Fast-Scan Cyclic Voltammetry (FSCV) Detection of Endogenous Octopamine in Drosophila melanogaster Ventral Nerve Cord.
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.
Department of Chemistry, University of Virginia , PO Box 400319, Charlottesville, Virginia 22904, United States.
Poojan
P
Pyakurel
Department of Chemistry, University of Virginia , PO Box 400319, Charlottesville, Virginia 22904, United States.
Eve
E
Privman Champaloux
Department of Chemistry, University of Virginia , PO Box 400319, Charlottesville, Virginia 22904, United States.
B Jill
BJ
Venton
D065086:Acetaldehyde Dehydrogenase Inhibitors / Q000494:pharmacology; D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D002490:Central Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004221:Disulfiram / Q000494:pharmacology; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D055664:Electrochemical Techniques; D005473:Fluoxetine / Q000031:analogs & derivatives / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D008027:Light; D009474:Neurons / Q000378:metabolism; D009655:Octopamine / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2 / Q000235:genetics / Q000378:metabolism; D012110:Reserpine / Q000494:pharmacology; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000378:metabolism
D065086:Acetaldehyde Dehydrogenase Inhibitors; D018759:Adrenergic Uptake Inhibitors; D050483:Dopamine Plasma Membrane Transport Proteins; D029721:Drosophila Proteins; C557617:GAL4 protein, Drosophila; D058476:Receptors, Purinergic P2X2; D014157:Transcription Factors; D005473:Fluoxetine; D009655:Octopamine; C011386:nisoxetine; D012110:Reserpine; D012243:Rhodopsin; D014445:Tyrosine Decarboxylase; D004221:Disulfiram
Drosophila melanogaster; electrochemistry; neuroscience; octopamine; optogenetics; voltammetry