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Results for “synaptic dysfunction”

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PubMed1986

Toxaphene inhibition of calmodulin-dependent calcium ATPase activity in rat brain synaptosomes.

Effect of toxaphene on Ca2+-ATPase activity in rat brain synaptosomes was studied in vitro and in vivo. Ca2+-ATPase in calmodulin-depleted synaptosomes was inhibited in vitro to a maximum of about 50% at 150 microM toxaphene. Substrate activation kinetics of Ca2+-ATPase in synaptosomes revealed that toxaphene inhibited the enzyme activity noncompetitively by decreasing Vmax values, without affecting the enzyme-substrate affinity. Toxaphene inhibited the calmodulin activated Ca2+-ATPase activity in a concentration-dependent manner with an IC50 of 10 microM, a concentration at which no significant effect was observed on basal enzyme activity. Nuclear and P2 fraction (synaptosomes) calmodulin levels were reduced significantly in toxaphene-treated rats. The synaptosomal Ca2+-ATPase was also reduced to about 45% in toxaphene-treated rats and the activity was restored to normal levels by the exogenously added calmodulin. These results suggest that toxaphene may cause synaptic dysfunction by interfering with calmodulin and its regulation of neuronal calcium.

Animals↗

PubMed2026

Multi-omics profiling of cerebrospinal fluid in autoimmune encephalitis: insights into pathogenesis and therapeutic targets.

BACKGROUND: Autoimmune encephalitis (AIE) is a rare, severe inflammatory brain disease, with its pathogenesis not yet fully elucidated. This study aimed to characterize proteomic and metabolomic alterations in the cerebrospinal fluid (CSF) of AIE patients and identify potential therapeutic targets. METHODS: 65 consecutive AIE patients and age-matched concurrent controls were enrolled, respectively. Clinical characteristics, including blood and CSF laboratory findings, were compared between the two groups, and CSF samples were collected for multi-omics analysis. Differentially expressed proteins (DEPs) and metabolites (DEMs) between AIE patients and controls were identified using data-independent acquisition-based proteomics and targeted liquid chromatography-mass spectrometry-based metabolomics, followed by integrated multi-omics analysis. RESULTS: Compared with controls, AIE patients had lower levels of triglyceride and C1q, but higher HDL-CH levels, neutrophil counts, and eosinophil counts in blood. CSF leukocyte, erythrocyte, lymphocyte, and mononuclear cell counts were also elevated in AIE patients. Proteomic analysis identified 163 DEPs, with enrichment of 87 canonical pathways primarily associated with immune-inflammatory responses, neuronal-synaptic dysfunction, and cell signaling and metabolic pathways. Metabolomic analysis recognized 21 DEMs, predominantly amino acids, lipids, and carbohydrates, which were involved in lipid-carbohydrate metabolism and immune regulation. Integrated multi-omics analysis validated these findings and identified several potential therapeutic targets for AIE, including the IL6-STAT3 axis. CONCLUSIONS: Integrated multi-omics analysis systematically delineates cellular and molecular alterations underlying AIE. Immune-inflammatory response and lipid metabolism are pivotal in AIE progression and the IL6-STAT3 axis holds promise as a potential therapeutic target.

Humans↗

PubMed2026

Integrative multi-omics identifies DOC2A as a novel pharmacological target for bipolar disorder.

