Myelin Basic Protein Staining Research Articles

Myelin water imaging of in vivo and ex vivo human brains using multi-echo gradient echo at 3 T and 7 T.

To compare the myelin water fraction (MWF) measurements between 3 T and 7 T and between in vivo and ex vivo human brains, and to investigate the relationship between multi-echo gradient-echo (mGRE)-based 3D MWF and myelin content using histological staining, which has not been validated in the human brain. In this study, we performed 3D mGRE-based MWF measurements on five ex vivo human brain hemispheres and five healthy volunteers at 3 T and 7 T with 1 mm isotropic resolution. The data were fitted with the based on a three compartment complex-valued model to estimate MWF. We obtained myelin basic protein (MBP) staining from two tissue blocks and co-registered the MWF map and histology image for voxel-wise correlation between the two. The MWF values measured from 7 T were overall higher than 7 T, but data between the two field strength demonstrated high correlations both in vivo (r = 0.88) and ex vivo (r = 0.83) across 19 white matter regions. Moreover, the MWF measurements showed a good agreement between in vivo and ex vivo assessments at 3 T (r = 0.61) and 7 T (r = 0.54). Based on MBP staining, the MWF values exhibited strong positive correlations with myelin content on both 3 T (r = 0.68 and r = 0.78 for the two tissue blocks) and 7 T (r = 0.64 and r = 0.82 for the two tissue blocks). The findings demonstrated that the mGRE-based MWF mapping can be used to quantify myelin content in the human brain, despite the field-strength dependency of the measurements.

Extracellular vesicles produced by HIV-1 Nef-expressing cells induce myelin impairment and oligodendrocyte damage in the mouse central nervous system

HIV-associated neurocognitive disorders (HAND) are a spectrum of cognitive impairments that continue to affect approximately half of all HIV-positive individuals despite effective viral suppression through antiretroviral therapy (ART). White matter pathologies have persisted in the ART era, and the degree of white matter damage correlates with the degree of neurocognitive impairment in patients with HAND. The HIV protein Nef has been implicated in HAND pathogenesis, but its effect on white matter damage has not been well characterized. Here, utilizing in vivo, ex vivo, and in vitro methods, we demonstrate that Nef-containing extracellular vesicles (Nef EVs) disrupt myelin sheaths and inflict damage upon oligodendrocytes within the murine central nervous system. Intracranial injection of Nef EVs leads to reduced myelin basic protein (MBP) staining and a decreased number of CC1 + oligodendrocytes in the corpus callosum. Moreover, cerebellar slice cultures treated with Nef EVs exhibit diminished MBP expression and increased presence of unmyelinated axons. Primary mixed brain cultures and enriched oligodendrocyte precursor cell cultures exposed to Nef EVs display a decreased number of O4 + cells, indicative of oligodendrocyte impairment. These findings underscore the potential contribution of Nef EV-mediated damage to oligodendrocytes and myelin maintenance in the pathogenesis of HAND.

A circRNA ceRNA network involved in cognitive dysfunction after chronic cerebral hypoperfusion.

Chronic Cerebral Hypoperfusion (CCH) is associated with cognitive dysfunction, the underlying mechanisms of which remain elusive, hindering the development of effective therapeutic approaches. In this study, we employed an established CCH animal model to delve into neuropathological alterations like oxidative stress, inflammation, neurotransmitter synthesis deficits, and other morphological alterations. Our findings revealed that while the number of neurons remained unchanged, there was a significant reduction in neuronal fibers post-CCH, as evidenced by microtubule-associated protein 2 (MAP2) staining. Moreover, myelin basic protein (MBP) staining showed exacerbated demyelination of neuronal fibers. Furthermore, we observed increased neuroinflammation, proliferation, and activation of astrocytes and microglia, as well as synaptic loss and microglial-mediated synapse engulfment post-CCH. Utilizing RNA sequencing, differential expression analysis displayed alterations in both mRNAs and circRNAs. Following gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, both showed significant enrichment in immunological and inflammation-related terms and pathways. Importantly, the differentially expressed circular RNAs (DE circRNAs) exhibited a notable coexpression pattern with DE mRNAs. The ternary circRNA-miRNA-mRNA competing endogenous RNAs (ceRNA) network was constructed, and subsequent analysis reiterated the significance of neuroimmunological and neuroinflammatory dysfunction in CCH-induced neuropathological changes and cognitive dysfunction. This study underscores the potential role of circRNAs in these processes, suggesting them as promising therapeutic targets to mitigate the detrimental effects of CCH.

