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Dunham KE, Khaled KH, Weizman L, Venton BJ. Microdosing ketamine in Drosophila does not block serotonin reuptake, but causes complex behavioral changes mediated by glutamate and serotonin receptors. J Neurochem 2024; 168:1097-1112. [PMID: 38323657 PMCID: PMC11136605 DOI: 10.1111/jnc.16070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/08/2024]
Abstract
Microdosing ketamine is a novel antidepressant for treatment-resistant depression. Traditional antidepressants, like selective serotonin reuptake inhibitors (SSRIs), inhibit serotonin reuptake, but it is not clear if ketamine shows a similar mechanism. Here, we tested the effects of feeding ketamine and SSRIs to Drosophila melanogaster larvae, which has a similar serotonin system to mammals and is a good model to track depressive behaviors, such as locomotion and feeding. Fast-scan cyclic voltammetry (FSCV) was used to measure optogenetically stimulated serotonin changes, and locomotion tracking software and blue dye feeding to monitor behavior. We fed larvae various doses (1-100 mM) of antidepressants for 24 h and found that 1 mM ketamine did not affect serotonin, but increased locomotion and feeding. Low doses (≤10 mM) of escitalopram and fluoxetine inhibited dSERT and also increased feeding and locomotion behaviors. At 100 mM, ketamine inhibited dSERT and increased serotonin concentrations, but decreased locomotion and feeding because of its anesthetic properties. Since microdosing ketamine causes behavioral effects, we further investigated behavioral changes with a SERT16 mutant and low doses of other NMDA receptor antagonists and 5-HT1A and 2 agonists. Feeding and locomotion changes were similar to ketamine in the mutant, and we found NMDA receptor antagonism increased feeding, while serotonin receptor agonism increased locomotion, which could explain these effects with ketamine. Ultimately, this work shows that Drosophila is a good model to discern antidepressant mechanisms, and that ketamine does not work on dSERT like SSRIs, but effects behavior with other mechanisms that should be investigated further.
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Affiliation(s)
- Kelly E Dunham
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Kani H Khaled
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Leah Weizman
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - B Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
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2
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Dunham KE, Khaled KH, Weizman L, Venton BJ. Microdosing ketamine in Drosophila does not inhibit SERT like SSRIs, but causes behavioral changes mediated by glutamate and serotonin receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566121. [PMID: 37986873 PMCID: PMC10659355 DOI: 10.1101/2023.11.07.566121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Recently, the FDA approved microdosing ketamine for treatment resistant depression. Traditional antidepressants, like serotonin selective reuptake inhibitors (SSRIs), block serotonin reuptake, but it is not clear if ketamine blocks serotonin reuptake. Here, we tested the effects of feeding ketamine and SSRIs to Drosophila melanogaster larvae, which has a similar serotonin system to mammals, and is a good model to track depression behaviors, such as locomotion and feeding. Fast-scan cyclic voltammetry (FSCV) was used to measure optogenetically-stimulated serotonin changes, and locomotion tracking software and blue dye feeding to monitor behavior. We fed larvae various doses (1-100 mM) of antidepressants for 24 hours and found that 1 mM ketamine did not affect serotonin, but increased locomotion and feeding. Low doses (≤ 10 mM) of escitalopram and fluoxetine inhibited dSERT and also increased feeding and locomotion behaviors. At 100 mM, ketamine inhibited dSERT and increased serotonin concentrations, but decreased locomotion and feeding due to its anesthetic properties. Since microdosing ketamine causes behavioral effects, we also investigated behavior changes with low doses of other NMDA receptor antagonists and 5-HT1A and 2 agonists, which are other possible sites for ketamine action. NMDA receptor antagonism increased feeding, while serotonin receptor agonism increased locomotion, which could explain these effects with ketamine. Ultimately, this work shows that Drosophila is a good model to discern antidepressant mechanisms, and that ketamine does not work on dSERT like SSRIs at microdoses, but affects behavior with other mechanisms.
