In vivo expression of major histocompatibility complex molecules on oligodendrocytes and neurons during viral infection

Demyelination in multiple sclerosis and in animal models is associated with infiltrating CD8+ and CD4+ T cells. Although oligodendrocytes and axons are damaged in these diseases, the roles T cells play in the demyelination process are not completely understood. Antigen-specific CD8+ T cell lysis of target cells is dependent on interactions between the T cell receptor and major histocompatibility complex (MHC) class I-peptide complexes on the target cell. In the normal central nervous system, expression of MHC molecules is very low but often increases during inflammation. We set out to precisely define which central nervous system cells express MHC molecules in vivo during infection with a strain of murine hepatitis virus that causes a chronic, inflammatory demyelinating disease. Using double immunofluorescence labeling, we show that during acute infection with murine hepatitis virus, MHC class I is expressed in vivo by oligodendrocytes, neurons, microglia, and endothelia, and MHC class II is expressed only by microglia. These data indicate that oligodendrocytes and neurons have the potential to present antigen to T cells and thus be damaged by direct antigen-specific interactions with CD8+ T lymphocytes.     

Detailed in vivo analysis of interferon-gamma induced major histocompatibility complex expression in the the central nervous system: astrocytes fail to express major histocompatibility complex class I and II molecules

To recognize and respond immunologically to foreign antigens, T lymphocytes require the presentation of foreign peptides by MHC molecules. To determine which cells of the central nervous system (CNS) are capable of expressing MHC molecules, we used confocal microscopy and dual immunofluorescence with cell-specific and MHC-specific antibodies to study brain sections of adult mice. We took advantage of transgenic mice that initiate CNS-specific expression of IFN-gamma at 8 weeks of age. This inflammatory cytokine is a strong inducer of MHC expression both in culture and in vivo. From this analysis, we clearly found MHC class I and II expression on endothelial, microglial, and oligodendrocyte cell types, but did not find astrocytes or neurons capable of expressing either MHC class I or II molecules under these conditions. This finding suggests that, although microglia and oligodendrocytes may participate in the antigen presentation process in the organism, we found no in vivo evidence to support the concept that astrocytes act as antigen-presenting cells.     

MHC gene related effects on microglia and macrophages in experimental autoimmune encephalomyelitis determine the extent of axonal injury

Myelin-oligodendrocyte-glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in rats is a chronic inflammatory demyelinating disease of the central nervous system (CNS) strongly mimicking multiple sclerosis (MS). We determined the involvement of macrophages and microglia in the lesions of MOG-EAE in relation to different major histocompatibility complex (MHC, RT1 in rat) haplotypes. We used intra-RT1 recombinant rat strains with recombinations between the RT1a and RT1u haplotypes on the disease permissive LEW non-MHC genome. Activated microglia and macrophages were identified morphologically and by expression of ED1 and allograft inhibitory factor-1 (AIF-1), and differentiated by their morphological phenotype. White matter lesions contained more macrophages and less microglia compared to grey matter lesions. Similarly active lesions were mainly infiltrated by macrophages, while microglia were abundant in inactive demyelinated plaques. In addition, we found a highly significant genetic association between a macrophage or microglia dominated lesional phenotype, which was independent from location and activity of the lesions. This was not only the case in demyelinating plaques of chronic EAE, but also in purely inflammatory lesions of acute passive transfer EAE. Rat strains with an u-haplotype in both the Class II and the telomeric non-classical Class I region revealed inflammatory and demyelinating lesions, which were dominated by activated microglia. The a-haplotype in any of these regions was associated with macrophage dominated lesions. A comparison of lesions, exactly matched for stages of demyelinating activity in these different rat strains, showed that in spite of a similar extent of demyelination, axonal injury was significantly less in microglia compared to macrophage dominated lesions. Thus, our studies document a genetic influence of the MHC-region on the relative contribution of macrophages versus microglia in the pathogenesis of EAE.     