GluN2A Mediates PS-Induced Depressive-Like Behavior by Activating CaMKII and Inhibiting Myelinization.

Prenatal stress (PS) can induce depression in offspring, but the underlying mechanisms are still unknown. The aim of this work was to investigate the mechanism that underlies PS-induced depressive-like behavior in offspring. A prenatal restraint stress procedure was developed in which pregnant rats at GD14 to GD20 were placed head-first into a well-ventilated bottle three times each day and for 45 min each time. Depressive-like behavior in the male offspring was examined using the sucrose preference test (SPT) and the forced swim test (FST). The level of glutamate and the expression levels of GluN2A, p-CaMKII and myelin basic protein (MBP) in the hippocampus of PS-susceptible (PS-S) offspring were also evaluated. To clarify the mechanism by which PS leads to depression in offspring, the effects of excessive corticosterone were also investigated using an in vitro "injured neuronal" model. The glutamate level in the hippocampus of PS-S male offspring was significantly elevated compared to controls. The expression levels of GluN2A and p-CaMKII were also altered. In addition, the optical density of MBP staining and the expression levels of MBP mRNA and MBP protein were decreased, demonstrating impaired myelinization in the hippocampus. Treatment of PS-S offspring with the GluN2A receptor antagonist NVP-AAM077 resulted in antidepressant-like effects in the FST, as well as rescue of the MBP and p-CaMKII abnormalities. These findings indicate that GluN2A is a promising target in the development of pharmacotherapies for PS-induced depression.

Valproic acid ameliorates cauda equina injury by suppressing HDAC2-mediated ferroptosis.

Persistent neuroinflammatory response after cauda equina injury (CEI) lowers nociceptor firing thresholds, accompanied by pathological pain and decreasing extremity dysfunction. Histone deacetylation has been considered a key regulator of immunity, inflammation, and neurological dysfunction. Our previous study suggested that valproic acid (VPA), a histone deacetylase inhibitor, exhibited neuroprotective effects in rat models of CEI, although the underlying mechanism remains elusive. The cauda equina compression surgery was performed to establish the CEI model. The Basso, Beattie, Bresnahan score, and the von Frey filament test were carried out to measure the animal behavior. Immunofluorescence staining of myelin basic protein and GPX4 was carried out. In addition, transmission electron microscope analysis was used to assess the effect of VPA on the morphological changes of mitochondria. RNA-sequencing was conducted to clarify the underlying mechanism of VPA on CEI protection. In this current study, we revealed that the expression level of HDAC1 and HDAC2 was elevated after cauda equina compression model but was reversed by VPA treatment. Meanwhile, HDAC2 knockdown resulted in the improvement of motor functions and pathologic pain, similar to treatment with VPA. Histology analysis also showed that knockdown of histone deacetylase (HDAC)-2, but not HDAC1, remarkably alleviated cauda equina injury and demyelinating lesions. The potential mechanism may be related to lowering oxidative stress and inflammatory response in the injured region. Notably, the transcriptome sequencing indicated that the therapeutic effect of VPA may depend on HDAC2-mediated ferroptosis. Ferroptosis-related genes were analyzed invivo and DRG cells further validated the reliability of RNA-sequencing results, suggesting HDAC2-H4K12ac axis participated in epigenetic modulation of ferroptosis-related genes. HDAC2 is critically involved in the ferroptosis and neuroinflammation in cauda equina injury, and VPA ameliorated cauda equina injury by suppressing HDAC2-mediated ferroptosis.

Glutamate delta-1 receptor regulates oligodendrocyte progenitor cell differentiation and myelination in normal and demyelinating conditions.

