Physiological Fluctuations in Brain Temperature as a Factor Affecting Electrochemical Evaluations of Extracellular Glutamate and Glucose in Behavioral Experiments
ACS Chem. Neurosci.. 2013-03-14; 4(5): 652-665
DOI: 10.1021/cn300232m
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Comment in
Temperature (Austin). 2014 Apr-Jun;1(1):12-3.
The rate of any chemical reaction or process occurring in the brain depends on
temperature. While it is commonly believed that brain temperature is a stable,
tightly regulated homeostatic parameter, it fluctuates within 1-4 °C following
exposure to salient arousing stimuli and neuroactive drugs, and during different
behaviors. These temperature fluctuations should affect neural activity and
neural functions, but the extent of this influence on neurochemical measurements
in brain tissue of freely moving animals remains unclear. In this Review, we
present the results of amperometric evaluations of extracellular glutamate and
glucose in awake, behaving rats and discuss how naturally occurring fluctuations
in brain temperature affect these measurements. While this temperature
contribution appears to be insignificant for glucose because its extracellular
concentrations are large, it is a serious factor for electrochemical evaluations
of glutamate, which is present in brain tissue at much lower levels, showing
smaller phasic fluctuations. We further discuss experimental strategies for
controlling the nonspecific chemical and physical contributions to
electrochemical currents detected by enzyme-based biosensors to provide greater
selectivity and reliability of neurochemical measurements in behaving animals.