Energy metabolism in the rat cortex under thiopental anaesthesia measured In Vivo by13C MRS.
Barbiturates, commonly used as general anaesthetics, depress neuronal activity and thus cerebral metabolism. Moreover, they are likely to disrupt the metabolic support of astrocytes to neurons, as well as the uptake of nutrients from circulation. By employing13C magnetic resonance spectroscopy (MRS) in vivo at high magnetic field, we characterized neuronal and astrocytic pathways of energy metabolism in the rat cortex under thiopental anaesthesia. The neuronal tricarboxylic acid (TCA) cycle rate was 0.46 ± 0.02 µmol/g/min, and the rate of the glutamate-glutamine cycle was 0.09 ± 0.02 µmol/g/min. In astrocytes, the TCA cycle rate was 0.16 ± 0.02 µmol/g/min, accounting for a quarter of whole brain glucose oxidation, pyruvate carboxylase rate was 0.02 ± 0.01 µmol/g/min, and glutamine synthetase was 0.12 ± 0.01 µmol/g/min. Relative to previous experiments under light α-chloralose anaesthesia, thiopental reduced oxidative metabolism in neurons and even more so in astrocytes. Interestingly, total oxidative metabolism in the cortex under thiopental anaesthesia surpassed the rate of pyruvate production by glycolysis, indicating substantial utilisation of substrates other than glucose, likely plasma lactate. © 2017 Wiley Periodicals, Inc.
Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland.
Sarah
S
Sonnay
Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland.
João M N
0000-0001-5984-1574
JMN
Duarte
Centre d'Imagerie Biomédicale - Animal and Technology Core, Lausanne, Switzerland.
Nathalie
N
Just
Laboratory for Functional and Metabolic Imaging, École Polytechnique Fédérale Lausanne, Switzerland.|Department of Radiology, University of Geneva, Switzerland.|Department of Radiology, University of Lausanne, Switzerland.
Rolf
R
Gruetter
D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013874:Thiopental / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D013874:Thiopental
MRS; glucose; metabolism; neuron-glia interaction; thiopental; α-chloralose