In this study, we investigated the role of glutamate delta 1 receptor (GluD1) in oligodendrocyte progenitor cell (OPC)-mediated myelination during basal (development) and pathophysiological (cuprizone-induced demyelination) conditions. Initially, we sought to determine the expression pattern of GluD1 in OPCs and found a significant colocalization of GluD1 puncta with neuron-glial antigen 2 (NG2, OPC marker) in the motor cortex and dorsal striatum. Importantly, we found that the ablation of GluD1 led to an increase in the number of myelin-associated glycoprotein (MAG+) cells in the corpus callosum and motor cortex at P40 without affecting the number of NG2+ OPCs, suggesting that GluD1 loss selectively facilitates OPC differentiation rather than proliferation. Further, deletion of GluD1 enhanced myelination in the corpus callosum and motor cortex, as indicated by increased myelin basic protein (MBP) staining at P40, suggesting that GluD1 may play an essential role in the developmental regulation of myelination during the critical window period. In contrast, in cuprizone-induced demyelination, we observed reduced MBP staining in the corpus callosum of GluD1 KO mice. Furthermore, cuprizone-fed GluD1 KO mice showed more robust motor deficits. Collectively, our results demonstrate that GluD1 plays a critical role in OPC regulation and myelination in normal and demyelinating conditions.

Comparing palm oil-derived tocotrienol-rich fraction with alpha-tocopherol in changes in locomotion and histological appearance in a cuprizone-induced animal model of multiple sclerosis

Aims: Alpha-tocopherol (AT) and tocotrienol (TT) are both naturally occurring forms of vitamin E found in palm oil. Previous studies found beneficial effects of AT in multiple sclerosis (MS) animal models. In the present study, the effects of palm oil-derived TT-rich fraction (TRF) and AT on the locomotor function, lipid peroxidation, and histological study of demyelination were compared in cuprizone (CPZ)-induced rat model of MS. Methods: Female Sprague-Dawley rats aged 8 weeks received pellets mixed with CPZ for a duration of 6 weeks, followed by 100 mg/kg AT (group AT, n = 10) daily and 60 mg/kg TRF (group TT, n = 10) daily and vehicle (group V, n = 10) through oral gavage for 2 weeks. Open field test (OFT) and beam walking test (BWT) were carried out every 10th day. The status of myelination in the corpus callosum was evaluated by Luxol fast blue (LFB) staining and immunohistochemical staining of myelin basic protein (MBP). Malondialdehyde (MDA) level was estimated using brain homogenate. Results: Compared with group V, total distance moved and movement speed increased by 42.6 and 52.9%, respectively in group TT (P < 0.05). Line crossing frequency increased by 39% (P < 0.05) and 36% (P < 0.05), respectively in groups TT and AT. Corpus callosum showed a maximum reduction of demyelinated areas and higher expression of MBP in group TT. MDA level in the cortex was significantly reduced in group AT. Conclusion: TRF improved locomotion and provided histological evidence of myelination in CPZ-withdrawn rats. AT reduced MDA levels in the cortex.

Acupuncture on “Huantiao” (GB30) and "Yanglingquan" (GB34) acupoints promotes nerve regeneration in mice model of peripheral nerve injury

ObjectiveTo investigate the effects of acupuncture on promoting nerve regeneration in mice with sciatic nerve crushed injury, an animal model of peripheral nerve injury (PNI). MethodsAcupuncture was performed on the "Huantiao" (GB30) and "Yanglingquan" (GB34) acupoints in PNI mice model for 2 weeks. Gait analysis, toe spreading test, electrophysiological test, toluidine blue staining and immunostaining of myelin basic protein (MBP), neurofilament-200 (NF200), p75 neurotrophin receptor (p75NTR), and growth associated protein-43 (GAP43) were respectively performed to investigate the effects of acupuncture on crushed sciatic nerve. ResultsAcupuncture stimulation of “Huantiao” (GB30) and "Yanglingquan" (GB34) acupoints promoted the recovery of motor function and electrophysiological function in PNI mice model, which was indicated by a better gait level, toe spreading level and CMAP value in acupuncture group. The number of myelinated nerve fibers and the fluorescence intensity of MBP, NF200, p75NTR and GAP43 staining demonstrated that the acupuncture stimulation promoted the regeneration of injured nerves in PNI mice model. ConclusionAcupuncture significantly promoted the functional and morphological recovery of crushed sciatic nerve via promoting the expression of p75NTR in Schwann cells.

Myelin Disruption, Neuroinflammation, and Oxidative Stress Induced by Sulfite in the Striatum of Rats Are Mitigated by the pan-PPAR agonist Bezafibrate.