BACKGROUND: Current bipolar disorder (BD) therapies suffer from limited efficacy and adverse effects, necessitating mechanistically grounded targets. METHODS: We integrated BD genome-wide association study data (158,036 cases; 2,796,499 controls) with brain proteomics (ROSMAP and Banner dorsolateral prefrontal cortex, n = 376 and 152) to perform proteome-wide association studies (PWAS). Bayesian colocalization and summary-data-based Mendelian randomization (SMR) prioritized causal genes. Cell-type-specific transcriptomics validated dysregulation in iPSC-derived neurons, astrocytes, and postmortem hippocampus/prefrontal cortex. Weighted gene co-expression networks (WGCNAs), functional enrichment, and molecular docking assessed functional pathways and druggability. RESULTS: PWAS identified eight BD-associated genes (false discovery rate < 0.05), with DOC2A emerging as the top candidate. Colocalization (H4 > 0.8) and SMR supported a causal association of DOC2A with BD, with no pleiotropy (heterogeneity in dependent instruments P > 0.01); DOC2A expression decreased in BD across neurons (P = 4.26 × 10-2), astrocytes (P = 2.09 × 10-2), hippocampus (P = 9.80 × 10-3, t = -2.738), and prefrontal cortex (P = 1.44 × 10-2, t = -2.580); WGCNA positioned DOC2A as a key regulator (module membership/gene significance P < 0.05) of co-expression networks enriched for BD-associated processes including neurotransmitter secretion and postsynaptic actin cytoskeleton organization (P < 0.05); molecular docking revealed favorable-affinity binding (ΔG < -4 kcal/mol) between DOC2A and BD-related drugs and neuroprotective compounds. CONCLUSIONS: Our convergent multi-omics framework highlights DOC2A dysregulation as a key contributor to synaptic dysfunction in BD and nominates it as a promising therapeutic target. The demonstrated interaction with existing neuroactive compounds provides immediate translational avenues.

Bipolar Disorder↗

PubMed2025

Single-cell analysis of dup15q syndrome reveals developmental and postnatal molecular changes in autism.

Duplication 15q (dup15q) syndrome is a leading genetic cause of autism spectrum disorder, offering a key model for studying autism-related mechanisms. Using single-cell and single-nucleus RNA sequencing of cortical organoids from dup15q patient-derived iPSCs and post-mortem brain samples, we identify increased glycolysis, disrupted layer-specific marker expression, and aberrant morphology in deep-layer neurons during fetal-stage organoid development. In adolescent-adult postmortem brains, upper-layer neurons exhibit heightened transcriptional burden related to synaptic signaling, a pattern shared with idiopathic autism. Using spatial transcriptomics, we confirm these cell-type-specific disruptions in brain tissue. By gene co-expression network analysis, we reveal disease-associated modules that are well preserved between postmortem and organoid samples, suggesting metabolic dysregulation that may lead to altered neuron projection, synaptic dysfunction, and neuron hyperexcitability in dup15q syndrome.

Humans↗

PubMed1991

[A morphological study on the brain in wriggle mouse Sagami, a new neurological mutant with dystonic disorders, with special reference to the abnormality of the cerebellum].

The 'Wriggle Mouse Sagami (WMS)' is a new neurological mutation that was discovered in an inbred strain of BALB/c mice at the Ohmura Institute for Laboratory Animals (Address: Zama 228, Kanagawa, Japan) in 1984. The affected characteristics are transmitted by an autosomal recessive gene (wri). The clinical symptoms are characterized by dystonic involuntary movements, such as fine tremors of the forelimbs, hypertonic musculature of the extremities, difficulty in maintaining an upright posture, writhing of the trunk, wriggling of the neck up-and-down and from side to side without any coordination between the movements of the limbs and trunk, and inability to walk a staigho that begin at 10 days to 2 weeks after birth and are progressive until 12 weeks of age. Here a morphological study on the brain of the WMS with special reference to the cerebellum was intended. The results were as follows: (1) In spite of these severe clinical symptoms, no marked abnormalities were observed in the cyto- and myeloarchitecture of the central nervous system, although the size of the whole brain was somewhat reduced and the molecular layer of the cerebellum was relatively hypotrophic compared with the granule cell layer. (2) The motor tracts investigated were normally detected by the retrograde HRP-labeling method. (3) Slight abnormality of the dendritic trees and spines, and remarkable axonal swellings of the Purkinje cells were demonstrated by a sensitive immunohistochemical method for inositol 1,4,5-trisphophate receptor protein (P400 protein). These changes were also evaluated by the Golgi method. (4) In electron microscopy of the molecular layer of the WMS cerebellum, parallel fibers seemed to be reduced and shrunken, and their synaptic contacts on the dendritic spines of the Purkinje cells were clearly reduced even at 17 days after birth. (5) Consequently, the Purkinje cells were possibly affected by failure of accurate connection with input fibers or by synaptic dysfunction, which might occur over the entire central nervous system.