Induction of human leukocyte antigen-A,B,C and -DR on cultured human oligodendrocytes and astrocytes by human gamma-interferon

gamma-Interferon (IFN-gamma) is known to induce expression of major histocompatibility complex (MHC) class II antigens on murine astrocytes and MHC class I antigens on murine oligodendrocytes. We studied whether the human IFN-gamma could induce the expression of Human Leukocyte Antigen (HLA)-A, B, C and -DR antigens on cultured human glia from autopsied brain white matter tissue. HLA-A, B, C antigens were induced on both human astrocytes and oligodendrocytes, whereas HLA-DR antigens were induced only on some astrocytes. From these results, it is suggested that IFN-gamma affects the expression of MHC class I and class II antigens on astrocytes and oligodendrocytes derived from human brain. The relationship between the induction of MHC class I and class II antigens by IFN-gamma and the pathogenesis of multiple sclerosis is discussed.     

Elevated neuronal expression of CD200 protects Wlds mice from inflammation-mediated neurodegeneration

Axonal damage secondary to inflammation is likely the substrate of chronic disability in multiple sclerosis and is found in the animal model of experimental autoimmune encephalomyelitis (EAE). Wld(s) mice have a triplication of the fusion gene Ube4b/Nmnat and a phenotype of axon protection. Wld(s) mice develop an attenuated disease course of EAE, with decreased demyelination, reduced axonal pathology, and decreased central nervous system (CNS) macrophage and microglial accumulation. We show that attenuated disease in Wld(s) mice was associated with robust constitutive expression of the nonsignaling CD200 molecule on neurons in the CNS compared with control mice. CD200 interacts with its signaling receptor CD200R, which we found to be expressed on microglia, astrocytes, and oligodendrocytes at similar levels in control and Wld(s) mice. Administration of blocking anti-CD200 antibody to Wld(s) mice abrogated disease attenuation and was associated with increased CNS inflammation and neurodegeneration. In vitro, Wld(s) neuronal cultures were protected from microglial-induced neurotoxicity compared with control cultures, but protection was abrogated by anti-CD200 antibody. The CD200-CD200R pathway plays a critical role in attenuating EAE and reducing inflammation-mediated damage in the CNS. Strategies that up-regulate the expression of CD200 in the CNS or molecules that ligate the CD200R may be relevant as neuroprotective strategies in multiple sclerosis.     

Infection of human T-lymphotropic virus type I to astrocytes in vitro with induction of the class II major histocompatibility complex

To clarify the pathogenesis of human T-lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM), we examined whether HTLV-I infects normal human glial cells in vitro with induction of the major histocompatibility complex (HMC) class II antigen by immunofluorescence method. It was found that about 10% of astrocytes were infected with HTLV-I with induction of class II MHC antigen. Fluorescence-conjugated HTLV-I was adsorbed to 10% of astrocytes. On the contrary, there was no class II MHC antigen expression and very few HTLV-I infection on oligodendrocytes. We speculated that in patients with HAM, HTLV-I-specific, MHC class II antigen restricted, activated CD4+ cells could damage the MHC class II antigen + HTLV-I-infected astrocytes, leading to the disturbance of blood-brain barrier and to the destructive lesion in the central nervous system.     

Augmentation of major histocompatibility complex class I and ICAM-1 expression on glial cells following measles virus infection: evidence for the role of type-1 interferon.

An intracellular staining procedure for the cytoskeletal marker, glial fibrillary acidic protein of astrocytes, has been developed which allows flow cytometric phenotyping of astrocytes within complex mixtures of glial cells. Employing this technique, we show here that measles virus infection of rat mixed glial cell cultures results in a rapid augmentation of major histocompatibility complex (MHC) class I and ICAM-1 on the majority of astrocytes in culture. MHC class I levels are increased on macrophages/microglia but ICAM-1 expression is not normally affected on this cell type. Some MHC class II induction is also observed after virus infection but only on astrocytes. A type-I interferon (IFN)-inducible protein, Mx, was identified in cultured glial cells after infection. Qualitatively comparable MHC class I and ICAM-1 enhancement after addition of type-I IFN, supports the conclusion that this cytokine(s) released as a result of virus infection, is responsible for alterations in the expression of molecules on glial cells, that are involved in T cell recognition. Astrocytes after viral infection were more susceptible to alloantigen-specific cytotoxic T lymphocytes and cytotoxic T lymphocyte activity was substantially reduced in the presence of mAb specific for MHC class I, ICAM-1 and LFA-1 but not MHC class II. The relevance of these findings to T cell recognition of virus-infected cells in the central nervous system is discussed.     

