title: Simultaneous NMR microdialysis study of brain glucose metabolism in relation to fasting or exercise in the rat.
abstract: To study the impact of exercise or fasting and of subsequent glucose supplementation on glucose metabolism in rats, a spectrophotometric method was used to determine peripheral blood glucose; a technique associating (1)H-NMR spectroscopy and cortical microdialysis was also used to observe intra- plus extracellular and extracellular brain glucose variations, respectively. Compared with control animals (204 +/- 19 microM in dialysate, n = 10), exercise increased brain extracellular glucose levels to 274 +/- 22 microM (n = 8; P < 0.05), whereas fasting induced a drop in glucose levels down to 140 +/- 9 microM (n = 8; P < 0.05). After fasting, glucose supplemented by infusion increased glycemia from 7.4 +/- 0.4 to 19.9 +/- 0.8 mM (n = 10; P < 0.001), as well as extracellular and extra- plus intracellular brain glucose to 263 +/- 20% (n = 8; P < 0.001) and 342 +/- 28% (n = 8; P < 0.001), respectively, over basal for that group. After exercise, a similar infusion increased glycemia from 7. 3 +/- 0.3 to 16.8 +/- 1.1 mM (n = 10; P < 0.001), as well as extracellular and extra- plus intracellular brain glucose to 178 +/- 19% (n = 8; P < 0.001) and 244 +/- 20% (n = 8; P < 0.001), respectively, over basal for that group. These results confirmed the existence of a link between glucose level variations in peripheral and cerebral areas but also showed that exercise increased extracellular brain glucose levels despite peripheral hypoglycemia, suggesting a specific regulation mechanism of cerebral glucose metabolism during exercise.
authors.affiliation: Department of Physiology, Institut de Médecine Aérospatiale du Service de Santé des Armées, 91223 Brétigny-sur-Orge, France. fbequet@club-internet.fr
authors.forename: F
authors.initials: F
authors.lastname: Béquet
authors.forename: M
authors.initials: M
authors.lastname: Pérès
authors.forename: D
authors.initials: D
authors.lastname: Gomez-Mérino
authors.forename: M
authors.initials: M
authors.lastname: Berthelot
authors.forename: P
authors.initials: P
authors.lastname: Satabin
authors.forename: C
authors.initials: C
authors.lastname: Piérard
authors.forename: C Y
authors.initials: CY
authors.lastname: Guezennec
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D005215:Fasting / Q000502:physiology*; D005508:Food Deprivation / Q000502:physiology; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D007003:Hypoglycemia / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D017551:Microdialysis; D008954:Models, Biological; D009043:Motor Activity / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D005947:Glucose