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Cells May 2024Pacemaking activity in substantia nigra dopaminergic neurons is generated by the coordinated activity of a variety of distinct somatodendritic voltage- and calcium-gated...
High-Resolution Proteomics Unravel a Native Functional Complex of Cav1.3, SK3, and Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in Midbrain Dopaminergic Neurons.
Pacemaking activity in substantia nigra dopaminergic neurons is generated by the coordinated activity of a variety of distinct somatodendritic voltage- and calcium-gated ion channels. We investigated whether these functional interactions could arise from a common localization in macromolecular complexes where physical proximity would allow for efficient interaction and co-regulations. For that purpose, we immunopurified six ion channel proteins involved in substantia nigra neuron autonomous firing to identify their molecular interactions. The ion channels chosen as bait were Cav1.2, Cav1.3, HCN2, HCN4, Kv4.3, and SK3 channel proteins, and the methods chosen to determine interactions were co-immunoprecipitation analyzed through immunoblot and mass spectrometry as well as proximity ligation assay. A macromolecular complex composed of Cav1.3, HCN, and SK3 channels was unraveled. In addition, novel potential interactions between SK3 channels and sclerosis tuberous complex (Tsc) proteins, inhibitors of mTOR, and between HCN4 channels and the pro-degenerative protein Sarm1 were uncovered. In order to demonstrate the presence of these molecular interactions in situ, we used proximity ligation assay (PLA) imaging on midbrain slices containing the substantia nigra, and we could ascertain the presence of these protein complexes specifically in substantia nigra dopaminergic neurons. Based on the complementary functional role of the ion channels in the macromolecular complex identified, these results suggest that such tight interactions could partly underly the robustness of pacemaking in dopaminergic neurons.
Topics: Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; Proteomics; Dopaminergic Neurons; Animals; Small-Conductance Calcium-Activated Potassium Channels; Mesencephalon; Humans; Calcium Channels, L-Type; Mice; Substantia Nigra
PubMed: 38891076
DOI: 10.3390/cells13110944 -
Alzheimer's Research & Therapy Jun 2024Autopsy work indicates that the widely-projecting noradrenergic pontine locus coeruleus (LC) is among the earliest regions to accumulate hyperphosphorylated tau, a...
BACKGROUND
Autopsy work indicates that the widely-projecting noradrenergic pontine locus coeruleus (LC) is among the earliest regions to accumulate hyperphosphorylated tau, a neuropathological Alzheimer's disease (AD) hallmark. This early tau deposition is accompanied by a reduced density of LC projections and a reduction of norepinephrine's neuroprotective effects, potentially compromising the neuronal integrity of LC's cortical targets. Previous studies suggest that lower magnetic resonance imaging (MRI)-derived LC integrity may signal cortical tissue degeneration in cognitively healthy, older individuals. However, whether these observations are driven by underlying AD pathology remains unknown. To that end, we examined potential effect modifications by cortical beta-amyloid and tau pathology on the association between in vivo LC integrity, as quantified by LC MRI signal intensity, and cortical neurodegeneration, as indexed by cortical thickness.
METHODS
A total of 165 older individuals (74.24 ± 9.72 years, ~ 60% female, 10% cognitively impaired) underwent whole-brain and dedicated LC 3T-MRI, Pittsburgh Compound-B (PiB, beta-amyloid) and Flortaucipir (FTP, tau) positron emission tomography. Linear regression analyses with bootstrapped standard errors (n = 2000) assessed associations between bilateral cortical thickness and i) LC MRI signal intensity and, ii) LC MRI signal intensity interacted with cortical FTP or PiB (i.e., EC FTP, IT FTP, neocortical PiB) in the entire sample and a low beta-amyloid subsample.
RESULTS
Across the entire sample, we found a direct effect, where lower LC MRI signal intensity was associated with lower mediolateral temporal cortical thickness. Evaluation of potential effect modifications by FTP or PiB revealed that lower LC MRI signal intensity was related to lower cortical thickness, particularly in individuals with elevated (EC, IT) FTP or (neocortical) PiB. The latter result was present starting from subthreshold PiB values. In low PiB individuals, lower LC MRI signal intensity was related to lower EC cortical thickness in the context of elevated EC FTP.
CONCLUSIONS
Our findings suggest that LC-related cortical neurodegeneration patterns in older individuals correspond to regions representing early Braak stages and may reflect a combination of LC projection density loss and emergence of cortical AD pathology. This provides a novel understanding that LC-related cortical neurodegeneration may signal downstream consequences of AD-related pathology, rather than being exclusively a result of aging.
