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Publication
High Dietary Fat Consumption Impairs Axonal Mitochondrial Function In Vivo.
Authors Sajic M, Rumora AE, Kanhai AA, Dentoni G, Varatharajah S, Casey C, Brown RDR,
Peters F, Hinder LM, Savelieff MG, Feldman EL, Smith KJ
Submitted By Submitted Externally on 12/3/2021
Status Published
Journal The Journal of neuroscience : the official journal of the Society for Neuroscience
Year 2021
Date Published 5/1/2021
Volume : Pages 41 : 4321 - 4334
PubMed Reference 33785643
Abstract Peripheral neuropathy (PN) is the most common complication of prediabetes and
diabetes. PN causes severe morbidity for Type 2 diabetes (T2D) and prediabetes
patients, including limb pain followed by numbness resulting from peripheral
nerve damage. PN in T2D and prediabetes is associated with dyslipidemia and
elevated circulating lipids; however, the molecular mechanisms underlying PN
development in prediabetes and T2D are unknown. Peripheral nerve sensory neurons
rely on axonal mitochondria to provide energy for nerve impulse conduction under
homeostatic conditions. Models of dyslipidemia in vitro demonstrate
mitochondrial dysfunction in sensory neurons exposed to elevated levels of
exogenous fatty acids. Herein, we evaluated the effect of dyslipidemia on
mitochondrial function and dynamics in sensory axons of the saphenous nerve of a
male high-fat diet (HFD)-fed murine model of prediabetes to identify
mitochondrial alterations that correlate with PN pathogenesis in vivo We found
that the HFD decreased mitochondrial membrane potential (MMP) in axonal
mitochondria and reduced the ability of sensory neurons to conduct at
physiological frequencies. Unlike mitochondria in control axons, which
dissipated their MMP in response to increased impulse frequency (from 1 to 50
Hz), HFD mitochondria dissipated less MMP in response to axonal energy demand,
suggesting a lack of reserve capacity. The HFD also decreased sensory axonal
Ca2+ levels and increased mitochondrial lengthening and expression of PGC1a, a
master regulator of mitochondrial biogenesis. Together, these results suggest
that mitochondrial dysfunction underlies an imbalance of axonal energy and Ca2+
levels and impairs impulse conduction within the saphenous nerve in prediabetic
PN.SIGNIFICANCE STATEMENT Diabetes and prediabetes are leading causes of
peripheral neuropathy (PN) worldwide. PN has no cure, but development in
diabetes and prediabetes is associated with dyslipidemia, including elevated
levels of saturated fatty acids. Saturated fatty acids impair mitochondrial
dynamics and function in cultured neurons, indicating a role for mitochondrial
dysfunction in PN progression; however, the effect of elevated circulating fatty
acids on the peripheral nervous system in vivo is unknown. In this study, we
identify early pathogenic events in sensory nerve axons of mice with high-fat
diet-induced PN, including alterations in mitochondrial function, axonal
conduction, and intra-axonal calcium, that provide important insight into
potential PN mechanisms associated with prediabetes and dyslipidemia in vivo.




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