SWI by 7T MR Imaging for the Microscopic Imaging Diagnosis of Astrocytic and Oligodendroglial Tumors.

BACKGROUND AND PURPOSE: Despite advances in molecular imaging, preoperative diagnosis of astrocytomas and oligodendrogliomas can be challenging. In the present study, we assessed whether 7T SWI can be used to distinguish astrocytomas and oligodendrogliomas and whether malignant grading of gliomas is possible. MATERIALS AND METHODS: 7T SWI was performed on 21 patients with gliomas before surgery with optimization for sharp visualization of the corticomedullary junction. Scoring for cortical thickening and displacement of medullary vessels, characteristic of oligodendroglial tumors, and cortical tapering, characteristic of astrocytic tumors, was performed. Additionally, characteristics of malignancy, including thickening of the medullary veins, the presence of microbleeds, and/or necrosis were scored. RESULTS: Scoring for oligodendroglial (highest possible score, +3) and astrocytic (lowest score possible, -3) characteristics yielded a significant difference between astrocytomas and oligodendrogliomas (mean, -1.93 versus +1.71, P < .01). Scoring for malignancy was significantly different among the World Health Organization grade II (n = 10), grade III (n = 4), and grade IV (n = 7) tumors (mean, 0.20 versus 1.38 versus 2.79). Cortical thickening was observed significantly more frequently in oligodendrogliomas (P < .02), with a sensitivity of 71.4% and specificity of 85.7%; observation of tapering of the cortex was higher in astrocytomas (P < .01) with a sensitivity of 85.7% and specificity of 100%. CONCLUSIONS: Visualization of the corticomedullary junction by 7T SWI was useful in distinguishing astrocytomas and oligodendrogliomas. Observation of tapering of the cortex was most sensitive and specific for diagnosing astrocytomas. Reliably predicting malignant grade was also possible by 7T SWI.

Clinical and pathological features affecting cardiac sympathetic denervation in autopsy-confirmed dementia with Lewy bodies.

BACKGROUND AND PURPOSE: The aim was to clarify the features affecting cardiac sympathetic denervation in autopsy-confirmed dementia with Lewy bodies (DLB) patients. METHODS: Fifty-four autopsy-confirmed DLB patients were enrolled. Tissue samples of the left ventricular anterior wall were immunostained with anti-tyrosine hydroxylase antibody to identify catecholaminergic nerve axons. Immunostained areas were quantified as residual cardiac sympathetic nerve (CSN) axons and the relationship between the degree of residual CSN axons and clinical and neuropathological features was examined. RESULTS: Virtually all patients showed small amounts of residual CSN axons (0.87%, range 0.02%-9.98%), with 50 patients (92.6%) showing <2.0% of residual axons. The patients who showed psychological symptoms within the first year of the disease had significantly more residual CSN axons than the remaining patients did (1.50% vs. 0.40%, P < 0.01). Patients with a short disease duration and neocortical-type Lewy body pathology tended to have more preserved CSN axons, although this difference was not statistically significant. Fifty-three patients (98.1%) who had neurofibrillary tangles in the brain and strong concomitant Alzheimer's disease pathology also had statistically significantly more preserved CSN axons. The patient with the most preserved CSN axons showed different characteristics from the results, except for the first symptom. CONCLUSION: Psychological symptoms within the first year of the disease, a short disease duration, neocortical-type Lewy body pathology and strong concomitant Alzheimer's disease pathology may be related to mild CSN degeneration in DLB patients. Thus, DLB patients with broad Lewy body pathology in the brain in the early stages may show mild CSN degeneration.

Morphological characterisation of glial and neuronal tau pathology in globular glial tauopathy (Types II and III).

