Brainstem Regions Research Articles

Mu-opioid receptors in tachykinin-1-positive cells mediate the respiratory and antinociceptive effects of the opioid fentanyl.

Opioid drugs are potent analgesics that carry the risk of respiratory side effects due to actions on μ-opioid receptors (MORs) in brainstem regions that control respiration. Substance P is encoded by the Tac1 gene and is expressed in neurons regulating breathing, nociception, and locomotion. Tac1-positive cells also express MORs in brainstem regions mediating opioid-induced respiratory depression. We determined the role of Tac1-positive cells in mediating the respiratory effects of opioid drugs. In situ hybridization was used to determine Oprm1 mRNA expression (gene encoding MORs) in Tac1-positive cells in regions regulating respiratory depression by opioid drugs. Conditional knockout mice lacking functional MORs in Tac1-positive cells were produced and the respiratory and locomotor responses to the opioid analgesic fentanyl were assessed using whole-body plethysmography. A tail immersion assay was used to assess the antinociceptive response to fentanyl. Oprm1 mRNA was highly expressed (>80%) in subpopulations of Tac1-positive cells in the preBötzinger Complex, nucleus tractus solitarius, and Kölliker-Fuse/lateral parabrachial region. Conditionally knocking out MORs in Tac1-positive cells abolished the effects of fentanyl on respiratory rate, relative tidal volume, and relative minute ventilation compared with control mice. Importantly, the antinociceptive response of fentanyl was eliminated in mice lacking functional MORs in Tac1-positive cells, whereas locomotor effects induced by fentanyl were preserved. Our findings suggest that Tac1-positive cells mediate the respiratory depressive and antinociceptive effects of the opioid fentanyl, providing important insights for the development of pain therapies with reduced risk of respiratory side effects.

Diversity of ancestral brainstem noradrenergic neurons across species and multiple biological factors.

The brainstem region, locus coeruleus (LC), has been remarkably conserved across vertebrates. Evolution has woven the LC into wide-ranging neural circuits that influence functions as broad as autonomic systems, the stress response, nociception, sleep, and high-level cognition among others. Given this conservation, there is a strong possibility that LC activity is inherently similar across species, and furthermore that age, sex, and brain state influence LC activity similarly across species. The degree to which LC activity is homogenous across these factors, however, has never been assessed due to the small sample size of individual studies. Here, we pool data from 20 laboratories (1,855 neurons) and show diversity across both intrinsic and extrinsic factors such as species, age, sex and brain state. We use a negative binomial regression model to compare activity from male monkeys, and rats and mice of both sexes that were recorded across brain states from brain slices ex vivo or under different anesthetics or during wakefulness in vivo . LC activity differed due to complex interactions of species, sex, and brain state. The LC became more active during aging, independent of sex. Finally, in contrast to the foundational principle that all species express two distinct LC firing modes ("tonic" or "phasic"), we discovered great diversity within spontaneous LC firing patterns. Different factors were associated with higher incidence of some firing modes. We conclude that the activity of the evolutionarily-ancient LC is not conserved. Inherent differences due to age and species-sex-brain state interactions have implications for understanding the role of LC in species-specific naturalistic behavior, as well as in psychiatric disorders, cardiovascular disease, immunology, and metabolic disorders.

18F]FDG Brain Imaging Assessment in Preclinical Acute and Chronic Stress Models Using Statistical Parametric Mapping

Previous studies have used [18F]FDG as a biomarker for depression, anxiety, or chronic stress in cancer patients1,2. However, they lack specific brain patterns and assessment in preclinical models, limiting their translational potential. Hence, we set out to establish preclinical [18F]FDG brain PET as a method to evaluate stress in vivo. Lean C57BL/6J mice were exposed to acute and chronic cooling, restraint, and surgical stress. Obese mice were on a high-fat diet for eight weeks and exposed to cooling and restraint stress. [18F]FDG was injected into fasted animals under brief isoflurane anesthesia via the tail vein. Following a 60-minute distribution phase during acute stress or one day after stress exposure (chronic), animals underwent static μPET/CT scans (Siemens® Inveon). Brain images were spatially normalized, and intensity normalization was performed using proportional and histogram-based scaling3 with PMOD (V. 3.8). Normalized images were analyzed using a brain atlas (M. Mirrione) to extract regional SUV and statistical parametric mapping (SPM12) for voxel-wise comparison. Overall, in lean mice, total brain [18F]FDG-uptake was significantly reduced across all stress models except for acute restraint, whereas total uptake was unaffected in obese mice. Subsequent brain atlas analysis of lean mice revealed changes in regional uptake for all stressors except for chronic cooling, while obese mice were affected by only acute and chronic restraint. Using SPM, we validated stress-specific hypo- and hypermetabolic areas in the brains of lean mice upon acute cooling, acute and chronic restraint, and surgery and in obese mice after chronic restraint (see Figure). We also identified overlapping areas in the brain stem and hypothalamus region following acute cooling and surgery, possibly due to post-surgical hypothermia. Our findings show that static [18F]FDG-imaging is a valuable tool for noninvasively assessing brain activity in a multitude of stress models and a suitable translational tool for stress research in mice. Please click on the 'PDF' for the full abstract!