Topics: Humans; Locus Coeruleus; Female; Alzheimer Disease; Male; Aged; Magnetic Resonance Imaging; tau Proteins; Aged, 80 and over; Cohort Studies; Amyloid beta-Peptides; Positron-Emission Tomography; Cerebral Cortex; Carbolines; Thiazoles; Aniline Compounds; Brain Cortical Thickness
PubMed: 38886798
DOI: 10.1186/s13195-024-01500-0 -
Nature Communications Jun 2024Mood disorders are an enigmatic class of debilitating illnesses that affect millions of individuals worldwide. While chronic stress clearly increases incidence levels of...
Mood disorders are an enigmatic class of debilitating illnesses that affect millions of individuals worldwide. While chronic stress clearly increases incidence levels of mood disorders, including major depressive disorder (MDD), stress-mediated disruptions in brain function that precipitate these illnesses remain largely elusive. Serotonin-associated antidepressants (ADs) remain the first line of therapy for many with depressive symptoms, yet low remission rates and delays between treatment and symptomatic alleviation have prompted skepticism regarding direct roles for serotonin in the precipitation and treatment of affective disorders. Our group recently demonstrated that serotonin epigenetically modifies histone proteins (H3K4me3Q5ser) to regulate transcriptional permissiveness in brain. However, this non-canonical phenomenon has not yet been explored following stress and/or AD exposures. Here, we employed a combination of genome-wide and biochemical analyses in dorsal raphe nucleus (DRN) of male and female mice exposed to chronic social defeat stress, as well as in DRN of human MDD patients, to examine the impact of stress exposures/MDD diagnosis on H3K4me3Q5ser dynamics, as well as associations between the mark and depression-related gene expression. We additionally assessed stress-induced/MDD-associated regulation of H3K4me3Q5ser following AD exposures, and employed viral-mediated gene therapy in mice to reduce H3K4me3Q5ser levels in DRN and examine its impact on stress-associated gene expression and behavior. We found that H3K4me3Q5ser plays important roles in stress-mediated transcriptional plasticity. Chronically stressed mice displayed dysregulated H3K4me3Q5ser dynamics in DRN, with both AD- and viral-mediated disruption of these dynamics proving sufficient to attenuate stress-mediated gene expression and behavior. Corresponding patterns of H3K4me3Q5ser regulation were observed in MDD subjects on vs. off ADs at their time of death. These findings thus establish a neurotransmission-independent role for serotonin in stress-/AD-associated transcriptional and behavioral plasticity, observations of which may be of clinical relevance to human MDD and its treatment.
Topics: Animals; Dorsal Raphe Nucleus; Histones; Male; Female; Stress, Psychological; Humans; Antidepressive Agents; Depressive Disorder, Major; Mice; Serotonin; Mice, Inbred C57BL; Epigenesis, Genetic; Behavior, Animal; Gene Expression Regulation; Social Defeat
PubMed: 38871707
DOI: 10.1038/s41467-024-49336-4 -
Biomedicine & Pharmacotherapy =... Jul 2024The advent of general anesthesia (GA) has significant implications for clinical practice. However, the exact mechanisms underlying GA-induced transitions in...
The advent of general anesthesia (GA) has significant implications for clinical practice. However, the exact mechanisms underlying GA-induced transitions in consciousness remain elusive. Given some similarities between GA and sleep, the sleep-arousal neural nuclei and circuits involved in sleep-arousal, including the 5-HTergic system, could be implicated in GA. Herein, we utilized pharmacology, optogenetics, chemogenetics, fiber photometry, and retrograde tracing to demonstrate that both endogenous and exogenous activation of the 5-HTergic neural circuit between the dorsal raphe nucleus (DR) and basolateral amygdala (BLA) promotes arousal and facilitates recovery of consciousness from sevoflurane anesthesia. Notably, the 5-HT1A receptor within this pathway holds a pivotal role. Our findings will be conducive to substantially expanding our comprehension of the neural circuit mechanisms underlying sevoflurane anesthesia and provide a potential target for modulating consciousness, ultimately leading to a reduction in anesthetic dose requirements and side effects.
Topics: Sevoflurane; Animals; Dorsal Raphe Nucleus; Consciousness; Anesthetics, Inhalation; Basolateral Nuclear Complex; Male; Mice; Mice, Inbred C57BL; Serotonin; Neural Pathways; Receptor, Serotonin, 5-HT1A; Optogenetics
PubMed: 38870632
DOI: 10.1016/j.biopha.2024.116937 -
ELife Jun 2024A social memory pathway connecting the ventral hippocampus, the lateral septum and the ventral tegmental area helps to regulate how mice react to unknown individuals.