Sulfite predominantly accumulates in the brain of patients with isolated sulfite oxidase (ISOD) and molybdenum cofactor (MoCD) deficiencies. Patients present with severe neurological symptoms and basal ganglia alterations, the pathophysiology of which is not fully established. Therapies are ineffective. To elucidate the pathomechanisms of ISOD and MoCD, we investigated the effects of intrastriatal administration of sulfite on myelin structure, neuroinflammation, and oxidative stress in rat striatum. Sulfite administration decreased FluoromyelinTM and myelin basic protein staining, suggesting myelin abnormalities. Sulfite also increased the staining of NG2, a protein marker of oligodendrocyte progenitor cells. In line with this, sulfite also reduced the viability of MO3.13 cells, which express oligodendroglial markers. Furthermore, sulfite altered the expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1), indicating neuroinflammation and redox homeostasis disturbances. Iba1 staining, another marker of neuroinflammation, was also increased by sulfite. These data suggest that myelin changes and neuroinflammation induced by sulfite contribute to the pathophysiology of ISOD and MoCD. Notably, post-treatment with bezafibrate (BEZ), a pan-PPAR agonist, mitigated alterations in myelin markers and Iba1 staining, and IL-1β, IL-6, iNOS and HO-1 expression in the striatum. MO3.13 cell viability decrease was further prevented. Moreover, pre-treatment with BEZ also attenuated some effects. These findings show the modulation of PPAR as a potential opportunity for therapeutic intervention in these disorders.

In Vitro Myelination of Peripheral Axons in a Coculture of Rat Dorsal Root Ganglion Explants and Schwann Cells.

The process of myelination is essential to enable rapid and sufficient signal transduction in the nervous system. In the peripheral nervous system, neurons and Schwann cells engage in a complex interaction to control the myelination of axons. Disturbances of this interaction and breakdown of the myelin sheath are hallmarks of inflammatory neuropathies and occur secondarily in neurodegenerative disorders. Here, we present a coculture model of dorsal root ganglion explants and Schwann cells, which develops a robust myelination of peripheral axons to investigate the process of myelination in the peripheral nervous system, study axon-Schwann cell interactions, and evaluate the potential effects of therapeutic agents on each cell type separately. Methodologically, dorsal root ganglions of embryonic rats (E13.5) were harvested, dissociated from their surrounding tissue, and cultured as whole explants for 3 days. Schwann cells were isolated from 3-week-old adult rats, and sciatic nerves were enzymatically digested. The resulting Schwann cells were purified by magnetic-activated cell sorting and cultured under neuregulin and forskolin-enriched conditions. After 3 days of dorsal root ganglion explant culture, 30,000 Schwann cells were added to one dorsal root ganglion explant in a medium containing ascorbic acid. The first signs of myelination were detected on day 10 of coculture, through scattered signals for myelin basic protein in immunocytochemical staining. From day 14 onward, myelin sheaths were formed and propagated along the axons. Myelination can be quantified by myelin basic protein staining as a ratio of the myelination area and axon area, to account for the differences in axonal density. This model provides experimental opportunities to study various aspects of peripheral myelination in vitro, which is crucial for understanding the pathology of and possible treatment opportunities for demyelination and neurodegeneration in inflammatory and neurodegenerative diseases of the peripheral nervous system.

Pharmacologic Toll-like receptor 4 inhibition skews toward a favorable A1/A2 astrocytic ratio improving neurocognitive outcomes following traumatic brain injury.