AIMS: Globular glial tauopathy (GGT) is a new category within the 4-repeat tauopathies that is characterised neuropathologically by tau-positive globular glial inclusions (GGIs), namely, globular oligodendrocytic and astrocytic inclusions (GOIs and GAIs). Occurrence of tau-positive neuronal cytoplasmic inclusions (NCIs) is also a feature. GGT is classified into three pathological subtypes (Types I, II and III). We studied the tau pathology in 6 cases of GGT (Type II, n = 3; Type III, n = 3), with special reference to GAIs and NCIs. METHODS: Neuropathological examinations were conducted, along with immunohistochemistry, morphometry and three-dimensional imaging, and biochemical and genetic analysis of tau. RESULTS: The cortical GAIs in Type II and those in Type III were distinguishable from each other. In the motor cortex, GAIs were much more numerous in Type III than in Type II. Prominent occurrence of perikaryal globular structures was a feature of GAIs in Type III. By contrast, prominent occurrence of radiating process-like structures was a feature of GAIs in Type II. Overall, the GAIs were significantly smaller in Type III than in Type II. NCIs were divisible into three subgroups in terms of shape: diffuse granular, thick cord-like, and round/horseshoe-shaped structures. In all cases, NCIs were a feature of the upper and lower motor neurons. Interestingly, the round/horseshoe-shaped NCIs were observed only in Type III cases. CONCLUSIONS: These findings, which characterised GAIs and NCIs, indicated that Type II and Type III constitute two distinct pathological subtypes, and also further strengthen the concept of GGT as a distinct entity.

Altered expression of glutamate transporter-1 and water channel protein aquaporin-4 in human temporal cortex with Alzheimer's disease.

AIMS: Glutamate neurotoxicity plays an important role in the pathogenesis of various neurodegenerative disorders. Many studies have demonstrated that glutamate transporter-1 (GLT-1), the dominant astrocytic glutamate transporter, is significantly reduced in the cerebral cortex of patients with Alzheimer's disease (AD), suggesting that glutamate-mediated excitotoxicity might contribute to the pathogenesis of AD. In a previous study, we have demonstrated marked alterations in the expression of the astrocytic water channel protein aquaporin-4 (AQP4) in relation to amyloid ß deposition in human AD brains. As a functional complex, GLT-1 and AQP4 in astrocytes may play a neuroprotective role in the progression of AD pathology. However, few studies have examined the correlation between the expression of GLT-1 and that of AQP4 in human AD brain. METHODS: Here, using immunohistochemistry with antibodies against GLT-1 and AQP4, we studied the expression levels and distribution patterns of GLT-1 in areas showing various patterns of AQP4 expression in autopsied temporal lobes from eight patients with AD and five controls without neurological disorders. RESULTS: GLT-1 staining in the control group was present throughout the neocortex as uniform neuropil staining with co-localized AQP4. The AD group showed a significant reduction in GLT-1 expression, whereas cortical AQP4 immunoreactivity was more intense in the AD group than in the control group. There were two different patterns of GLT-1 and AQP4 expression in the AD group: (i) uneven GLT-1 expression in the neuropil where diffuse but intense AQP4 expression was evident, and (ii) senile plaque-like co-expression of GLT-1 and AQP4. CONCLUSIONS: These findings suggest disruption of glutamate/water homoeostasis in the AD brain.

Depression-like episodes in mice harboring mtDNA deletions in paraventricular thalamus.

Depression is a common debilitating human disease whose etiology has defied decades of research. A critical bottleneck is the difficulty in modeling depressive episodes in animals. Here, we show that a transgenic mouse with chronic forebrain expression of a dominant negative mutant of Polg1, a mitochondrial DNA (mtDNA) polymerase, exhibits lethargic behavioral changes, which are associated with emotional, vegetative and psychomotor disturbances, and response to antidepression drug treatment. The results suggested a symptomatic similarity between the lethargic behavioral change that was recurrently and spontaneously experienced by the mutant mice and major depressive episode as defined by DSM-5. A comprehensive screen of mutant brain revealed a hotspot for mtDNA deletions and mitochondrial dysfunction in the paraventricular thalamic nucleus (PVT) with similar defects observed in postmortem brains of patients with mitochondrial disease with mood symptoms. Remarkably, the genetic inhibition of PVT synaptic output by Cre-loxP-dependent expression of tetanus toxin triggered de novo depression-like episodes. These findings identify a novel preclinical mouse model and brain area for major depressive episodes with mitochondrial dysfunction as its cellular mechanism.

Involvement of inhibitory PAS domain protein in neuronal cell death in Parkinson's disease.