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Affiliation(s)
- Kelly E Dunham
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - Kani H Khaled
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - Leah Weizman
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
| | - B Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, 22904, USA
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3
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Dumitrescu E, Copeland JM, Venton BJ. Parkin Knockdown Modulates Dopamine Release in the Central Complex, but Not the Mushroom Body Heel, of Aging Drosophila. ACS Chem Neurosci 2023; 14:198-208. [PMID: 36576890 PMCID: PMC9897283 DOI: 10.1021/acschemneuro.2c00277] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons leading to reduced locomotion. Mutations of parkin gene in Drosophila produce the same phenotypes as vertebrate models, but the effect of parkin knockdown on dopamine release is not known. Here, we report age-dependent, spatial variation of dopamine release in the brain of parkin-RNAi adult Drosophila. Dopamine was repetitively stimulated by local application of acetylcholine and quantified by fast-scan cyclic voltammetry in the central complex or mushroom body heel. In the central complex, the main area controlling locomotor function, dopamine release is maintained for repeated stimulations in aged control flies, but lower concentrations of dopamine are released in the central complex of aged parkin-RNAi flies. In the mushroom body heel, the dopamine release decrease in older parkin-RNAi flies is similar to controls. There is not significant dopaminergic neuronal loss even in older parkin knockdown flies, which indicates that the changes in stimulated dopamine release are due to alterations of neuronal function. In young parkin-RNAi flies, locomotion is inhibited by 30%, while in older parkin-RNAi flies it is inhibited by 85%. Overall, stimulated dopamine release is modulated by parkin in an age and brain region dependent manner. Correlating the functional state of the dopaminergic system with behavioral phenotypes provides unique insights into the PD mechanism. Drosophila can be used to study dopamine functionality in PD, elucidate how genetics influence dopamine, and test potential therapies to maintain dopamine release.
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Affiliation(s)
- Eduard Dumitrescu
- Department of Chemistry, University of Virginia, Charlottesville, VA 22901
| | | | - B. Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, VA 22901,Corresponding Author: , 434-243-2132
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4
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Dunham KE, Venton BJ. SSRI antidepressants differentially modulate serotonin reuptake and release in Drosophila. J Neurochem 2022; 162:404-416. [PMID: 35736504 PMCID: PMC9427694 DOI: 10.1111/jnc.15658] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 05/27/2022] [Accepted: 06/17/2022] [Indexed: 11/26/2022]
Abstract
Selective serotonin reuptake inhibitor (SSRI) antidepressants are commonly prescribed treatments for depression, but their effects on serotonin reuptake and release are not well understood. Drosophila melanogaster, the fruit fly, expresses the serotonin transporter (dSERT), the major target of SSRIs, but real-time serotonin changes after SSRIs have not been characterized in this model. The goal of this study was to characterize effects of SSRIs on serotonin concentration and reuptake in Drosophila larvae. We applied various doses (0.1-100 μM) of fluoxetine (Prozac), escitalopram (Lexapro), citalopram (Celexa), and paroxetine (Paxil), to ventral nerve cord (VNC) tissue and measured optogenetically-stimulated serotonin release with fast-scan cyclic voltammetry (FSCV). Fluoxetine increased reuptake from 1 to 100 μM, but serotonin concentration only increased at 100 μM. Thus, fluoxetine occupies dSERT and slows clearance but does not affect concentration. Escitalopram and paroxetine increased serotonin concentrations at all doses, but escitalopram increased reuptake more. Citalopram showed lower concentration changes and faster reuptake profiles compared with escitalopram, so the racemic mixture of citalopram does not change reuptake as much as the S-isomer. Dose response curves were constructed to compare dSERT affinities and paroxetine showed the highest affinity and fluoxetine the lowest. These data demonstrate SSRI mechanisms are complex, with separate effects on reuptake or release. Furthermore, dynamic serotonin changes in Drosophila are similar to previous studies in mammals. This work establishes how antidepressants affect serotonin in real-time, which is useful for future studies that will investigate pharmacological effects of SSRIs with different genetic mutations in Drosophila.