Caspase-mediated oligodendrocyte cell death in the pathogenesis of autoimmune demyelination

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. MS is believed to be an autoimmune disorder mediated by activated immune cells such as T- and B-lymphocytes and macrophages/microglia. Lymphocytes are primed in the peripheral tissues by antigens, and clonally expanded cells infiltrate the CNS. They produce large amounts of inflammatory and cytokines that lead to demyelination and axonal degeneration. Although several studies have shown that oligodendrocytes (OLGs), the myelin-forming glial cells in the CNS, are sensitive to cell death stimuli, such as cytotoxic cytokines, anti-myelin antibodies, nitric oxide, and oxidative stress, in vitro, the mechanisms underlying injury to the OLGs in MS/EAE remain unclear. Transgenic mice that express the anti-apoptotic protein specifically in OLGs and caspase-11-deficient mice are significantly resistant to EAE induction. Histopathological analyses show that the number of caspase-activated OLGs and dead OLGs are reduced in the CNS of these mice. The numbers of infiltrating immune cells and the amounts of cytokines are also markedly reduced in EAE lesions. Therefore, caspase-mediated OLG death leads to the exacerbation of demyelination and the deterioration of neurological manifestations by inducing local inflammatory events.     

Antigen presentation in brain: MHC induction on brain endothelium and astrocytes compared

Primary cultures of rat brain endothelium and astrocytes were cultured in vitro, stimulated with interferon-gamma (IFN gamma), and the levels of MHC expression were then measured by an enzyme immunoassay (EIA). Class I expression is enhanced on brain endothelium by Day 1 following stimulation, and attains a plateau level of expression. Class II is normally absent, but starts to appear at Day 2, and continues to increase until Day 5. Class II rat I-A homologue is induced much more strongly than I-E, and the dose-response curves show that I-A expression is dependent on interferon dose within the range 2-500 units/ml, whereas class I enhancement is uniform over this range. The endothelium was compared with astrocytes, in regard to MHC induction. The surface density of class I and class II molecules was lower on the astrocytes in all conditions, and both class I enhancement and class II induction were in some cases slower to appear than on endothelium treated similarly. We also describe a pre-astrocytic cell line, C9, which shows strong I-E expression when stimulated with IFN gamma, but is apparently unable to express I-A. The implications of these findings for the development of immune reactions in the brain are discussed.     

Expression and regulation of major histocompatibility complex on neural stem cells and their lineages

The expression of major histocompatibility complex (MHC) antigens on neural stem cells (NSCs) and their lineages is tightly related to the fate of these cells as grafts in allogenic transplantation. In this study, we observed that NSCs derived from embryonic rat forebrain expressed MHC class I and class II molecules at a low level, whereas the cells differentiated from NSCs, including neurons, astrocytes, and oligodendrocytes, lost their MHC expression. However, a proinflammatory factor, interferon-gamma (IFN-gamma), could induce and up-regulate the expression of MHC in both NSCs and their differentiated lineages in vitro. These results suggest that predifferentiating NSCs into lineage-limited cells prior to transplantation combined with controlling the local production of proinflammatory cytokines moderately may potentially benefit the survival of transplants.     

Cannabinoid receptor and N-acyl phosphatidylethanolamine phospholipase D--evidence for altered expression in multiple sclerosis

Cannabinoids have been shown to have a beneficial effect in both animal models of multiple sclerosis (MS) and human disease, although the mechanisms of action are unclear. We examined expression of the major cannabinoid receptors [(CBRs) cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2)] and a key enzyme involved in synthesis of the endocannabinoid anandamide [N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD)] in autopsy brain samples from patients with MS. CB1 was expressed in neurons, injured axons, oligodendrocytes, macrophages/microglia, some astrocytes, endothelial cells, smooth muscle cells and pericytes. CB2 and NAPE-PLD were localized to cerebral endothelial cells, pericytes, smooth muscle cells, astrocytes and macrophages/microglia. NAPE-PLD immunoreactivity was also seen in neurons. Endothelial CB2 expression was greatest in chronic inactive plaques, and in areas was seen in segments of endothelium where the endothelial expression of adhesion molecules (VCAM-1 and ICAM-1) was focally undetectable, and was often expressed in areas of blood-brain barrier damage. Vascular density was increased in chronic active plaques and normal-appearing white matter compared with controls. These data support findings from animal models which suggest a role for the endocannabinoid system in the MS, particularly in the regulation of endothelial leukocyte adhesion and the cellular response to injury.     