Inhibitory PAS domain protein (IPAS), a repressor of hypoxia-inducible factor-dependent transcription under hypoxia, was found to exert pro-apoptotic activity in oxidative stress-induced cell death. However, physiological and pathological processes associated with this activity are not known. Here we show that IPAS is a key molecule involved in neuronal cell death in Parkinson's disease (PD). IPAS was ubiquitinated by Parkin for proteasomal degradation following carbonyl cyanide m-chlorophenyl hydrazone treatment. Phosphorylation of IPAS at Thr12 by PTEN-induced putative kinase 1 (PINK1) was required for ubiquitination to occur. Activation of the PINK1-Parkin pathway attenuated IPAS-dependent apoptosis. IPAS was markedly induced in the midbrain following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration, and IPAS-deficient mice showed resistance to MPTP-induced degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). A significant increase in IPAS expression was found in SNpc neurons in patients with sporadic PD. These results indicate a mechanism of neurodegeneration in PD.

Genes associated with the progression of neurofibrillary tangles in Alzheimer's disease.

The spreading of neurofibrillary tangles (NFTs), intraneuronal aggregates of highly phosphorylated microtubule-associated protein tau, across the human brain is correlated with the cognitive severity of Alzheimer's disease (AD). To identify genes relevant to NFT expansion defined by the Braak stage, we conducted whole-genome exon array analysis with an exploratory sample set consisting of 213 human post-mortem brain tissue specimens from the entorinal, temporal and frontal cortices of 71 brain-donor subjects: Braak NFT stages 0 (N=13), I-II (N=20), III-IV (N=19) and V-VI (N=19). We identified eight genes, RELN, PTGS2, MYO5C, TRIL, DCHS2, GRB14, NPAS4 and PHYHD1, associated with the Braak stage. The expression levels of three genes, PHYHD1, MYO5C and GRB14, exhibited reproducible association on real-time quantitative PCR analysis. In another sample set, including control subjects (N=30), and in patients with late-onset AD (N=37), dementia with Lewy bodies (N=17) and Parkinson disease (N=36), the expression levels of two genes, PHYHD1 and MYO5C, were obviously associated with late-onset AD. Protein-protein interaction network analysis with a public database revealed that PHYHD1 interacts with MYO5C via POT1, and PHYHD1 directly interacts with amyloid beta-peptide 42. It is thus likely that functional failure of PHYHD1 and MYO5C could lead to AD development.

DPP6 as a candidate gene for neuroleptic-induced tardive dyskinesia.

We implemented a two-step approach to detect potential predictor gene variants for neuroleptic-induced tardive dyskinesia (TD) in schizophrenic subjects. First, we screened associations by using a genome-wide (Illumina HumanHapCNV370) SNP array in 61 Japanese schizophrenia patients with treatment-resistant TD and 61 Japanese schizophrenia patients without TD. Next, we performed a replication analysis in 36 treatment-resistant TD and 138 non-TD subjects. An association of an SNP in the DPP6 (dipeptidyl peptidase-like protein-6) gene, rs6977820, the most promising association identified by the screen, was significant in the replication sample (allelic P=0.008 in the replication sample, allelic P=4.6 × 10(-6), odds ratio 2.32 in the combined sample). The SNP is located in intron-1 of the DPP6 gene and the risk allele was associated with decreased DPP6 gene expression in the human postmortem prefrontal cortex. Chronic administration of haloperidol increased Dpp6 expression in mouse brains. DPP6 is an auxiliary subunit of Kv4 and regulates the properties of Kv4, which regulates the activity of dopaminergic neurons. The findings of this study indicate that an altered response of Kv4/DPP6 to long-term neuroleptic administration is involved in neuroleptic-induced TD.

Progression of paralysis is the most useful factor for differentiating malignant from benign intramedullary tumors.

STUDY DESIGN: Retrospective study. OBJECTIVES: The purpose of this study was to identify the clinical factors for differentiating malignant from benign intramedullary spinal cord tumors. SETTING: Niigata, Japan. METHODS: We conducted a retrospective review of charts and images. Preoperative paralysis including walking ability, urinary function, magnetic resonance imaging (MRI) findings and pathological diagnosis were evaluated in 33 consecutive cases of intramedullary spinal cord tumor, and the clinical factors that were useful for differentiating malignant from benign tumors were identified. RESULTS: Early progression of paralysis was the most valuable feature for differentiating malignant from benign tumors. Malignant tumors were suspected in only three of ten cases on the basis of MRI findings. CONCLUSION: Simple assessment of walking ability is easy to perform and is useful for predicting the pathological malignancy of intramedullary tumors of the spinal cord.

Co-occurrence of argyrophilic grain disease in sporadic amyotrophic lateral sclerosis.