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Affiliation(s)
- Kelly E Dunham
- Department of Chemistry, University of Virginia, Virginia, USA
| | - B Jill Venton
- Department of Chemistry, University of Virginia, Virginia, USA
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5
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Lim WK, Kaur P, Huang H, Jo RS, Ramamoorthy A, Ng LF, Suresh J, Maisha FI, Mathuru AS, Tolwinski NS. Optogenetic approaches for understanding homeostatic and degenerative processes in Drosophila. Cell Mol Life Sci 2021; 78:5865-5880. [PMID: 34232330 PMCID: PMC8260576 DOI: 10.1007/s00018-021-03836-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/22/2021] [Accepted: 04/08/2021] [Indexed: 12/18/2022]
Abstract
Many organs and tissues have an intrinsic ability to regenerate from a dedicated, tissue-specific stem cell pool. As organisms age, the process of self-regulation or homeostasis begins to slow down with fewer stem cells available for tissue repair. Tissues become more fragile and organs less efficient. This slowdown of homeostatic processes leads to the development of cellular and neurodegenerative diseases. In this review, we highlight the recent use and future potential of optogenetic approaches to study homeostasis. Optogenetics uses photosensitive molecules and genetic engineering to modulate cellular activity in vivo, allowing precise experiments with spatiotemporal control. We look at applications of this technology for understanding the mechanisms governing homeostasis and degeneration as applied to widely used model organisms, such as Drosophila melanogaster, where other common tools are less effective or unavailable.
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Affiliation(s)
- Wen Kin Lim
- Science Division, Yale-NUS College, Singapore, Singapore
| | - Prameet Kaur
- Science Division, Yale-NUS College, Singapore, Singapore
| | - Huanyan Huang
- Science Division, Yale-NUS College, Singapore, Singapore
| | | | | | - Li Fang Ng
- Science Division, Yale-NUS College, Singapore, Singapore
| | - Jahnavi Suresh
- Science Division, Yale-NUS College, Singapore, Singapore
| | | | - Ajay S Mathuru
- Science Division, Yale-NUS College, Singapore, Singapore
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6
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Dunham KE, Venton BJ. Improving serotonin fast-scan cyclic voltammetry detection: new waveforms to reduce electrode fouling. Analyst 2021; 145:7437-7446. [PMID: 32955048 DOI: 10.1039/d0an01406k] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Serotonin is a neuromodulator implicated in depression that is often measured in real-time by fast-scan cyclic voltammetry (FSCV). A specialized "Jackson" waveform (JW, 0.2, 1.0 V, -0.1 V, 0.2 V, 1000 V s-1) was developed to reduce serotonin fouling, but the 1.0 V switching potential limits sensitivity and electrodes still foul. The goal of this study was to test the effects of extending the FSCV switching potential to increase serotonin sensitivity and decrease fouling. We compared the Jackson waveform, the dopamine waveform (DA, -0.4 V, 1.3 V, 400 V s-1), and two new waveforms: the extended serotonin waveform (ESW, 0.2, 1.3, -0.1, 0.2, 1000 V s-1) and extended hold serotonin waveform (EHSW, 0.2, 1.3 (hold 1 ms), -0.1, 0.2, 400 V s-1). The EHSW was the most sensitive (LOD = 0.6 nM), and the JW the least sensitive (LOD = 2.4 nM). With the Jackson waveform, electrode fouling was significant with repeated injections of serotonin or exposure to its metabolite, 5-hydroxyindoleacetic acid (5-HIAA). Using the extended waveforms, electrodes fouled 50% less than with the Jackson waveform for both analytes. No electrode fouling was observed with the dopamine waveform because of the negative holding potential. The Jackson waveform was the most selective for serotonin over dopamine (800×), and the ESW was also highly selective. All waveforms were useful for measuring serotonin with optogenetic stimulation in Drosophila larvae. These results provide new FSCV waveforms to measure dynamic serotonin changes with different experimental requirements, like high sensitivity (EHSW), high selectivity (ESW, JW), or eliminating electrode fouling (DA).
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Affiliation(s)
- Kelly E Dunham
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA.
