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BioRxiv : the Preprint Server For... Aug 2023Climbing fibers supervise cerebellar learning by providing signals to Purkinje cells (PCs) that instruct adaptive changes to mistakenly performed movements. Yet,...
Climbing fibers supervise cerebellar learning by providing signals to Purkinje cells (PCs) that instruct adaptive changes to mistakenly performed movements. Yet, climbing fibers are regularly active, even during well performed movements, suggesting that a mechanism dynamically regulates the ability of climbing fibers to induce corrective plasticity in response to motor errors. We found that molecular layer interneurons (MLIs), whose inhibition of PCs powerfully opposes climbing-fiber-mediated excitation, serve this function. Optogenetically suppressing the activity of floccular MLIs in mice during the vestibulo-ocular reflex (VOR) induces a learned increase in gain despite the absence of performance errors. Suppressing MLIs when the VOR is mistakenly underperformed reveled that their inhibitory output is necessary to orchestrate gain-increase learning by conditionally permitting climbing fibers to instruct plasticity induction during ipsiversive head turns. Ablation of an MLI circuit for PC disinhibition prevents gain-increase learning during VOR performance errors which was rescued by re-imposing PC disinhibition through MLI activity suppression. Our findings point to a decisive role for MLIs in gating climbing-fiber-mediated learning through their context-dependent inhibition of PCs.
PubMed: 38654827
DOI: 10.1101/2023.08.04.552059 -
Journal of Molecular Histology Jun 2024Tramadol is a novel centrally acting analgesic. Despite, its implementation during pregnancy may impair neuronal survival and synaptic development in neonatal cerebella....
Evaluation of histological and ultrastructural changes provoked by prenatal tramadol on postnatal cortical cerebellar neuronal development in rats: possible implication of Ki67, GFAP and MicroRNA-7/P53 signalling trajectories.
Tramadol is a novel centrally acting analgesic. Despite, its implementation during pregnancy may impair neuronal survival and synaptic development in neonatal cerebella. The current investigation assessed the histological and ultrastructural alterations in postnatal cortical cerebellar neuronal development induced by prenatal tramadol. 30 offsprings were divided to control group I: fifteen pups born to mothers given saline from D10 till D21 of gestation. Tramadol-treated group II: fifteen pups born to mothers received tramadol HCL (50 mg/kg/day) from D10 till D21 of gestation. Pups were categorized into three subgroups (a, b, and c) and offered for sacrifice on the seventh, fourteenth and twenty-first post-natal days. Light microscopic examination revealed the overcrowding and signs of red degeneration affecting purkinje cell layer. Neurodegenerative signs of both purkinje and granule cell neurons were also confirmed by TEM in form of chromatin condensation, dilated Golgi channels, disrupted endoplasmic reticulum, marked infolding of the nuclear envelope and decrease in granule cell precursors. In addition, the astrocytic processes and terminal nerve axons appeared with different degrees of demyelination and decreased number of oligodendrocytes and degenerated mitochondria. Furthermore, group II exhibited an increase in P53 immune expression. The area percentage of apoptotic cells detected by TUNEL assay was significantly increased. Besides to the significant decrease of Ki67 immunoreactivity in the stem neuronal cell progenitors. Quantitative PCR results showed a significant decline in micro RNA7 gene expression in tramadol treated groups resulting in affection of multiple target genes in P53 signaling pathways, improper cortical size and defect in neuronal development.
Topics: Animals; Tramadol; MicroRNAs; Pregnancy; Signal Transduction; Female; Rats; Tumor Suppressor Protein p53; Prenatal Exposure Delayed Effects; Glial Fibrillary Acidic Protein; Ki-67 Antigen; Cerebellum; Neurons; Apoptosis; Rats, Wistar; Animals, Newborn
PubMed: 38639812
DOI: 10.1007/s10735-024-10189-2 -
Proceedings of the National Academy of... Apr 2024Neurons in the inferior olive are thought to anatomically organize the Purkinje cells (P-cells) of the cerebellum into computational modules, but what is computed by...
