Rotating disk electrode voltammetric measurements of serotonin transporter kinetics in synaptosomes

Abstract

Altered serotonin (5-HT) signaling is implicated in several neuropsychiatric disorders, including depression, anxiety, obsessive-compulsive disorder, and autism. The 5-HT transporter (SERT) modulates 5-HT neurotransmission strength and duration. This is the first study using rotating disk electrode voltammetry (RDEV) to measure 5-HT clearance. SERT kinetics were measured in whole brain synaptosomes. Uptake kinetics of exogenous 5-HT were measured using glassy carbon electrodes rotated in 500 uL glass chambers containing synaptosomes from SERTknockout (−/−), heterozygous (+/−), or wild-type (+/+) mice. RDEV detected 5-HT concentrations of 5 nM and higher. Initial velocities were kinetically resolved with K m and V max values of 99 ± 35 standard error of regression (SER) nM and 181 ± 11 SER fmol / (s x mg protein), respectively in wild-type synaptosomes. The method enables control over drug and chemical concentrations, facilitating interpretation of results. Results are compared in detail to other techniques used to measure SERT kinetics, including tritium labeled assays, chronoamperometry, and fast scan cyclic voltammetry. RDEV exhibits decreased 5-HT detection limits, decreased vulnerability to 5-HT oxidation products that reduce electrode sensitivity, and also overcomes diffusion limitations via forced convection by providing a continuous, kinetically resolved signal. Finally, RDEV distinguishes functional differences between genotypes, notably, between wild-type and heterozygous mice, an experimental problem with other experimental approaches.

Use of Nano-Sensors of the Interferences between Pb((II) with Each of Mg(II), Zn(II), Mn(II), Ca(II), Co(II) and PO4-3 in Blood Medium: An Electrochemical Study

“…One of the diseases that afflict children is autism which is due to the exposure to pollution of lead element in the blood and its effect on the brain [20,21]. One of the main subjects in this field was the presence of lead ions in blood medium and its impact on the brain which causes autism by electrochemical study with cyclic voltammetric technique [22][23][24][25].…”

MWCNT-Chitosan-ZrO2 Nanocomposite Modified Sensor for Sensitive and Selective Electrochemical Determination of Serotonin

“…3) was also checked to examine their electrocatalytic properties. In comparison to bare GCE, better electrochemical response was observed for K 3 Fe(CN) 6 at modified electrodes. The maximum enhancement was seen in case of MCZ/GCE with decreasing over potential.…”

“…The electrochemical response of K 3 Fe(CN) 6 at bare and modified GCE (Fig. 3) was also checked to examine their electrocatalytic properties.…”

“…The separation of redox potential peaks E p was found to be 117 mV and the I pa /I pc was 1.02. The electro-active area of the MWCNT/GCE, MWCNT-CHIT/GCE, MCZ/GCE and bare GCE were obtained by the CV using 1 mM K 3 Fe(CN) 6 (1) For K 3 Fe(CN) 6 , n=1 and D= 7.6 X 10 -6 cm 2 /s. From slope of Ip (µA) vs ν 1/2 the area were determined to be 0.028 cm 2 for bare GCE, 0.051 cm 2 for MWCNT/GCE, 0.085 cm 2 for MWCNT-CHIT/GCE and 0.213 cm 2 for MCZ/GCE.…”

“…Fluctuations in the normal serotonin level are associated with a number of diseases. While low levels of 5-HT can cause depression, anxiety and migraines, high levels can result in toxicity and in extreme cases fatal effects such as serotonin syndrome, obsessive compulsive disorder, and autism [2][3][4][5][6].…”