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7
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Privman Champaloux E, Donelson N, Pyakurel P, Wolin D, Ostendorf L, Denno M, Borman R, Burke C, Short-Miller JC, Yoder MR, Copeland JM, Sanyal S, Venton BJ. Ring Finger Protein 11 (RNF11) Modulates Dopamine Release in Drosophila. Neuroscience 2020; 452:37-48. [PMID: 33176188 DOI: 10.1016/j.neuroscience.2020.10.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 02/06/2023]
Abstract
Recent work indicates a role for RING finger protein 11 (RNF11) in Parkinson disease (PD) pathology, which involves the loss of dopaminergic neurons. However, the role of RNF11 in regulating dopamine neurotransmission has not been studied. In this work, we tested the effect of RNF11 RNAi knockdown or overexpression on stimulated dopamine release in the larval Drosophila central nervous system. Dopamine release was stimulated using optogenetics and monitored in real-time using fast-scan cyclic voltammetry at an electrode implanted in an isolated ventral nerve cord. RNF11 knockdown doubled dopamine release, but there was no decrease in dopamine from RNF11 overexpression. RNF11 knockdown did not significantly increase stimulated serotonin or octopamine release, indicating the effect is dopamine specific. Dopamine clearance was also changed, as RNF11 RNAi flies had a higher Vmax and RNF11 overexpressing flies had a lower Vmax than control flies. RNF11 RNAi flies had increased mRNA levels of dopamine transporter (DAT) in RNF11, confirming changes in DAT. In RNF11 RNAi flies, release was maintained better for stimulations repeated at short intervals, indicating increases in the recycled releasable pool of dopamine. Nisoxetine, a DAT inhibitor, and flupenthixol, a D2 antagonist, did not affect RNF11 RNAi or overexpressing flies differently than control. Thus, RNF11 knockdown causes early changes in dopamine neurotransmission, and this is the first work to demonstrate that RNF11 affects both dopamine release and uptake. RNF11 expression decreases in human dopaminergic neurons during PD, and that decrease may be protective by increasing dopamine neurotransmission in the surviving dopaminergic neurons.
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Affiliation(s)
- Eve Privman Champaloux
- Neuroscience Graduate Program and Medical Scientist Training Program, University of Virginia, Charlottesville, VA, United States
| | | | - Poojan Pyakurel
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States
| | - Danielle Wolin
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States
| | - Leah Ostendorf
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States
| | - Madelaine Denno
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States
| | - Ryan Borman
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States
| | | | - Jonah C Short-Miller
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, United States
| | - Maria R Yoder
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, United States
| | - Jeffrey M Copeland
- Department of Chemistry, University of Virginia, Charlottesville, VA, United States; Department of Biology, Eastern Mennonite University, Harrisonburg, VA, United States
| | | | - B Jill Venton
- Neuroscience Graduate Program and Medical Scientist Training Program, University of Virginia, Charlottesville, VA, United States; Department of Chemistry, University of Virginia, Charlottesville, VA, United States.
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8
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Shin M, Copeland JM, Venton BJ. Real-Time Measurement of Stimulated Dopamine Release in Compartments of the Adult Drosophila melanogaster Mushroom Body. Anal Chem 2020; 92:14398-14407. [PMID: 33048531 DOI: 10.1021/acs.analchem.0c02305] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Drosophila melanogaster, a fruit fly, is an exquisite model organism to understand neurotransmission. Dopaminergic signaling in the Drosophila mushroom body (MB) is involved in olfactory learning and memory, with different compartments controlling aversive learning (heel) vs. appetitive learning (medial tip). Here, the goal was to develop techniques to measure endogenous dopamine in compartments of the MB for the first time. We compared three stimulation methods: acetylcholine (natural stimulus), P2X2 (chemogenetics), and CsChrimson (optogenetics). Evoked dopamine release was measured with fast-scan cyclic voltammetry in isolated adult Drosophila brains. Acetylcholine stimulated the largest dopamine release (0.40 μM) followed by P2X2 (0.14 μM) and CsChrimson (0.07 μM). With the larger acetylcholine and P2X2 stimulations, there were no regional or sex differences in dopamine release. However, with CsChrimson, dopamine release was significantly higher in the heel than the medial tip, and females had more dopamine than males. Michaelis-Menten modeling of the single-light pulse revealed no significant regional differences in Km, but the heel had a significantly lower Vmax (0.12 μM/s vs. 0.19 μM/s) and higher dopamine release (0.05 μM vs. 0.03 μM). Optogenetic experiments are challenging because CsChrimson is also sensitive to blue light used to activate green fluorescent protein, and thus, light exposure during brain dissection must be minimized. These experiments expand the toolkit for measuring endogenous dopamine release in Drosophila, introducing chemogenetic and optogenetic experiments for the first time. With a variety of stimulations, different experiments will help improve our understanding of neurochemical signaling in Drosophila.