A social memory pathway connecting the ventral hippocampus, the lateral septum and the ventral tegmental area helps to regulate how mice react to unknown individuals.
Topics: Animals; Mice; Social Behavior; Ventral Tegmental Area; Hippocampus; Memory
PubMed: 38865180
DOI: 10.7554/eLife.99363 -
Journal of Neural Transmission (Vienna,... Jun 2024For a special issue, we review studies on the pathogenesis of nigral cell death and the treatment of sporadic Parkinson's disease (sPD) over the past few decades, with a... (Review)
Review
For a special issue, we review studies on the pathogenesis of nigral cell death and the treatment of sporadic Parkinson's disease (sPD) over the past few decades, with a focus on the studies performed by Prof. Mizuno and our group. Prof. Mizuno proposed the initial concept that mitochondrial function may be impaired in sPD. When working at Jichi Medical School, he found a decrease in complex I of the mitochondrial electron transfer complex in the substantia nigra of patients with Parkinson's disease (PD) and MPTP models. After moving to Juntendo University as a professor and chairman, he continued to study the mechanisms of cell death in the substantia nigra of patients with sPD. Under his supervision, I studied the relationships between PD and apoptosis, PD and iron involvement, mitochondrial dysfunction and apoptosis, and PD and neuroinflammation. Moving to Kitasato University, we focused on PD and the cytotoxicity of alpha synuclein (αSyn) as well as brain neuropathology. Eventually, I moved to Osaka University, where I continued working on PD and αSyn projects to promote therapeutic research. In this paper, we present the details of these studies in the following order: past, present, and future.
Topics: Humans; Parkinson Disease; Animals; Substantia Nigra; alpha-Synuclein
PubMed: 38864935
DOI: 10.1007/s00702-024-02788-w -
Nature Communications Jun 2024The potential brain mechanism underlying resilience to socially transferred allodynia remains unknown. Here, we utilize a well-established socially transferred allodynia...
The potential brain mechanism underlying resilience to socially transferred allodynia remains unknown. Here, we utilize a well-established socially transferred allodynia paradigm to segregate male mice into pain-susceptible and pain-resilient subgroups. Brain screening results show that ventral tegmental area glutamatergic neurons are selectively activated in pain-resilient mice as compared to control and pain-susceptible mice. Chemogenetic manipulations demonstrate that activation and inhibition of ventral tegmental area glutamatergic neurons bi-directionally regulate resilience to socially transferred allodynia. Moreover, ventral tegmental area glutamatergic neurons that project specifically to the nucleus accumbens shell and lateral habenula regulate the development and maintenance of the pain-resilient phenotype, respectively. Together, we establish an approach to explore individual variations in pain response and identify ventral tegmental area glutamatergic neurons and related downstream circuits as critical targets for resilience to socially transferred allodynia and the development of conceptually innovative analgesics.
Topics: Animals; Male; Hyperalgesia; Ventral Tegmental Area; Mice; Glutamic Acid; Nucleus Accumbens; Neurons; Mesencephalon; Mice, Inbred C57BL; Resilience, Psychological; Habenula; Disease Models, Animal
PubMed: 38858350
DOI: 10.1038/s41467-024-49340-8 -
Journal of Obstetrics and Gynaecology :... Dec 2024There are several international guidelines for foetal anomalies scanning at 11-14 weeks' gestation. The aim of this study is to present our first-trimester specialist...
BACKGROUND
There are several international guidelines for foetal anomalies scanning at 11-14 weeks' gestation. The aim of this study is to present our first-trimester specialist neurosonography protocol with examples of pathology in order to develop a systematic approach to evaluating the first-trimester foetal brain.
METHODS
Women undergoing a first-trimester foetal medicine ultrasound scan between 2010 and 2020 for multiple indications underwent neurosonography according to a set protocol. 3D transvaginal brain examination was performed in all cases (2000 pregnancies scanned). We retrospectively reviewed all imaging to develop this protocol.
RESULTS
We propose that the following five axial-plane parallel views should be obtained when performing neurosonography in the first trimester, moving from cranial to caudal: 1. Lateral ventricles; 2. Third ventricle; 3. Thalamus and mesencephalon; 4. Cerebellum; 5. Fourth ventricle. Examples of these images and abnormalities that can be seen in each plane are given.
CONCLUSIONS
We have presented a specialist protocol for systematically assessing the foetal brain in the first trimester and given examples of pathology which may be seen in each plane. Further work is needed to prospectively assess detection rates of major abnormalities using this protocol and assess the reproducibility and learning curve of this technique.