8600 Acute Peripheral Pro-inflammatory Cytokine Injection Results in a Rapid Increase in Microglia Density in the Nucleus of the Solitary Tract

Abstract Disclosure: E.A. Castellanos: None. S.A. Tobet: None. The autonomic nervous system (ANS) is a major integrator of stress responses throughout the body. Physical or psychological stressors lead to neuroendocrine outputs from the hypothalamus and neurotransmitter mediated alterations in circuitry that control peripheral body systems including cardiovascular, pulmonary, and gastrointestinal, among others. Chronic stress can activate immune components, including microglia, leading to increased levels of proinflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-a) in the blood. Increased levels of these cytokines have been associated with several psychiatric disorders including major depressive disorder. In the current study, the impact of pro-inflammatory cytokines was examined in the dorsal vagal complex (DVC), a key brainstem region responsible for integrating autonomic inputs and outputs. The DVC includes the area postrema (AP), a sensory circumventricular organ, the nucleus of the solitary tract (NTS), and the vagal dorsal motor complex. The AP is in the middle of the DVC region, adjacent to cerebrospinal fluid and lacking a blood brain barrier (i.e., fenestrated capillaries). These traits make the AP uniquely located to integrate peripheral and central interactions between circulating cytokines and select immune cells in the DVC. This study concentrated on the effects of a single peripheral injection on microglia quantities in the DVC. TNF-a (50µg/Kg) and IL-6 (50µg/Kg) were administered by intraperitoneal injection and 2h later animals were perfused with 4% paraformaldehyde. Immunoreactive ionized calcium-binding adapter molecule 1 (IBA1) was used to identify microglia in the brainstem. In the area postrema there was a trend towards more immunoreactive IBA1 total area (µm^2; p = 0.08, ns) in mice that were injected with TNF-a and IL-6 compared to controls. By contrast, in the adjacent NTS there was 1.5x’s more immunoreactive IBA1 in mice that were injected with IL-6 and TNF-a (µm^2; p < 0.001) compared to control vehicle injections. Comparing brain regions in the DVC, there is 1.7x more microglia cells in the area postrema per section (50µm) compared to the NTS (p < 0.001), but in the NTS cells are 1.3x larger in size in comparison to the microglia cells in the AP overall (µm^2/ number of cells; p < 0.05). Finally, in the NTS there was a 1.5x larger total area of the IBA1 immunoreactivity following TNF-a injections compared to IL-6 injected mice (µm^2; p < 0.05). These data reveal a rapid effect of peripherally injected pro-inflammatory cytokines on microglial quantities and size in the brainstem. Future investigations will elucidate the role of neural-immune pathways in influencing the ANS during a chronic immune stress response. Supported by ORWH U54-MH118919. Presentation: 6/3/2024

Prediction of feeding difficulties in neonates with hypoxic-ischemic encephalopathy using magnetic resonance imaging-derived radiomics features.

The mechanisms behind brain and spinal cord injuries in hypoxic-ischemic encephalopathy (HIE) and associated feeding difficulties are unclear, with previous magnetic resonance imaging (MRI) attempts yielding inconclusive results. We aim to evaluate an MRI radiomics model for predicting feeding difficulties in HIE infants. Additionally, we investigate changes in predictive capability after incorporating the duration of mechanical ventilation and the timing of MRI examination. Retrospective study with 151 HIE infants (January 2013 to December 2021), randomly divided into training and validation sets. Radiomics features extracted from basal ganglia-thalamus and brainstem in T1-weighted and T2-weighted MRI. Established single-modality, single-site, and multimodality/multisite models. Receiver operating characteristic analysis and area under the curve evaluated models. Decision curve analysis assessed changes in predictive capability. The combined radiomics model of the basal ganglia-thalamus and brainstem regions on the T2-weighted imaging demonstrated superior performance (area under the curve: 0.958 and 0.875 for training and validation, respectively). Combining scores with duration of mechanical ventilation and MRI examination time in a calibration plot model improved and stabilized performance, showing high fitting and clinical utility. Decision curve analysis favored the combined calibration plot model. The MRI-based radiomics model predicts feeding difficulties in HIE infants, with basal ganglia-thalamus and brainstem as relevant factors. The combined calibration plot model exhibits the highest clinical predictive efficacy.

