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Joy MSH, Nall DL, Emon B, Lee KY, Barishman A, Ahmed M, Rahman S, Selvin PR, Saif MTA. Synapses without tension fail to fire in an in vitro network of hippocampal neurons. Proc Natl Acad Sci U S A 2023; 120:e2311995120. [PMID: 38113266 PMCID: PMC10756289 DOI: 10.1073/pnas.2311995120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 11/02/2023] [Indexed: 12/21/2023] Open
Abstract
Neurons in the brain communicate with each other at their synapses. It has long been understood that this communication occurs through biochemical processes. Here, we reveal that mechanical tension in neurons is essential for communication. Using in vitro rat hippocampal neurons, we find that 1) neurons become tout/tensed after forming synapses resulting in a contractile neural network, and 2) without this contractility, neurons fail to fire. To measure time evolution of network contractility in 3D (not 2D) extracellular matrix, we developed an ultrasensitive force sensor with 1 nN resolution. We employed Multi-Electrode Array and iGluSnFR, a glutamate sensor, to quantify neuronal firing at the network and at the single synapse scale, respectively. When neuron contractility is relaxed, both techniques show significantly reduced firing. Firing resumes when contractility is restored. This finding highlights the essential contribution of neural contractility in fundamental brain functions and has implications for our understanding of neural physiology.
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Affiliation(s)
- Md Saddam Hossain Joy
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Duncan L. Nall
- Department of Physics and Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Bashar Emon
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Ki Yun Lee
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Alexandra Barishman
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Movviz Ahmed
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Saeedur Rahman
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Paul R. Selvin
- Department of Physics and Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - M. Taher A. Saif
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
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Da Y, Luo S, Tian Y. Real-Time Monitoring of Neurotransmitters in the Brain of Living Animals. ACS APPLIED MATERIALS & INTERFACES 2023; 15:138-157. [PMID: 35394736 DOI: 10.1021/acsami.2c02740] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Neurotransmitters, as important chemical small molecules, perform the function of neural signal transmission from cell to cell. Excess concentrations of neurotransmitters are often closely associated with brain diseases, such as Alzheimer's disease, depression, schizophrenia, and Parkinson's disease. On the other hand, the release of neurotransmitters under the induced stimulation indicates the occurrence of reward-related behaviors, including food and drug addiction. Therefore, to understand the physiological and pathological functions of neurotransmitters, especially in complex environments of the living brain, it is urgent to develop effective tools to monitor their dynamics with high sensitivity and specificity. Over the past 30 years, significant advances in electrochemical sensors and optical probes have brought new possibilities for studying neurons and neural circuits by monitoring the changes in neurotransmitters. This Review focuses on the progress in the construction of sensors for in vivo analysis of neurotransmitters in the brain and summarizes current attempts to address key issues in the development of sensors with high selectivity, sensitivity, and stability. Combined with the latest advances in technologies and methods, several strategies for sensor construction are provided for recording chemical signal changes in the complex environment of the brain.
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Affiliation(s)
- Yifan Da
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China
| | - Shihua Luo
- Department of Traumatology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Yang Tian
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, School of Chemistry and Molecular Engineering, East China Normal University, Dongchuan Road 500, Shanghai 200241, China
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Llanes LC, Sa NB, Cenci AR, Teixeira KF, de França IV, Meier L, de Oliveira AS. Witches, potions, and metabolites: an overview from a medicinal perspective. RSC Med Chem 2022; 13:405-412. [PMID: 35647543 PMCID: PMC9020611 DOI: 10.1039/d2md00025c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 03/28/2022] [Indexed: 11/21/2022] Open
Abstract
Witches were popularly imagined as older women (above middle age), with large warty noses, whose clothes were shabby and used pointy hats. They are usually associated with a cauldron and...