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Affiliation(s)
- Mimi Shin
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, United States
| | - Jeffrey M Copeland
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, United States.,Department of Biology, Eastern Mennonite University, Harrisonburg, Virginia 22802, United States
| | - B Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, United States
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9
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Cao Q, Shin M, Lavrik NV, Venton BJ. 3D-Printed Carbon Nanoelectrodes for In Vivo Neurotransmitter Sensing. NANO LETTERS 2020; 20:6831-6836. [PMID: 32813535 PMCID: PMC7484348 DOI: 10.1021/acs.nanolett.0c02844] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Direct laser writing, a nano 3D-printing approach, has enabled fabrication of customized carbon microelectrode sensors for neurochemical detection. However, to detect neurotransmitters in tiny biological organisms or synapses, submicrometer nanoelectrodes are required. In this work, we used 3D printing to fabricate carbon nanoelectrode sensors. Customized structures were 3D printed and then pyrolyzed, resulting in free-standing carbon electrodes with nanotips. The nanoelectrodes were insulated with atomic layer deposition of Al2O3 and the nanotips were polished by a focused ion beam to form 600 nm disks. Using fast-scan cyclic voltammetry, the electrodes successfully detected stimulated dopamine in the adult fly brain, demonstrating that they are robust and sensitive enough to use in tiny biological systems. This work is the first demonstration of 3D printing to fabricate free-standing carbon nanoelectrode sensors and will enable batch fabrication of customized nanoelectrode sensors with precise control and excellent reproducibility.
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Affiliation(s)
- Qun Cao
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Mimi Shin
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Nickolay V. Lavrik
- Center for Nanophase Material Science, Oak Ridge National Lab, Oak Ridge, Tennessee 37831, United States
| | - B. Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
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10
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Hidalgo S, Fuenzalida-Uribe N, Molina-Mateo D, Escobar AP, Oliva C, España RA, Andrés ME, Campusano JM. Study of the release of endogenous amines in Drosophila brain in vivo in response to stimuli linked to aversive olfactory conditioning. J Neurochem 2020; 156:337-351. [PMID: 32596813 DOI: 10.1111/jnc.15109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 11/27/2022]
Abstract
A highly challenging question in neuroscience is to understand how aminergic neural circuits contribute to the planning and execution of behaviors, including the generation of olfactory memories. In this regard, electrophysiological techniques like Local Field Potential or imaging methods have been used to answer questions relevant to cell and circuit physiology in different animal models, such as the fly Drosophila melanogaster. However, these techniques do not provide information on the neurochemical identity of the circuits of interest. Different approaches including fast scan cyclic voltammetry, allow researchers to identify and quantify in a timely fashion the release of endogenous neuroactive molecules, but have been only used in in vitro Drosophila brain preparations. Here, we report a procedure to record for the first time the release of endogenous amines -dopamine, serotonin and octopamine- in adult fly brain in vivo, by fast scan cyclic voltammetry. As a proof of principle, we carried out recordings in the calyx region of the Mushroom Bodies, the brain area mainly associated to the generation of olfactory memories in flies. By using principal component regression in normalized training sets for in vivo recordings, we detect an increase in octopamine and serotonin levels in response to electric shock and olfactory cues respectively. This new approach allows the study of dynamic changes in amine neurotransmission that underlie complex behaviors in Drosophila and shed new light on the contribution of these amines to olfactory processing in this animal model.
