1
|
Rijal K, Müller NIC, Friauf E, Singh A, Prasad A, Das D. Exact Distribution of the Quantal Content in Synaptic Transmission. PHYSICAL REVIEW LETTERS 2024; 132:228401. [PMID: 38877921 DOI: 10.1103/physrevlett.132.228401] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 01/26/2024] [Accepted: 04/25/2024] [Indexed: 08/23/2024]
Abstract
During electrochemical signal transmission through synapses, triggered by an action potential (AP), a stochastic number of synaptic vesicles (SVs), called the "quantal content," release neurotransmitters in the synaptic cleft. It is widely accepted that the quantal content probability distribution is a binomial based on the number of ready-release SVs in the presynaptic terminal. But the latter number itself fluctuates due to its stochastic replenishment, hence the actual distribution of quantal content is unknown. We show that exact distribution of quantal content can be derived for general stochastic AP inputs in the steady state. For fixed interval AP train, we prove that the distribution is a binomial, and corroborate our predictions by comparison with electrophysiological recordings from MNTB-LSO synapses of juvenile mice. For a Poisson train, we show that the distribution is nonbinomial. Moreover, we find exact moments of the quantal content in the Poisson and other general cases, which may be used to obtain the model parameters from experiments.
Collapse
Affiliation(s)
- Krishna Rijal
- Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Nicolas I C Müller
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Abhyudai Singh
- Departments of Electrical and Computer Engineering, Biomedical Engineering and Mathematical Sciences, University of Delaware, Newark, Delaware 19716, USA
| | - Ashok Prasad
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado, USA
| | - Dibyendu Das
- Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| |
Collapse
|
2
|
McMillen A, Chew Y. Neural mechanisms of dopamine function in learning and memory in Caenorhabditis elegans. Neuronal Signal 2024; 8:NS20230057. [PMID: 38572143 PMCID: PMC10987485 DOI: 10.1042/ns20230057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/03/2023] [Accepted: 12/11/2023] [Indexed: 04/05/2024] Open
Abstract
Research into learning and memory over the past decades has revealed key neurotransmitters that regulate these processes, many of which are evolutionarily conserved across diverse species. The monoamine neurotransmitter dopamine is one example of this, with countless studies demonstrating its importance in regulating behavioural plasticity. However, dopaminergic neural networks in the mammalian brain consist of hundreds or thousands of neurons, and thus cannot be studied at the level of single neurons acting within defined neural circuits. The nematode Caenorhabditis elegans (C. elegans) has an experimentally tractable nervous system with a completely characterized synaptic connectome. This makes it an advantageous system to undertake mechanistic studies into how dopamine encodes lasting yet flexible behavioural plasticity in the nervous system. In this review, we synthesize the research to date exploring the importance of dopaminergic signalling in learning, memory formation, and forgetting, focusing on research in C. elegans. We also explore the potential for dopamine-specific fluorescent biosensors in C. elegans to visualize dopaminergic neural circuits during learning and memory formation in real-time. We propose that the use of these sensors in C. elegans, in combination with optogenetic and other light-based approaches, will further illuminate the detailed spatiotemporal requirements for encoding behavioural plasticity in an accessible experimental system. Understanding the key molecules and circuit mechanisms that regulate learning and forgetting in more compact invertebrate nervous systems may reveal new druggable targets for enhancing memory storage and delaying memory loss in bigger brains.
