Simultaneous voltammetric detection of glucose and lactate fluctuations in rat striatum evoked by electrical stimulation
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RESEARCH PAPER
Simultaneous voltammetric detection of glucose and lactate fluctuations in rat striatum evoked by electrical stimulation of the midbrain Alexandra G. Forderhase 1 & Hannah C. Styers 1 & Christie A. Lee 1 & Leslie A. Sombers 1,2 Received: 17 January 2020 / Revised: 2 June 2020 / Accepted: 1 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Glucose and lactate provide energy for cellular function in the brain and serve as an important carbon source in the synthesis of a variety of biomolecules. Thus, there is a critical need to quantitatively monitor these molecules in situ on a time scale commensurate with neuronal function. In this work, carbon-fiber microbiosensors were coupled with fast-scan cyclic voltammetry to monitor glucose and lactate fluctuations at a discrete site within rat striatum upon electrical stimulation of the midbrain projection to the region. Systematic variation of stimulation parameters revealed the distinct dynamics by which glucose and lactate responded to the metabolic demand of synaptic function. Immediately upon stimulation, extracellular glucose and lactate availability rapidly increased. If stimulation was sufficiently intense, concentrations then immediately fell below baseline in response to incurred metabolic demand. The dynamics were dependent on stimulation frequency, such that more robust fluctuations were observed when the same number of pulses was delivered at a higher frequency. The rates at which glucose was supplied to, and depleted from, the local recording region were dependent on stimulation intensity, and glucose dynamics led those of lactate in response to the most substantial stimulations. Glucose fluctuated over a larger concentration range than lactate as stimulation duration increased, and glucose fell further from baseline concentrations. These real-time measurements provide an unprecedented direct comparison of glucose and lactate dynamics in response to metabolic demand elicited by neuronal activation. Keywords Fast-scan cyclic voltammetry . Biosensor . In vivo . Carbon-fiber microelectrode . Astrocyte-to-neuron lactate shuttle . Neuroenergetics
Introduction The brain consumes about 20% of the body’s total energy in order to sustain normal brain function, despite making up only ~ 2% of the overall mass [1, 2]. The majority of this energetic demand is attributed to neuronal activation and the exocytotic release of chemical neurotransmitters [1, 3, 4]. Dysregulation in
Published in the topical collection featuring Female Role Models in Analytical Chemistry. * Leslie A. Sombers [email protected] 1
Department of Chemistry, College of Sciences, North Carolina State University, Raleigh, NC 27695-8204, USA
2
Comparative Medicine Institute, North Carolina State University, Raleigh, NC 27695-8204, USA
brain metabolism has been linked to many neurodegenerative and dopamine-associated diseases, such as Parkinson’s and Alzheimer’s diseases, and even drug addiction and obesity [5–10]. In order to get a better sense of adapta
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