Brain extracellular glucose assessed by voltammetry throughout the rat sleep-wake cycle.
In the present study, cortical extracellular levels of glucose were monitored for the first time throughout the sleep-wake states of the freely moving rat. For this purpose, polygraphic recordings (electroencephalogram of the fronto-occipital cortices and electromyogram of the neck muscles) were achieved in combination with differential normal pulse voltammetry (DNPV) using a specific glucose sensor. Data obtained reveal that the basal extracellular glucose concentration in the conscious rat is 0.59 +/- 0.3 m M while under chloral hydrate anaesthesia (0.4 g/kg, i.p.) it increases up to 180% of its basal concentration. Regarding the sleep-wake cycle, the existence of spontaneous significant variations in the mean glucose level during slow-wave sleep (SWS = +13%) and paradoxical sleep (PS = -11%) compared with the waking state (100%) is also reported. It is to be noticed that during long periods of active waking, glucose level tends towards a decrease that becomes significant after 15 min (active waking = -32%). On the contrary, during long episodes of slow-wave sleep, it tends towards an increase which becomes significant after 12 min (SWS = +28%). It is suggested that voltammetric techniques using enzymatic biosensors are useful tools allowing direct glucose measurements in the freely moving animal. On the whole, paradoxical sleep is pointed out as a state highly dependent on the availability of energy and slow-wave sleep as a period of energy saving.
Netchiporouk
L
L
INSERM Unit 480, Claude Bernard University, 8 avenue Rockefeller, F-69373 Lyon Cedex 08, France.
Shram
N
N
Salvert
D
D
Cespuglio
R
R
D000758:Anesthesia; D018686:Anesthetics, Intravenous; D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D015374:Biosensing Techniques; D001921:Brain / Q000098:blood supply / Q000166:cytology / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology; D002697:Chloral Hydrate; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*
D018686:Anesthetics, Intravenous; D002697:Chloral Hydrate; D006003:Glycogen; D005947:Glucose