Animals↗

PubMed1975

Abnormal neuronal differentiation (functional maturation) in mental retardation.

A review is presented of a variety of human pathologic conditions, including some forms of mental retardation, and of experimental situations involving the nervous system proved (with the Golgi method) to be associated with detectable morphologic abnormalities. The postsynaptic elements (the dendritic spines) have been found to be especially sensitive and frequently they are found to be structurally abnormal. Structural abnormalities involving one of the synaptic components could result in synaptic dysfunction which could explain some degree of mental or motor retardation or incoordination. It is hoped that this review will stimulate and encourage the use of the Golgi method in the study of abnormal conditions (clinical or experimental) affecting the nervous system.

Cell Differentiation↗

PubMed1991

[Lambert-Eaton myasthenic syndrome. Physiopathological aspects and therapeutic modalities].

A 68-year old man experienced a progressive proximal tetraparesis with anhidrosis and a single episode of horizontal diplopia before presenting exertional dyspnea; pulmonary investigations revealed a small cell carcinoma of the lung. Clinical and electrophysiological investigations with abnormal SFEMG, repetitive stimulations and autonomic assessment pointed to a pre-synaptic neuromuscular dysfunction compatible with a Lambert-Eaton syndrome. Antibodies to acetylcholine receptors and calcium channels were negative. Thoracic radiotherapy combined with chemotherapy produced marked improvement: repeated electrophysiological evaluations showed a strong correlation between median nerve CMAP amplitude and clinical course. This case prompted us to discuss current concepts of pre-synaptic dysfunction, and paraneoplastic syndrome, and to review therapeutic strategies, in the light of recent studies of Lambert-Eaton syndrome.

Aged↗

PubMed1979

Selective neuronal, dendritic, and postsynaptic localization of viral antigen in measles-infected mice.

The pathology of acute disease produced by intracerebral inoculation of hamster neurotropic strain of measles virus was studied in adult BALB/c mice using immunolabeling techniques at a light and electron microscopic level. Brains of animals with acute disease showed an abundance of viral antigen but no inflammatory cells, giant cells, or inclusions. Infection was limited to neurons which were rarely necrotic, indicating that the process was not cytolytic. Mapping of infected neurons identified a consistent predilection to the rhinencephalon, other components of the limbic system, and the striatum. Ultrastructural examination revealed similar findings in all of the involved areas. No evidence of viral assembly at the cell membrane was found. Viral antigen was identified in neuronal perikaryon with somatofugal spread into dendritic and synaptic sites. Unlabeled smooth nucleocapsid and labeled tubular structures were detected both in the cytoplasm and nucleus of neurons. Dendritic labeling when present was occasionally associated with the neurotubules. The most remarkable and frequent finding was identification of viral antigen in postsynaptic endings. This consisted of clumps of viral antigen and occasional staining of the postsynaptic density. This localization of viral antigen may create dysfunction of synaptic transmission, and in the absence of overt pathology, may account for clinical disease.

Animals↗

PubMed1986

Somatosensory evoked potentials after experimental head injury in the awake rat.