Characteristics of locus coeruleus functional connectivity network in patients with comorbid migraine and insomnia

BackgroundMigraine and insomnia are prevalent conditions that often co-occur, each exacerbating the other and substantially impacting the quality of life. The locus coeruleus (LC), a brainstem region responsible for norepinephrine synthesis, participates in pain modulation, sleep/wake cycles, and emotional regulation, rendering it a potential nexus in the comorbidity of migraine and insomnia. Disruptions in the LC-noradrenergic system have been hypothesized to contribute to the comorbidities of migraine and insomnia, although neuroimaging evidence in humans remains scarce. In this study, we aimed to investigate the intrinsic functional connectivity (FC) network of the LC in patients with comorbid migraine and subjective chronic insomnia and patients with migraine with no insomnia (MnI) using resting-state functional magnetic resonance imaging (rs-fMRI) and seed-based FC analyses.MethodsIn this cross-sectional study, 30 patients with comorbid migraine and chronic insomnia (MI), 30 patients with MnI, and 30 healthy controls (HCs) were enrolled. Participants underwent neuropsychological testing and rs-fMRI. The LC-FC network was constructed using seed-based voxel-wise FC analysis. To identify group differences in LC-FC networks, voxel-wise covariance analysis was conducted with sex and age as covariates. Subsequently, a partial correlation analysis was conducted to probe the clinical relevance of aberrant LC-FC in patients with MI and MnI.ResultsExcept for the insomnia score, no other significant difference was detected in demographic characteristics and behavioral performance between the MI and MnI groups. Compared with HCs, patients with MI exhibited altered LC-FC in several brain regions, including the dorsomedial prefrontal cortex (DMPFC), anterior cerebellum, dorsolateral prefrontal cortex (DLPFC), thalamus, and parahippocampal gyrus (PHG). Lower FC between the LC and DLPFC was associated with greater insomnia severity, whereas higher FC between the LC and DMPFC was linked to longer migraine attack duration in the MI group.ConclusionOur findings reveal the presence of aberrant LC-FC networks in patients with MI, providing neuroimaging evidence of the interplay between these conditions. The identified LC-FC alterations may serve as potential targets for therapeutic interventions and highlight the importance of considering the LC-noradrenergic system in the management of MI.

Uncovering the correlation between neurotransmitter-specific functional connectivity and multidimensional anxiety in a non-clinical cohort.

Research on anxiety faces challenges due to the wide range of symptoms, making it difficult to determine if different aspects of anxiety are linked to distinct neurobiological processes. Both alterations in functional brain connectivity (FC) and monoaminergic neurotransmitter systems are implicated as potential neural bases of anxiety. We aimed to investigate whole-brain FC involving monoaminergic nuclei and its association with anxiety dimensions in 178 non-clinical participants. Nine anxiety-related scales were used, encompassing trait and state anxiety scores, along with measures of cost-probability, hypervigilance, reward-punishment sensitivity, uncertainty, and trait worry. Resting-state functional magnetic resonance imaging data were acquired, focusing on seven brainstem regions representing serotonergic, dopaminergic, and noradrenergic nuclei, with their FC patterns voxel-wise correlated with the scales. All models underwent family-wise-error correction for multiple comparisons. We observed intriguing relationships: trait and state anxiety scores exhibited opposing correlations in FC between the dorsal raphe nucleus and the paracingulate gyrus. Additionally, we identified shared neural correlates, such as a negative correlation between the locus coeruleus and the frontal pole. This connection was significantly associated with scores on measures of probability, hypervigilance, reward sensitivity, and trait worry. These findings underscore the intricate interplay between anxiety dimensions and subcortico-cortical FC patterns, shedding light on the underlying neural mechanisms governing anxiety.

