Presynaptic Regulation of Extracellular Dopamine as Studied by Continuous Amperometry in Anesthetized Animals

Excerpt

In the peripheral and central nervous systems, neurotransmission is achieved by the release of neurotransmitters from nerve terminals into the extracellular fluid bathing postsynaptic receptors. Therefore, locally monitoring neurotransmitters in the extracellular fluid is an important technical goal. Because neurotransmission in the brain is a rapid process, with the transfer of chemical messages between neurons occurring in milliseconds, monitoring techniques that provide high temporal resolution are especially significant. Dopamine (DA) is an important neurotransmitter in several structures of the central nervous system such as the striatum, which contains the highest density of dopaminergic terminals. Since the 1970s, two main approaches to monitoring DA in the extracellular fluid have been developed: in vivo microdialysis and various in vivo electrochemical techniques. Electrochemical techniques can be used to monitor DA because the DA molecule is easily oxidized at the surface of carbon electrodes. Among the electrochemical techniques, continuous amperometry provides the fastest available temporal response with a low selectivity for DA over other oxidizable molecules. This chapter explains how to take advantage of the high temporal resolution of continuous amperometry while simultaneously avoiding the potential pitfalls associated with its low selectivity.