Experimental acceleration concussion was induced in 30 male rats who were immobilized with curare, artificially ventilated but not anaesthetised. Serial recordings of cortical somatosensory evoked potentials (SEPs) were made from the onset of concussion and for the following 30 min. Immediately after the head blow the initial three components of the SEP (P1, N1 and P2) were all either absent or markedly increased in latency. The late negative component (N2) was always abolished. All components reappeared and returned to approximately pre-concussion latencies within 5-6 min. The most persisting abnormality was in N2 whose post-concussion amplitude stabilized and remained depressed at only 50% of baseline value. The results suggest that experimental head injury produces a significant abnormality in every component of the evoked potential. The findings are therefore inconsistent with the theory that concussion differentially affects the diffuse nonspecific pathways whose activity is mediated by the reticular formation while leaving the lemniscal system comparatively intact. It is also shown that the morphology of the post-concussion SEP waveform can be quite accurately simulated by recording SEPs from normal animals at high rates of stimulation (50/s). This implies that the pathophysiology of concussion involves a temporary dysfunction in synaptic transmission although the level at which this is occurring has yet to be determined.

Afferent Pathways↗

PubMed2026

Post-Translational Modifications in Traumatic Brain Injury: Decoding the Proteomic Landscape and Molecular Mechanisms of Secondary Injury.

Traumatic brain injury (TBI) initiates a complex secondary injury cascade that significantly contributes to long-term neurological deficits, with post-translational modifications (PTMs) emerging as pivotal molecular regulators of this process. Unlike primary mechanical damage, secondary injury evolves over hours to years and involves intricate proteomic alterations that changes in gene expression alone cannot fully explain. PTMs-including phosphorylation, ubiquitination, acetylation, SUMOylation, glycosylation, and emerging modifications such as succinylation, lactylation, and nitrosylation-serve as dynamic molecular switches that fine-tune protein function, stability, localization, and interactions in response to TBI-induced stressors. These modifications play dual roles: they can either promote neuroprotection and recovery or drive pathological processes such as neuronal cell death (via apoptosis, necroptosis, and ferroptosis), neuroinflammation through glial activation and inflammasome signaling, blood-brain barrier disruption, mitochondrial dysfunction, and impaired synaptic plasticity. Critically, extensive crosstalk exists among different PTM pathways-such as the interplay between phosphorylation and ubiquitination in protein degradation or the competitive balance between acetylation and SUMOylation-that collectively shape cellular fate after injury. This nuanced regulatory network presents both challenges and opportunities for therapeutic intervention. Targeting PTM-related enzymes, including kinases, phosphatases, E3 ligases, and histone deacetylases, has shown promise in preclinical models, while novel strategies like Proteolysis-Targeting Chimeras (PROTACs) and repurposed drugs (e.g., metformin, resveratrol) offer innovative avenues for modulating the PTM landscape. Advances in high-throughput proteomics and mass spectrometry are enabling the mapping of TBI-specific PTM signatures across spatiotemporal phases, facilitating the identification of pro-survival versus pro-death modification thresholds. Despite hurdles in clinical translation-such as blood-brain barrier penetration and off-target effects-the growing understanding of PTM dynamics underscores their potential as both biomarkers and therapeutic targets. Future TBI management may thus rely on precision medicine approaches that integrate multi-PTM profiling to guide combination therapies aimed at tipping the balance toward neural repair and functional recovery.

Brain Injuries, Traumatic↗

PubMed1992

Electrophysiologic changes in lumbar spinal cord after cervical cord injury.

Spontaneous activity on the EMG examination is traditionally ascribed to disease of the lower motor neuron when present in muscles well below the level of para- or quadriplegia despite the absence of any detectable peripheral nerve injury. It is uncertain whether it reflects transient paralysis of transmission (related to clinical spinal shock) or irreversible postsynaptic damage. We performed serial EMG studies of lower extremities and paraspinal muscles on eight young, previously healthy adults, commencing 2 to 9 weeks after acute cervical cord injury. All had stimulated single-fiber EMG (SFEMG) studies at 6-month intervals to determine whether irreversible postsynaptic damage of the anterior horn cell had occurred. MRI and nerve conduction excluded patients with evidence of distal cord injury or peripheral neuropathy. All patients had spontaneous activity in all muscles tested, persisting after spinal shock had resolved. Jitter was present on SFEMG in three of eight patients 6 months after injury. Four of five patients retested 12 months after injury had abnormal jitter, including three who initially had normal SFEMG studies. We conclude that there is electrophysiologic evidence of trans-synaptic distal cord dysfunction following acute spinal cord injury. SFEMG studies suggest that anterior horn cell dropout occurs during the 1st year after injury.

Adolescent↗

PubMed1975

[Morphological aspects of organic brain syndromes (author's transl)].

Organic psychoses are caused by a variety of disorders. In general, they are due to diffuse dysfunction of the brain without any specific anatomical basis, but they may be modified by disorders of some distinct neuronal systems as a result of local accentuation of a dissuse morbid process or localized brain damage. Acute organic psychoses are usually caused by disorders of the blood-brain barrier (cerebral oedema), acute neuronal dysfunction of disorders of synaptic transmission. Acute lesions may be reversible or terminate in stationary defective states or progressive neuronal degeneration. In late stages, the anatomical sequelae of the basic process and of secondary lesions are hardly to be separated. The non-specificity and inconsistency of brain lesions is demonstrated in chronic alcoholic psychoses. In senile organic psychoses there are quantitative correlations between psychopathological, neurophysiological (slowing of the basic rhythm) and morphological changes, mainly characterized by loss of neurons and synaptic contacts. Vascular syndromes are often over-diagnosed clinically. Localized mental syndromes are non-specific, but show characteristic locations, as they are commonly associated with dysfunction of neuronal systems engaged in storing and recall of information (frontobasal region and limbic system). Further detailed studies are needed in order to achieve better correlation between specific features of behavioural and intellectual defects and anatomical location and quantitiy of lesions.

Aging↗

PubMed2026

Impact of sex differences on microglial function in Alzheimer's disease.

Aging is the strongest risk factor for Alzheimer's disease (AD), a multifactorial neurodegenerative disorder characterized by amyloid-β (Aβ) accumulation, tau pathology (hyperphosphorylated tau and neurofibrillary tangles [NFTs]), and associated neuroinflammatory processes. Age-related cellular and molecular stressors, including mitochondrial dysfunction, genomic instability, and chronic low-grade inflammation, progressively increase vulnerability to neurodegeneration. In parallel, sex is increasingly recognized as a biological variable that shapes AD risk, clinical course, and neuropathological burden. Women account for roughly two-thirds of AD cases, a disparity not fully explained by longevity. Multiple factors likely contribute, including hormonal transitions across the lifespan (particularly menopausal estrogen decline), sex chromosome-linked immune regulation, sex-dependent interactions between genetic risk factors (e.g., APOE4 and TREM2) and brain aging, and differences in vascular risk, cognitive reserve, and sociocultural exposures that influence disease expression and detection. Microglia, the brain's resident immune cells, are sexually dimorphic, and respond to Aβ and tau pathology, modulating inflammatory signaling, synaptic remodeling, and neurovascular dysfunction implicated in AD. Emerging human and experimental evidence indicate that microglial activation states, immunometabolism, and functional responses differ between males and females and may contribute to sex-specific AD trajectories. Here, we synthesize current evidence supporting microglial sexual dimorphism across aging and AD, highlight possible candidates (hormonal signaling, immuno-aging, disease-associated microglial states, and immunometabolic remodeling), and discuss key knowledge gaps toward sex-informed precision approaches for prevention and treatment.

Humans↗

PubMed1978

Endorphins, opiate receptors and migraine headache.

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Constipation↗

PubMed1988

Calcium-sensitive recovery of extracellular potassium and synaptic transmission in rat hippocampal slices exposed to brief anoxia.

