[Synaptic utilization of lactate/pyruvate and neural function in the aging].
Neuronal cells usually utilize glucose as a principal metabolic fuel and monocarboxylates including lactate and pyruvate are alternative energetic substrates in the central nervous system. In the present study, we investigated the synaptic utilization of lactate/pyruvate in the hippocampal slices from adult and aged guinea pig brains. Synaptic activity was estimated in terms of the amplitude of field population spikes (PS) recorded in the granular cell layer of the hippocampal dentate gyrus. Replacement of extracellular glucose with lactate suppressed the synaptic activity, followed by spontaneous recovery of PS amplitudes in the slices from 3-4-weeks old guinea pigs. In the presence of chelerythrine, an inhibitor of protein kinase C (PKC), substitution of lactate for glucose did not maintain synaptic activity. In contrast, application of H-89 and lavendustin A. inhibitors of cAMP-dependent protein kinase and tyrosine kinase, respectively, did not influence the synaptic utilization of lactate. In the hippocampal dentate gyrus from 24-months old guinea pigs, extracellular lactate did not sustain the synaptic function. These results indicate that the PKC-dependent metabolic process is involved for the synaptic utilization of lactate in the adult brain, and that lactate metabolism in synapse is impaired in the aged brain.
Sakurai
Takashi
T
Department of Internal and Geriatric Medicine, Kobe University Graduate School of Medicine.
Yang
Bo
B
Yokono
Koichi
K
D000375:Aging / Q000502:physiology*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006168:Guinea Pigs; D006624:Hippocampus / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D009474:Neurons / Q000502:physiology; D019289:Pyruvic Acid / Q000378:metabolism*; D013569:Synapses / Q000502:physiology*
D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose