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Tau is a microtubule (MT)-associated protein that is localized to the axon. In Alzheimer's disease, the distribution of tau undergoes a remarkable alteration, leading to the formation of tau inclusions in the somatodendritic compartment. To investigate how this mislocalization occurs, we recently developed immunohistochemical tools that can separately detect endogenous mouse and exogenous human tau with high sensitivity, which allows us to visualize not only the pathological but also the pre-aggregated tau in mouse brain tissues of both sexes. Using these antibodies, we found that in tau-transgenic mouse brains, exogenous human tau was abundant in dendrites and somata even in the presymptomatic period, whereas the axonal localization of endogenous mouse tau was unaffected. In stark contrast, exogenous tau was properly localized to the axon in human tau knock-in mice. We tracked this difference to the temporal expression patterns of tau. Endogenous mouse tau and exogenous human tau in human tau knock-in mice exhibited high expression levels during the neonatal period and strong suppression into the adulthood. However, human tau in transgenic mice was expressed continuously and at high levels in adult animals. These results indicated the uncontrolled expression of exogenous tau beyond the developmental period as a cause of mislocalization in the transgenic mice. Superresolution microscopic and biochemical analyses also indicated that the interaction between MTs and exogenous tau was impaired only in the tau-transgenic mice, but not in knock-in mice. Thus, the ectopic expression of tau may be critical for its somatodendritic mislocalization, a key step of the tauopathy. SIGNIFICANCE STATEMENT Somatodendritic localization of tau may be an early step leading to the neuronal degeneration in tauopathies. However, the mechanisms of the normal axonal distribution of tau and the mislocalization of pathological tau remain obscure. Our immunohistochemical and biochemical analyses demonstrated that the endogenous mouse tau is transiently expressed in neonatal brains, that exogenous human tau expressed corresponding to such tau expression profile can distribute into the axon, and that the constitutive expression of tau into adulthood (e.g., human tau in transgenic mice) results in abnormal somatodendritic localization. Thus, the expression profile of tau is tightly associated with the localization of tau, and the ectopic expression of tau in matured neurons may be involved in the pathogenesis of tauopathy., (Copyright © 2019 the authors.)

Oligodendrocyte progenitor cells (OPCs) are widely distributed cells of ramified morphology in adult brain that express PDGFRα and NG2. They retain mitotic activities in adulthood and contribute to oligodendrogenesis and myelin turnover; however, the regulatory mechanisms of their cell dynamics in adult brain largely remain unknown. Here, we found that global Pdgfra inactivation in adult mice rapidly led to elimination of OPCs due to synchronous maturation toward oligodendrocytes. Surprisingly, OPC densities were robustly reconstituted by the active expansion of Nestin + immature cells activated in meninges and brain parenchyma, as well as a few OPCs that escaped from Pdgfra inactivation. The multipotent immature cells were induced in the meninges of Pdgfra-inactivated mice, but not of control mice. Our findings revealed powerful homeostatic control of adult OPCs, engaging dual cellular sources of adult OPC formation. These properties of the adult oligodendrocyte lineage and the alternative OPC source may be exploited in regenerative medicine., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Exposure to pesticides can induce neurobehavioral effects in rodents, as well as in other mammals, including humans. However, the effects of the toxicity of pesticides on the central nervous system (CNS) remain largely unclear. The expression of the activity-regulated cytoskeleton-associated protein gene (Arc) is induced in a neuronal-activity-dependent manner and is implicated in synaptic and experience-dependent plasticity. We previously developed Arc-promoter-driven luciferase transgenic (Tg) mouse strains to monitor the neuronal-activity-dependent gene expression under physiological and pathological conditions in vivo. In this study, we examined the effect of acute administration of four different pesticides (deltamethrin, glufosinate, methylcarbaryl, and imidacloprid) on neuronal activity using Arc-Luc Tg mice. The change in the bioluminescence signal in mouse brain upon treatment with deltamethrin and glufosinate occurred more slowly than that of kainic acid, a potent neuroexcitatory amino acid agonist. These two pesticides also caused convulsive responses in adult Arc-Luc Tg mice. In the case of glufosinate, we detected the long-term upregulation of bioluminescence signal intensity of Arc-Luc over 24 h after the treatment. Furthermore, we observed greater changes of bioluminescence signal in adults than in juveniles, and a lower incidence of convulsions at the juvenile stage. In contrast to the acute treatment, we detected a decrease of bioluminescence signal after low-dose chronic treatment with glufosinate, without neuronal overexcitation. From these results, we suggest that Arc-Luc Tg mice are useful for assessing the acute and chronic effects of pesticides on the CNS., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Protein disulfide isomerase (PDI) is a chaperone protein located in the endoplasmic reticulum (ER). Nitric oxide-induced S-nitrosylation of PDI inhibits its enzymatic activity, leading to protein accumulation and activation of the unfolded protein response. Protein disulfide isomerase P5 (P5) is a member of the PDI family that mostly localizes to the ER lumen. Both S-nitrosylated PDI and S-nitrosylated P5 are found in Alzheimer's disease (AD) brain. Previously, we showed that expression of the ER stress marker, growth arrest, and DNA damage protein (GADD34) was significantly increased in neurons and oligodendrocytes in AD brain. In the present study, we showed that PDI and P5 levels were significantly decreased in oligodendrocytes in the brains of AD patients and an AD mouse model. Interestingly, these decreases were evident before the animals displayed typical AD pathology. Because we previously showed that small short interfering RNA knockdown of PDI or P5 could affect the viability of neuronal cells under ER stress, dysfunction of PDI and P5 under ER stress could cause apoptosis of neuronal cells. In summary, we showed that the levels of PDI and P5 were significantly decreased in the oligodendrocytes of AD patients. This phenomenon was also found in an AD mouse model before the animals displayed AD pathology. The overall findings suggest that oligodendrocytes may play important roles in AD pathogenesis., (© 2017 Japanese Society of Neuropathology.)

Alzheimer's disease (AD) is histopathologically characterized by the build-up of fibrillar amyloid beta (Aβ) in the form of amyloid plaques and the development of intraneuronal neurofibrillary tangles consisting of aggregated hyperphosphorylated Tau. Although amyloid fibrils were originally considered responsible for AD pathogenesis, recent convincing evidence strongly implicates soluble oligomeric Aβ as the primary neurotoxic species driving disease progression. A third largely ignored pathological hallmark, originally described by Alois Alzheimer, is the presence of "adipose inclusions", suggestive of aberrant lipid metabolism. The molecular mechanisms underlying these "lipoid granules", as well as their potential link to soluble and/or fibrillar Aβ remain largely unknown. Seeking to better-understand these conundrums, we took advantage of the powerful technology of multidimensional mass spectrometry-based shotgun lipidomics and an AD transgenic mouse model overexpressing mutant amyloid precursor protein (APP E693Δ-Osaka-), where AD-like pathology and neurodegeneration occur as a consequence of oligomeric Aβ accumulation in the absence of amyloid plaques. Our results revealed for the first time that APP overexpression and oligomeric Aβ accumulation lead to an additive global accumulation of nonesterified polyunsaturated fatty acids (PUFAs) independently of amyloid plaques. Furthermore, we revealed that this accumulation is mediated by an increase in phospholipase A 2 (PLA 2 ) activity, evidenced by an accumulation of sn-1 lysophosphatidylcholine and by MAPK-mediated phosphorylation/activation of group IV Ca 2+ -dependent cytosolic (cPLA 2 ) and the group VI Ca 2+ -independent PLA 2 (iPLA 2 ) independently of PKC. We further revealed that Aβ-induced oxidative stress also disrupts lipid metabolism via reactive oxygen species-mediated phospholipid cleavage leading to increased sn-2 lysophosphatidylcholine as well as lipid peroxidation and the subsequent accumulation of 4-hydroxynonenal. Brain histological studies implicated cPLA 2 activity with arachidonic acid accumulation within myelin-rich regions, and iPLA 2 activity with docosahexaenoic acid accumulation within pyramidal neuron-rich regions. Taken together, our results suggest that PLA 2 -mediated accumulation of free PUFAs drives AD-related disruption of brain lipid metabolism.

The abnormal expression and function of myelin-related proteins contribute to nervous system dysfunction associated with neuropsychiatric disorders; however, the underlying mechanism of this remains unclear. We found here that breast carcinoma amplified sequence 1 (BCAS1), a basic protein abundant in the brain, was expressed specifically in oligodendrocytes and Schwann cells, and that its expression level was decreased by demyelination. This suggests that BCAS1 is a novel myelin-associated protein. BCAS1 knockout mice displayed schizophrenia-like behavioral abnormalities and a tendency toward reduced anxiety-like behaviors. Moreover, we found that the loss of BCAS1 specifically induced hypomyelination and the expression of inflammation-related genes in the brain. These observations provide a novel insight into the functional link between oligodendrocytes and inflammation and/or abnormal behaviors., (© 2017 Wiley Periodicals, Inc.)

Objective: Lacunar stroke may be caused by infarction of small perforating branches of the middle cerebral artery. We developed a microangiographic X-ray system using a cerium anode to evaluate the perforating branches., Methods: Iodine has K-edges at 33.2 kilo electron volts. Cerium yields a characteristic X-ray of 34.6 kilo electron volts, therefore, the cerium anode X-ray system could detect tiny amounts of contrast material. First, an X-ray chart was used to evaluate the resolution. Second, the brains of mice were dissected and irradiated. Third, the brains of dogs were excluded and irradiated. Fourth, iodine was perfused into the carotid artery of living dogs during brain imaging., Results: In the first experiment, the cerium anode X-ray system elicited 4.86 clear line pairs. In mice, the perforating branches of the middle cerebral artery could be visualized. The perforating branches were clearly observed in dog brains ex situ even through an acrylic plate, but not in conventional X-ray images. Iodine moving inside the perforating branches was visualized in dog brains in situ using the cerium anode X-ray system., Conclusion: The cerium anode X-ray system allowed us to visualize the perforating branches of the middle cerebral artery in living dogs.

Background: Bioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain. However, the black fur, skin pigmentation and hair regrowth after depilation of mouse interfere with BLI during developmental and daily examination. The aim of this study was to extend the application of Arc-Luc transgenic (Tg) mice to the BLI of neuronal activity in the mouse brain by introducing the hairless (HL) gene and to examine Arc-Luc expression at various developmental stages without interference from black fur, skin pigmentation, and hair regrowth., Results: The Arc-Luc Tg HL mice were established by crossing the Tg C57BL/6 mouse strain with the HL mouse strain. Under physiological and pathological conditions, BLI was performed to detect the signal intensity changes at various developmental stages and at an interval of <7 days. The established Arc-Luc Tg HL mice exhibited clear and stable photon signals from the brain without interference during development. After surgical monocular deprivation during visual-critical period, large signal intensity changes in bioluminescence were observed in the mouse visual cortex. Exposure of mice to a novel object changed the photon distribution in the caudal and rostral cerebral areas. The temporal pattern of kainic-acid-induced Arc-Luc expression showed biphasic changes in signal intensity over 24 h., Conclusions: This study showed the advantages of using the mutant HL gene in BLI of Arc expression in the mouse brain at various developmental stages. Thus, the use of the Arc-Luc Tg HL mice enabled the tracking of neuronal-activity-dependent processes over a wide range from a focal area to the entire brain area with various time windows.

MRI in a 2-year-old female presenting afebrile seizures and left blepharoptosis revealed multiple well-marginated round-shaped lesions, isointensity to gray matter on T1- and T2-weighted images with homogenously reduced diffusion and diffuse contrast enhancement. MRS revealed elevation of taurine, choline and glutamate, and reduction of N-acetylaspartate. A brain biopsy confirmed a diagnosis of juvenile xanthogranuloma (JXG). JXG should be considered when MR spectroscopy shows elevated taurine and glutamate, which has only previously been reported in medulloblastomas., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Background and Purpose: Some branches of the internal maxillary artery have anastomoses with the inferolateral trunk that are important as intracranial-extracranial collateral pathways and as dangerous anastomoses for transarterial embolization of these branches. We present here an undescribed branch potentially anastomosing with the anteromedial branch of the inferolateral trunk, which is provisionally named the artery of the superior orbital fissure, defined as an arterial branch from the pterygopalatine segment of the maxillary artery to the orbital apex at the superior orbital fissure., Materials and Methods: Two neuroradiologists reviewed 3D and MPR images of the external and/or common carotid artery with particular interest paid to the artery of the superior orbital fissure in 54 patients who underwent 3D angiography with a field of view covering the pterygopalatine fossa and the cavernous sinus. The underlying diseases in these patients were 17 parasellar hypervascular lesions (including 13 cavernous sinus dural arteriovenous fistulas and 4 meningiomas), 18 internal carotid artery stenoses/occlusions, and 19 other diseases., Results: The artery of the superior orbital fissure was identified in 20 of 54 patients; it arose at the pterygopalatine segment of the maxillary artery, either singly or from a common trunk with the artery of the foramen rotundum, and ran upward to reach the superior orbital fissure. It anastomosed with the anteromedial branch of the inferolateral trunk at the superior orbital fissure with blood flow toward the cavernous sinus (n = 14) and/or the ophthalmic artery (n = 2). It was more prominent in parasellar hypervascular lesions and internal carotid artery stenoses/occlusions than in other diseases., Conclusions: The artery of the superior orbital fissure, a remnant of the anastomotic artery, was often identified, especially in patients with parasellar hypervascular lesions., (© 2015 by American Journal of Neuroradiology.)

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) and abnormally phosphorylated tau which contribute to endoplasmic reticulum (ER) stress. Previous studies demonstrated that Aβ and a truncated fragment of Aβ induced death of oligodendrocytes in vitro. In addition, a triple-transgenic AD mouse model exhibits significant region-specific alterations in myelination patterns at time points preceding the appearance of Aβ accumulation. The growth arrest and DNA damage protein (GADD) 34 is up-regulated in response to ER stress and regulates subunit of protein phosphatase 1 (PP1) complex that dephosphorylates eukaryotic translation initiator factor 2α (elF2α). Thus, GADD34 is known as an ER stress regulator or ER stress marker. In a recent study, GADD34 was induced in the spinal cord glial cells of an amyotrophic lateral sclerosis (ALS) mouse model. It is interesting that reduced GADD34 delayed the onset of ALS and prolonged the survival period in the mouse model. In this study, we have demonstrated that GADD34 was increased in neurons of human AD brains. Additionally, this finding was also observed in oligodendrocytes in human AD brains. Furthermore, we showed that the expression levels of GADD34 in neurons and oligodendrocytes were significantly increased in the early stage of AD in the mouse model. As oligodendrocytes were more affected in the early stages of AD in this experimental model, ER stress of Aβ oligomers may be more related to oligodendrocytes than to neurons. These results suggest that GADD34 could be a therapeutic target for preventing ER stress in neuronal cells in AD., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

The cyclic adenosine monophosphate response element binding protein (CREB) is a phosphorylation-dependent transcription factor that plays important roles in memory consolidation and several neuropsychological disorders. Although analyzing the spatiotemporal pattern of CREB phosphorylation is required for elucidating the mechanism of memory consolidation, imaging of phosphorylation of a particular protein in the brain of live animals is impossible at present. Here, we developed a method for visualizing the CREB phosphorylation in the cerebral cortex of an awake mouse using a split luciferase technique. Using this technique, we demonstrated the correlation between the change in CREB phosphorylation at a particular region in the brain and behavioral consequences induced by the administration of reserpine, a psychotropic agent.

Background: The paper presents a report on the recently developed BCI alternative for users suffering from impaired vision (lack of focus or eye-movements) or from the so-called "ear-blocking-syndrome" (limited hearing). We report on our recent studies of the extents to which vibrotactile stimuli delivered to the head of a user can serve as a platform for a brain computer interface (BCI) paradigm., New Method: In the proposed tactile and bone-conduction auditory BCI novel multiple head positions are used to evoke combined somatosensory and auditory (via the bone conduction effect) P300 brain responses, in order to define a multimodal tactile and bone-conduction auditory brain computer interface (tbcaBCI). In order to further remove EEG interferences and to improve P300 response classification synchrosqueezing transform (SST) is applied. SST outperforms the classical time-frequency analysis methods of the non-linear and non-stationary signals such as EEG. The proposed method is also computationally more effective comparing to the empirical mode decomposition. The SST filtering allows for online EEG preprocessing application which is essential in the case of BCI., Results: Experimental results with healthy BCI-naive users performing online tbcaBCI, validate the paradigm, while the feasibility of the concept is illuminated through information transfer rate case studies., Comparison With Existing Method(s): We present a comparison of the proposed SST-based preprocessing method, combined with a logistic regression (LR) classifier, together with classical preprocessing and LDA-based classification BCI techniques., Conclusions: The proposed tbcaBCI paradigm together with data-driven preprocessing methods are a step forward in robust BCI applications research., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Our aim was to show whether sensitivity for detecting volume changes in regional gray matter in default mode network (DMN) at converted [from mild cognitive impairment to Alzheimer's disease (from MCI to AD)] phase was improved by use of a standardized volume with global gray-matter volume. T1-weighted MR images (T1WI) of seven normal subjects and seven converted (from MCI to AD) patients were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Gray-matter images segmented with Statistical Parametric Mapping 5 were measured by the atlas-based method. We focused on five nodes of the DMN. For each phase, region of interest (ROI) volumes in the five nodes were standardized by two methods: (1) the ratio to the screening phase (S&#95;volume) and (2) the ratio to the screening phase after both volumes were standardized by the global gray-matter volume (S&#95;N&#95;volume). Significant group differences between longitudinal gray-matter volume change of the converted (from MCI to AD) group and that of the normal group were found in lateral temporal cortex by S&#95;N&#95;volume, and precuneus by S&#95;N&#95;volume. These findings are useful for improving the understanding of DMN volume changes at the converted (from MCI to AD) phase.

Objectives: To investigate whether reproducibility of gray matter volumetry is influenced by parameter settings for VBM 8 using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) with region-of-interest (ROI) analyses., Methods: We prepared three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects. All subjects were imaged with each of five MRI systems. Voxel-based morphometry 8 (VBM 8) and WFU PickAtlas software were used for gray matter volumetry. The bilateral ROI labels used were those provided as default settings with the software: Frontal Lobe, Hippocampus, Occipital Lobe, Orbital Gyrus, Parietal Lobe, Putamen, and Temporal Lobe. All 3D-T1WIs were segmented to gray matter with six parameters of VBM 8, with each parameter having between three and eight selectable levels. Reproducibility was evaluated as the standard deviation (mm³) of measured values for the five MRI systems., Results: Reproducibility was influenced by 'Bias regularization (BiasR)', 'Bias FWHM', and 'De-noising filter' settings, but not by 'MRF weighting', 'Sampling distance', or 'Warping regularization' settings. Reproducibility in BiasR was influenced by ROI. Superior reproducibility was observed in Frontal Lobe with the BiasR1 setting, and in Hippocampus, Parietal Lobe, and Putamen with the BiasR3*, BiasR1, and BiasR5 settings, respectively., Conclusion: Reproducibility of gray matter volumetry was influenced by parameter settings in VBM 8 using DARTEL and ROI. In multi-center studies, the use of appropriate settings in VBM 8 with DARTEL results in reduced scanner effect.

Senile plaques comprised of Aβ aggregates and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau filaments are the hallmarks of Alzheimer's disease (AD). A number of amyloid precursor protein (APP) transgenic (Tg) mice harboring APP mutations have been generated as animal models of AD. These mice successfully display amyloid plaque formation and subsequent tau hyperphosphorylation, but seldom induce NFT formations. We have demonstrated that the APPOSK-Tg mice, which possess the E693Δ (Osaka) mutation in APP and thereby accumulate Aβ oligomers without plaques, exhibit tau hyperphosphorylation at 8 months, but not NFT formation even at 24 months. We assumed that APP-Tg mice, including ours, failed to form NFTs because NFT formation requires human tau. To test this hypothesis, we crossbred APPOSK-Tg mice with tau-Tg mice (tau264), which express low levels of 3-repeat and 4-repeat wild-type human tau without any pathology. The resultant double Tg mice displayed tau hyperphosphorylation at 6 months and NFT formation at 18 months in the absence of tau mutations. Importantly, these NFTs contained both 3-repeat and 4-repeat human tau, similar to those in AD. Furthermore, the double Tg mice exhibited Aβ oligomer accumulation, synapse loss, and memory impairment at 6 months and neuronal loss at 18 months, all of which appeared earlier than in the parent APPOSK-Tg mice. These results suggest that Aβ and human tau synergistically interact to accelerate each other's pathology, that the presence of human tau is critical for NFT formation, and that Aβ oligomers can induce NFTs in the absence of amyloid plaques.

Purpose: To show the gray matter volumes in the default mode network (DMN) using the atlas-based method and to evaluate age-related volume change in the DMN region. Estimation of gray matter volumes is interesting research because previous reports showed an association with gray matter volume (GMV) and diseases., Materials and Methods: We focused on five nodes of the DMN (posterior cingulate, precuneus, lateral temporal cortex [LTC], medial prefrontal cortex, and inferior parietal lobule). In all, 1122 healthy adults were included in the present study. T1-weighted magnetic resonance (MR) images were obtained using a 3T-MR scanner. To investigate GMV in the DMN, segmented gray matter images were measured by the atlas-based method, using Statistical Parametric Mapping 5. Volumes were expressed using three different methods: region of interest (ROI)-volume (mL), the volume itself; ROI-TIV (%), as a percentage of total intracranial volume (individual difference of head size is corrected); and ROI-GMV (%), as a percentage of gray matter volume (individual difference of atrophy speed for aging is corrected)., Results: Negative correlations between measurement values on ROI and age were observed in all five ROIs of the DMN region by two measures of volume (ROI-volume (mL) and ROI-TIV (%)), in both genders. In contrast, positive correlations between measurement values on ROI and age were observed in the posterior cingulate and LTC with ROI-GMV (%), in both genders., Conclusion: The present study is the first report about volume change in the DMN that includes age-related effects., (Copyright © 2013 Wiley Periodicals, Inc.)

Purpose: To show an association between T2-weighted signal intensity (T2-SI) variation and missegmentation in the putamen of healthy adults, using 3.0-tesla magnetic resonance scanner and voxel-based morphomery (VBM)., Materials and Methods: Contiguous sagittal T1-weighted images and axial T2-weighted images of the brain were obtained from 1380 healthy participants using a 3.0 Tesla (T) MR scanner. After image preprocessing with Statistical Parametric Mapping 5, the association between T2-SI ratio (= A/B, where A is the mean of the T2-SI in the putamen, and B is that in the thalamus) variation and gray matter missegmentation was assessed using VBM., Results: A significant positive correlation was revealed between T2-SI ratio and bilateral putamen volume on the gray matter images. In addition, we found a significant negative correlation between T2-SI ratio and bilateral putamen volume on the white matter images. We consider that these results show the influence of missegmentation., Conclusion: To the best of our knowledge, this is the first VBM study to demonstrate an association between T2-SI variation and gray matter missegmentation. These results indicate the possibility that VBM may be more affected by individual differences in iron content levels than by individual differences in tissue volumes if detected-regions with VBM contained substantial iron deposition., (Copyright © 2012 Wiley Periodicals, Inc.)

Introduction: This study aimed to investigate whether the effect of scanner for cortex volumetry with atlas-based method is reduced using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) normalization compared with standard normalization., Methods: Three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects were obtained and evaluated for effect of scanner in cortex volumetry. 3D-T1WIs of the 21 subjects were obtained with five MRI systems. Imaging of each subject was performed on each of five different MRI scanners. We used the Voxel-Based Morphometry 8 tool implemented in Statistical Parametric Mapping 8 and WFU PickAtlas software (Talairach brain atlas theory). The following software default settings were used as bilateral region-of-interest labels: "Frontal Lobe," "Hippocampus," "Occipital Lobe," "Orbital Gyrus," "Parietal Lobe," "Putamen," and "Temporal Lobe.", Results: Effect of scanner for cortex volumetry using the atlas-based method was reduced with DARTEL normalization compared with standard normalization in Frontal Lobe, Occipital Lobe, Orbital Gyrus, Putamen, and Temporal Lobe; was the same in Hippocampus and Parietal Lobe; and showed no increase with DARTEL normalization for any region of interest (ROI)., Conclusion: DARTEL normalization reduces the effect of scanner, which is a major problem in multicenter studies.

Purpose: To investigate age-related differences, gender differences, and age-by-gender interactions on the volumes of 18 neuroanatomical structures, with a large sample at a single institution., Materials and Methods: A total of 861 normal subjects (mean age = 56.1 ± 9.8 years, age range = 24.0-84.8 years) were included in this study. All subjects were scanned at 3.0 T. Measurement of the 18 neuroanatomical volumes was performed with FreeSurfer v. 4.5. Differences in volumes of neuroanatomical structures were tested using analysis of covariance with intracranial volume-normalized volume as the dependent variable, and independent variables of age, sex, age × sex, age × age, age × age × sex, and scanner. Nonsignificant higher-order terms were removed sequentially from the model. A P value of < 0.0028 (=0.5/18) was considered to indicate a statistically significant difference., Results: All neuroanatomical volumes, except for the caudate nucleus, pallidum, and 4th ventricle, were significantly related to age (linearly or quadratically). Significant gender differences were found in all neuroanatomical volumes, except for cerebral white matter, cerebellar cortex, caudate nucleus, and amygdala. No neuroanatomical volume showed a significant interaction between age (age × age) and gender., Conclusion: Our results showed age and gender effects on neuroanatomical volumes, and indicate no gender difference in the aging process of neuroanatomical volumes., (Copyright © 2012 Wiley Periodicals, Inc.)

Purpose: This study aimed to evaluate whether the image quality of virtual monochromatic spectral imaging with fast kVp switching dual-energy CT (DECT) can be comparable to that of 120-kVp single-energy CT (SECT) without increasing the radiation dose., Materials and Methods: We retrospectively identified 15 postoperative patients who had undergone both DECT and 120-kVp SECT within a short period of time for follow-up after brain surgery. Simulated 65 keV monochromatic images were reconstructed from DECT data. Subjective image noise, gray-white matter contrast, and overall image quality were rated using a four-point scale. Quantitative measurement of noise, contrast-to-noise ratio (CNR), and posterior fossa beam-hardening artifact were also performed. The figure of merit (FOM), calculated as CNR(2)/CTDIvol, was used to quantify image quality improvement per exposure risk., Results: The mean CTDIvol was 70.2 ± 0.3 mGy for DECT, which was 11 % lower than SECT (78.9 ± 2.1 mGy). All images were graded above clinically acceptable. Quantitative and qualitative measures for simulated 65-keV images were comparable with SECT images, except for increase in subjective noise. FOM was significantly greater for simulated 65-keV images (P = .03)., Conclusion: Our results indicate that virtual monochromatic imaging possibly provides comparable image quality to that afforded by 120-kVp SECT without increasing the dose in routine head CT.

Astrocytes play a critical role in neurovascular coupling by providing a physical linkage from synapses to arterioles and releasing vaso-active gliotransmitters. We identified a gliotransmitter pathway by which astrocytes influence arteriole lumen diameter. Astrocytes synthesize and release NMDA receptor coagonist, D-serine, in response to neurotransmitter input. Mouse cortical slice astrocyte activation by metabotropic glutamate receptors or photolysis of caged Ca(2+) produced dilation of penetrating arterioles in a manner attenuated by scavenging D-serine with D-amino acid oxidase, deleting the enzyme responsible for D-serine synthesis (serine racemase) or blocking NMDA receptor glycine coagonist sites with 5,7-dichlorokynurenic acid. We also found that dilatory responses were dramatically reduced by inhibition or elimination of endothelial nitric oxide synthase and that the vasodilatory effect of endothelial nitric oxide synthase is likely mediated by suppressing levels of the vasoconstrictor arachidonic acid metabolite, 20-hydroxy arachidonic acid. Our results provide evidence that D-serine coactivation of NMDA receptors and endothelial nitric oxide synthase is involved in astrocyte-mediated neurovascular coupling.

Background: Brain structural changes accompany major depressive disorder, but whether subclinical depression is accompanied by similar changes in brain volume and white matter integrity is unknown. By using voxel-based morphometry (VBM) of the gray matter and tract-specific analysis based on diffusion tensor imaging (DTI) of the white matter, we explored the extent to which abnormalities could be identified in specific brain structures of healthy adults with subclinical depression., Methods: The subjects were 21 community-dwelling adults with subclinical depression, as measured by their Center for Epidemiologic Studies Depression Scale (CES-D) scores. They were not demented and had no neurological or psychiatric history. We collected brain magnetic resonance images of the patients and of 21 matched control subjects, and we used VBM to analyze the differences in regional gray matter volume between the two groups. Moreover, we examined the white matter integrity by using tract-specific analysis based on the gray matter volume changes revealed by VBM., Results: VBM revealed that the volumes of both anterior cingulate gyri and the right rectal gyrus were smaller in subclinically depressed women than in control women. Calculation of DTI measures in the anterior cingulum bundle revealed a positive correlation between CES-D scale score and radial diffusivity in the right anterior cingulum in subclinically depressed women., Limitations: The small sample size limits the stability of the reported findings., Conclusions: Gray matter volume reduction and white matter integrity change in specific frontal brain regions may be associated with depressive symptoms in women, even at a subclinical level., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Summary: IgG4-related disease is characterized by histologic fibrosis with IgG4-positive plasma cell infiltration. Our study evaluated MR imaging features of IgG4-related disease in the head and neck and brain. Images from 15 patients were retrospectively evaluated for the location, signal intensity, and enhancement patterns of lesions. Lacrimal gland enlargement was observed in 8 cases. Other lesions included orbital pseudotumor in 5, pituitary enlargement in 5, and cranial nerve enlargement in 7; the infraorbital nerve was involved in 4. All lesions were hypointense on T2-weighted images, which is typical for IgG4-related lesions. Multiple sites were involved in the head and neck and brain in 11 patients. The diagnosis of IgG4-related disease should be considered in a patient presenting with T2 hypointense lacrimal gland, pituitary, or cranial nerve enlargement, or a T2 hypointense orbital mass, especially if multiple sites in the head and neck are involved in the presence of elevated serum IgG4.

The discovery of large amounts of D-serine in the brain challenged the dogma that only L-amino acids are relevant for eukaryotes. The levels of D-serine in the brain are higher than many L-amino acids and account for as much as one-third of L-serine levels. Several studies in the last decades have demonstrated a role of D-serine as an endogenous agonist of N-methyl-D-aspartate receptors (NMDARs). D-Serine is required for NMDAR activity during normal neurotransmission as well as NMDAR overactivation that takes place in neurodegenerative conditions. Still, there are many unanswered questions about D-serine neurobiology, including regulation of its synthesis, release and metabolism. Here, we review the mechanisms of D-serine synthesis by serine racemase and discuss the lessons we can learn from serine racemase knockout mice, focusing on the roles attributed to D-serine and its cellular origin.

Sexual differentiation of the brain can be considered as a process during which effects of sex steroid hormones secreted during early development is maintained into adulthood. Epigenetic regulation is emerging as a potentially important mechanism of conveyance of long-lasting effects of the hormonal and environmental milieu in the developing brain. Evidence has accumulated to show that epigenetic regulation is involved in the control of sexual differentiation of the brain. In the preoptic area (POA), which is important for male sexual behavior, histones associated with the estrogen receptor (ER) α and aromatase (Arom) gene promoters are differentially acetylated between the sexes, and two subtypes of histone deacetylase (HDAC2 and 4) are associated with the same promoters at higher frequencies in males in the early postnatal period. Since ERα and Arom are essential genes in masculinization of the brain, these findings suggest that histone deacetylation in the early postnatal period is involved in masculinization of the brain. Indeed, inhibition of HDAC activity in males during this period abrogates brain masculinization: structural sexual dimorphism of the bed nucleus of the stria terminalis is eliminated and expression of male sexual behavior is reduced in adulthood. Previous reports have demonstrated that ERα gene expression in the POA is higher in females during the developmental and pubertal periods and in adulthood, indicating that sexually dimorphic ERα expression that appears in early postnatal development is maintained until adulthood by epigenetic programming. The ERα promoter is also more sparsely methylated in females, with an inverse correlation with ERα expression. In addition to the hormonal effect, the amount of maternal care received during postnatal development has a lasting effect on ERα expression mediated by DNA methylation of its promoter. Taken together, these results suggest that epigenetic mechanisms play a central role in the transduction and maintenance of early hormonal and social cues to organize sexually differentiated brain functions.

Amyloid β (Aβ) oligomers are presumed to be one of the causes of Alzheimer's disease (AD). Previously, we identified the E693Δ mutation in amyloid precursor protein (APP) in patients with AD who displayed almost no signals of amyloid plaques in amyloid imaging. We generated APP-transgenic mice expressing the E693Δ mutation and found that they possessed abundant Aβ oligomers from 8months of age but no amyloid plaques even at 24months of age, indicating that these mice are a good model to study pathological effects of Aβ oligomers. To elucidate whether Aβ oligomers affect proteome levels in the brain, we examined the proteins and phosphoproteins for which levels were altered in 12-month-old APP(E693Δ)-transgenic mice compared with age-matched non-transgenic littermates. By two-dimensional gel electrophoresis (2DE) followed by staining with SYPRO Ruby and Pro-Q Diamond and subsequent mass spectrometry techniques, we identified 17 proteins and 3 phosphoproteins to be significantly changed in the hippocampus and cerebral cortex of APP(E693Δ)-transgenic mice. Coactosin like-protein, SH3 domain-bind glutamic acid-rich-like protein 3 and astrocytic phosphoprotein PEA-15 isoform 2 were decreased to levels less than 0.6 times those of non-transgenic littermates, whereas dynamin, profilin-2, vacuolar adenosine triphosphatase and creatine kinase B were increased to levels more than 1.5 times those of non-transgenic littermates. Furthermore, 2DE Western Blotting validated the changed levels of dynamin, dihydropyrimidinase-related protein 2 (Dpysl2), and coactosin in APP(E693Δ)-transgenic mice. Glyoxalase and isocitrate dehydrogenase were increased to levels more than 1.5 times those of non-transgenic littermates. The identified proteins could be classified into several groups that are involved in regulation of different cellular functions, such as cytoskeletal and their interacting proteins, energy metabolism, synaptic component, and vesicle transport and recycling. These findings indicate that Aβ oligomers altered the levels of some proteins and phosphoproteins in the hippocampus and cerebral cortex, which could illuminate novel therapeutic avenues for the treatment of AD., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The aims of this study were to (1) investigate the repeatability of measured volumes using the atlas-based method in each area of the brain, and (2) validate our hypothesis that the repeatability of the measured volumes with the atlas-based method was improved by using smoothed images. T1-weighted magnetic resonance images were obtained in five healthy subjects using the 1.5-T scanner. We used Statistical Parametric Mapping 5 and WFU PickAtlas software (theory of the Talairach brain atlas). Volumes inside region-of-interest (ROI) were measured in ten sets (five subjects × right and left) on six ROIs, respectively. One set comprises five images (one subject × five 3D-T1WIs). The percentage change was defined as [100 × (measured volume-mean volume in each set)/mean volume in each set)]. As a result, the average percentage changes using non-smoothed image on each ROI were as follows: gray matter, 0.482%; white matter, 0.375%; cerebrospinal fluid images, 0.731%; hippocampus, 0.864%; orbital gyrus, 1.692%; cerebellum posterior lobe, 0.854%. Using smoothed images with large FWHM resulted in improved repeatability on orbital gyrus. This is the first report of repeatability in each brain structure and improved repeatability with smoothed images using the atlas-based method.

Purpose: We aimed to show that correcting image distortion significantly affects brain volumetry using voxel-based morphometry (VBM) and to assess whether the processing of distortion correction reduces system dependency., Materials and Methods: We obtained contiguous sagittal T(1)-weighted images of the brain from 22 healthy participants using 1.5- and 3-tesla magnetic resonance (MR) scanners, preprocessed images using Statistical Parametric Mapping 5, and tested the relation between distortion correction and brain volume using VBM., Results: Local brain volume significantly increased or decreased on corrected images compared with uncorrected images. In addition, the method used to correct image distortion for gradient nonlinearity produced fewer volumetric errors from MR system variation., Conclusion: This is the first VBM study to show more precise volumetry using VBM with corrected images. These results indicate that multi-scanner or multi-site imaging trials require correction for distortion induced by gradient nonlinearity.

Amyloid imaging has been used to detect amyloid deposition in the brain. We performed Pittsburgh compound B (PiB)-positron emission tomography on 63 patients with dementia having cognitive decline or memory disturbance. In addition, we measured the patients' apolipoprotein E4 (apo E4) status and cerebrospinal fluid (CSF) levels of amyloid-β (Aβ)1-42, tau, and P-tau. Finally, the patients were diagnosed as having probable Alzheimer disease (AD) on the basis of their neuropsychological findings and because they met the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria. Among the patients diagnosed with probable AD, 10 patients were PiB negative. The CSF levels of P-tau and tau in PiB-negative patients were significantly lower than those in the PiB-positive patients. In addition, the CSF levels of Aβ1-42 in the PiB-negative patients were significantly higher than those in the PiB-positive patients. None of the PiB-negative patients were apo E4 carriers. These results suggest that the PiB-negative patient group included not only AD patients but also non-AD-type dementia patients. However, our finding is based on a relatively small number of patients and therefore should be replicated in a larger cohort. In addition, it will be necessary to categorize these participants by longitudinal follow-up and postmortem pathological examinations.

Epigenetic histone modifications are emerging as important mechanisms for conveyance of and maintenance of effects of the hormonal milieu to the developing brain. We hypothesized that alteration of histone acetylation status early in development by sex steroid hormones is important for sexual differentiation of the brain. It was found that during the critical period for sexual differentiation, histones associated with promoters of essential genes in masculinization of the brain (estrogen receptor α and aromatase) in the medial preoptic area, an area necessary for male sexual behavior, were differentially acetylated between the sexes. Consistent with these findings, binding of histone deacetylase (HDAC) 2 and 4 to the promoters was higher in males than in females. To examine the involvement of histone deacetylation on masculinization of the brain at the behavioral level, we inhibited HDAC in vivo by intracerebroventricular infusion of the HDAC inhibitor trichostatin A or antisense oligodeoxynucleotide directed against the mRNA for HDAC2 and -4 in newborn male rats. Aspects of male sexual behavior in adulthood were significantly reduced by administration of either trichostatin A or antisense oligodeoxynucleotide. These results demonstrate that HDAC activity during the early postnatal period plays a crucial role in the masculinization of the brain via modifications of histone acetylation status.

Phosphorylated tau (p-tau) is the principal component of neurofibrillary tangles, a pathological hallmark, and likely plays a neurotoxic role in tauopathies including Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). We subjected brains from autopsy cases of AD, PSP, and CBD to a variety of immunohistochemical, immunoblotting, and pull-down assays. In this study, we show that excitatory amino acid transporter 2 (EAAT2) preferentially interacted with phosphorylated tau and was localized in neurofibrillary tangles in the brains of such patients. These results strongly indicate that EAAT2 acts in tauopathy-related neurodegeneration, and abnormalities in glutamate transport play an important role in the pathogenesis of tauopathies.

Diffusion tensor imaging of magnetic resonance imaging, including diffusion tensor tractography, is a unique tool to visualize and segment the white matter pathways in vivo and one can evaluate the segmented trace quantitatively. Three dimensional visualization of the white matter fibers, such as corticospinal (pyramidal) tracts, with relationship to brain lesions (infarcts, vascular malformations and brain tumors) is extremely helpful for stereotactic radiosurgery, preoperative evaluation and intraoperative navigation. Quantitative measurement of the tract is a very sensitive method to detect differences in the tract in neurodegenerative/neurocognitive/psychiatric patients such as amyotrophic lateral sclerosis, schizophrenia and Alzheimer diseases. Importance of this tool will become more significant in clinical and neuroscience fields in the future.