We examined the possibility that Ca2+-sensitive inhibition of synaptic transmission following anoxia involves compromise of ion transport activity. Rat hippocampal slices were superfused with artificial cerebrospinal fluids containing different concentrations of CaCl2, and subjected to short anoxia. Durations of anoxia were sufficient to provoke anoxic depolarization, indicated by a sudden rise in extracellular K+ (K+o). Following anoxia, apparent K+ transport was assessed by measuring the magnitude of subnormal K+o (the K+o undershoot) in hippocampal region CA1. Recovery of synaptic transmission 1 h after anoxia was determined by evaluation of the magnitudes of the orthodromically stimulated population spike recorded from CA1 pyramidal cells. K+o undershoots and recovery of synaptic transmission decreased as CaCl2 or the duration of anoxic depolarization increased. These data suggest: (1) that increased artificial cerebrospinal fluid CaCl2 compromised K+ reaccumulation after anoxia; and (2) that ion transport dysfunction may inhibit recovery of synaptic transmission.

Action Potentials↗

PubMedDate not supplied

Midlatency auditory evoked responses: P1 abnormalities in adult autistic subjects.

MLR recordings from a group of 11 high-functioning adult autistic subjects were compared with those from a control group of 11 normal subjects. Components selected for analysis were "Pa", the maximum positivity in the 25-40 msec latency range following stimulus onset, "P1", the maximum positivity within the 50-65 msec latency range, and "Nb," the maximum negative deflection in the 40-50 msec latency range. Statistical analyses of amplitude and latency data were conducted using repeated measures analysis of variance and t test group comparisons. The Pa component showed no significant difference between autistic and control groups. However, 2 types of abnormality were noted in the P1 component: (1) the P1 component was significantly smaller in the autistic subjects at slow rates of stimulation, and (2) the autistic P1 did not change as rates of click stimulation increased from 0.5 to 10/sec, in contrast to the normally produced P1 decrement. Data from the P1 model in the cat, and complementary data from the human, closely link the generator substrate of the P1 potential to cholinergic components of the ascending reticular activating system (RAS) and their thalamic target cells. This is the first report of abnormal P1 responses in autism and strongly suggests that the RAS and/or its post-synaptic thalamic targets may be dysfunctional in this syndrome.

Acoustic Stimulation↗

PubMedDate not supplied

Visual evoked potentials, brainstem auditory evoked potentials, and quantitative EEG in Baltic progressive myoclonus epilepsy.

Visual and brainstem auditory evoked potentials (VEP and BAEP, respectively) and quantitative EEG were studied in 16 patients with Baltic progressive myoclonus epilepsy (PME). The study demonstrated significantly delayed VEP latencies but normal amplitudes in Baltic PME. BAEPs showed slight but significant prolongation in central conduction time. Quantitative EEG revealed diminution of beta and alpha activity and accentuation of theta and delta activity. The slowing in VEP latencies is suggested to be due to impaired synaptic transmission and to reflect dopaminergic dysfunction in Baltic PME. We conclude that there is a multimodal disturbance in sensory projections to cortical areas in Baltic PME. The results give further evidence that nondemyelinating disorders--but with synaptic transmission defects--can produce changes in evoked potentials. The changes in epileptic brain are not confined to hyperexcitable epileptic neurons, but more widespread electrophysiological phenomena are produced.

Adolescent↗

PubMed1986

Diminished interaction of norepinephrine with climbing fiber inputs to cerebellar Purkinje neurons in aged Fischer 344 rats.

The ability of norepinephrine (NE) to modulate climbing fiber activation of complex spike discharge in cerebellar Purkinje neurons was compared in young (3-6 months) and aged (18-20 months) Fischer 344 rats. In young rats, NE selectively inhibits spontaneous activity while climbing fiber evoked activity remains intact or increased. NE also increases the probability of observing 4 bursts of full-sized action potentials rather than partially inactivated action potentials in the complex spike. In older rats, both of these modulatory actions of NE on climbing fiber complex spike activation are markedly diminished. These data support the concept that age-related reductions in catecholamine modulation of synaptic inputs may contribute to CNS dysfunction found in senescence.

Aging↗