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Affiliation(s)
- Sergio Hidalgo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,School of Physiology, Pharmacology and Ncxeuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Nicolás Fuenzalida-Uribe
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniela Molina-Mateo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Angélica P Escobar
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Oliva
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo A España
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Maria Estela Andrés
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge M Campusano
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencia UC, Santiago, Chile
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11
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Dopamine release in mushroom bodies of the honey bee (Apis mellifera L.) in response to aversive stimulation. Sci Rep 2018; 8:16277. [PMID: 30389979 PMCID: PMC6214997 DOI: 10.1038/s41598-018-34460-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/20/2018] [Indexed: 01/13/2023] Open
Abstract
In Drosophila melanogaster, aversive (electric shock) stimuli have been shown to activate subpopulations of dopaminergic neurons with terminals in the mushroom bodies (MBs) of the brain. While there is compelling evidence that dopamine (DA)-induced synaptic plasticity underpins the formation of aversive memories in insects, the mechanisms involved have yet to be fully resolved. Here we take advantage of the accessibility of MBs in the brain of the honey bee to examine, using fast scan cyclic voltammetry, the kinetics of DA release and reuptake in vivo in response to electric shock, and to investigate factors that modulate the release of this amine. DA increased transiently in the MBs in response to electric shock stimuli. The magnitude of release varied depending on stimulus duration and intensity, and a strong correlation was identified between DA release and the intensity of behavioural responses to shock. With repeated stimulation, peak DA levels increased. However, the amount of DA released on the first stimulation pulse typically exceeded that evoked by subsequent pulses. No signal was detected in response to odour alone. Interestingly, however, if odour presentation was paired with electric shock, DA release was enhanced. These results set the stage for analysing the mechanisms that modulate DA release in the MBs of the bee.
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12
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Abstract
Understanding how activity patterns in specific neural circuits coordinate an animal’s behavior remains a key area of neuroscience research. Genetic tools and a brain of tractable complexity make Drosophila a premier model organism for these studies. Here, we review the wealth of reagents available to map and manipulate neuronal activity with light.
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13
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Shin M, Venton BJ. Electrochemical Measurements of Acetylcholine-Stimulated Dopamine Release in Adult Drosophila melanogaster Brains. Anal Chem 2018; 90:10318-10325. [PMID: 30073836 PMCID: PMC6135655 DOI: 10.1021/acs.analchem.8b02114] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The fruit fly, Drosophila melanogaster, is a popular model organism for studying neurological processes and diseases due to the availability of sophisticated genetic tools. While endogenous neurotransmitter release has been characterized in Drosophila larvae, here, we measured endogenous dopamine release in isolated adult Drosophila brains for the first time. Dopamine was measured with fast-scan cyclic voltammetry (FSCV), and acetylcholine or nicotine were used as the stimulus, as both interact with nicotinic acetylcholine receptors (nAChRs) to evoke endogenous dopamine release. Stimulations with 10 pmol of acetylcholine elicited 0.26 ± 0.05 μM dopamine, while 70 fmol nicotine stimulations evoked 0.29 ± 0.03 μM in the central complex. Nicotine-stimulated dopamine release lasted much longer than acetylcholine-stimulated release. Dopamine release is reduced in the presence of nAChR antagonist α-bungarotoxin and the sodium channel blocker tetrodotoxin, indicating release is mediated by nAChRs and exocytosis. The identity of dopamine was confirmed by using 3-iodotyrosine, a dopamine synthesis inhibitor, and by confirming that release was not changed in octopamine synthesis mutant flies, Tdc2 RO54. Additionally, the half-decay time ( t50) in fumin (67 ± 15 s), dopamine transporter mutant flies, was larger than in wild-type flies (16 ± 3.7 s) further proving that acetylcholine stimulation evokes dopamine release. This study demonstrates that stimulation of nAChRs can be used to elicit endogenous dopamine release in adult fly brains, which will be a useful technique for future studies probing dopamine changes during aging or in neurodegenerative diseases.
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Affiliation(s)
- Mimi Shin
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
| | - B. Jill Venton
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901
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14
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Shin M, Copeland JM, Venton BJ. Drosophila as a Model System for Neurotransmitter Measurements. ACS Chem Neurosci 2018; 9:1872-1883. [PMID: 29411967 DOI: 10.1021/acschemneuro.7b00456] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Drosophila melanogaster, the fruit fly, is an important, simple model organism for studying the effects of genetic mutations on neuronal activity and behavior. Biologists use Drosophila for neuroscience studies because of its genetic tractability, complex behaviors, well-known and simple neuroanatomy, and many orthologues to human genes. Neurochemical measurements in Drosophila are challenging due to the small size of the central nervous system. Recently, methods have been developed to measure real-time neurotransmitter release and clearance in both larvae and adults using electrochemistry. These studies have characterized dopamine, serotonin, and octopamine release in both wild type and genetic mutant flies. Tissue content measurements are also important, and separations are predominantly used. Capillary electrophoresis, with either electrochemical, laser-induced fluorescence, or mass spectrometry detection, facilitates tissue content measurements from single, isolated Drosophila brains or small samples of hemolymph. Neurochemical studies in Drosophila have revealed that flies have functioning transporters and autoreceptors, that their metabolism is different than in mammals, and that flies have regional, life stage, and sex differences in neurotransmission. Future studies will develop smaller electrodes, expand optical imaging techniques, explore physiological stimulations, and use advanced genetics to target single neuron release or study neurochemical changes in models of human diseases.