Neurons in the inferior olive are thought to anatomically organize the Purkinje cells (P-cells) of the cerebellum into computational modules, but what is computed by each module? Here, we designed a saccade task in marmosets that dissociated sensory events from motor events and then recorded the complex and simple spikes of hundreds of P-cells. We found that when a visual target was presented at a random location, the olive reported the direction of that sensory event to one group of P-cells, but not to a second group. However, just before movement onset, it reported the direction of the planned movement to both groups, even if that movement was not toward the target. At the end of the movement if the subject experienced an error but chose to withhold the corrective movement, only the first group received information about the sensory prediction error. We organized the P-cells based on the information content of their olivary input and found that in the group that received sensory information, the simple spikes were suppressed during fixation, then produced a burst before saccade onset in a direction consistent with assisting the movement. In the second group, the simple spikes were not suppressed during fixation but burst near saccade deceleration in a direction consistent with stopping the movement. Thus, the olive differentiated the P-cells based on whether they would receive sensory or motor information, and this defined their contributions to control of movements as well as holding still.
Topics: Cerebellum; Purkinje Cells; Neurons; Saccades; Movement
PubMed: 38630714
DOI: 10.1073/pnas.2318849121 -
JCI Insight Apr 2024Dysregulated lipid homeostasis is emerging as a potential cause of neurodegenerative disorders. However, evidence of errors in lipid homeostasis as a pathogenic...
Dysregulated lipid homeostasis is emerging as a potential cause of neurodegenerative disorders. However, evidence of errors in lipid homeostasis as a pathogenic mechanism of neurodegeneration remains limited. Here, we show that cerebellar neurodegeneration caused by Sorting Nexin 14 (SNX14) deficiency is associated with lipid homeostasis defects. Recent studies indicate that SNX14 is an interorganelle lipid transfer protein that regulates lipid transport, lipid droplet (LD) biogenesis, and fatty acid desaturation, suggesting that human SNX14 deficiency belongs to an expanding class of cerebellar neurodegenerative disorders caused by altered cellular lipid homeostasis. To test this hypothesis, we generated a mouse model that recapitulates human SNX14 deficiency at a genetic and phenotypic level. We demonstrate that cerebellar Purkinje cells (PCs) are selectively vulnerable to SNX14 deficiency while forebrain regions preserve their neuronal content. Ultrastructure and lipidomic studies reveal widespread lipid storage and metabolism defects in SNX14-deficient mice. However, predegenerating SNX14-deficient cerebella show a unique accumulation of acylcarnitines and depletion of triglycerides. Furthermore, defects in LD content and telolysosome enlargement in predegenerating PCs suggest lipotoxicity as a pathogenic mechanism of SNX14 deficiency. Our work shows a selective cerebellar vulnerability to altered lipid homeostasis and provides a mouse model for future therapeutic studies.
Topics: Sorting Nexins; Animals; Mice; Homeostasis; Lipid Metabolism; Humans; Purkinje Cells; Disease Models, Animal; Neurodegenerative Diseases; Mice, Knockout; Cerebellum; Male; Lipid Droplets
PubMed: 38625743
DOI: 10.1172/jci.insight.168594 -
BioRxiv : the Preprint Server For... Apr 2024The heterotrimeric G-protein α subunit, Gα , acts to transduce extracellular signals through G-protein coupled receptors (GPCRs) and stimulates adenylyl cyclase...
The heterotrimeric G-protein α subunit, Gα , acts to transduce extracellular signals through G-protein coupled receptors (GPCRs) and stimulates adenylyl cyclase mediated production of the second messenger cyclic adenosine monophosphate. Numerous mutations in the gene, which encodes Gα , have been identified as causative for an adult-onset dystonia. These mutations disrupt GPCR signaling cascades in assays through several mechanisms, and this disrupted signaling is hypothesized to lead to dystonic motor symptoms in patients. However, the cells and circuits that mutations in corrupt are not well understood. Published patterns of Gα expression outside the context of the striatum are sparse, conflicting, often lack cell type specificity, and may be confounded by expression of the close homolog of . Here, we use RNAScope in-situ hybridization to quantitatively characterize mRNA expression in brain tissue from wildtype C57BL/6J adult mice. We observed widespread expression of puncta throughout the brain, suggesting Gα is expressed in more brain structures and neuron types than previously accounted for. We quantify transcripts at a single cell level, and use neuron type specific markers to further classify and understand patterns of expression. Our data suggests that brain regions classically associated with motor control, initiation, and regulation show the highest expression of , with Purkinje Cells of the cerebellum showing the highest expression of any neuron type examined. Subsequent conditional knockout in Purkinje cells led to markedly decreased intracellular cAMP levels and downstream cAMP-dependent enzyme activation. Our work provides a detailed characterization of expression throughout the brain and the biochemical consequences of loss of Gα signaling in neurons that highly express .