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Affiliation(s)
- Luana Canzian Llanes
- Department of Chemistry and Biochemistry, University of California Santa Barbara California 93106 USA
| | - Nathalia Biazotto Sa
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
| | - Arthur Ribeiro Cenci
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
| | - Kerolain Faoro Teixeira
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
| | - Igor Vinícius de França
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
| | - Lidiane Meier
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
| | - Aldo Sena de Oliveira
- Department of Exact Sciences and Education, Federal University of Santa Catarina - Campus of Blumenau Rua João Pessoa, 2750 - Velha Blumenau - SC 89036-256 Brazil
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Houy S, Martins JS, Mohrmann R, Sørensen JB. Measurements of Exocytosis by Capacitance Recordings and Calcium Uncaging in Mouse Adrenal Chromaffin Cells. Methods Mol Biol 2021; 2233:233-251. [PMID: 33222139 DOI: 10.1007/978-1-0716-1044-2_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Fusion of vesicles with the plasma membrane and liberation of their contents is a multistep process involving several proteins. Correctly assigning the role of specific proteins and reactions in this cascade requires a measurement method with high temporal resolution. Patch-clamp recordings of cell membrane capacitance in combination with calcium measurements, calcium uncaging, and carbon-fiber amperometry allow for the accurate determination of vesicle pool sizes, their fusion kinetics, and their secreted oxidizable content. Here, we will describe this method in a model system for neurosecretion, the adrenal chromaffin cells, which secrete adrenaline.
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Affiliation(s)
- Sébastien Houy
- Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark
| | - Joana S Martins
- Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark
| | - Ralf Mohrmann
- Institute for Physiology, Otto-von-Guericke University, Magdeburg, Germany
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Afuwape OAT, Wasser CR, Schikorski T, Kavalali ET. Synaptic vesicle pool-specific modification of neurotransmitter release by intravesicular free radical generation. J Physiol 2016; 595:1223-1238. [PMID: 27723113 DOI: 10.1113/jp273115] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/04/2016] [Indexed: 01/22/2023] Open
Abstract
KEY POINTS Synaptic transmission is mediated by the release of neurotransmitters from synaptic vesicles in response to stimulation or through the spontaneous fusion of a synaptic vesicle with the presynaptic plasma membrane. There is growing evidence that synaptic vesicles undergoing spontaneous fusion versus those fusing in response to stimuli are functionally distinct. In this study, we acutely probe the effects of intravesicular free radical generation on synaptic vesicles that fuse spontaneously or in response to stimuli. By targeting vesicles that preferentially release spontaneously, we can dissociate the effects of intravesicular free radical generation on spontaneous neurotransmission from evoked neurotransmission and vice versa. Taken together, these results further advance our knowledge of the synapse and the nature of the different synaptic vesicle pools mediating neurotransmission. ABSTRACT Earlier studies suggest that spontaneous and evoked neurotransmitter release processes are maintained by synaptic vesicles which are segregated into functionally distinct pools. However, direct interrogation of the link between this putative synaptic vesicle pool heterogeneity and neurotransmission has been difficult. To examine this link, we tagged vesicles with horseradish peroxidase (HRP) - a haem-containing plant enzyme - or antibodies against synaptotagmin-1 (syt1). Filling recycling vesicles in hippocampal neurons with HRP and subsequent treatment with hydrogen peroxide (H2 O2 ) modified the properties of neurotransmitter release depending on the route of HRP uptake. While strong depolarization-induced uptake of HRP suppressed evoked release and augmented spontaneous release, HRP uptake during mild activity selectively impaired evoked release, whereas HRP uptake at rest solely potentiated spontaneous release. Expression of a luminal HRP-tagged syt1 construct and subsequent H2 O2 application resulted in a similar increase in spontaneous release and suppression as well as desynchronization of evoked release, recapitulating the canonical syt1 loss-of-function phenotype. An antibody targeting the luminal domain of syt1, on the other hand, showed that augmentation of spontaneous release and suppression of evoked release phenotypes are dissociable depending on whether the antibody uptake occurred at rest or during depolarization. Taken together, these findings indicate that vesicles that maintain spontaneous and evoked neurotransmitter release preserve their identity during recycling and syt1 function in suppression of spontaneous neurotransmission can be acutely dissociated from syt1 function to synchronize synaptic vesicle exocytosis upon stimulation.
