Development of a Microelectrode Array System for Simultaneous Measurement of Field Potential and Glutamate Release in Brain Slices

Disorders of the central nervous system and complex side effects caused by abnormal neurotransmitter release have been widely reported. If neurotransmitter release and field potential (FP) could be simultaneously measured in real time, it would be possible to capture the relationship between changes in neurotransmitter release and alterations in electrical activity. In this study, we developed a novel microelectrode array (MEA) system capable of simultaneously measuring FP and electrochemical (EC) signals. Additionally, we developed an enzyme-modified carbon nanotube (CNT)-MEA capable of detecting glutamate, a major neurotransmitter, with high sensitivity in the range of several nM to several hundred nM. Using the developed enzyme-modified CNT-MEA and the simultaneous FP/EC measurement system, we successfully recorded extracellular potentials and glutamate release from hippocampal brain slices, detecting both an increase in oscillatory activity and temporal changes in glutamate release following caffeine administration. Furthermore, we also achieved the recording of dopamine release from brain slices using this system. We believe that the enzyme-modified CNT-MEA and the simultaneous FP/EC measurement system, which enable the real-time, simultaneous measurement of FP, glutamate release, and dopamine release, will contribute to a deeper understanding of brain circuit mechanisms, pathological brain conditions, and the evaluation of pharmacological compounds.