Demyelination, and remyelination by Schwann cells and oligodendrocytes after kainate-induced neuronal depletion in the central nervous system.

Excitotoxins are thought to kill neurons while sparing afferent fibers and axons of passage. The validity of this classical conclusion has recently been questioned by the demonstration of axonal demyelination. In addition, axons are submitted to a profound alteration of their glial environment. This work was, therefore, undertaken to reassess axonoglial interactions over time after an excitotoxic lesion in the rat. Ultrastructural studies were carried out in the ventrobasal thalamus two days to 18 months after neuronal depletion by in situ injections of kainic acid. In some cases, lemniscal afferents were identified by using anterograde transport of wheatgerm agglutinin conjugated to horseradish peroxidase from the dorsal column nuclei. Two and four days after kainate injection, numerous dying axons displaying typical signs of Wallerian degeneration were observed in a neuropile characterized by the loss of neuronal somata and dendrites, an increase in number of microglia/macrophages and the disappearance of astrocytes. Ten and 12 days after kainate injection, degenerating axons were no longer observed although myelin degeneration of otherwise unaltered axons was ongoing with an accumulation of myelin remnants in the neuropile. At 16 and 20 days, the demyelination process was apparently complete and axons of different diameters were sometimes packed together. One and two months after kainate injection, the axonal environment changed again: remyelination of large-caliber axons occurred at the same time as reactive astrocytes, oligodendrocytes and numerous Schwann cells appeared in the tissue. Schwann cell processes surrounded aggregates of axons of diverse calibers, ensheathed small ones and myelinated larger ones. Axons were also remyelinated by oligodendrocytes. Horseradish peroxidase-labeled lemniscal afferents could be myelinated by either of the two cell types. After three months, the neuropile exhibited an increase in number of hypertrophied astrocytes and the progressive loss of any other cellular or axonal element. At this stage, remaining Schwann cells were surrounded by a glia limitans formed by astrocytic processes. These data indicate that although excitotoxins are sparing the axons, they are having a profound and complex effect on the axonal environment. Demyelination occurs over the first weeks, accompanying the loss of astrocytes and oligodendrocytes. Axonal ensheathment and remyelination takes place in a second period, associated with the reappearance of oligodendrocytes and recruitment of numerous Schwann cells, while reactive astrocytes appear in the tissue at a slightly later time. Over the following months, astrocytes occupy a greater proportion of the neuron-depleted territory and other elements decrease in number.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mouse hepatitis virus A59 increases steady-state levels of MHC mRNAs in primary glial cell cultures and in the murine central nervous system

Infection of mixed glial cell cultures with mouse hepatitis virus (MHV)-A59 results in an approximately six-fold increase in the level of major histocompatibility complex (MHC) class I mRNA. In situ hybridization of glial cell cultures infected with MHV-A59 again showed enhanced MHC mRNA expression, both in infected and uninfected cells. These results extend our earlier finding that MHC surface antigens are enhanced on astrocytes and oligodendrocytes after MHV-A59 infection and suggest that this enhancement is a result of an increase in the steady-state level of MHC mRNA. We further demonstrate that increases in MHC mRNA occur in the murine central nervous system (CNS) following infection in vivo. Northern blot analysis of RNA from the brains of infected animals showed transient expression of both MHC class I and class II mRNA over the first 14 days of infection. Expression coincided with viral replication and clearance. In situ hybridization of brain sections from infected animals showed that class I and class II expression was widespread throughout all portions of the brain and in uninfected as well as infected cells. Viral RNA, in contrast, was observed in small foci of cells and mostly within the limbic system. Thus enhancement of MHC mRNA was not restricted either to areas of infection or inflammation. The spatial relationship between viral and MHC expression supports our hypothesis that a soluble mediator is involved in the mechanism of the increase in MHC levels. The fact that MHC induction occurs in vivo as well as in vitro suggests MHC may be important in the mechanism of MHV-induced disease.     