D-Serine is the endogenous ligand for the glycine binding site of the N-methyl-D-aspartate (NMDA)-type glutamate receptor (GluR) channel and is involved in the regulation of synaptic plasticity, neural network formation, and neurodegenerative disorders. D-Serine is synthesized from L-serine by serine racemase (SR), which was first reported to be localized in astrocytes. However, recently, SR mRNA and its protein have been detected in neurons. In this study, we examined the SR distribution in the brain during postnatal development and in cultured cells by using novel SR knockout mice as negative controls. We found that SR is predominantly localized in pyramidal neurons in the cerebral cortex and hippocampal CA1 region. Double immunofluorescence staining revealed that SR signals colocalized with those of the neuron-specific nuclear protein, but not with the astrocytic markers glial fibrillary acid protein and 3-phosphoglycerate dehydrogenase. In the striatum, we observed SR expression in gamma-aminobutyric acid (GABA)ergic medium-spiny neurons. Furthermore, in the adult cerebellum, we detected weak but significant SR signals in GABAergic Purkinje cells. From these findings, we conclude that SR is expressed predominantly in many types of neuron in the brain and plays a key role in the regulation of brain functions under physiological and pathological conditions via the production of the neuromodulator D-serine.

We report a patient with linear scleroderma en coup de sabre without neurological symptoms despite the presence of large white matter lesions. The patient underwent 3.0-T magnetic resonance (MR) examinations including diffusion tensor imaging, time-resolved contrast-enhanced MR angiography, susceptibility-weighted imaging, and proton MR spectroscopy. These imaging findings suggested increased vascular permeability and microbleeding without abnormalities of metabolites. Our observation is consistent with vasculopathy and may be helpful in the proper diagnosis and treatment of linear scleroderma en coup de sabre.

Studies with green fluorescent protein (GFP) have revealed the subcellular distribution of many steroid hormone receptors to be much more dynamic than previously thought. Fluorescence resonance energy transfer (FRET) and fluorescence recovery after photobleaching (FRAP) are powerful techniques with which to examine protein-protein interaction and the mobility of tagged proteins, respectively. FRET analysis revealed that steroid treatment (with corticosterone or testosterone) induces direct interaction of the glucocorticoid receptor (GR) and importin alpha in the cytoplasm and that, shortly after nuclear entry, the GR detaches from importin alpha. The mineralocorticoid receptor (MR) and androgen receptor (AR) show the same trafficking. Upon oestradiol treatment, ERalpha and ERbeta in the same cell are relocalised to form a discrete pattern and are localised in the same discrete cluster (subnuclear foci). FRAP analysis showed that nuclear ERalpha and ERbeta are most dynamic and mobile in the absence of the ligand, and that mobility decreases slightly after ligand treatment. Genomic as well as non-genomic actions of steroid hormones influence the cellular function of target tissues spacio-temporally.

Objective: To investigate clinical characteristics, outcome, and risk factor for cerebrovascular disease in patients who had major depressive disorder and white matter hyperintensity (WMHI)., Method: A total of 123 new patients diagnosed with major depressive disorder by semi-structured interview underwent magnetic resonance imaging (MRI) and were placed into one of three groups based on results. Patients with no abnormal findings (NF), patients with WMHI and no lacunar infarction (WMHI), and patients with lacunar infarction (LI)., Results: In the WMHI group, age at initial onset of depression and age at time of interview were both higher than in the NF group, as was severity of depression. Hamilton Rating Scale for Depression (HRSD) scores were significantly higher in the WMHI group than in the NF group. Total WMHI was significantly correlated only with age at initial onset of depression and age at time of interview. In the WMHI group, age at interview was lower than in the LI group and systolic and diastolic blood pressures were lower. Survival analysis regarding the clinical outcome of remission was conducted, but no significant differences were discovered among the three groups, WMHI, LI, and NF. However, the suicide rate was significantly higher in the LI group than in the other two groups., Conclusions: The origin and clinical characteristics of depression accompanied by WMHI may be specific; additional stringent study in comparison with individuals with LI is needed.

A series of novel chalcones and their related derivatives were synthesized and evaluated as beta-amyloid imaging probes. In the structure-activity relationship of binding affinities to synthetic Abeta(1-42) aggregates, compound 14 displayed the highest binding affinity in vitro. beta-Amyloid plaques in the Alzheimer's model mouse brain were visualized with 14. In biodistribution studies using normal mice, [(125)I]14 showed good brain uptake (2.56% ID/g, 2min postinjection) and rapid washout from the brain (0.21% ID/g, 60min postinjection). These results suggest that [(125)I]14 should be further investigated as a potentially useful beta-amyloid imaging probe.

D-Serine has recently been identified as a major gliotransmitter in the mammal central nervous system (CNS). The distribution of D-serine is analogous to the N-methyl-D-aspartate (NMDA)-type glutamate receptors in the brain. D-Serine is as potent as glycine as a coagonist at the glycine-binding site of NMDA receptors. Thus, D-serine has been considered as an endogenous ligand of the NMDA receptors in the brain. D-Serine is synthesized by serine racemase (SR) from L-serine. Both D-serine and SR have been enriched to astrocytes which are the dynamic partners of neurons at synapses and participate in controlling synaptic transmission, synaptic plasticity and synaptogenesis. The present review highlights the most recent findings on the molecular mechanisms of controlling D-serine metabolism in the CNS, the physiological role of D-serine in synaptic plasticity, and the pathological relevance of D-serine to schizophrenia, excitotoxicity- and neuroinflammation-induced neuronal death as well as neuropathic pain. Finally, as we have recently established SR knockout mouse strain with pure C57BL/6 genetic background, this novel mouse model will contribute the analysis of physiological and pathophysiological role of D-serine in vivo.

Rett syndrome (RTT) is a major neurodevelopmental disorder, characterized by mental retardation and autistic behavior. Mutation of the MeCP2 gene, encoding methyl CpG-binding protein 2, causes the disease. The pathomechanism by which MeCP2 dysfunction leads to the RTT phenotype has not been elucidated. We found that MeCP2 directly regulates expression of insulin-like growth factor binding protein 3 (IGFBP3) gene in human and mouse brains. A chromatin immunoprecipitation assay showed that the IGFBP3 promoter contained an MeCP2 binding site. IGFBP3 overexpression was observed in the brains of mecp2-null mice and human RTT patients using real-time quantitative polymerase chain reaction and Western blot analyses. Moreover, mecp2-null mice showed a widely distributed and increased number of IGFBP3-positive cells in the cerebral cortex, whereas wild-type mice at the same age showed fewer IGFBP3-positive cells. These results suggest that IGFBP3 is a downstream gene regulated by MeCP2 and that the previously reported BDNF and DLX5 genes and MeCP2 may contribute directly to the transcriptional expression of IGFBP3 in the brain. Interestingly, the pathologic features of mecp2-null mice have some similarities to those of IGFBP3-transgenic mice, which show a reduction of early postnatal growth. IGFBP3 overexpression due to lack of MeCP2 may lead to delayed brain maturation.