Collapse
Affiliation(s)
- Anna McMillen
- College of Medicine and Public Health and Flinders Health and Medical Research Institute, Flinders University, Bedford Park, 5042, South Australia, Australia
| | - Yee Lian Chew
- College of Medicine and Public Health and Flinders Health and Medical Research Institute, Flinders University, Bedford Park, 5042, South Australia, Australia
| |
Collapse
|
3
|
Vahdat Z, Gambrell O, Singh A. Characterizing the role of autaptic feedback in enhancing precision of neuronal firing times. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561207. [PMID: 37873216 PMCID: PMC10592613 DOI: 10.1101/2023.10.06.561207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
In a chemical synapse, information flow occurs via the release of neurotransmitters from a presynaptic neuron that triggers an Action potential (AP) in the postsynaptic neuron. At its core, this occurs via the postsynaptic membrane potential integrating neurotransmitter-induced synaptic currents, and AP generation occurs when potential reaches a critical threshold. This manuscript investigates feedback implementation via an autapse, where the axon from the postsynaptic neuron forms an inhibitory synapse onto itself. Using a stochastic model of neuronal synaptic transmission, we formulate AP generation as a first-passage time problem and derive expressions for both the mean and noise of AP-firing times. Our analytical results supported by stochastic simulations identify parameter regimes where autaptic feedback transmission enhances the precision of AP firing times consistent with experimental data. These noise attenuating regimes are intuitively based on two orthogonal mechanisms - either expanding the time window to integrate noisy upstream signals; or by linearizing the mean voltage increase over time. Interestingly, we find regimes for noise amplification that specifically occur when the inhibitory synapse has a low probability of release for synaptic vesicles. In summary, this work explores feedback modulation of the stochastic dynamics of autaptic neurotransmission and reveals its function of creating more regular AP firing patterns.
Collapse
Affiliation(s)
- Zahra Vahdat
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE USA 19716
| | - Oliver Gambrell
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE USA 19716
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, Biomedical Engineering, Mathematical Sciences, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE USA 19716
| |
Collapse
|
4
|
Salgueiro WG, Soares MV, Martins CF, Paula FR, Rios-Anjos RM, Carrazoni T, Mori MA, Müller RU, Aschner M, Dal Belo CA, Ávila DS. Dopaminergic modulation by quercetin: In silico and in vivo evidence using Caenorhabditis elegans as a model. Chem Biol Interact 2023; 382:110610. [PMID: 37348670 PMCID: PMC10527449 DOI: 10.1016/j.cbi.2023.110610] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 06/12/2023] [Accepted: 06/19/2023] [Indexed: 06/24/2023]
Abstract
Quercetin is a flavonol widely distributed in plants and has various described biological functions. Several studies have reported on its ability to restore neuronal function in a wide variety of disease models, including animal models of neurodegenerative disorders such as Parkinson's disease. Quercetin per se can act as a neuroprotector/neuromodulator, especially in diseases related to impaired dopaminergic neurotransmission. However, little is known about how quercetin interacts with the dopaminergic machinery. Here we employed the nematode Caenorhabditis elegans to study this putative interaction. After observing behavioral modulation, mutant analysis and gene expression in C. elegans upon exposure to quercetin at a concentration that does not protect against MPTP, we constructed a homology-based dopamine transporter protein model to conduct a docking study. This led to suggestive evidence on how quercetin may act as a dopaminergic modulator by interacting with C. elegans' dopamine transporter and alter the nematode's exploratory behavior. Consistent with this model, quercetin controls C. elegans behavior in a way dependent on the presence of both the dopamine transporter (dat-1), which is up-regulated upon quercetin exposure, and the dopamine receptor 2 (dop-2), which appears to be mandatory for dat-1 up-regulation. Our data propose an interaction with the dopaminergic machinery that may help to establish the effects of quercetin as a neuromodulator.