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Affiliation(s)
- Olusoji A T Afuwape
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, 75390-9111, USA
| | - Catherine R Wasser
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, 75390-9111, USA
| | - Thomas Schikorski
- Department of Anatomy, Universidad Central Del Caribe, Bayamon, PR, 00960, Puerto Rico
| | - Ege T Kavalali
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, 75390-9111, USA.,Department of Physiology, UT Southwestern Medical Center, Dallas, TX, 75390-9111, USA
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Abstract
The vesicular glutamate transporter VGLUT1 loads synaptic vesicles with the neurotransmitter glutamate and thereby determines glutamate release at many synapses in the mammalian brain. Due to its function and selective localization, VGLUT1 is one of the most specific markers for glutamatergic synaptic vesicles. It has been used widely to identify glutamatergic synapses, and its expression levels are tightly correlated with changes in quantal size, modulations of synaptic plasticity, and corresponding behaviors. We generated a fluorescent VGLUT1(Venus) knock-in mouse for the analysis of VGLUT1 and glutamatergic synaptic vesicle trafficking. The mutation does not affect glutamatergic synapse function, and thus the new mouse model represents a universal tool for the analysis of glutamatergic transmitter systems in the forebrain. Previous studies demonstrated synaptic vesicle exchange between terminals in vitro. Using the VGLUT1(Venus) knock-in, we show that synaptic vesicles are dynamically shared among boutons in the cortex of mice in vivo. We provide a detailed analysis of synaptic vesicle sharing in vitro, and show that network homeostasis leads to dynamic scaling of synaptic VGLUT1 levels.
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Mani M, Ryan TA. Live imaging of synaptic vesicle release and retrieval in dopaminergic neurons. Front Neural Circuits 2009; 3:3. [PMID: 19521540 PMCID: PMC2694661 DOI: 10.3389/neuro.04.003.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 05/13/2009] [Indexed: 11/13/2022] Open
Abstract
Dopaminergic (DA) neurons represent <0.01% of neurons in the human brain, but are essential for normal neurological and psychiatric function. The majority of these neurons reside in the ventral midbrain, but they exert their profound influences on brain function through projections to both the cortex and the basal ganglia. These projections secrete dopamine from small clear synaptic vesicles (SVs) in axonal varicosities. DA signaling has unique spatial and temporal characteristics as compared to the fast, focal synaptic transmission of excitatory and inhibitory neurons. However, as with fast-acting neurotransmitters, DA SVs must be locally recycled for use following exocytosis. Little is known about these DA SV recycling properties and how they might impact efficacy of DA neurotransmission. Here we used the pH-sensitive fluorescent probe synaptopHluorin to investigate SV recycling in DA neurons and compared their properties to prototypical fast neurotransmitter synapses of the hippocampus. These measurements showed that DA SVs, like hippocampal SVs, have a resting pH of ∼5.6. However, compared to hippocampal neurons, DA neurons show limited depletion of the recycling pool of vesicles as the stimulus frequency is increased from 5 to 30 Hz. Additional measurements show that exocytosis rates at this frequency are comparable between hippocampal and DA neurons. Thus, limited vesicle depletion likely arises from a stimulus frequency-dependent acceleration of DA SV endocytosis or re-acidification. Our observations imply differential regulation of endocytic–exocytic balance in DA neurons. Finally, our assay can also be used to investigate the effects of genetic and chemical modulation of the SV cycle.
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Affiliation(s)
- Meera Mani
- Department of Biochemistry, Weill Medical College of Cornell University New York, NY, USA
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