TY - JOUR
T1 - Compartmentalised energy metabolism supporting glutamatergic neurotransmission in response to increased activity in the rat cerebral cortex
T2 - A 13C MRS study in vivo at 14.1 T
AU - Sonnay, Sarah
AU - Duarte, João Mn
AU - Just, Nathalie
AU - Gruetter, Rolf
N1 - © The Author(s) 2016.
PY - 2016/5
Y1 - 2016/5
N2 - Many tissues exhibit metabolic compartmentation. In the brain, while there is no doubt on the importance of functional compartmentation between neurons and glial cells, there is still debate on the specific regulation of pathways of energy metabolism at different activity levels. Using (13)C magnetic resonance spectroscopy (MRS) in vivo, we determined fluxes of energy metabolism in the rat cortex under α-chloralose anaesthesia at rest and during electrical stimulation of the paws. Compared to resting metabolism, the stimulated rat cortex exhibited increased glutamate-glutamine cycle (+67 nmol/g/min, +95%, P < 0.001) and tricarboxylic (TCA) cycle rate in both neurons (+62 nmol/g/min, +12%, P < 0.001) and astrocytes (+68 nmol/g/min, +22%, P = 0.072). A minor, non-significant modification of the flux through pyruvate carboxylase was observed during stimulation (+5 nmol/g/min, +8%). Altogether, this increase in metabolism amounted to a 15% (67 nmol/g/min, P < 0.001) increase in CMRglc(ox), i.e. the oxidative fraction of the cerebral metabolic rate of glucose. In conclusion, stimulation of the glutamate-glutamine cycle under α-chloralose anaesthesia is associated to similar enhancement of neuronal and glial oxidative metabolism.
AB - Many tissues exhibit metabolic compartmentation. In the brain, while there is no doubt on the importance of functional compartmentation between neurons and glial cells, there is still debate on the specific regulation of pathways of energy metabolism at different activity levels. Using (13)C magnetic resonance spectroscopy (MRS) in vivo, we determined fluxes of energy metabolism in the rat cortex under α-chloralose anaesthesia at rest and during electrical stimulation of the paws. Compared to resting metabolism, the stimulated rat cortex exhibited increased glutamate-glutamine cycle (+67 nmol/g/min, +95%, P < 0.001) and tricarboxylic (TCA) cycle rate in both neurons (+62 nmol/g/min, +12%, P < 0.001) and astrocytes (+68 nmol/g/min, +22%, P = 0.072). A minor, non-significant modification of the flux through pyruvate carboxylase was observed during stimulation (+5 nmol/g/min, +8%). Altogether, this increase in metabolism amounted to a 15% (67 nmol/g/min, P < 0.001) increase in CMRglc(ox), i.e. the oxidative fraction of the cerebral metabolic rate of glucose. In conclusion, stimulation of the glutamate-glutamine cycle under α-chloralose anaesthesia is associated to similar enhancement of neuronal and glial oxidative metabolism.
KW - Animals
KW - Astrocytes
KW - Carbon Isotopes
KW - Cell Compartmentation
KW - Cerebral Cortex
KW - Electric Stimulation
KW - Energy Metabolism
KW - Glutamic Acid
KW - Magnetic Resonance Imaging
KW - Neuroglia
KW - Neurons
KW - Rats
KW - Synaptic Transmission
KW - Journal Article
U2 - 10.1177/0271678X16629482
DO - 10.1177/0271678X16629482
M3 - Article
C2 - 26823472
SN - 1559-7016
VL - 36
SP - 928
EP - 940
JO - Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
JF - Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
IS - 5
ER -