Ubiquitin-positive tau-negative neuronal cytoplasmic inclusions and dystrophic neurites are common pathological features in frontotemporal lobar degeneration (FTLD) with or without symptoms of motor neuron disease and in amyotrophic lateral sclerosis (ALS). Using biochemical and immunohistochemical analyses, we have identified a TAR DNA-binding protein of 43 kDa (TDP-43), a nuclear factor that functions in regulating transcription and alternative splicing, as a component of these structures in FTLD. Furthermore, skein-like inclusions, neuronal intranuclear inclusions, and glial inclusions in the spinal cord of ALS patients are also positive for TDP-43. Dephosphorylation treatment of the sarkosyl insoluble fraction has shown that abnormal phosphorylation takes place in accumulated TDP-43. The common occurrence of intracellular accumulations of TDP-43 supports the hypothesis that these disorders represent a clinicopathological entity of a single disease, and suggests that they can be newly classified as a proteinopathy of TDP-43.

A simple radiochemical choline acetyltransferase (ChAT) assay screening test was developed by measuring for [(3)H]acetylcholine ([(3)H]ACh) formed from 0.2 mM [(3)H]acetyl-coenzyme A ([(3)H]acetyl-CoA) and 1 mM choline by 0.2 mg of rat brain homogenates containing ChAT into 96-well microplates. A simple and rapid procedure for isolating [(3)H]ACh from the incubation mixture into 96-well microplates was achieved by using a sodium tetraphenylboron (Kalibor) solution (in ethyl acetate, 0.75%, w/v) and a hydrophobic liquid scintillator mixture (1:5, v/v, 0.2 mL) as an extraction solvent. The benefits of this radiochemical method using 96-well microplates are as follows: (1) this method is reliable and reproducible; (2) many samples can be examined at the same time by this method; (3) this method is economical and effective in reducing radioactive waste. The development of a new simple radiochemical ChAT assay screening test is the first stage of development of radiolabeled ChAT mapping agent.

Platelet-derived growth factors (PDGFs) and PDGF receptors (PDGFRs) are widely expressed in the mammalian CNS, though their functional significance remains unclear. The corresponding null-knockout mutations are lethal. Here, we developed novel mutant mice in which the gene encoding the beta subunit of PDGFR (PDGFR-beta) was genetically deleted in CNS neurons to elucidate the role of PDGFR-beta, particularly in the post-natal stage. Our mutant mice reached adulthood without apparent anatomical defects. In the mutant brain, immunohistochemical analyses showed that PDGFR-beta detected in neurons and in the cells in the subventricular zone of the lateral ventricle in wild-type mice was depleted, but PDGFR-beta detected in blood vessels remained unaffected. The cerebral damage after cryogenic injury was severely exacerbated in the mutants compared with controls. Furthermore, TdT-mediated dUTP-biotin nick end labeling (TUNEL)-positive neuronal cell death and lesion formation in the cerebral hemisphere were extensively exacerbated in our mutant mice after direct injection of NMDA without altered NMDA receptor expression. Our results clearly demonstrate that PDGFR-beta expressed in neurons protects them from cryogenic injury and NMDA-induced excitotoxicity.

(-)-O-Methylvesamicol ((-)-OMV) exhibited in vitro a high affinity for vesicular acetylcholine transporter (VAChT) (Ki, 6.7 nM) and a relatively low affinity for sigmal receptor (Ki, 33.7 nM). We prepared (-)-[11C]OMV by a palladium-promoted cross-coupling reaction using [11C]methyl iodide, in a radiochemical yield of 38 +/- 6.9% (n=3), a radiochemical purity of 98 +/- 2.3% (n = 5), and a specific activity of 11 +/- 7.0 TBq/mmol at 30 minutes after EOB (n=5). Then, we evaluated in vivo whether (-)-[11C]OMV has properties as a PET radioligand for mapping VAChT. In rats, the brain uptake of (-)-[11C]OMV was 1.1%ID/g at 5 minutes postinjection, and was retained of a high level for 60 minutes. The brain uptake was significantly inhibited by the co-injection (500 nmol/kg) of cold (-)-OMV (58-66%), (-)-vesamicol (57-65%), and two sigma receptor ligands with modulate affinities for VAChTs: SA4503 (56-71%) and haloperidol (39-64%) in all of the brain regions, including the cerebellum with a low density of VAChTs, but not of sigmal-selective ligand (+)-pentazocine. However, the pretreatment with a large excess amount of (+/-)-pentazocine (50 micromol/kg) reduced the uptake in a different manner in the brain regions: 25% reduction in the striatum with a high density of VAChTs, and a 50-55% reduction in the other regions with a lower density of VAChTs. Ex vivo autoradiography using (-)-[11C]OMV showed a similar regional brain distribution of [3H](-)-vesamicol. In the PET study of the monkey brain, the regional brain distribution pattern of (-)-[11C]OMV was different from that of [11C]SA4503. The uptake of (-)-[11C]OMV was relatively higher in the striatum, was reversible, and an apparent equilibrium state was found at 20-40 minutes. In conclusion, (-)-[11C]OMV exhibited appropriate brain kinetics during the time frame of 11C-labeled tracers and bound mainly to VAChTs; however, the binding to sigmal receptors was not disregarded. Therefore, (-)-[11C]OMV-PET together with help of [11C]SA4503-PET may evaluate VAChTs.

Vesamicol is a leading compound for positron emission tomography (PET) and single photon emission computed tomography (SPECT) tracers for mapping the vesicular acetylcholine transporter (VAChT). Recently, we found that (+)-p-methylvesamicol ((+)-PMV) has low affinity for VAChT (K(i)=199 nM), but has moderate to high affinity for sigma receptors: K(i)=3.0 nM for sigma1 and K(i)=40.7 nM for sigma2, and that sigma1-selective SA4503 (K(i)=4.4 nM for sigma1 and K(i)=242 nM for sigma2) has moderate affinity for VAChT (K(i)=50.2 nM). In the present study, we examined the potential of (+)-[11C]PMV as a PET radioligand for mapping sigma1 receptors as compared with [11C]SA4503. In rat brain, similar regional distribution patterns of (+)-[11C]PMV and [11C]SA4503 were shown by tissue dissection and by ex vivo autoradiography. Blocking experiments using (+/-)-PMV, (-)-vesamicol, SA4503, haloperidol and (+/-)-pentazocine showed that the two tracers specifically bound to sigma1 receptors, and that [11C]SA4503 exhibited greater specific binding than (+)-[11C]PMV. No sign of VAChT-specific binding by [11C]SA4503 was observed in the striatum, which is rich in VAChT sites. In conclusion, (+)-[11C]PMV specifically bound to sigma1 receptors in the brain, but to a lesser extent than [11C]SA4503, suggesting that (+)-[11C]PMV is a less preferable PET ligand than [11C]SA4503. On the other hand, the moderate affinity of [11C]SA4503 for VAChT is negligible in vivo.