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Affiliation(s)
- Mimi Shin
- Department of Chemistry and Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22901, United States
| | - Jeffrey M. Copeland
- Department of Chemistry and Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22901, United States
- Department of Biology, Eastern Mennonite University, Harrisonburg, Virginia 22802, United States
| | - B. Jill Venton
- Department of Chemistry and Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22901, United States
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Majdi S, Larsson A, Hoang Philipsen M, Ewing AG. Electrochemistry in and of the Fly Brain. ELECTROANAL 2018. [DOI: 10.1002/elan.201700790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Soodabeh Majdi
- Department of Chemistry and Molecular Biology; University of Gothenburg; Kemivägen 10 41296 Gothenburg Sweden
| | - Anna Larsson
- Department of Chemistry and Molecular Biology; University of Gothenburg; Kemivägen 10 41296 Gothenburg Sweden
| | - Mai Hoang Philipsen
- Department of Chemistry and Chemical Engineering; Chalmers University of Technology; Kemivägen 10 41296 Gothenburg Sweden
| | - Andrew G. Ewing
- Department of Chemistry and Molecular Biology; University of Gothenburg; Kemivägen 10 41296 Gothenburg Sweden
- Department of Chemistry and Chemical Engineering; Chalmers University of Technology; Kemivägen 10 41296 Gothenburg Sweden
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Pyakurel P, Shin M, Venton BJ. Nicotinic acetylcholine receptor (nAChR) mediated dopamine release in larval Drosophila melanogaster. Neurochem Int 2018; 114:33-41. [PMID: 29305920 DOI: 10.1016/j.neuint.2017.12.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/04/2017] [Accepted: 12/29/2017] [Indexed: 01/13/2023]
Abstract
Acetylcholine is an excitatory neurotransmitter in the central nervous system of insects and the nicotinic acetylcholine receptor (nAChR) is a target for neonicotinoid insecticides. Functional insect nAChRs are difficult to express in host cells, and hence difficult to study. In mammals, acetylcholine and nicotine evoke dopamine release, but the extent to which this mechanism is conserved in insects is unknown. In intact larval ventral nerve cords (VNCs), we studied dopamine evoked by acetylcholine, nicotine, or neonicotinoids. Using fast-scan cyclic voltammetry, we confirmed dopamine was measured by its cyclic voltammogram and also by feeding Drosophila the synthesis inhibitor, 3-iodotyrosine, which lowered the evoked dopamine response. Acetylcholine (1.8 pmol) evoked on average 0.43 ± 0.04 μM dopamine. Dopamine release significantly decreased after incubation with α-bungarotoxin, demonstrating the release is mediated by nAChR, but atropine, a muscarinic AChR antagonist, had no effect. Nicotine (t1/2 = 71 s) and the neonicotinoids nitenpyram and imidacloprid (t1/2 = 86 s, 121 s respectively) also evoked dopamine release, which lasted longer than acetylcholine-stimulated release (t1/2 = 19 s). Nicotine-stimulated dopamine was significantly lower in the presence of sodium channel blocker, tetrodotoxin, showing that the release is exocytotic. Drosophila that have mutations in the nAChR subunit α1 or β2 have significantly lower neonicotinoid-stimulated release but no changes in nicotine-stimulated release. This work demonstrates that nAChR agonists mediate dopamine release in Drosophila larval VNC and that mutations in nAChR subunits affect how insecticides stimulate dopamine release.
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Affiliation(s)
- Poojan Pyakurel
- Department of Chemistry, University of Virginia, United States
| | - Mimi Shin
- Department of Chemistry, University of Virginia, United States
| | - B Jill Venton
- Department of Chemistry, University of Virginia, United States.
