroups of TMEV with regard to the demyelinating activity, and that virus cell binding may play an important role in virus persistence and TMEV-induced demyelination.

Topics: Animals; Antigens, Viral; Cell Movement; Cells, Cultured; Cytopathogenic Effect, Viral; Demyelinating Diseases; Female; Galactosylceramides; Kinetics; Maus Elberfeld virus; Mice; Mice, Inbred C3H; Neurons; Oligodendroglia; Species Specificity; Virus Replication

The mechanism of antibody-mediated central nervous system (CNS) demyelination in vivo was studied using rabbit eyes. Injection of anti-galactocerebroside (Gal C) antiserum alone into the normal rabbit vitreous body induced demyelination in the epiretinal myelinated fibers. This activity of the antiserum disappeared after heat treatment at 56 degrees C for 30 min and was restored by supplement of normal fresh serum, suggesting the complement dependency of the activity. Heated anti-Gal C antiserum could induce demyelination, however, when macrophages were introduced by injecting lymphocyte supernatants together with antiserum. Electron microscopic study revealed penetration of macrophage process between the myelin lamella. These findings suggest that the cooperation of anti-Gal C antibody and macrophage can result in the antibody-dependent cell-mediated demyelination in the absence of complement. Because oligodendrocyte generally appeared normal, myelin, not oligodendrocyte is suspected to be the primary target by anti-Gal C antiserum. In contrast, neither anti-MBP nor anti-gangliosides antiserum had the in vivo-demyelinating activity. In CNS demyelination by anti-Gal C antibody, complement-mediated and macrophage-mediated mechanisms may cooperate in varying degrees.

Topics: Animals; Autoantibodies; Central Nervous System Diseases; Cerebrosides; Demyelinating Diseases; Eye; Galactosylceramides; Male; Rabbits

To study the pathophysiology of immunologically mediated demyelination in the central nervous system (CNS), we injected 20 to 30 microliters of polyclonal antigalactocerebroside serum (AGC) into the lower thoracic dorsal column of the spinal cord in 20 Wistar rats. AGC-injected spinal cords contained areas of fascicular demyelination adjacent to the focus of axonal degeneration at the injection site. Somatosensory evoked potentials were recorded serially after tibial nerve stimulation. In 85% of AGC-injected animals, the following characteristics were observed by 3 days after injection: (1) decreased amplitude of the cortically generated potential (P15); (2) failure of transmission of high-frequency (50 Hz) impulses (rate-dependent block); (3) delayed conduction velocity of the compound action potentials through the lesion. None of these changes was seen in 90% of 20 rats injected with normal saline or control rabbit sera. In 7 rats with acrylamide-induced axonopathy or wallerian degeneration, the rate-dependent block was not observed. The onset of clinical symptoms (hindlimb ataxia) in AGC-injected rats was best correlated with development of the rate-dependent block. Clinical recovery was observed by 14 days after injection concurrent with restoration of P15 amplitude, when the rate-dependent block and decreased conduction velocities were unchanged. High-frequency-resistant conduction was re-established much later than clinical recovery in 3 rats. These findings suggest that failure of high-frequency impulse transmission may produce clinical symptoms and that a central adaptive mechanism to remodulated trains of impulses plays a role in clinical recovery from CNS demyelination.

Topics: Acrylamide; Acrylamides; Animals; Central Nervous System Diseases; Demyelinating Diseases; Evoked Potentials, Somatosensory; Galactosylceramides; Immune Sera; Injections; Neural Conduction; Rats; Reaction Time; Time Factors; Wallerian Degeneration

The pathology of demyelination in rabbits with experimental allergic neuritis (EAN) or galactocerebroside-induced neuritis was compared to that in rabbits inoculated with either an emulsion of lipid haptens (gangliosides, lecithin and cholesterol) and Freund's complete adjuvant or Freund's complete adjuvant (FCA) alone. In rabbits inoculated with bovine peripheral myelin in FCA, perivenular demyelination associated with infiltrates of lymphocytes and macrophages occurred after 30 days, while those animals inoculated with galactocerebroside (GC) in Freund's adjuvant did not develop lesions until 60-90 days. GC rabbits had demyelination and severe nerve edema without cellular infiltrates. In rabbits inoculated with FCA alone, demyelination was restricted to ganglia and proximal nerve roots. Myelin basic protein (MBP) and GC antibodies from EAN, GC and lipid hapten-inoculated rabbits were detected by ELISA in sera at all post-inoculation time points. Appreciable P0 and P2 antibody titers were detected only in EAN animals. The results indicate that Freund's complete adjuvant alone or in combination with lipid haptens is capable of producing neuropathic effects in the rabbit independent of those produced by EAN or galactocerebroside neuritis.

Topics: Animals; Antibodies; Demyelinating Diseases; Female; Freund's Adjuvant; Galactosylceramides; Haptens; Lipids; Myelin Basic Protein; Myelin Sheath; Neuritis; Peripheral Nerves; Rabbits

To determine if galactocerebroside (GalC) is a target antigen in the human demyelinating disorders multiple sclerosis, Guillain-Barré syndrome, and chronic demyelinating inflammatory polyneuropathy, we examined the serum and cerebrospinal fluid from patients with these disorders and from control subjects using four assay systems. In none of these assays could we detect significant differences in anti-GalC antibody titer between patients with demyelinating diseases and normal subjects or patients with other neurological disorders. Our data suggest that there is no humoral immune response to GalC in human demyelinating disorders.