PubMed: 38617339
DOI: 10.1101/2024.04.03.587766 -
Molecular Therapy. Methods & Clinical... Jun 2024Viral vector gene therapy has immense promise for treating central nervous system (CNS) disorders. Although adeno-associated virus vectors (AAVs) have had success, their...
Viral vector gene therapy has immense promise for treating central nervous system (CNS) disorders. Although adeno-associated virus vectors (AAVs) have had success, their small packaging capacity limits their utility to treat the root cause of many CNS disorders. Adenoviral vectors (Ad) have tremendous potential for CNS gene therapy approaches. Currently, the most common vectors utilize the Group C Ad5 serotype capsid proteins, which rely on the Coxsackievirus-Adenovirus receptor (CAR) to infect cells. However, these Ad5 vectors are unable to transduce many neuronal cell types that are dysfunctional in many CNS disorders. The human CD46 (hCD46) receptor is widely expressed throughout the human CNS and is the primary attachment receptor for many Ad serotypes. Therefore, to overcome the current limitations of Ad vectors to treat CNS disorders, we created chimeric first generation Ad vectors that utilize the hCD46 receptor. Using a "humanized" hCD46 mouse model, we demonstrate these Ad vectors transduce cerebellar cell types, including Purkinje cells, that are refractory to Ad5 transduction. Since Ad vector transduction properties are dependent on their capsid proteins, these chimeric first generation Ad vectors open new avenues for high-capacity helper-dependent adenovirus (HdAd) gene therapy approaches for cerebellar disorders and multiple neurological disorders.
PubMed: 38605812
DOI: 10.1016/j.omtm.2024.101243 -
The Journal of Comparative Neurology Apr 2024The cerebellum is involved in higher order cognitive function and is susceptible to age-related atrophy. However, limited evidence has directly examined the cerebellum's...
The cerebellum is involved in higher order cognitive function and is susceptible to age-related atrophy. However, limited evidence has directly examined the cerebellum's role in cognitive aging. To interrogate potential substrates of the relationship between cerebellar structure and memory in aging, here we target the Purkinje cells (PCs). The sole output neurons of the cerebellum, PC loss and/or degeneration underlie a variety of behavioral abnormalities. Using a rat model of normal cognitive aging, we immunostained sections through the cerebellum for the PC-specific protein, calbindin-D28k. Although morphometric quantification revealed no significant difference in total PC number as a function of age or cognitive status, regional cell number was a more robust correlate of memory performance in the young cerebellum than in aged animals. Parallel biochemical analysis of PC-specific protein levels in whole cerebellum additionally revealed that calbindin-D28k and Purkinje cell protein-2 (pcp-2) levels were lower selectively in aged rats with spatial memory impairment compared to both young animals and aged rats with intact memory. These results suggest that cognitive aging is associated with cerebellum vulnerability, potentially reflecting disruption of the cerebellum-medial temporal lobe network.
Topics: Rats; Animals; Purkinje Cells; Calbindin 1; S100 Calcium Binding Protein G; Cerebellum; Neurons
PubMed: 38605461
DOI: 10.1002/cne.25610 -
Redox Biology Jun 2024Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by impaired motor coordination due to neurological defects and cerebellar dysfunction...
Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by impaired motor coordination due to neurological defects and cerebellar dysfunction caused by the accumulation of cholesterol in endolysosomes. Besides the increase in lysosomal cholesterol, mitochondria are also enriched in cholesterol, which leads to decreased membrane fluidity, impaired mitochondrial function and loss of GSH, and has been shown to contribute to the progression of NPC disease. S-Adenosyl-l-methionine (SAM) regulates membrane physical properties through the generation of phosphatidylcholine (PC) from phosphatidylethanolamine (PE) methylation and functions as a GSH precursor by providing cysteine in the transsulfuration pathway. However, the role of SAM in NPC disease has not been investigated. Here we report that Npc1 mice exhibit decreased brain SAM levels but unchanged S-adenosyl-l-homocysteine content and lower expression of Mat2a. Brain mitochondria from Npc1 mice display decreased mitochondrial GSH levels and liquid chromatography-high resolution mass spectrometry analysis reveal a lower PC/PE ratio in mitochondria, contributing to increased mitochondrial membrane order. In vivo treatment of Npc1 mice with SAM restores SAM levels in mitochondria, resulting in increased PC/PE ratio, mitochondrial membrane fluidity and subsequent replenishment of mitochondrial GSH levels. In vivo SAM treatment improves the decline of locomotor activity, increases Purkinje cell survival in the cerebellum and extends the average and maximal life spam of Npc1 mice. These findings identify SAM as a potential therapeutic approach for the treatment of NPC disease.