Astrocytes are critical neuroimmune cells that modulate the neuroinflammatory response following traumatic brain injury (TBI) because of their ability to acquire neurotoxic (A1) or neuroprotective (A2) phenotypes. Using C34, a novel pharmacologic Toll-like receptor (TLR) 4 inhibitor, we explored their respective polarization states after TBI. A murine controlled cortical impact model was used, and the results were analyzed on postinjury days (PIDs) 1, 7, and 28. The experimental groups are as follows: (1) sham, (2) sham + C34, (3) TBI, and (4) TBI + C34. Quantitative real-time polymerase chain reaction was used to quantify gene expression associated with proinflammatory (A1) and anti-inflammatory (A2) phenotypes. Morris water maze was used to assess neurocognitive outcomes. Fixed frozen cortical samples were sectioned, stained for myelin basic protein and 4',6-diamidino-2-phenylindole, and then imaged. Student t test and one-way analysis of variance were used for statistical analysis with significance achieved when p < 0.05. On quantitative real-time polymerase chain reaction, C34-treated groups showed a significant decrease in the expression of A1 markers such as Gbp2 and a significant increase in the expression of A2 markers such as Emp1 when compared with untreated groups on PID 1. On PIDs 7 and 28, the expression of most A1 and A2 markers was also significantly decreased in the C34-treated groups. On immunohistochemistry, C34-treated groups demonstrated increased myelin basic protein staining into the lesion by PID 28. C34-treated groups showed more platform entries on Morris water maze when compared with untreated groups on PID 7 and PID 28. Following TBI, early TLR4 blockade modulates astrocytic function and shifts its polarization toward the anti-inflammatory A2-like phenotype. This is accompanied by an increase in myelin regeneration, providing better neuroprotection and improved neurocognitive outcomes. Targeting A1/A2 balance with TLR4 inhibition provides a potential therapeutic target to improve neurobehavioral outcomes in the setting of TBI.

Presence of eosinophil extracellular trap cell death in the affected skin of eosinophilic granulomatosis with polyangiitis.

Eosinophil activation in tissue might be associated with disease severity. Eosinophil cytolysis, a process of active cell death, has been referred to as eosinophil extracellular trap cell death (EETosis). In the present study, the authors investigated EETosis in the affected skin of four patients with eosinophilic granulomatosis with polyangiitis (EGPA) using an immunofluorescence staining method. Immunofluorescence staining for myelin basic protein, galectin-10, and DNA revealed various degrees of EETosis and Charcot-Leyden crystals in skin tissue, suggesting the different degree of eosinophil activation status. The histopathological characteristic features may help physicians establish an earlier diagnosis of intractable eosinophilic-related disease including EGPA. Furthermore, ETotic eosinophil infiltration in perineurium of skin tissue might play a primary role in peripheral neuropathy of this disorder.

Activation of liver X receptors protects oligodendrocytes in CA3 of stress-induced mice

Depression is a complex disorder that is associated with various structural abnormalities. Oligodendrocyte (OL) dysfunction is associated with the pathogenesis of depression and the promotion of hippocampal oligodendrocyte maturation and myelination could be a novel therapeutic strategy for ameliorating depressive behaviors. Recent studies have shown that activation of liver X receptors (LXRs) by GW3965 improves depressive phenotypes, but the effects of GW3965 on OL function and myelination in the hippocampus of depression remain relatively unclear. To address this issue, we investigated the effects of GW3965 on mature OL in the hippocampus and on the myelin sheaths of mice subjected to chronic unpredictable stress (CUS). Behavioral tests were performed to assess depressive behaviors. Then, the number of mature OLs (CC1+) in each hippocampal subregion was precisely quantified with immunohistochemical and stereological methods, and the density of newborn mature OLs (BrdU+/Olig2+/CC1+ cells) in each hippocampal subregion was quantified with immunofluorescence. In addition, myelin basic protein (MBP) staining intensity in the cornu ammonis 3 (CA3) region was assessed by using immunofluorescence. We found that both the number of CC1+ OLs and the density of BrdU+/Olig2+/CC1+ cells were obviously decreased in each hippocampal subregion of mice subjected to CUS, and 4 weeks of GW3965 treatment reversed these effects only in the CA3 region. Furthermore, the decreased MBP expression in the CA3 region of mice subjected to CUS was ameliorated by GW3965 treatment. Collectively, these results suggested that improvement of OL maturation and enhancement of myelination may be structural mechanisms underlying the antidepressant effects of LXR agonists.

