Abstract
Dopamine is a crucial neurotransmitter important for several behavioral, pharmacological, and disease states. Cocaine, amphetamine, and other psychostimulants elicit their effects by increasing dopamine in the extracellular space, while Parkinson’s disease is caused by the lack of extracellular dopamine due to the death of dopaminergic neurons. Techniques such as fast scan cyclic voltammetry (FSCV) have been utilized to measure extracellular dopamine and other neurotransmitters through the application of a triangle waveform, which can oxidize and, subsequently, reduce neurotransmitters at the surface of the electrode, producing a cyclic voltammogram where peak oxidative current is proportional to concentration. Utilizing FSCV with carbon fiber microelectrodes (CFMEs) is useful because the carbon electrodes are biocompatible and have both high temporal and spatial resolution. This makes the electrode amenable for the detection of neurotransmitters on a fast subsecond timescale comparable to the fast, phasic firing of dopaminergic neurons.Preliminary studies have illustrated the utility of CFMEs with FSCV for neurochemical detection in zebrafish (Danio rerio). CFMEs were implanted into zebrafish brain preserved in oxygenated buffer ex vivo with a micromanipulator. The electrodes were also inserted into zebrafish retina for the measurement of neurotransmitter release. The release of neurotransmitters was stimulated by the application of potassium chloride (KCl), amphetamine and cocaine, or electrical stimulation. Significant differences in dopamine levels were observed between wildtype control animals and hyperglycemic (diabetic) zebrafish. Moreover, behavioral assays such locomotor measurement displayed cognitive defects in hyperglycemic animals in addition to the thinning of the retina, which correlated to significant increases in extracellular dopamine in comparison to wildtype animals. Further work includes the examination of raclopride to increase extracellular dopamine, selective serotonin reuptake inhibitors to monitor serotonin, and desipramine to measure norepinephrine dynamics. This study allows for the further investigation of the neurochemical and behavioral effects of hyperglycemia in zebrafish. Future work will extend to the analysis of other monoamines such as serotonin and other dopamine metabolites.Support or Funding InformationNIH STTR: 1R41NS113702‐01Raw for the detection of dopamine in zebrafish retina after potassium chloride stimulation.Figure 1
Published Version
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