Electrochemical Quantification of Serotonin in the Live Embryonic Zebrafish Intestine

Abstract

We monitored real-time in vivo levels of serotonin release in the digestive system of intact zebrafish embryos during early development (5 dpf) using differential pulse voltammetry with implanted carbon fiber microelectrodes modified with carbon nanotubes dispersed in nafion. A detection limit of 1 nM, a linear range between 5 to 200 nM and a sensitivity of 83.65 nA·μM −1 were recorded. The microelectrodes were implanted at various locations in the intestine of zebrafish embryos. Serotonin levels of up to 29.9(±1.13) nM were measured in vivo in normal physiological conditions. Measurements were performed in intact live embryos without additional perturbation beyond electrode insertion. The sensor was able to quantify pharmacological alterations in serotonin release and provide the longitudinal distribution of this neurotransmitter along the intestine with high spatial resolution. In the presence of fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), concentrations of 54.1(±1.05) nM were recorded while in the presence of p-chloro-phenylalanine (PCPA), a tryptophan hydroxylase inhibitor, the serotonin levels decreased to 7.2(±0.45) nM. The variation of serotonin levels was correlated with immunohistochemical analysis. We have demonstrated the first use of electrochemical microsensors for in vivo monitoring of intestinal serotonin levels in intact zebrafish embryos.

Analytical Techniques in Neuroscience: Recent Advances in Imaging, Separation, and Electrochemical Methods

“…196 Voltammetric measurements of serotonin were made in vivo in the intestine of intact zebrafish embryos during early development. 197 Recently, FSCV recordings were performed in zebrafish brain for the first time. 198 Simultaneous releases of dopamine and histamine was measured after stimulation of the telencephalon in sagittal slices of the adult zebrafish.…”

Development of the Zebrafish Enteric Nervous System

“…In addition to being present in some ENS neurons, serotonin is produced by enterochromaffin cells in the gut epithelium and drugs that alter 5HT-4 and 5HT-3 serotonin receptors have become major therapeutic agents for a variety of intestinal tract malfunctions, including irritable bowel syndrome (IBS) (Gershon and Tack, 2007). A recent study using differential pulse voltammetry with implantable carbon-fiber microelectrodes to monitor changes in serotonin levels in the zebrafish intestine in vivo (Njagi et al, 2010) opens the door to studying serotonin actions in relation to location and numbers of particular receptors in specific intestinal regions of living animals. Finally, intestinal diseases, such as irritable bowel syndrome and inflammatory bowel disease alter gut motility and can also affect enteric neuron function (Furness, 2006; Lomax et al, 2005).…”

Alterations of intestinal serotonin following nanoparticle exposure in embryonic zebrafish

“…Our goal in this study is to assess physiological changes of 5HT within the intestine following NPs exposure. We use carbon fiber microelectrodes (CFME) and differential pulse voltammetry (DPV), which we have previously developed to detect real time physiological concentrations of 5HT in the live zebrafish intestine 30, 31 . CFMEs are commonly used in neuroscience research to analyze the physiological concentrations of neurotransmitters 30 .…”

“…We use carbon fiber microelectrodes (CFME) and differential pulse voltammetry (DPV), which we have previously developed to detect real time physiological concentrations of 5HT in the live zebrafish intestine 30, 31 . CFMEs are commonly used in neuroscience research to analyze the physiological concentrations of neurotransmitters 30 . The small electrode size provides real-time in vivo measurement capabilities with high spatial resolution allowing for detection of 5HT concentrations within different regions of the intestine.…”