AIMS: Phosphorylated TDP-43 (pTDP-43) is the pathological protein responsible for amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease. Recently, it has been reported that accumulation of pTDP-43 can occur in the brains of patients with argyrophilic grain disease (AGD), in which phosphorylated 4-repeat tau is the pathological protein. To elucidate the association of ALS with AGD, we examined the brains from 37 consecutively autopsied patients with sporadic ALS (age range 45-84 years, mean 71.5 ± 9.0 years). METHODS: Sections from the frontotemporal lobe were stained with the Gallyas-Braak method and also immunostained with antibodies against phosphorylated tau, 4-repeat tau and pTDP-43. RESULTS: Fourteen (38%) of the 37 ALS patients were found to have AGD. With regard to staging, 5 of these 14 cases were rated as I, 4 as II and 5 as III. pTDP-43 immunohistochemistry revealed the presence of positive neuronal and glial cytoplasmic inclusions in the affected medial temporal lobe in many cases (93% and 64%, respectively). On the other hand, pTDP-43-positive small structures corresponding to argyrophilic grains were observed only in one case. A significant correlation was found between AGD and the Braak stage for neurofibrillary pathology (stage range 0-V, mean 2.1). However, there were no significant correlations between AGD and any other clinicopathological features, including dementia. CONCLUSIONS: The present findings suggest that co-occurrence of AGD in ALS is not uncommon, and in fact comparable with that in a number of diseases belonging to the tauopathies or α-synucleinopathies.

Unmyelinated axons are more vulnerable to degeneration than myelinated axons of the cardiac nerve in Parkinson's disease.

AIMS: We recently demonstrated accumulation of α-synuclein aggregates of the cardiac sympathetic nerve in Parkinson's disease (PD) and a possible relationship between degeneration of the cardiac sympathetic nerve and α-synuclein aggregates. The aim of this study is to determine whether there is a difference in the degenerative process between unmyelinated and myelinated axons of the cardiac nerve. METHODS: We immunohistochemically examined cardiac tissues from four pathologically verified PD patients, nine patients with incidental Lewy body disease (ILBD) and five control subjects, using antibodies against neurofilament, myelin basic protein (MBP) and α-synuclein. First, we counted the number of neurofilament-immunoreactive axons not surrounded by MBP (unmyelinated axons) and those surrounded by MBP (myelinated axons). Next, we counted the number of unmyelinated and myelinated axons with α-synuclein aggregates. RESULTS: (i) The percentage of unmyelinated axons in PD (77.5 ± 9.14%) was significantly lower compared to that in control subjects (92.2 ± 2.40%). (ii) The ratio of unmyelinated axons with α-synuclein aggregates to total axons with α-synuclein aggregates in ILBD ranged from 94.4 to 100 (98.2 ± 2.18%). Among axons with α-synuclein aggregates, unmyelinated axons were the overwhelming majority, comprising 98.2%. CONCLUSION: These findings suggest that in PD unmyelinated axons are more vulnerable to degeneration than myelinated axons of the cardiac nerve, because α-synuclein aggregates accumulate much more abundantly in unmyelinated axons.

Transient exposure of neonatal mice to neuregulin-1 results in hyperdopaminergic states in adulthood: implication in neurodevelopmental hypothesis for schizophrenia.

Neuregulin-1 (NRG1) is implicated in the etiology or pathology of schizophrenia, although its biological roles in this illness are not fully understood. Human midbrain dopaminergic neurons highly express NRG1 receptors (ErbB4). To test its neuropathological role in the neurodevelopmental hypothesis of schizophrenia, we administered type-1 NRG1 protein to neonatal mice and evaluated the immediate and subsequent effects on dopaminergic neurons and their associated behaviors. Peripheral NRG1 administration activated midbrain ErbB4 and elevated the expression, phosphorylation and enzyme activity of tyrosine hydroxylase (TH), which ultimately increased dopamine levels. The hyperdopaminergic state was sustained in the medial prefrontal cortex after puberty. There were marked increases in dopaminergic terminals and TH levels. In agreement, higher amounts of dopamine were released from this brain region of NRG1-treated mice following high potassium stimulation. Furthermore, NRG1-treated mice exhibited behavioral impairments in prepulse inhibition, latent inhibition, social behaviors and hypersensitivity to methamphetamine. However, there were no gross abnormalities in brain structures or other phenotypic features of neurons and glial cells. Collectively, our findings provide novel insights into neurotrophic contribution of NRG1 to dopaminergic maldevelopment and schizophrenia pathogenesis.