Topics: Humans; Female; Pregnancy; Pregnancy Trimester, First; Ultrasonography, Prenatal; Imaging, Three-Dimensional; Retrospective Studies; Brain; Adult; Fetus
PubMed: 38845462
DOI: 10.1080/01443615.2024.2361848 -
Nature Jun 2024All drugs of abuse induce long-lasting changes in synaptic transmission and neural circuit function that underlie substance-use disorders. Another recently appreciated...
All drugs of abuse induce long-lasting changes in synaptic transmission and neural circuit function that underlie substance-use disorders. Another recently appreciated mechanism of neural circuit plasticity is mediated through activity-regulated changes in myelin that can tune circuit function and influence cognitive behaviour. Here we explore the role of myelin plasticity in dopaminergic circuitry and reward learning. We demonstrate that dopaminergic neuronal activity-regulated myelin plasticity is a key modulator of dopaminergic circuit function and opioid reward. Oligodendroglial lineage cells respond to dopaminergic neuronal activity evoked by optogenetic stimulation of dopaminergic neurons, optogenetic inhibition of GABAergic neurons, or administration of morphine. These oligodendroglial changes are evident selectively within the ventral tegmental area but not along the axonal projections in the medial forebrain bundle nor within the target nucleus accumbens. Genetic blockade of oligodendrogenesis dampens dopamine release dynamics in nucleus accumbens and impairs behavioural conditioning to morphine. Taken together, these findings underscore a critical role for oligodendrogenesis in reward learning and identify dopaminergic neuronal activity-regulated myelin plasticity as an important circuit modification that is required for opioid reward.
Topics: Ventral Tegmental Area; Animals; Reward; Dopaminergic Neurons; Mice; Myelin Sheath; Morphine; Male; Nucleus Accumbens; Neuronal Plasticity; Oligodendroglia; GABAergic Neurons; Optogenetics; Analgesics, Opioid; Dopamine; Female; Mice, Inbred C57BL
PubMed: 38839962
DOI: 10.1038/s41586-024-07525-7 -
Scientific Reports Jun 2024The inflow of CSF into perivascular spaces (PVS) in the brain is crucial for clearing waste molecules. Inefficiency in PVS flow leads to neurodegeneration. Failure of...
The inflow of CSF into perivascular spaces (PVS) in the brain is crucial for clearing waste molecules. Inefficiency in PVS flow leads to neurodegeneration. Failure of PVS flushing is associated with CSF flow impairment in the intracranial hydrodynamic condition of CSF hypo-pulsatility. However, enlarged PVS (ePVS), a finding indicative of PVS flow dysfunction, is also present in patients with derangement of CSF dynamics characterized by CSF hyper-pulsatility, which increases CSF flow. Intriguingly, two opposite intracranial hydrodynamic conditions would lead to the same result of impairing the PVS flushing. To investigate this issue, we assessed the subsistence of a dysfunctional interplay between CSF and PVS flows and, if the case, the mechanisms preventing a hyper-pulsatile brain from providing an effective PVS flushing. We analyzed the association between phase contrast MRI aqueductal CSF stroke volume (aqSV), a proxy of CSF pulsatility, and the burden of ePVS in chronic adult hydrocephalus, a disease involving a broad spectrum of intracranial hydrodynamics disturbances. In the 147 (85 males, 62 females) patients, the age at diagnosis ranged between 28 and 88 years (median 73 years). Ninety-seven patients had tri-ventriculomegaly and 50 tetra-ventriculomegaly. According to the extent of ePVS, 113 patients had a high ePVS burden, while 34 had a low ePVS burden. aqSV, which ranged between 0 and 562 μL (median 86 μL), was increased with respect to healthy subjects. Patients presenting with less ePVS burden had higher aqSV (p < 0.002, corrected for the multiple comparisons) than those with higher ePVS burden. The present study confirmed the association between CSF dynamics and PVS flow disturbances and demonstrated this association in intracranial hyper-pulsatility. Further studies should investigate the association between PVS flow failure and CSF hypo- and hyper-pulsatility as responsible/co-responsible for glymphatic failure in other neurodegenerative diseases, particularly in diseases in which CSF disturbances can be corrected, as in chronic adult hydrocephalus.
Topics: Humans; Hydrocephalus; Male; Female; Aged; Middle Aged; Adult; Glymphatic System; Aged, 80 and over; Magnetic Resonance Imaging; Cerebrospinal Fluid; Hydrodynamics; Stroke Volume; Cerebral Aqueduct; Chronic Disease
PubMed: 38839864
DOI: 10.1038/s41598-024-63926-8