Rapid Changes in Local Extracellular Rat Brain Glucose Observed with an In Vivo Glucose Sensor

Abstract: A needle‐type electrochemically based microsensor for glucose (110 µm o.d.) is described. This sensor, designed for monitoring transient glucose content changes in response to neural stimuli, has a response time of ∼5 s and has been shown to be free of interference from endogenous electroactive species such as ascorbate, urate, and various neurotransmitters. It exhibits linear response to glucose up to 10 mM. The usefulness of the sensor has been demonstrated by examining the time‐dependent interstitial glucose concentration in the rat hippocampus in response to KCl depolarization and by stimulation of glutamate neurons through a perforant pathway. Simultaneous monitoring of oxygen is also carried out and demonstrates that for both oxygen and glucose there is substantial local depletion of both species and that their pools are replenished by increased regional cerebral blood flow. The transient initial rapid (10–13 s) decrease up to 20–34%, observed on a time scale comparable to that for neurotransmitter release, may be involved in a recently suggested astrocytic uptake for glutamate‐stimulated aerobic glycolysis possibly needed to meet energy homeostasis in brain. These studies demonstrate the importance of microsensors in monitoring transient events linked to neuronal stimulation.

[1]  G. S. Wilson,et al.  Modification of the sensitivity of glucose sensor implanted into subcutaneous tissue. , 1996, Diabetes & metabolism.

[2]  Lübbers Dw.  Microcirculation and oxygen supply of the brain. , 1974 .

[3]  A Santoro,et al.  On-line monitoring. , 1995, Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association.

[4]  H. Benveniste,et al.  Microdialysis—Theory and application , 1990, Progress in Neurobiology.

[5]  M. Mintun,et al.  Nonoxidative glucose consumption during focal physiologic neural activity. , 1988, Science.

[6]  J. Rawlins,et al.  Voltammetrically monitored brain ascorbate as an index of excitatory amino acid release in the unrestrained rat , 1984, Neuroscience Letters.

[7]  G. S. Wilson,et al.  Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor , 1994, Brain Research.

[8]  R. Forsyth.  Astrocytes and the delivery of glucose from plasma to neurons , 1996, Neurochemistry International.

[9]  Jonathan A. Stamford,et al.  In vivo voltammetry: Some methodological considerations , 1986, Journal of Neuroscience Methods.

[10]  I A Silver,et al.  Cellular microenvironment in relation to local blood flow. , 1978, Ciba Foundation symposium.

[11]  H Lund-Andersen,et al.  Transport of glucose from blood to brain. , 1979, Physiological reviews.

[12]  C Crone,et al.  Facilitated transfer of glucose from blood into brain tissue. , 1965, The Journal of physiology.

[13]  P. Magistretti,et al.  Glutamate uptake into astrocytes stimulates aerobic glycolysis: a mechanism coupling neuronal activity to glucose utilization. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[14]  L. Sokoloff,et al.  Relationships among local functional activity, energy metabolism, and blood flow in the central nervous system. , 1981, Federation proceedings.

[15]  B. Siesjö,et al.  Brain energy metabolism , 1978 .

[16]  M. Fillenz,et al.  An amperometric enzyme electrode for monitoring brain glucose in the freely moving rat , 1986, Neuroscience Letters.

[17]  R. Grünewald.  Ascorbic acid in the brain , 1993, Brain Research Reviews.