The phenotype spectrum of Japanese multiple system atrophy.

OBJECTIVE: This study aimed to determine the spectrum of pathological involvement of the striatonigral (StrN) and olivopontocerebellar (OPC) systems in Japanese patients with multiple system atrophy (MSA). This study also aimed to compare the pathological spectrum of Japanese MSA patients with the previously reported results in British MSA patients. METHODS: A semiquantitative pathological analysis of 50 MSA patients' brains that were referred to the Brain Research Institute, Niigata University, Japan, was performed. The severity of neuronal cell loss was determined as previously described by the study from the Queen Square Brain Bank (QSBB), UK. RESULTS: The mean neuronal cell loss score was significantly higher in the OPC area than in the basal ganglia sites examined, except the dorsolateral putamen. The relative prevalence of pathological phenotypes showed that 40% of cases had OPC-predominant pathology, 18% had StrN-predominant pathology and the remaining (42%) had equivalent StrN and OPC pathology. None of the MSA cases had coexistent Lewy bodies in the dorsal motor nucleus of the vagus and the substantia nigra. CONCLUSIONS: In contrast to the previously reported results involving British patients' brains from the QSBB (OPC-predominant pathology 17%, StrN-predominant pathology 34%, equivalent StrN and OPC pathology 49%), the results of the present study showed more pathological involvement of the OPC system than of the StrN system. The rarity of Lewy bodies may underlie the phenotypic expression of Japanese MSA. The present observations reflect the disequilibrium in the phenotype distribution between the two populations.

Relationship between Bunina bodies and TDP-43 inclusions in spinal anterior horn in amyotrophic lateral sclerosis.

AIMS: Amyotrophic lateral sclerosis (ALS) is characterized by upper and lower motor neurone involvement with Bunina bodies (BBs) and TDP-43 inclusions. To elucidate the relationship between BBs and TDP-43 inclusions, we examined the spinal cord from 18 patients with ALS. METHODS: Five serial sections from lumbar cord were first stained with haematoxylin and eosin to detect BBs and subsequently immunostained with anti-TDP-43 antibody. Immunoelectron microscopy was performed on vibratome sections from two cases of ALS. RESULTS: BBs were found in 15 out of 18 cases. TDP-43 inclusions were found in all the cases. The average incidence of anterior horn cells with BBs and TDP-43 inclusions relative to the total number of neurones was 17.1% and 46.4%, respectively. The concurrence of both inclusions in the same neurones was found in 15 cases. The incidence of co-localization of BBs and TDP-43 inclusions was 15.7% of total neurones. The frequency of TDP-43 inclusions was significantly higher in neurones with BBs than in those without. Ultrastructurally, TDP-43-immunoreactive filamentous structures were intermingled with early-stage BBs, but not associated with advanced-stage BBs. CONCLUSION: These findings suggest that there is a close relationship in the occurrence between BBs and TDP-43 inclusions.

Pathologic and immunologic profiles of a limited form of neuromyelitis optica with myelitis.

BACKGROUND: Neuromyelitis optica (NMO) is a demyelinating syndrome characterized by myelitis and optic neuritis. Detection of anti-NMO immunoglobulin G antibody that binds to aquaporin-4 (AQP4) water channels allows the diagnosis of a limited form of NMO in the early stage with myelitis, but not optic neuritis. However, the detailed clinicopathologic features and long-term course of this limited form remain elusive. METHODS: We investigated 8 patients with the limited form of NMO with myelitis in comparison with 9 patients with the definite form. RESULT: All patients with limited and definite form showed uniform relapsing-remitting courses, with no secondary progressive courses. Pathologic findings of biopsy specimens from the limited form were identical to those of autopsy from the definite form, demonstrating extremely active demyelination of plaques, extensive loss of AQP4 immunoreactivity in plaques, and diffuse infiltration by macrophages containing myelin basic proteins with thickened hyalinized blood vessels. Moreover, the definite form at the nadir of relapses displayed significantly higher amounts of the inflammatory cytokines interleukin (IL)-1beta and IL-6 in CSF than the limited form and multiple sclerosis. CONCLUSION: This consistency of pathologic findings and uniformity of courses indicates that aquaporin 4-specific autoantibodies as the initiator of the neuromyelitis optica (NMO) lesion consistently play an important common role in the pathogenicity through the entire course, consisting of both limited and definite forms, and NMO continuously displays homogeneity of pathogenic effector immune mechanisms through terminal stages, whereas multiple sclerosis should be recognized as the heterogeneous 2-stage disease that could switch from inflammatory to degenerative phase. This report is a significant description comparing the pathologic and immunologic data of limited NMO with those of definite NMO.

