TY - JOUR

T1 - Stable isotope tracing reveals disturbed cellular energy and glutamate metabolism in hippocampal slices of aged male mice

AU - McNair, Laura Mikél

AU - Andersen, Jens Velde

AU - Waagepetersen, Helle Sønderby

N1 - Publisher Copyright: © 2023 The Authors

PY - 2023

Y1 - 2023

N2 - Neurons and astrocytes work in close metabolic collaboration, linking neurotransmission to brain energy and neurotransmitter metabolism. Dysregulated energy metabolism is a hallmark of the aging brain and may underlie the progressive age-dependent cognitive decline. However, astrocyte and neurotransmitter metabolism remains understudied in aging brain research. In particular, how aging affects metabolism of glutamate, being the primary excitatory neurotransmitter, is still poorly understood. Here we investigated critical aspects of cellular energy metabolism in the aging male mouse hippocampus using stable isotope tracing in vitro. Metabolism of [U–13C]glucose demonstrated an elevated glycolytic capacity of aged hippocampal slices, whereas oxidative [U–13C]glucose metabolism in the TCA cycle was significantly reduced with aging. In addition, metabolism of [1,2–13C]acetate, reflecting astrocyte energy metabolism, was likewise reduced in the hippocampal slices of old mice. In contrast, uptake and subsequent metabolism of [U–13C]glutamate was elevated, suggesting increased capacity for cellular glutamate handling with aging. Finally, metabolism of [15N]glutamate was maintained in the aged slices, demonstrating sustained glutamate nitrogen metabolism. Collectively, this study reveals fundamental alterations in cellular energy and neurotransmitter metabolism in the aging brain, which may contribute to age-related hippocampal deficits.

AB - Neurons and astrocytes work in close metabolic collaboration, linking neurotransmission to brain energy and neurotransmitter metabolism. Dysregulated energy metabolism is a hallmark of the aging brain and may underlie the progressive age-dependent cognitive decline. However, astrocyte and neurotransmitter metabolism remains understudied in aging brain research. In particular, how aging affects metabolism of glutamate, being the primary excitatory neurotransmitter, is still poorly understood. Here we investigated critical aspects of cellular energy metabolism in the aging male mouse hippocampus using stable isotope tracing in vitro. Metabolism of [U–13C]glucose demonstrated an elevated glycolytic capacity of aged hippocampal slices, whereas oxidative [U–13C]glucose metabolism in the TCA cycle was significantly reduced with aging. In addition, metabolism of [1,2–13C]acetate, reflecting astrocyte energy metabolism, was likewise reduced in the hippocampal slices of old mice. In contrast, uptake and subsequent metabolism of [U–13C]glutamate was elevated, suggesting increased capacity for cellular glutamate handling with aging. Finally, metabolism of [15N]glutamate was maintained in the aged slices, demonstrating sustained glutamate nitrogen metabolism. Collectively, this study reveals fundamental alterations in cellular energy and neurotransmitter metabolism in the aging brain, which may contribute to age-related hippocampal deficits.

KW - Astrocytes

KW - Glutamate uptake

KW - Glutamate-glutamine cycle

KW - Isotope tracing

U2 - 10.1016/j.neuint.2023.105626

DO - 10.1016/j.neuint.2023.105626

M3 - Journal article

C2 - 37838084

AN - SCOPUS:85174348073

VL - 171

JO - Neurochemistry International

JF - Neurochemistry International

SN - 0197-0186

M1 - 105626

ER -