Optimized Sawhorse Waveform for the Measurement of Oxytocin Release in Zebrafish

Abstract

Oxytocin is a nonapeptide hormone involved in numerous physiological functions. Real-time electrochemical measurements of oxytocin in living tissue are challenging due to electrode fouling and the large potentials needed to oxidize the tyrosine residue. Here, we used fast-scan cyclic voltammetry at carbon-fiber microelectrodes and flow injection analysis to optimize a waveform for the measurement of oxytocin. This optimized waveform employed an accumulation potential of −0.6 V, multiple scan rates, and a 3 ms holding potential at a positive, oxidizing potential of +1.4 V before linearly scanning the potential back to −0.6 V (versus Ag/AgCl). We obtained a limit of quantitation of 0.34 ± 0.02 μM, and our electrodes did not foul upon multiple injections. Moreover, to demonstrate the utility of our method, we measured the release of oxytocin, evoked by light application and mechanical perturbation, in whole brains from genetically engineered adult zebrafish that express channelrhodopsin-2 selectively on oxytocinergic neurons. Collectively, this work expands the toolkit for the measurement of peptides in living tissue preparations.

In Vitro Biofouling Performance of Boron-Doped Diamond Microelectrodes for Serotonin Detection Using Fast-Scan Cyclic Voltammetry

“…The effects of varying waveform parameters (Figure 2) largely followed previously reported literature for waveform optimization on a CFME [25,[44][45][46]. Elevated scan rates increased the oxidative current response linearly for the CFMEs, indicating adsorptioncontrolled processes at this electrode [25].…”

Impaired Dopamine Release and Latent Learning in Alzheimer’s Disease Model Zebrafish

“…The electrochemical measurement was carried out the same day as the behavioral probe trial. The procedure to harvest the zebrafish brain was described elsewhere. ,, Briefly, the examined fish was euthanized by a rapid cooling method, followed by decapitation. Immediately following euthanasia, the whole brain was harvested using previously described methods and transferred to a perfusion chamber.…”

Perspective—Advances in Voltammetric Methods for the Measurement of Biomolecules

“…15 When applied with MSW (multiple scan rates) on CFMEs, FSCV also provides information on real-time oxytocin effects on rat brain slices, exposing its impact on physiology and social behavior. 15,50 The Jackson (serotonin) N-shaped waveform was also shown to be optimal for the detection of serotonin with FSCV. 51 This waveform holds at a potential of +0.2 V to avoid serotonin fouling byproduct adsorption, and rapidly increases to 1.0 V at 1000 V s −1 to prevent fouling, and then scans down to −0.1 V during the reverse sweep to produce the cathodic peaks.…”