Topics: Animals; Mice; Membrane Fluidity; S-Adenosylmethionine; Mitochondrial Membranes; Niemann-Pick Disease, Type C; Glutathione; Brain; Mitochondria; Niemann-Pick C1 Protein; Disease Models, Animal; Mice, Knockout; Phosphatidylcholines
PubMed: 38599016
DOI: 10.1016/j.redox.2024.103150 -
Communications Biology Apr 2024Better understanding of the earliest molecular pathologies of all neurodegenerative diseases is expected to improve human therapeutics. We investigated the earliest...
Better understanding of the earliest molecular pathologies of all neurodegenerative diseases is expected to improve human therapeutics. We investigated the earliest molecular pathology of spinocerebellar ataxia type 1 (SCA1), a rare familial neurodegenerative disease that primarily induces death and dysfunction of cerebellum Purkinje cells. Extensive prior studies have identified involvement of transcription or RNA-splicing factors in the molecular pathology of SCA1. However, the regulatory network of SCA1 pathology, especially central regulators of the earliest developmental stages and inflammatory events, remains incompletely understood. Here, we elucidated the earliest developmental pathology of SCA1 using originally developed dynamic molecular network analyses of sequentially acquired RNA-seq data during differentiation of SCA1 patient-derived induced pluripotent stem cells (iPSCs) to Purkinje cells. Dynamic molecular network analysis implicated histone genes and cytokine-relevant immune response genes at the earliest stages of development, and revealed relevance of ISG15 to the following degradation and accumulation of mutant ataxin-1 in Purkinje cells of SCA1 model mice and human patients.
Topics: Animals; Humans; Mice; Cytokines; Induced Pluripotent Stem Cells; Mice, Transgenic; Purkinje Cells; Spinocerebellar Ataxias; Ubiquitins
PubMed: 38594382
DOI: 10.1038/s42003-024-06066-z -
Acta Neurobiologiae Experimentalis Mar 2024Neuroinflammation is a process associated with degeneration and loss of neurons in different parts of the brain. The most important damage mechanisms in its formation...
Neuroinflammation is a process associated with degeneration and loss of neurons in different parts of the brain. The most important damage mechanisms in its formation are oxidative stress and inflammation. This study aimed to investigate the protective effects of cannabidiol (CBD) against neuroinflammation through various mechanisms. Thirty‑two female rats were randomly divided into 4 groups as control, lipopolysaccharide (LPS), LPS + CBD and CBD groups. After six hours following LPS administration, rats were sacrificed, brain and cerebellum tissues were obtained. Tissues were stained with hematoxylin‑eosin for histopathological analysis. Apelin and tyrosine hydroxylase synthesis were determined immunohistochemically. Total oxidant status and total antioxidant status levels were measured, and an oxidative stress index was calculated. Protein kinase B (AKT), brain-derived neurotrophic factor (BDNF), cyclic‑AMP response element‑binding protein (CREB) and nuclear factor erythroid 2‑related factor 2 (NRF2) mRNA expression levels were also determined. In the LPS group, hyperemia, degeneration, loss of neurons and gliosis were seen in all three tissues. Additionally, Purkinje cell loss in the cerebellum, as well as neuronal loss in the cerebral cortex and hippocampus, were found throughout the LPS group. The expressions of AKT, BDNF, CREB and NRF2, apelin and tyrosine hydroxylase synthesis all decreased significantly. CBD treatment reversed these changes and ameliorated oxidative stress parameters. CBD showed protective effects against neuroinflammation via regulating AKT, CREB, BDNF expressions, NRF2 signaling, apelin and tyrosine hydroxylase synthesis.
Topics: Female; Rats; Animals; Proto-Oncogene Proteins c-akt; Cannabidiol; Neuroprotective Agents; NF-E2-Related Factor 2; Dopamine; Apelin; Cyclic AMP Response Element-Binding Protein; Brain-Derived Neurotrophic Factor; Neuroinflammatory Diseases; Lipopolysaccharides; Tyrosine 3-Monooxygenase; Hippocampus; Gene Expression
PubMed: 38587319
DOI: 10.55782/ane-2024-2546