Sex-dependent differences in bioenergetics of young mouse brain microvasculature: implications for oxygen-glucose deprivation and reoxygenation injury

Sex differences are evident in vascular mitochondrial function; however, the impact of sex on microvascular bioenergetics has never been studied. We investigated the bioenergetics of freshly isolated mouse brain microvessels (BMVs) from young mice (6-8 wk). Oxygen consumption rate and extracellular acidification rates of BMVs were measured using Agilent Seahorse XFe24 analyzer. The real-time ATP rate assay showed reduced total ATP production with contributions from both glycolysis and oxidative phosphorylation (OxPhos) in BMVs from females compared with males. The mitochondrial stress test revealed lower basal respiration and ATP production in BMVs of females versus males. The glycolytic rate assay indicated reduced basal glycolysis and proton efflux rate (PER) in females, with no sex differences in basal PER and post-2-DG acidification. Mito fuel flex test found no differences in fuel substrate utilization. Measurements using homogenates of BMVs confirmed lower ATP levels in females, with no sex differences in citrate synthase activity or key mitochondrial protein/mRNA levels. Ex vivo oxygen-glucose deprivation followed by reoxygenation (OGD/R) of mouse BMVs displayed significantly reduced mitochondrial respiratory function as well as glycolytic activity in females versus males. However, OGD/R paradoxically increased lactate dehydrogenase release, a marker of cellular injury, from male BMVs but has no effect on female BMVs. Thus, female BMVs exhibited decreased mitochondrial respiratory and glycolytic function compared with males, despite similar substrate utilization for energy production. In young mice, the sex-dependent differences in OxPhos and glycolysis may increase the vulnerability of the microvasculature to OGD/R injury in males and vasoprotection in females.<b>NEW & NOTEWORTHY</b> Impact of sex on microvascular bioenergetics has never been studied. We measured oxygen consumption rates and extracellular acidification rates in mouse brain microvessels using Agilent Seahorse XFe24 analyzer. For the first time, we observed decreased mitochondrial respiratory and glycolytic function in brain microvessels of female mice compared with male mice. These sex-dependent differences in glycolysis and oxidative phosphorylation may increase the vulnerability/protection of the microvasculature to vascular cell injury.