The cellular and behavioral consequences of interleukin-1 alpha penetration through the blood-brain barrier of neonatal rats: a critical period for efficacy.

Proinflammatory cytokines circulating in the periphery of early postnatal animals exert marked influences on their subsequent cognitive and behavioral traits and are therefore implicated in developmental psychiatric diseases such as schizophrenia. Here we examined the relationship between the permeability of the blood-brain barrier to interleukin-1 alpha (IL-1 alpha) in neonatal and juvenile rats and their later behavioral performance. Following s.c. injection of IL-1 alpha into rat neonates, IL-1 alpha immunoreactivity was first detected in the choroid plexus, brain microvessels, and olfactory cortex, and later diffused to many brain regions such as neocortex and hippocampus. In agreement, IL-1 alpha administration to the periphery resulted in a marked increase in brain IL-1 alpha content of neonates. Repeatedly injecting IL-1 alpha to neonates triggered astrocyte proliferation and microglial activation, followed by behavioral abnormalities in startle response and putative prepulse inhibition at the adult stage. Analysis of covariance with a covariate of startle amplitude suggested that IL-1 alpha administration may influence prepulse inhibition. However, adult rats treated with IL-1 alpha as neonates exhibited normal learning ability as measured by contextual fear conditioning, two-way passive shock avoidance, and a radial maze task and had no apparent sign of structural abnormality in the brain. In comparison, when IL-1 alpha was administered to juveniles, the blood-brain barrier permeation was limited. The increases in brain IL-1 alpha content and immunoreactivity were less pronounced following IL-1 alpha administration and behavioral abnormalities were not manifested at the adult stage. During early development, therefore, circulating IL-1 alpha efficiently crosses the blood-brain barrier to induce inflammatory reactions in the brain and influences later behavioral traits.

Loss of aquaporin 4 in lesions of neuromyelitis optica: distinction from multiple sclerosis.

Neuromyelitis optica (NMO) is an inflammatory and necrotizing disease clinically characterized by selective involvement of the optic nerves and spinal cord. There has been a long controversy as to whether NMO is a variant of multiple sclerosis (MS) or a distinct disease. Recently, an NMO-specific antibody (NMO-IgG) was found in the sera from patients with NMO, and its target antigen was identified as aquaporin 4 (AQP4) water channel protein, mainly expressed in astroglial foot processes. However, the pathogenetic role of the AQP4 in NMO remains unknown. We did an immunohistopathological study on the distribution of AQP4, glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), activated complement C9neo and immunoglobulins in the spinal cord lesions and medulla oblongata of NMO (n = 12), MS (n = 6), brain and spinal infarction (n = 7) and normal control (n = 8). The most striking finding was that AQP4 immunoreactivity was lost in 60 out of a total of 67 acute and chronic NMO lesions (90%), but not in MS plaques. The extensive loss of AQP4 accompanied by decreased GFAP staining was evident, especially in the active perivascular lesions, where immunoglobulins and activated complements were deposited. Interestingly, in those NMO lesions, MBP-stained myelinated fibres were relatively preserved despite the loss of AQP4 and GFAP staining. The areas surrounding the lesions in NMO had enhanced expression of AQP4 and GFAP, which reflected reactive gliosis. In contrast, AQP4 immunoreactivity was well preserved and rather strongly stained in the demyelinating MS plaques, and infarcts were also stained for AQP4 from the very acute phase of necrosis to the chronic stage of astrogliosis. In normal controls, AQP4 was diffusely expressed in the entire tissue sections, but the staining in the spinal cord was stronger in the central grey matter than in the white matter. The present study demonstrated that the immunoreactivities of AQP4 and GFAP were consistently lost from the early stage of the lesions in NMO, notably in the perivascular regions with complement and immunoglobulin deposition. These features in NMO were distinct from those of MS and infarction as well as normal controls, and suggest that astrocytic impairment associated with the loss of AQP4 and humoral immunity may be important in the pathogenesis of NMO lesions.