Characterization of the inflammatory infiltrate in ovarian dysgerminoma: an immunocytochemical study

The inflammatory infiltrate has been characterized in 10 cases of ovarian dysgerminoma using a panel of antisera to T-cells, B-cells and macrophages. The expression of Class II major histocompatibility complex (MHC) antigens and the distribution of interferons alpha and gamma were also examined. T-lymphocytes were present in all tumours, often closely admixed with neoplastic elements. T-cells in most areas were immunoreactive with gamma interferon. B-cells were generally scanty although germinal centres were present in three tumours. Immunocytochemistry revealed greater numbers of macrophages than had been appreciated on routinely stained sections. Macrophages were closely related to both lymphoid and tumour cells, and many macrophages were immunoreactive for alpha interferon. Class II MHC expression was mainly restricted to macrophages and B-cell areas although occasional T-cells were also stained. Dysgerminoma cells did not express Class II MHC antigens.     

Analysis of murine hepatitis virus (JHM strain) tropism toward Lewis rat glial cells in vitro. Type I astrocytes and brain macrophages (microglia) as primary glial cell targets

The murine hepatitis virus, JHM strain, causes a relapsing subacute demyelinating encephalomyelitis in Lewis rats after intracranial infection. The disease process involves both virus persistence within glial cells and the induction of autoimmunological attack of myelin, however, the relative importance of these features involved in chronic relapsing demyelination remains to be determined. In this report, we analyze the tropism of JHM virus to various neural cell types present within primary Lewis rat central nervous system cultures. Infection of primary cultures with JHM virus revealed that type I astrocytes and brain macrophages are the initial target cells of infection and that the myelin-forming oligodendrocytes are comparatively resistant, becoming infected only rarely through virus mediated cell fusion with previously infected cells. In addition, infection of cultures after removal of oligodendrocytes by various means had no effect on the tropism of JHM virus for the cultures. Cytopathic effects of JHM virus proceed rapidly by cell fusion within the astrocyte-macrophage monolayer, leaving the oligodendrocyte population largely unaffected. Therefore, the highly selective infection of type I astrocytes and macrophages appears to form the basis of JHM virus neurotropism in Lewis rats. These results indicate that JHM virus infection of astrocytes and brain macrophages may be more important in inducing chronic relapsing demyelinating processes than direct infection of the myelin-forming oligodendrocytes. Other possible pathways leading to chronic demyelination in rats involving type I astrocytes and brain macrophages are discussed.     

Regulation of Fc receptor and major histocompatibility complex antigen expression on isolated rat microglia by tumour necrosis factor, interleukin-1 and lipopolysaccharide: effects on interferon-gamma induced activation.

Isolated rat brain microglia display enhanced expression of Fc receptors on treatment with interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and lipopolysaccharide (LPS), whereas major histocompatibility complex (MHC) antigen expression is enhanced only by IFN-gamma. Although TNF and LPS individually have no effect on MHC expression by microglia, they both antagonize IFN-gamma-induced expression. The enhanced expression of Fc receptors observed in the presence of IFN-gamma, TNF or LPS is significantly inhibited by the combination of IFN-gamma with either LPS or TNF. IL-1 alpha has little effect on IFN-gamma-induced MHC or Fc receptor expression by microglia. Peritoneal macrophages behave similarly to microglia, with the notable exception that IL-1 alpha enhances IFN-gamma-induced FcR expression. These observations suggest that the functional activity of microglia during inflammation or demyelination in the central nervous system can be influenced by the changing profile of cytokines present during lesion development.     

