Fast-scan cyclic voltammetry with carbon-fiber microelectrodes: Applications in brain slices

Fast-scan cyclic voltammetry with carbon-fiber microelectrodes has been established as an effective tool to monitor in real time the changes in neurotransmitter concentration in living brain tissue. In this work, carbonfiber microelectrodes are utilized to monitor electrically evoked exocytotic release of dopamine and norepinephrine in mouse brain slices. The local environment of the carbon-fiber microelectrode affects the performance of the electrode and therefore the interpretation of the obtained results. The effects of environmental influences such as changes in the biological pH or the addition of pharmacological agents were examined in order to bring awareness and/or provide solutions to potential analytical challenges. It was found that treating the electrode surface before use in biological systems can serve to minimize the adverse effects of either endogenous or added species as well as provide greater selectivity between electroactive species. Norepinephrine neurotransmission and regulation in the bed nucleus of the stria terminalis (BNST) was found to differ from that of dopamine in the caudate putamen (CPu). Less norepinephrine is released into the extracellular fluid of the BNST per stimulation pulse, and its clearance from the extracellular space by uptake through transporters is much slower than that observed for dopamine in the CPu. This evidence suggests that the regulation of norepinephrine transmission may allow longer-range diffusion than is the case for DA in the CPu and that NE in the BNST has the potential to act at receptors distant from the site of release.