Collapse
Affiliation(s)
- Willian Goulart Salgueiro
- Research Group in Biochemistry and Toxicology in Caenorhabditis elegans (GBToxCe), Federal University of Pampa - UNIPAMPA, CEP 97500-970, Uruguaiana, RS, Brazil; Department of Biochemistry and Tissue Biology, University of Campinas, Monteiro Lobato Avenue, 255, Campinas, São Paulo, 13083-862, Brazil; Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, 50931, Germany; Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Marcell Valandro Soares
- Research Group in Biochemistry and Toxicology in Caenorhabditis elegans (GBToxCe), Federal University of Pampa - UNIPAMPA, CEP 97500-970, Uruguaiana, RS, Brazil; Department of Biochemistry and Molecular Biology, Post-graduate Program in Biological Sciences, Federal University of Santa Maria, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Cassiano Fiad Martins
- Research Group in Biochemistry and Toxicology in Caenorhabditis elegans (GBToxCe), Federal University of Pampa - UNIPAMPA, CEP 97500-970, Uruguaiana, RS, Brazil
| | - Fávero Reisdorfer Paula
- Laboratory for Development and Quality Control in Medicines (LDCQ), Federal University of Pampa, Uruguaiana, RS, Brazil
| | | | - Thiago Carrazoni
- Neurobiology and Toxinology Laboratory, (LANETOX), Federal University of Pampa - UNIPAMPA, CEP 97300-000, São Gabriel, RS, Brazil
| | - Marcelo A Mori
- Department of Biochemistry and Tissue Biology, University of Campinas, Monteiro Lobato Avenue, 255, Campinas, São Paulo, 13083-862, Brazil; Obesity and Comorbidities Research Center (OCRC), University of Campinas, Campinas, SP, Brazil; Experimental Medicine Research Cluster, University of Campinas, Campinas, SP, Brazil
| | - Roman-Ulrich Müller
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne, 50931, Germany; Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Cháriston André Dal Belo
- Department of Biochemistry and Molecular Biology, Post-graduate Program in Biological Sciences, Federal University of Santa Maria, Camobi, 97105-900, Santa Maria, RS, Brazil; Neurobiology and Toxinology Laboratory, (LANETOX), Federal University of Pampa - UNIPAMPA, CEP 97300-000, São Gabriel, RS, Brazil; Multidisciplinar Department, Federal University of São Paulo (UNIFESP), Angelica Street, 100- CEP 06110295, Osasco, SP, Brazil
| | - Daiana Silva Ávila
- Research Group in Biochemistry and Toxicology in Caenorhabditis elegans (GBToxCe), Federal University of Pampa - UNIPAMPA, CEP 97500-970, Uruguaiana, RS, Brazil; Department of Biochemistry and Molecular Biology, Post-graduate Program in Biological Sciences, Federal University of Santa Maria, Camobi, 97105-900, Santa Maria, RS, Brazil.
| |
Collapse
|
5
|
Rosikon KD, Bone MC, Lawal HO. Regulation and modulation of biogenic amine neurotransmission in Drosophila and Caenorhabditis elegans. Front Physiol 2023; 14:970405. [PMID: 36875033 PMCID: PMC9978017 DOI: 10.3389/fphys.2023.970405] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/23/2023] [Indexed: 02/18/2023] Open
Abstract
Neurotransmitters are crucial for the relay of signals between neurons and their target. Monoamine neurotransmitters dopamine (DA), serotonin (5-HT), and histamine are found in both invertebrates and mammals and are known to control key physiological aspects in health and disease. Others, such as octopamine (OA) and tyramine (TA), are abundant in invertebrates. TA is expressed in both Caenorhabditis elegans and Drosophila melanogaster and plays important roles in the regulation of essential life functions in each organism. OA and TA are thought to act as the mammalian homologs of epinephrine and norepinephrine respectively, and when triggered, they act in response to the various stressors in the fight-or-flight response. 5-HT regulates a wide range of behaviors in C. elegans including egg-laying, male mating, locomotion, and pharyngeal pumping. 5-HT acts predominantly through its receptors, of which various classes have been described in both flies and worms. The adult brain of Drosophila is composed of approximately 80 serotonergic neurons, which are involved in modulation of circadian rhythm, feeding, aggression, and long-term memory formation. DA is a major monoamine neurotransmitter that mediates a variety of critical organismal functions and is essential for synaptic transmission in invertebrates as it is in mammals, in which it is also a precursor for the synthesis of adrenaline and noradrenaline. In C. elegans and Drosophila as in mammals, DA receptors play critical roles and are generally grouped into two classes, D1-like and D2-like based on their predicted coupling to downstream G proteins. Drosophila uses histamine as a neurotransmitter in photoreceptors as well as a small number of neurons in the CNS. C. elegans does not use histamine as a neurotransmitter. Here, we review the comprehensive set of known amine neurotransmitters found in invertebrates, and discuss their biological and modulatory functions using the vast literature on both Drosophila and C. elegans. We also suggest the potential interactions between aminergic neurotransmitters systems in the modulation of neurophysiological activity and behavior.
Collapse
Affiliation(s)
- Katarzyna D Rosikon
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Megan C Bone
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Hakeem O Lawal
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| |
Collapse
|