TY - JOUR
T1 - Brain energy metabolism and neurotransmission at near-freezing temperatures
T2 - In vivo 1H MRS study of a hibernating mammal
AU - Henry, Pierre-Gilles
AU - Russeth, Kevin P.
AU - Tkac, Ivan
AU - Drewes, Lester R
AU - Andrews, Matthew T.
AU - Gruetter, Rolf
PY - 2007/6
Y1 - 2007/6
N2 - The brain of a hibernating mammal withstands physiological extremes that would result in cerebral damage and death in a non-hibernating species such as humans. To examine the possibility that this neuroprotection results from alterations in cerebral metabolism, we used in vivo 1H NMR spectroscopy at high field (9.4 T) to measure the concentration of 18 metabolites (neurochemical profile) in the brain of 13-lined ground squirrels (Spermophilus tridecemlineatus) before, during, and after hibernation. Resolved in vivo1H NMR spectra were obtained even at low temperature in torpid hibernators (∼7°C). The phosphocreatine-to-creatine ratio was increased during torpor (+143%) indicating energy storage, and remained increased to a lesser extent during interbout arousal (IBA) (+83%). The total γ-aminobutyric acid concentration was increased during torpor (+135%) and quickly returned to baseline during IBA. Glutamine (Gln) was decreased (-54%) during torpor but quickly returned to normal levels during IBA and after terminal arousal in the spring. Glutamate (Glu) was also decreased during torpor (-17%), but remained decreased during IBA (-20% compared with fall), and returned to normal level in the spring. Our observation that Glu and Gln levels are depressed in the brain of hibernators suggests that the balance between anaplerosis and loss of Glu and Gln (because of glutamatergic neurotransmission or other mechanisms) is altered in hibernation.
AB - The brain of a hibernating mammal withstands physiological extremes that would result in cerebral damage and death in a non-hibernating species such as humans. To examine the possibility that this neuroprotection results from alterations in cerebral metabolism, we used in vivo 1H NMR spectroscopy at high field (9.4 T) to measure the concentration of 18 metabolites (neurochemical profile) in the brain of 13-lined ground squirrels (Spermophilus tridecemlineatus) before, during, and after hibernation. Resolved in vivo1H NMR spectra were obtained even at low temperature in torpid hibernators (∼7°C). The phosphocreatine-to-creatine ratio was increased during torpor (+143%) indicating energy storage, and remained increased to a lesser extent during interbout arousal (IBA) (+83%). The total γ-aminobutyric acid concentration was increased during torpor (+135%) and quickly returned to baseline during IBA. Glutamine (Gln) was decreased (-54%) during torpor but quickly returned to normal levels during IBA and after terminal arousal in the spring. Glutamate (Glu) was also decreased during torpor (-17%), but remained decreased during IBA (-20% compared with fall), and returned to normal level in the spring. Our observation that Glu and Gln levels are depressed in the brain of hibernators suggests that the balance between anaplerosis and loss of Glu and Gln (because of glutamatergic neurotransmission or other mechanisms) is altered in hibernation.
KW - Anaplerosis
KW - Brain
KW - Glutamate - glutamine cycle
KW - Ground squirrel
KW - Hibernation
KW - Magnetic resonance spectroscopy
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U2 - 10.1111/j.1471-4159.2007.04514.x
DO - 10.1111/j.1471-4159.2007.04514.x
M3 - Article
C2 - 17437538
AN - SCOPUS:34249798448
SN - 0022-3042
VL - 101
SP - 1505
EP - 1515
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
IS - 6
ER -