Topics: Antibodies; Cerebrosides; Demyelinating Diseases; Enzyme-Linked Immunosorbent Assay; Galactosylceramides; Humans; Radioimmunoassay

Experimental demyelination was induced by intraneural injection of anti-galactocerebroside serum into the sciatic nerves of rats. Schwann cells undergoing mitotic division were observed between days 3 to 9 after the injection and demyelinated segments were still associated with macrophages. Dividing Schwann cells were often present in association with both unmyelinated and myelinated fibers. Whether or not, daughter Schwann cells migrate along the same fiber towards neighboring demyelinated segments remains unclear. When Schwann cells attached to axon membranes of demyelinated segments were studied at later time points, they were present in clusters randomly at various regions of the segments. There was no proximo-distal gradient for the wave of Schwann cell proliferation. Mean Schwann cell internuclear distances were around 40-50 microns at the earliest time of remyelination. Schwann cell redistribution and remyelination progressed regardless of the length of demyelinated segments.

Topics: Animals; Demyelinating Diseases; Disease Models, Animal; Galactosylceramides; Immune Sera; Male; Microscopy, Electron; Mitosis; Peripheral Nervous System Diseases; Rats; Schwann Cells

To clarify the role of nonspecific myelin destruction mediated by delayed type hypersensitivity (DTH) in primary demyelination, DTH to tuberculin was induced within the endoneurium by intraneural injection of purified protein derivative (PPD) or sonicated Mycobacterium tuberculosis into the sciatic nerves of Lewis rats and guinea pigs which had previously been sensitized to tuberculin. The morphological features of the nerves proximal to the site of needle insertion were assessed 5 days after injection. By changing the PPD concentration of solution for intraneural injection, various degrees of DTH reaction could be produced in the nerve. Infiltration of mononuclear cells including macrophages was observed around the vessels and in the vicinity of the myelin sheaths. Although nonspecific damage of axons, myelin sheaths and Schwann cells was observed in areas heavily infiltrated with inflammatory cells, primary demyelination was hardly recognized. Another group of Lewis rats previously immunized with galactocerebroside (GC), the major glycolipid hapten of myelin, in Freund's complete adjuvant received intraneural injection of PPD or GC liposomes. Neither cellular nor humoral immunity to GC was detected in these rats. The nerves injected with GC liposomes showed no inflammatory cell infiltration except for a few macrophages containing liposomes and those injected with PPD showed infiltration of mononuclear cells without primary demyelination. Our findings reveal that nonspecific myelin destruction induced by DTH does not play an important role in immune-mediated demyelination.

Topics: Animals; Demyelinating Diseases; Freund's Adjuvant; Galactosylceramides; Guinea Pigs; Hypersensitivity, Delayed; Microscopy, Electron; Myelin Sheath; Peripheral Nerves; Rats; Rats, Inbred Lew; Tuberculin

A model of immune-mediated optic nerve demyelination is described. Micro-injection of small volumes (less than 5 microliter) of high titer polyclonal anti-Gal-C serum into the cat optic nerve resulted in a focal, highly selective demyelinative lesion followed by remyelination. Demyelination appears to be due to a dual effect on myelin and on oligodendrocytes. The numbers of these cells within the lesion were initially reduced but subsequently increased as remyelination occurred.

Topics: Animals; Cats; Cerebrosides; Demyelinating Diseases; Disease Models, Animal; Galactosylceramides; Immune Sera; Microscopy, Electron; Optic Nerve; Optic Nerve Diseases

To study the demyelinative effects of antibodies to glycolipids, well-myelinated cultures of mouse spinal cord tissue were exposed to antisera against galactocerebroside and two gangliosides (GM1 and GM4), as well as to anti-white matter antiserum. The demyelinative process was evaluated by morphologic and biochemical techniques. Cultures exposed to anti-white matter and anti-galactocerebroside antisera showed the most marked changes. These consisted of a decrease in the number of oligodendroglial cells and dissolution and phagocytosis of myelin. Concomitantly, the activity of 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNPase) was decreased by 60-70%. This occurred within 24 h of exposure to a relatively low concentration of serum (10%). Cultures exposed to anti-GM1 and anti-GM4 antisera showed similar changes but to a lesser degree. The CNPase activity was decreased about 30% within 48 h of exposure to a 25% concentration of these antisera. This diminution represents about a 20% loss of myelin, an observation corroborated by electron microscopy where myelin but not oligodendroglial cell loss was observed. Therefore, in addition to anti-galactocerebroside activity, which was previously found to be the major antibody responsible for the demyelinating activity induced by anti-whole CNS tissue antiserum, these data suggest that antibodies to gangliosides like GM1 and GM4 might also play a role in immune-mediated demyelination, including perhaps, the human demyelinating diseases.

Topics: Animals; Autoimmune Diseases; Culture Techniques; Demyelinating Diseases; G(M1) Ganglioside; Galactosylceramides; Gangliosides; Glycolipids; Immune Sera; Mice; Microscopy, Electron; Spinal Cord