Electrochemical Methods Optimization to Study the Function of Transient Adenosine Changes in Brain Slices

Adenosine is found throughout the brain and is an important signaling molecule. Fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes is an electrochemical technique which allows rapid detection of neurotransmitters in vivo, and has become increasingly popular for adenosine detection in the brain. Adenosine detection can be difficult because a few neurochemicals have similar electrochemical signatures as adenosine and it also requires a high oxidizing potential; so optimizing electrochemical methods for rapid detection of adenosine is beneficial. This thesis describes optimized methods for adenosine detection and uses FSCV to study adenosine signaling in the brain.
Adenosine is introduced in Chapter 1. This chapter goes into detail about adenosine signaling, function, and mechanisms of release. The chapter also reviews the latest literature on rapid adenosine detection in the brain and what is still unknown. FSCV is introduced and types of methods optimization are discussed. Chapters 2-4 go into detail about specific methods used for optimized adenosine detection. Chapter 2 focuses on comparing electrode modification techniques for dopamine, and Chapter 3 uses the Nafion-CNT modified electrodes, described in Chapter 2, for adenosine detection. In this chapter, Nafion-CNT modified electrodes show enhanced sensitivity and selectivity for adenosine over ATP both in vitro and in situ. Chapter 4 proposes a new waveform for adenosine detection which allows increased sensitivity for adenosine at lower switching potentials and enhanced analyte differentiation. Together, these new techniques provide tools in which optimal adenosine detection can be achieved, specifically when interferents are expected.
Chapters 5-6 describe the use of FSCV to study rapid changes in extracellular adenosine concentration in the brain. Chapter 5 explains a new method of evoking adenosine in the prefrontal cortex via mechanically stimulating the tissue using either the electrode or a pulled glass pipette. The mechanism of evoked adenosine is proven to be both activity-dependent and partially a downstream result of ATP metabolism. Chapter 6 studies the function of transient adenosine release. The Chapter demonstrates how transient adenosine release modulates stimulated dopamine release in the caudate putamen. This was the first characterized function of transient adenosine in the brain. Together, these findings provide new information on how adenosine can be stimulated and the function of these rapid changes in the brain.
Overall, this thesis optimizes methods for rapid adenosine detection in the brain and uses FSCV to characterize previously unknown adenosine phenomenon. New electrode and waveform modifications provide the field new methods for not only enhanced adenosine detection, but ideas for enhancing current tools for other analytes that are difficult to detect; while mechanically evoked adenosine, along with a function for transient adenosine release, provides the field new information of rapid adenosine signaling. The combination of new analytical tools for enhanced adenosine detection and the new methods to evoke and study adenosine in the brain will help piece together the intricate role of rapid adenosine release in the brain.