An in vivo accelerated developmental myelination model for testing promyelinating therapeutics

BackgroundTherapeutic agents stimulating the process of myelination could be beneficial for the treatment of demyelinating diseases, such as multiple sclerosis. The efficient translation of compounds promoting myelination in vitro to efficacy in vivo is inherently time-consuming and expensive. Thyroid hormones accelerate the differentiation and maturation of oligodendrocytes, thereby promoting myelination. Systemic administration of the thyroid hormone thyroxine (T4) accelerates brain maturation, including myelination, during early postnatal development. The objective of this study was to validate an animal model for rapid testing of promyelinating therapeutic candidates for their effects on early postnatal development by using T4 as a reference compound.MethodsDaily subcutaneous injections of T4 were given to Sprague Dawley rat pups from postnatal day (PND) 2 to PND10. Changes in white matter were determined at PND10 using diffusion tensor magnetic resonance imaging (DTI). Temporal changes in myelination from PND3 to PND11 were also assessed by quantifying myelin basic protein (MBP) expression levels in the brain using the resonance Raman spectroscopy/enzyme-linked immunosorbent assay (RRS-ELISA) and quantitative immunohistochemistry.ResultsDTI of white matter tracts showed significantly higher fractional anisotropy in the internal capsule of T4-treated rat pups. The distribution of total FA values in the forebrain was significantly shifted towards higher values in the T4-treated group, suggesting increased myelination. In vivo imaging data were supported by in vitro observations, as T4 administration significantly potentiated the developmental increase in MBP levels in brain lysates starting from PND8. MBP levels in the brain of animals that received treatment for 9 days correlated with the FA metric determined in the same pups in vivo a day earlier. Furthermore, accelerated developmental myelination following T4 administration was confirmed by immunohistochemical staining for MBP in coronal brain sections of treated rat pups.ConclusionsT4-treated rat pups had increased MBP expression levels and higher MRI fractional anisotropy values, both indications of accelerated myelination. This simple developmental myelination model affords a rapid test of promyelinating activity in vivo within several days, which could facilitate in vivo prescreening of candidate therapeutic compounds for developmental hypomyelinating diseases. Further research will be necessary to assess the utility of this platform for screening promyelination compounds in more complex demyelination disease models, such us multiple sclerosis.

Ginsenoside Rg1 Plays a Neuroprotective Role in Regulating the Iron-Regulated Proteins and Against Lipid Peroxidation in Oligodendrocytes.

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Progressive loss of dopaminergic neurons in the substantia nigra (SN) is one of the major pathological changes. However, the reasons for the dopaminergic neuron loss are still ambiguous and further studies are needed to evaluate the in-depth mechanisms of neuron death. Oxidative stress is a significant factor causing neuronal damage. Dopaminergic neurons in the SN are susceptible to oxidative stress, which is closely associated with iron dyshomeostasis in the brain. Ginsenoside Rg1 from ginseng plays a crucial role in neuroprotective effects through anti-inflammation and attenuating the aggregation of abnormal α-synuclein. In our study, we established a chronic PD mouse model by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine combined with probenecid and explored the effect of Rg1 on the oxidative stress and brain iron homeostasis. Rg1 was verified to improve the level of tyrosine hydroxylase and anti-oxidant stress. In addition, Rg1 maintained the iron-regulated protein homeostasis by increasing the expression of ferritin heavy chain and decreasing ferritin light chain in oligodendrocytes, especially the mature oligodendrocytes (OLs). Furthermore, Rg1 had a positive effect on the myelin sheath protection and increased the number of mature oligodendrocytes, proved by the increased staining of myelin basic protein and CC-1. In conclusion, Rg1 could play a neuroprotective role through remitting the iron-regulated protein dyshomeostasis by ferritin and against lipid peroxidation stress in oligodendrocytes.

Autophagy Inhibition Reduces Irradiation-Induced Subcortical White Matter Injury Not by Reducing Inflammation, but by Increasing Mitochondrial Fusion and Inhibiting Mitochondrial Fission