Chronic toxic demyelination in the central nervous system leads to axonal damage despite remyelination

The majority of multiple sclerosis lesions fail to remyelinate after chronic demyelinating episodes resulting in neurologic disability. In the current study, chronic demyelination was investigated by using the cuprizone model, a toxic demyelination model. C57BL/6 mice were administered a 0.2% cuprizone diet up to 16 weeks to induce chronic demyelination. For comparison, another group was maintained only for 6 weeks on cuprizone to model acute demyelination. Both groups were analysed regarding the remyelination process after withdrawal of the toxin. Reexpression of myelin proteins after chronic demyelination was reduced by a factor of two as judged by LFB and myelin protein stainings compared to acute demyelination after 2 weeks on remyelination. During chronic demyelination mature oligodendrocytes (Nogo-A positive cells) were severely depleted by 90% compared to age matched controls. Nevertheless, extensive remyelination occurred after withdrawal of cuprizone and was nearly complete after 12 weeks. There was only minimal acute axonal damage as judged by APP staining, with the course of APP positive axons correlating with macrophage/microglia accumulation. Chronic axonal damage detected by SMI-32 positive staining was only seen after chronic demyelination and was still observable during the whole remyelination period. These data suggest that two pattern of axonal injury occur in the cuprizone model.     

Axonal loss and neurofilament phosphorylation changes accompany lesion development and clinical progression in multiple sclerosis

Neuroaxonal damage and loss are increasingly recognized as disability determining features in multiple sclerosis (MS) pathology. However, little is known about the long-term sequelae of inflammatory demyelination on neurons and axons. Spinal cord tissue of 31 MS patients was compared to three amyotrophic lateral sclerosis (ALS) and 10 control subjects. MS lesions were staged according to the density of KiM-1P positive macrophages and microglia and the presence of myelin basic protein (MBP) positive phagocytes. T cells were quantified in the parenchyma and meninges. Neuroaxonal changes were studied by immunoreactivity (IR) for amyloid precursor protein (APP) and variably phosphorylated neurofilaments (SMI312, SMI31, SMI32). Little T cell infiltration was still evident in chronic inactive lesions. The loss of SMI32 IR in ventral horn neurons correlated with MS lesion development and disease progression. Similarly, axonal loss in white matter (WM) lesions correlated with disease duration. A selective reduction of axonal phosphorylated neurofilaments (SMI31) was observed in WM lesions. In ALS, the loss of neuronal SMI32 IR was even more pronounced, whereas the relative axonal reduction resembled that found in MS. Progressive neuroaxonal neurofilament alterations in the context of chronic inflammatory demyelination may reflect changes in neuroaxonal metabolism and result in chronic neuroaxonal dysfunction as a putative substrate of clinical progression.     

Mouse hepatitis virus pathogenesis in the central nervous system is independent of IL-15 and natural killer cells

Infection by the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in an acute encephalomyelitis associated with demyelination. T cells are critical in controlling viral replication, but also contribute to central nervous system (CNS) pathogenesis. To reveal a role for innate effectors in anti-viral immunity and neurological disease, JHMV pathogenesis was studied in mice deficient in interleukin-15 (IL-15-/-) and natural killer (NK) cells. Clinical disease, CNS inflammation and demyelination in infected IL-15-/- mice were similar to wild-type mice. Despite the absence of NK cells and suboptimal CD8+ T cell responses, IL-15-/- mice controlled JHMV replication as efficiently as wild-type mice. Similar kinetics of class I and class II upregulation on microglia further suggested no role of NK cells in regulating major histocompatibility complex (MHC) molecule expression on resident CNS cells. IL-15 and NK cells thus appear dispensable for anti-viral immunity and CNS pathogenesis during acute JHMV infection.     

Cellular localization of TRPC3 channel in rat brain: preferential distribution to oligodendrocytes

In the present work we describe the cellular localization of TRPC3 in non-excitable cells as compared to the neurons in normal rat brain. We performed a double labeling study for TRPC3 and one of the following cell-specific markers: mouse anti-glial fibrillary acidic protein (GFAP) for astrocytes; mouse anti-RIP for oligodendrocytes, or mouse anti-OX42 for microglia, or mouse anti-NeUN for neuronal nuclei or mouse anti-tyrosine hydroxylase (TH) for detection of dopaminergic neurons of the substantia nigra. Our double label immunofluorescence study showed that that TRPC3 is mainly localized in oligodendrocytes. These result were confirmed by the electron microscopy study, which showed TRPC3 immunoreactivity in oligodendrocytes. Consistent with the evidence that calcium homeostasis is important to oligodendrocytes for development, myelination, and demyelination [Microsc. Res. Tech. 52 (2001) 672], we can speculate that the distribution of TRPC3 in oligodendrocytes plays a role in myelination and or demyelination processes.