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17
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Qi C, Varga S, Oh SJ, Lee CJ, Lee D. Optogenetic Rescue of Locomotor Dysfunction and Dopaminergic Degeneration Caused by Alpha-Synuclein and EKO Genes. Exp Neurobiol 2017; 26:97-103. [PMID: 28442946 PMCID: PMC5403912 DOI: 10.5607/en.2017.26.2.97] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/12/2017] [Accepted: 04/12/2017] [Indexed: 11/19/2022] Open
Abstract
α-Synuclein (α-Syn) is a small presynaptic protein and its mutant forms (e.g. A53T) are known to be directly associated with Parkinson's disease (PD). Pathophysiological mechanisms underlying α-Syn-mediated neurodegeneration in PD still remain to be explored. However, several studies strongly support that overexpression of mutant α-Syn causes reduced release of dopamine (DA) in the brain, and contributes to motor deficits in PD. Using a favorable genetic model Drosophila larva, we examined whether reduced DA release is enough to induce key PD symptoms (i.e. locomotion deficiency and DA neurodegeneration), mimicking a PD gene α-Syn. In order to reduce DA release, we expressed electrical knockout (EKO) gene in DA neurons, which is known to make neurons hypo-excitable. EKO led to a decrease in a DA neuronal marker signal (i.e., TH - tyrosine hydroxylase) and locomotion deficits in Drosophila larva. In contrast, acute and prolonged exposure to blue light (BL, 470 nm) was sufficient to activate channelrhodopsin 2 (ChR2) and rescue PD symptoms caused by both α-Syn and EKO. We believe this is for the first time to confirm that locomotion defects by a genetic PD factor such as α-Syn can be rescued by increasing DA neuronal excitability with an optogenetic approach. Our findings strongly support that PD is a failure of DA synaptic transmission, which can be rescued by optogenetic activation of ChR2.
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Affiliation(s)
- Cheng Qi
- Neuroscience Program, Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
| | - Scott Varga
- Neuroscience Program, Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
| | - Soo-Jin Oh
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.,Center for Neuroscience, Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - C Justin Lee
- Center for Neuroscience, Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Daewoo Lee
- Neuroscience Program, Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
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Pyakurel P, Privman Champaloux E, Venton BJ. Fast-Scan Cyclic Voltammetry (FSCV) Detection of Endogenous Octopamine in Drosophila melanogaster Ventral Nerve Cord. ACS Chem Neurosci 2016; 7:1112-9. [PMID: 27326831 DOI: 10.1021/acschemneuro.6b00070] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Octopamine is an endogenous biogenic amine neurotransmitter, neurohormone, and neuromodulator in invertebrates and has functional analogy with norepinephrine in vertebrates. Fast-scan cyclic voltammetry (FSCV) can detect rapid changes in neurotransmitters, but FSCV has not been optimized for octopamine detection in situ. The goal of this study was to characterize octopamine release in the ventral nerve cord of Drosophila larvae for the first time. A FSCV waveform was optimized so that the potential for octopamine oxidation would not be near the switching potential where interferences can occur. Endogenous octopamine release was stimulated by genetically inserting either the ATP sensitive channel, P2X2, or the red-light sensitive channelrhodopsin, CsChrimson, into cells expressing tyrosine decarboxylase (TDC), an octopamine synthesis enzyme. To ensure that release is due to octopamine and not the precursor tyramine, the octopamine synthesis inhibitor disulfiram was applied, and the signal decreased by 80%. Stimulated release was vesicular, and a 2 s continuous light stimulation of CsChrimson evoked 0.22 ± 0.03 μM of octopamine release in the larval ventral nerve cord. Repeated stimulations were stable with 2 or 5 min interstimulation times. With pulsed stimulations, the release was dependent on the frequency of applied light pulse. An octopamine transporter has not been identified, and blockers of the dopamine transporter and serotonin transporter had no significant effect on the clearance time of octopamine, suggesting that they do not take up octopamine. This study shows that octopamine can be monitored in Drosophila, facilitating future studies of how octopamine release functions in the insect brain.
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Affiliation(s)
- Poojan Pyakurel
- Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, Virginia 22904, United States
| | - Eve Privman Champaloux
- Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, Virginia 22904, United States
| | - B. Jill Venton
- Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, Virginia 22904, United States
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