Radiotherapy is an effective tool in the treatment of malignant brain tumors, but irradiation-induced late-onset toxicity remains a major problem. The purpose of this study was to investigate if genetic inhibition of autophagy has an impact on subcortical white matter development in the juvenile mouse brain after irradiation. Ten-day-old selective neural Atg7 knockout (KO) mice and wild-type (WT) littermates were subjected to a single 6-Gy dose of whole-brain irradiation and evaluated at 5 days after irradiation. Neural Atg7 deficiency partially prevented myelin disruption compared to the WT mice after irradiation, as indicated by myelin basic protein staining. Irradiation induced oligodendrocyte progenitor cell loss in the subcortical white matter, and Atg7 deficiency partly prevented this. There was no significant change between the KO and WT mice in the number of microglia and astrocytes in the subcortical white matter after irradiation. Transcriptome analysis showed that the GO mitochondrial gene expression pathway was significantly enriched in the differentially expressed genes between the KO and WT group after irradiation. Compared with WT mice, expression of the mitochondrial fusion protein OPA1 and phosphorylation of the mitochondrial fission protein DRP1 (P-DRP1) were dramatically decreased in KO mice under physiological conditions. The protein levels of OPA1and P-DRP1 showed no differences in WT mice between the non-irradiated group and the irradiated group but had remarkably increased levels in the KO mice after irradiation. These results indicate that inhibition of autophagy reduces irradiation-induced subcortical white matter injury not by reducing inflammation, but by increasing mitochondrial fusion and inhibiting mitochondrial fission.

Myelination, axonal loss and Schwann cell characteristics in axonal polyneuropathy compared to controls.

IntroductionPolyneuropathy is a debilitating condition characterized by distal sensory and motor deficits. Schwann cell dysfunction and axonal loss are integral factors in pathophysiology and disease progression of polyneuropathy.AimsThe aim of this study was the assessment of Schwann cell characteristics, nerve fibers and myelination parameters in polyneuropathy patients compared to controls.MethodsNerve tissue was obtained from polyneuropathy patients (n = 10) undergoing diagnostic sural nerve biopsies. Biopsies of healthy peripheral nerves (n = 5) were harvested during elective sural nerve grafting for chronic peripheral nerve lesions. Exclusion criteria for the healthy control group were recent neurological trauma, diabetes, neurological and cardiovascular disease, as well as active malignancies and cytotoxic medication within the last 12 months. The over-all architecture of nerve sections and myelination parameters were histomorphometrically analyzed. Immunofluorescent imaging was used to evaluate Schwann cell phenotypes, senescence markers and myelination parameters.ResultsHistomorphometric analysis of nerve biopsies showed significant axonal loss in polyneuropathy patients compared to controls, which was in accordance with the neuropathological findings. Immunofluorescent staining of Schwann cells and myelin basic protein indicated a significant impairment of myelination and lower Schwann cell counts compared to controls. Phenotypic alterations and increased numbers of non-myelinating p75-positive Schwann cells were found in polyneuropathy patients.DiscussionThis study provided quantitative data of axonal loss, reduced myelination and Schwann cell dysfunction of polyneuropathy patients compared to neurologically healthy controls. Phenotypic alterations of Schwann cells were similar to those seen after peripheral nerve injury, highlighting the clinical relevance of Schwann cell dysfunction.

Fourier Transform Infrared Imaging-A Novel Approach to Monitor Bio Molecular Changes in Subacute Mild Traumatic Brain Injury.

Traumatic brain injury (TBI) can be defined as a disorder in the function of the brain after a bump, blow, or jolt to the head, or penetrating head injury. Mild traumatic brain injury (mTBI) can cause devastating effects, such as the initiation of long-term neurodegeneration in brain tissue. In the current study, the effects of mTBI were investigated on rat brain regions; cortex (Co) and corpus callosum (CC) after 24 h (subacute trauma) by Fourier transform infrared (FTIR) imaging and immunohistochemistry (IHC). IHC studies showed the formation of amyloid-β (Aβ) plaques in the cortex brain region of mTBI rats. Moreover, staining of myelin basic protein presented the shearing of axons in CC region in the same group of animals. According to FTIR imaging results, total protein and lipid content significantly decreased in both Co and CC regions in mTBI group compared to the control. Due to this significant decrease in both lipid and protein content, remarkable consistency in lipid/protein band ratio in mTBI and control group, was observed. Significant decrease in methyl content and a significant increase in olefinic content were observed in Co and CC regions of mTBI rat brain tissues. Classification amongst distinguishable groups was performed using principal component analysis (PCA) and hierarchical clustering (HCA). This study established the prospective of FTIR imaging for assessing biochemical changes due to mTBI with high sensitivity, precision and high-resolution.

