Wednesday, January 15, 2025
1/15/2025
Summary Brain microvessels (BMVs) play an important role in the neurovascular coupling (NVC). Mitochondria are energy sensors of cells and impaired mitochondrial respiratory function initiate critical signaling detrimental to NVC leading to impaired cognitive function associated with Alzheimer's disease (AD). Our recent technological breakthrough utilizing Agilent Seahorse XFe extracellular flux analyzer developed a mitochondrial respiration assay in BMVs. Using this novel method, we observed age-dependent impairment of mitochondrial respiration and bioenergetics in BMVs from male and female C57Bl/6 mice. Notably, we found that BMVs from APP NL-G-F Knock-in model of AD display impaired mitochondrial respiration and accelerated senescence. Furthermore, we observed that young and aged female mice display sex-dependent differences in microvascular energetics related to the relative contribution of oxidative phosphorylation and glycolysis to overall energy production. Finally, we found that peroxynitrite scavenger (FeTMPyP) treatment enhanced non-mitochondrial respiration young female mice but enhanced proton leak in young male mice indicating that the differential peroxynitrite activity is sex-dependent. Therefore, we hypothesize that peroxynitrite differentially regulates microvascular mitochondrial function sex-dependently and is the molecular determinant of exaggerated age-related impairment of NVC and cognitive function in AD. We will employ male and female AD and C57Bl/6 mice of 8 months and 20 months age. Aim 1 will determine the sex dependent differential impact of peroxynitrite on the bioenergetics and enzyme activities (Krebs cycle, glycolysis, and antioxidants) in BMVs ex vivo. Aim 2 will determine the sex dependent differential impact of peroxynitrite on in vivo NVC responses to whisker deflections by two-photon excitation microscopy in awake mice. Aim 3 will determine the sex dependent differential impact of FeTMPyP on cognitive function by assessing whisker-dependent perceptual learning using the novel texture discrimination task. The results of this proposal would challenge the existing dogma and will demonstrate the sex-specific physiological role of peroxynitrite in regulating the microvascular bioenergetics and neurovascular unit. Furthermore, our results will firmly establish microvascular peroxynitrite as a potential therapeutic target in sex- dependent vulnerability and severity of AD and other neurodegenerative diseases.
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