Hendricks 2013 Abstract MiP2013
|Hendricks E, Nathan BP, Menze MA (2013) Bioenergetics of permeabilized and intact nerve cell terminals from ApoE deficient and wild type mice. Mitochondr Physiol Network 18.08.|
Reductions in ATP production by oxidative phosphorylation and glycolysis have been observed in many neurological diseases including Alzheimer’s disease (AD) . One of the known risk factors for the development of AD is the inheritance of a specific genotype of a lipid transporting protein known as apolipoprotein E (ApoE). How ApoE contributes to the development of AD is poorly understood . The purpose of this study was to determine if the lack of ApoE leads to mitochondrial dysfunctions. Mitochondrial bioenergetics were investigated in mice that lack ApoE (ApoE KO) and in wild-type mice. Since AD develops with age, mitochondrial performance was studied in both old (12-22 months old) and young mice (4-6 months old).
We isolated nerve cell terminals (synaptosomes) from wild-type (C57BL/6J) and ApoE KO (Apoetn1Unc) mice using Percoll gradient centrifugation. Oxygen consumption of permeabilized and nonpermeabilized synaptosomes was measured using the Oroboros Oxygraph-2k at 37 °C. ROUTINE respiration of nonpermeabilized synaptosomes was significantly higher in young mice than in old mice (0.183 ± 0.02 vs. 0.136 ± 0.02 pmol O2 s-1 µg protein-1, n=6, P<0.001). Respiration increased after addition of FCCP to 0.90 ± 0.15 pmol O2 s-1 µg protein-1 in young mice which was significantly higher in comparison to old mice (0.65 ± 0.12 pmol O2 s-1 µg protein-1, n=6, P=0.008). In the presence of the F0F1-ATPase inhibitor, oligomycin, oxygen consumption significantly dropped to 0.09 ± 0.02 and 0.06 ± 0.01 pmol O2 s-1 µg protein-1 in old and young mice, respectively (n=6, P=0.002). However, oxygen flux did not differ significantly between the two genotypes (2-way ANOVA, P>0.05). Oxygen consumption of permeabilized synaptosomes from young wild-type mice in the presence of malate, glutamate, and pyruvate was 0.32 ± 0.03 pmol O2 s-1 µg protein-1 and increased to 2.50 ± 0.2 pmol O2 s-1 µg protein-1 in the presence of saturating levels of ADP. The addition of succinate increased oxygen flux by approximately 40% under these conditions and successive FCCP titrations induced an additional increase in oxygen flux of about 15%. Surprisingly, oxygen flux in permeabilized synaptosomes did not differ significantly among genotypes or age groups (2-way ANOVA, P>0.05, n=3). Our preliminary results suggest that ApoE deficiency does not impact mitochondrial function. Significantly reduced mitochondrial activity has been previously demonstrated in aged rodents . Interestingly, our study only revealed reductions in oxygen utilization of glycolytic poised synaptosomes from aged mice.
• Keywords: Synaptosome
Labels: MiParea: Respiration, Genetic knockout;overexpression Pathology: Aging;senescence, Alzheimer's, Neurodegenerative
Organism: Mouse Tissue;cell: Nervous system Preparation: Intact cells, Permeabilized cells, Isolated mitochondria
Regulation: Threshold;excess capacity, Uncoupler Coupling state: LEAK, ROUTINE, OXPHOS, ET Pathway: N, S, NS HRR: Oxygraph-2k
Eastern Illinois University, Dept Biological Sciences, Charleston, USA. - Email: [email protected]
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