Dynamic balance and gait impairments in Parkinson's disease: novel cholinergic patterns.

The cholinergic system has been implicated in postural deficits, in particular falls, in Parkinson's disease (PD). Falls and freezing of gait typically occur during dynamic and challenging balance and gait conditions, such as when initiating gait, experiencing postural perturbations, or making turns. However, the precise cholinergic neural substrate underlying dynamic postural and gait changes remains poorly understood. The aim of this study was to investigate whether brain vesicular acetylcholine transporter binding, as measured with [18F]-fluoroethoxybenzovesamicol binding PET, correlates with dynamic gait and balance impairments in 125 patients with PD (mean age 66.89 ± 7.71 years) using the abbreviated balance evaluation systems test total and its four functional domain sub-scores (anticipatory postural control, reactive postural control, dynamic gait, and sensory integration). Whole brain false discovery-corrected (P < 0.05) correlations for total abbreviated balance evaluation systems test scores included the following bilateral or asymmetric hemispheric regions: gyrus rectus, orbitofrontal cortex, anterior part of the dorsomedial prefrontal cortex, dorsolateral prefrontal cortex, cingulum, frontotemporal opercula, insula, fimbria, right temporal pole, mesiotemporal, parietal and visual cortices, caudate nucleus, lateral and medial geniculate bodies, thalamus, lingual gyrus, cerebellar hemisphere lobule VI, left cerebellar crus I, superior cerebellar peduncles, flocculus, and nodulus. No significant correlations were found for the putamen or anteroventral putamen. The four domain-specific sub-scores demonstrated overlapping cholinergic topography in the metathalamus, fimbria, thalamus proper, and prefrontal cortices but also showed distinct topographic variations. For example, reactive postural control functions involved the right flocculus but not the upper brainstem regions. The anterior cingulum associated with reactive postural control whereas the posterior cingulum correlated with anticipatory control. The spatial extent of associated cholinergic system changes were least for dynamic gait and sensory orientation functional domains compared to the anticipatory and reactive postural control functions. We conclude that specific aspects of dynamic balance and gait deficits in PD associate with overlapping but also distinct patterns of cerebral cholinergic system changes in numerous brain regions. Our study also presents novel evidence of cholinergic topography involved in dynamic balance and gait in PD that have not been typically associated with mobility disturbances, such as the right anterior temporal pole, right anterior part of the dorsomedial prefrontal cortex, gyrus rectus, fimbria, lingual gyrus, flocculus, nodulus, and right cerebellar hemisphere lobules VI and left crus I.

Blood inflammation relates to neuroinflammation and survival in frontotemporal lobar degeneration.

Neuroinflammation is an important pathogenic mechanism in many neurodegenerative diseases, including those caused by frontotemporal lobar degeneration (FTLD). Postmortem and in vivo imaging studies have shown brain inflammation early in these conditions, proportionate to symptom severity and rate of progression. However, evidence for corresponding blood markers of inflammation and their relationship with central inflammation and clinical outcome are limited. There is a pressing need for such scalable, accessible and mechanistically relevant blood markers as these will reduce the time, risk, and costs of experimental medicine trials. We therefore assessed inflammatory patterns of serum cytokines from 214 patients with clinical syndromes associated with FTLD as compared to healthy controls, including their correlation with brain regional microglial activation and disease progression. Serum assays used the MesoScale Discovery V-Plex-Human Cytokine 36 plex panel plus five additional cytokine assays. A sub-group of patients underwent 11C-PK11195 TSPO PET imaging, as an index of microglial activation. A Principal Component Analysis (PCA) was used to reduce the dimensionality of cytokine data, excluding cytokines that were undetectable in >50% of participants. Frequentist and Bayesian analyses were performed on the principal components, to compare each patient cohort to controls, and test for associations with central inflammation, neurodegeneration-related plasma markers and survival. The first component identified by the PCA (explaining 21.5% variance) was strongly loaded by pro-inflammatory cytokines, including TNF-α, TNF-R1, M-CSF, IL-17A, IL-12, IP-10 and IL-6. Individual scores of the component showed significant differences between each patient cohort and controls. The degree to which a patient expressed this peripheral inflammatory profile at baseline correlated negatively with survival (higher inflammation, shorter survival), even when correcting for baseline clinical severity. Higher pro-inflammatory profile scores were associated with higher microglial activation in frontal and brainstem regions, as quantified with 11C-PK11195 TSPO PET. A permutation-based Canonical Correlation Analysis confirmed the association between the same cytokine-derived pattern and central inflammation across brain regions in a fully data-based manner. This data-driven approach identified a pro-inflammatory profile across the FTLD clinical spectrum, which is associated with central neuroinflammation and worse clinical outcome. Blood-based markers of inflammation could increase the scalability and access to neuroinflammatory assessment of people with dementia, to facilitate clinical trials and experimental medicine studies.

Uncovering the hidden effects of repetitive subconcussive head impact exposure: A mega-analytic approach characterizing seasonal brain microstructural changes in contact and collision sports athletes.

Repetitive subconcussive head impacts (RSHI) are believed to induce sub-clinical brain injuries, potentially resulting in cumulative, long-term brain alterations. This study explores patterns of longitudinal brain white matter changes across sports with RSHI-exposure. A systematic literature search identified 22 datasets with longitudinal diffusion magnetic resonance imaging data. Four datasets were centrally pooled to perform uniform quality control and data preprocessing. A total of 131 non-concussed active athletes (American football, rugby, ice hockey; mean age: 20.06 ± 2.06 years) with baseline and post-season data were included. Nonparametric permutation inference (one-sample t tests, one-sided) was applied to analyze the difference maps of multiple diffusion parameters. The analyses revealed widespread lateralized patterns of sports-season-related increases and decreases in mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) across spatially distinct white matter regions. Increases were shown across one MD-cluster (3195 voxels; mean change: 2.34%), one AD-cluster (5740 voxels; mean change: 1.75%), and three RD-clusters (817 total voxels; mean change: 3.11 to 4.70%). Decreases were shown across two MD-clusters (1637 total voxels; mean change: -1.43 to -1.48%), two RD-clusters (1240 total voxels; mean change: -1.92 to -1.93%), and one AD-cluster (724 voxels; mean change: -1.28%). The resulting pattern implies the presence of strain-induced injuries in central and brainstem regions, with comparatively milder physical exercise-induced effects across frontal and superior regions of the left hemisphere, which need further investigation. This article highlights key considerations that need to be addressed in future work to enhance our understanding of the nature of observed white matter changes, improve the comparability of findings across studies, and promote data pooling initiatives to allow more detailed investigations (e.g., exploring sex- and sport-specific effects).

Association of polygenic scores for autism with volumetric MRI phenotypes in cerebellum and brainstem in adults

Previous research on autism spectrum disorders (ASD) have showed important volumetric alterations in the cerebellum and brainstem. Most of these studies are however limited to case-control studies with small clinical samples and including mainly children or adolescents. Herein, we aimed to explore the association between the cumulative genetic load (polygenic risk score, PRS) for ASD and volumetric alterations in the cerebellum and brainstem, as well as global brain tissue volumes of the brain among adults at the population level. We utilized the latest genome-wide association study of ASD by the Psychiatric Genetics Consortium (18,381 cases, 27,969 controls) and constructed the ASD PRS in an independent cohort, the UK Biobank. Regression analyses controlled for multiple comparisons with the false-discovery rate (FDR) at 5% were performed to investigate the association between ASD PRS and forty-four brain magnetic resonance imaging (MRI) phenotypes among ~ 31,000 participants. Primary analyses included sixteen MRI phenotypes: total volumes of the brain, cerebrospinal fluid (CSF), grey matter (GM), white matter (WM), GM of whole cerebellum, brainstem, and ten regions of the cerebellum (I_IV, V, VI, VIIb, VIIIa, VIIIb, IX, X, CrusI and CrusII). Secondary analyses included twenty-eight MRI phenotypes: the sub-regional volumes of cerebellum including the GM of the vermis and both left and right lobules of each cerebellar region. ASD PRS were significantly associated with the volumes of seven brain areas, whereby higher PRS were associated to reduced volumes of the whole brain, WM, brainstem, and cerebellar regions I-IV, IX, and X, and an increased volume of the CSF. Three sub-regional volumes including the left cerebellar lobule I-IV, cerebellar vermes VIIIb, and X were significantly and negatively associated with ASD PRS. The study highlights a substantial connection between susceptibility to ASD, its underlying genetic etiology, and neuroanatomical alterations of the adult brain.

Repeated seizure-induced brainstem neuroinflammation contributes to post-ictal ventilatory control dysfunction.

Patients with epilepsy face heightened risk of post-ictal cardiorespiratory suppression and sudden unexpected death in epilepsy (SUDEP). Studies have shown that neuroinflammation, mediated by the activation of microglia and astrocytes, may be a cause or consequence of seizure disorders. Kcnj16 (Kir5.1) knockout rats (SS kcnj16-/- ) are susceptible to repeated audiogenic seizures and recapitulate features of human SUDEP, including post-ictal ventilatory suppression, which worsens with repeated seizures and seizure-induced mortality. In this study, we tested the hypothesis that repeated seizures cause neuroinflammation within key brainstem regions that contribute to the control of breathing. Audiogenic seizures were elicited once/day for up to 10days in groups of adult male SS kcnj16-/- rats, from which frozen brainstem biopsies of the pre-Bötzinger complex/nucleus ambiguus (preBötC/NA), Bötzinger complex (BötC), and raphe magnus (RMg) regions were subjected to a cytokine array. Several cytokines/chemokines, including IL-1α and IL-1ß, were increased selectively in preBötC/NA after 3 or 5days of seizures with fewer changes in other regions tested. In additional groups of male SS kcnj16-/- rats that underwent repeated seizures, we quantified microglial (IBA-1+) cell counts and morphology, specifically within the preBötC/NA region, and showed increased microglial cell counts, area, and volume consistent with microglial activation. To further test the role of inflammation in physiological responses to seizures and seizure-related mortality, additional groups of SS kcnj16-/- rats were treated with anakinra (IL-1R antagonist), ketoprofen (non-selective COX inhibitor), or saline for 3days before and up to 10days of seizures (1/day), and breathing was measured before, during, and after each seizure. Remarkably, IL-1R antagonism mitigated changes in post-ictal ventilatory suppression on days 7-10 but failed to prevent seizure-related mortality, whereas ketoprofen treatment exacerbated post-ictal ventilatory suppression compared to other treatment groups but prevented seizure-related mortality. These data demonstrate neuroinflammation and microglial activation within the key brainstem region of respiratory control following repeated seizures, which may functionally but differentially contribute to the pathophysiological consequences of repeated seizures.

Gene Electrotransfer via Conductivity-Clamped Electric Field Focusing Pivots Sensori-Motor DNA Therapeutics: "A Spoonful of Sugar Helps the Medicine Go Down".

Viral vectors and lipofection-based gene therapies have dispersion-dependent transduction/transfection profiles that thwart precise targeting. The study describes the development of focused close-field gene electrotransfer (GET) technology, refining spatial control of gene expression. Integration of fluidics for precise delivery of "naked" plasmid deoxyribonucleic acid (DNA)in sucrose carrier within the focused electric field enables negative biasing of near-field conductivity ("conductivity-clamping"-CC), increasing the efficiency of plasma membrane molecular translocation. This enables titratable gene delivery with unprecedently low charge transfer. The clinic-ready bionics-derived CC-GET device achieved neurotrophin-encoding miniplasmid DNA delivery to the cochlea to promote auditory nerve regeneration; validated in deafened guinea pig and cat models, leading to improved central auditory tuning with bionics-based hearing. The performance of CC-GET is evaluated in the brain, an organ problematic for pulsed electric field-based plasmid DNA delivery, due to high required currents causing Joule-heating and damaging electroporation. Here CC-GET enables safe precision targeting of gene expression. In the guinea pig, reporter expression is enabled in physiologically critical brainstem regions, and in the striatum (globus pallidus region) delivery of a red-shifted channelrhodopsin and a genetically-encoded Ca2+sensor, achieved photoactivated neuromodulation relevant to the treatment of Parkinson's Disease and other focal brain disorders.

Ageing-related tau astrogliopathy severely affecting the substantia nigra.