Inhalation of particulate and emissions from 3 dimensional (3D) printers: Effects on the olfactory bulb (OB) and hypothalamic‐pituitary‐endocrine axes

There is increasing concern regarding the potential health effects associated with exposure to plastic nanoparticles and the chemicals released when plastic is heated or dissolved in water. Although exposure to plastic particles and their composite chemicals can be generated by a number of different processes, 3D printers used in manufacturing, schools and homes, are sources of fumes and particulate that humans are exposed to. This study examined whether inhalation of particulate and fumes generated during 3D printing with polycarbonate (PC) affects the OB and neuroendocrine system, and if there is a dose-response relationship between exposure levels and measures of cell function. Methods Male rats (n= 6/group, 200 – 250 g at arrival) were exposed to filtered air, or black PC particulate and fumes generated by 3 desktop 3D-printers (exposure was 4 h/day). The 4h average particulate concentration delivered to the animals breathing space was 500 µg/m3. Animals were exposed 4 days/week until the specified number of days of exposure (1, 4, 8, 15 or 30) had been reached. The morning after the last exposure, animals were euthanized, blood was collected and circulating hormone levels were measured in serum samples using ELISAs. The OB and brain were also collected, frozen, sectioned and stored at -80°C until processed for immunohistochemistry. Results In the OB, exposure to 3D-emissions resulted in reductions in tyrosine hydroxylase (TH; rate limiting enzyme in dopamine synthesis) and glial derived neurotrophic factor immunolabeling. There were also reductions in myelin basic protein and cAMP nucleotide phosphatase staining, suggesting that there was myelin damage and dysfunction in the OB. In the hypothalamus, the major effects of exposure to 3D-emissions were reductions in immunostaining for TH and glial fibrillary acidic protein, a marker of astrocyte activation. Changes in immunostaining in the OB suggest there is cellular dysfunction and potentially an alteration in the transmission of olfactory information to the brain. Changes in activity and morphology of astrocytes in the hypothalamus have been shown to affect the release of hormones, including those regulating reproductive and metabolic processes; In the current study, exposure to 3D-emissions also resulted in changes in circulating concentrations of follicle stimulating hormone, and thyroid stimulating hormone. Conclusions Inhalation of PC particulate and/or fumes may act through olfactory pathways and affect neuroendocrine function. Although is not clear if these changes are the result of particulate matter interfering with various cellular and physiological processes, or due to endocrine disrupting bisphenols that are present in polycarbonate plastics, the results of this study are consistent with other experiments showing that exposure to PC particulate and the composite chemicals interfere with neuroendocrine processes that regulate reproduction and metabolism.

Temperature dependence and histological correlation of inhomogeneous magnetization transfer and myelin water imaging in ex vivo brain

PurposeThe promise of inhomogeneous magnetization transfer (ihMT) as a new myelin imaging method was studied in ex vivo human brain tissue and in relation to myelin water fraction (MWF). The temperature dependence of both methods was characterized, as well as their correspondence with a histological measure of myelin content. Unfiltered and filtered ihMT protocols were studied by adjusting the saturation scheme to preserve or attenuate signal from tissue with short dipolar relaxation time T1D. MethodsihMT ratio (ihMTR) and MWF maps were acquired at 7 T from formalin-fixed human brain samples at 22.5 °C, 30 °C and 37 °C. The impact of temperature on unfiltered ihMTR, filtered ihMTR and MWF was investigated and compared to myelin basic protein staining. ResultsUnfiltered ihMTR exhibited no temperature dependence, whereas filtered ihMTR increased with increasing temperature. MWF decreased at higher temperature, with an increasing prevalence of areas where the myelin water signal was unreliably determined, likely related to a reduction in T2 peak separability at higher temperatures ex vivo. MWF and ihMTR showed similar per-sample correlation with myelin staining at room temperature. At 37 °C, filtered ihMTR was more strongly correlated with myelin staining and had increased dynamic range compared to unfiltered ihMTR. ConclusionsGiven the temperature dependence of filtered ihMT, increased dynamic range, and strong myelin specificity that persists at higher temperatures, we recommend carefully controlled temperatures close to 37 °C for filtered ihMT acquisitions. Unfiltered ihMT may also be useful, due to its independence from temperature, higher amplitude values, and sensitivity to short T1D components. Ex vivo myelin water imaging should be performed at room temperature, to avoid fitting issues found at higher temperatures.