Using high-speed chronoamperometry to measure biogenic amine release and uptake in vivo

Here, we describe the method of high-speed chronoamperometry and its application for measuring release and clearance of biogenic amine neurotransmitters (serotonin, dopamine, and norepinephrine) in the intact and living mammalian brain. Chronoamperometry belongs to a family of electrochemical techniques collectively known as voltammetry, the only techniques currently available for “real-time” measurement of neurotransmitter transporter activity in vivo. Because of the small size of recording electrodes (<30 μm) and the relatively rapid sampling rate (sub-second), these techniques can be used to quantify release and clearance kinetics for biogenic amines in discrete brain regions. Chronoamperometry has been effectively used to study the impact of drugs, various environmental influences (e.g. stress), the estrous cycle, and age, among other stimuli, on the function of biogenic amine transporters in vivo. A major part of performing high-speed chronoamperometry is the preparatory work, including fabricating and calibrating carbon fiber electrodes, creating electrode-micropipette assemblies and stereotaxically implanting them in brain. Details for all steps are provided here, including how to histologically verify electrode placement at the conclusion of recordings. Chronoamperometry provides a unique window to “view” biogenic amine transporter function in the living animal.