Astrocytic tau pathology is a major feature of tauopathies and ageing-related tau astrogliopathy (ARTAG). The substantia nigra (SN) is one of the important degenerative areas in tauopathies with parkinsonism. Nigral tau pathology is usually reported as neuronal predominant with less prominent astrocytic involvement. We aimed to identify cases with prominent astrocytic tau pathology in the SN. We use the term nigral tau-astrogliopathy (NITAG) to describe cases showing an unusually high density of ARTAG with less neuronal tau pathology in the SN. We collected clinical information and studied the distribution of tau pathology, morphological features and immunostaining profiles in three cases. Three cases, all males with parkinsonism, were identified with the following clinicopathological diagnoses: (i) atypical parkinsonism with tau pathology reminiscent to that in postencephalitic parkinsonism (69-year-old); (ii) multiple system atrophy (73-year-old); (iii) traumatic encephalopathy syndrome/chronic traumatic encephalopathy (84-year-old). Double-labelling immunofluorescence confirmed co-localization of GFAP and phosphorylated tau in affected astrocytes. Staining profiles of NITAG revealed immunopositivity for various phosphorylated tau antibodies. Some astrocytic tau lesions were also seen in other brainstem regions and cerebral grey matter. We propose NITAG is a rare neuropathological feature, and not a distinct disease entity, in the frame of multiple system ARTAG, represented by abundant tau-positive astrocytes in various brain regions but having the highest density in the SN. The concept of NITAG allows the stratification of cases with various background pathologies to understand its relevance and contribution to neuronal dysfunction.

Endoscopic-Assisted Microsurgical Removal of a Tectal Plate Pilocytic Astrocytoma Through the Occipital Inter Hemispheric Transtentorial Approach: 2-Dimensional Operative Video

Pilocytic astrocytomas are challenging benign midline lesions which occur rarely in adults where they represent 2.3% of the tumours. 1,2 Posterior fossa location is the most frequent, but they also can be seen in the brainstem, tectal plate, and optochiasmatic region. 1,2 Tectal plate location is very challenging and can be reached through a infraoccipital supracerebellar approach 1,2 or the occipital inter hemispheric transtentorial approach. We present the case of a 32-years-old patient who presented with acute hydrocephalus 2 years previously and was treated by third ventriculostomy in an outside institution. Follow-up showed slight increase of the tumor while the patient remained asymptomatic. Microsurgical treatment was offered to the patient given the size of the lesion, the progression of the tumor, and her young age. We present the main surgical steps of the surgery through an occipital interhemispheric approach with section of the tentorium. The lesion was removed piecemeal through the intercollicular sulcus. The postoperative course was favorable; at 3 months of follow-up, the patient showed no neurological deficit. Brain MRI showed a complete resection of the astrocytoma and no postoperative complications. We present the surgical technique for endoscopic-assisted microsurgical removal of a tectal plate pilocytic astrocytoma through the occipital inter hemispheric transtentorial approach. We discuss the prognostic survival factors reported in the literature. 2 The patient consented to the procedure and to the publication of the images. Our institutional review board ethics committee do not require an approval for this type of publication.

Severe Hypoplasia/Aplasia of the Medullary Arcuate Nucleus in a 4-Month-Old Patient with Sudden Infant Death Syndrome

AbstractThe aim of this study was to verify and confirm the close correlation between the absence of the medullary arcuate nucleus and sudden death in a 4-month-old infant. Careful neuropathological examination of the cerebral hemispheres, basal ganglia, and cerebellum demonstrated no relevance to the death. The brainstem region, normally occupied by the nuclei, was cut into several serial sections so as not to lose any details. The largest median part of the medullary arcuate nucleus was completely absent, and only very small groups of residual neurons in its most lateral part were still detectable; the rest of the brainstem showed no abnormalities. In the absence of other lesional, degenerative, or malformative causes, the sudden and unexpected death of this infant was likely due to severe hypoplasia/aplasia of the medullary arcuate nucleus. The anatomo-functional development of the nucleus and its crucial role in the control of respiratory and cardiac autonomic reactivity in sleep during the first year of life may provide an important contribution to the pathogenic interpretation.

A case report of seronegative neuromyelitis optica spectrum disorder treated with corticosteroids and intravenous immunoglobulin

Neuromyelitis optical spectrum disorders (NMOSD) are inflammatory and demyelinating autoimmune diseases ofthe central nervous system. We present the case of a male patient with seronegative NMOSD, who presented with area postrema syndrome; During hospitalization, he presented progressive neurological deterioration. In T2 flair of the brain MRI, hyperintense intramedullary lesions were evidenced, in the area postrema, in the brainstem and bilateral periventricular regions; the AQP4 dosage in serum and CSF were negative. The patient received treatment with Human Immunoglobulin for five days, which had a partial response to treatment.

Downregulation of Tnf-α and Cat Expression in a Wistar Rat Diabetic Model during Diabetes Onset.

Diabetes Mellitus (DM) is a metabolic disorder characterized by persistent hyperglycemia and/or insulin resistance. If left uncontrolled, it can lead to a combination of cardiac and renal alterations known as cardiorenal syndrome. Additionally, oxidative stress and inflammation contribute to tissue damage, thereby reducing the life expectancy of individuals with diabetes. The aim of this study was to identify early molecular markers associated with cardiorenal syndrome, oxidative stress, and inflammation, and to investigate their correlation with the duration of exposure to DM. An experimental DM model was employed using Wistar rats. The rats were divided into four groups: diabetic rats at 7 days (DM7), diabetic rats at 30 days (DM30), control sham at 7 days (CS7), and control sham at 30 days (CS30). Blood and brain tissue from the brainstem region were collected at 7 and 30 days after confirming DM induction. Gene expression analysis of Bnp, Anp, Cat, Gpx, Sod, Tnf-α, and Il-6 was performed. The analysis revealed lower expression values of Cat in the brainstem tissue of the DM7 group compared to the NDS7 group. Moreover, diabetic animals exhibited statistically lower levels of Tnf-α in their peripheral blood compared to the control animals. This study concluded that DM alters the oxidative balance in the brainstem after 7 days of DM induction, resulting in lower Cat expression levels. Although some genes did not show statistical differences after 30 days of DM induction, other genes exhibited no expression values, indicating possible gene silencing. The study identified an imbalance in the studied pathways and concluded that the organism undergoes a compensatory state in response to the initial metabolic alterations caused by DM.

DIPG-49. SPATIAL TRANSCRIPTOMIC SEQUENCING OF A DIPG PATIENT TUMOUR RESOURCE

Abstract BACKGROUND Diffuse Intrinsic Pontine Glioma (DIPG), the most common subtype of Diffuse Midline Glioma (DMG), is a brainstem high-grade glioma arising in young children and always proves fatal. Major challenges include the disease’s intratumoural genetic and cellular heterogeneity as well as its diffusely invasive phenotype. Research of the last few years has highlighted that interactions between cancer cells, the nervous system and immune cells crucially contribute to tumour cell invasion and disease malignancy. Hence, a better understanding of cancer-promoting interactions is a key requirement to elucidate novel strategies for the treatment of this devastating disease. METHOD We performed spatial transcriptomic sequencing on 10 sequential tumour-infiltrated DIPG patient brainstem regions, using the 10x Genomics Visium platform. RESULTS Spatially-informed analysis and cell type clustering overall highlighted the molecular intratumoural heterogeneity present in the disease. We assessed cell cluster interactions as well as receptor-ligand (RL) pairing, illustrating communication between neuronal, immune cell and tumour clusters. We further determined respective RL pairs involved in such. To address the question whether invasive edges genetically differ from the tumour core, we evaluated genes that are significantly correlated with distal brainstem regions compared to tumour proximal sites. Results revealed gene signatures that are highly associated with neuronal signalling and communication, validating previous findings emphasising the importance of neuron-to-glioma interactions driving DIPG disease progression. CONCLUSION DIPG is a lethal paediatric brainstem glioma for which more durable therapeutic modalities remain to be found. In-depth analysis of this disease is often hampered due to the lack of patient tissue suitable for laboratory studies. Our patient autopsy specimen, spanning the entire tumour-infiltrated brainstem provided a platform to study this aggressive disease in a spatio-temporal manner. This analysis elucidates how DIPG is driven by the tumour microenvironment, including associated receptor-ligand interactions. This has the potential to ultimately discover new treatment targets.

Disease progression modelling reveals heterogeneity in trajectories of Lewy-type α-synuclein pathology

Lewy body (LB) diseases, characterized by the aggregation of misfolded α-synuclein proteins, exhibit notable clinical heterogeneity. This may be due to variations in accumulation patterns of LB neuropathology. Here we apply a data-driven disease progression model to regional neuropathological LB density scores from 814 brain donors with Lewy pathology. We describe three inferred trajectories of LB pathology that are characterized by differing clinicopathological presentation and longitudinal antemortem clinical progression. Most donors (81.9%) show earliest pathology in the olfactory bulb, followed by accumulation in either limbic (60.8%) or brainstem (21.1%) regions. The remaining donors (18.1%) initially exhibit abnormalities in brainstem regions. Early limbic pathology is associated with Alzheimer’s disease-associated characteristics while early brainstem pathology is associated with progressive motor impairment and substantial LB pathology outside of the brain. Our data provides evidence for heterogeneity in the temporal spread of LB pathology, possibly explaining some of the clinical disparities observed in Lewy body disease.