Compromised microvascular oxygen delivery increases brain tissue vulnerability with age

• Published in: Scientific reports Vol. 8; no. 1; pp. 8219 - 17
• Main Authors: Moeini, Mohammad, Lu, Xuecong, Avti, Pramod K., Damseh, Rafat, Bélanger, Samuel, Picard, Frédéric, Boas, David, Kakkar, Ashok, Lesage, Frédéric
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.05.2018; Nature Publishing Group
• Subjects: 14/69; 631/1647/245/2226; 631/1647/328/2057; 631/378/2607; 631/378/2612; 631/443/7; 64/60; Age; Arterioles; Cognitive ability; Cortex (barrel); Geriatrics; Hematocrit; Heterogeneity; Humanities and Social Sciences; Hypoxia; Microvasculature; Middle age; multidisciplinary; Oxygen; Oxygenation; Science; Science (multidisciplinary); Somatosensory cortex; Tissues
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-26543-w

Despite the possible role of impaired cerebral tissue oxygenation in age-related cognition decline, much is still unknown about the changes in brain tissue pO 2 with age. Using a detailed investigation of the age-related changes in cerebral tissue oxygenation in the barrel cortex of healthy, awake aged mice, we demonstrate decreased arteriolar and tissue pO 2 with age. These changes are exacerbated after middle-age. We further uncovered evidence of the presence of hypoxic micro-pockets in the cortex of awake old mice. Our data suggests that from young to middle-age, a well-regulated capillary oxygen supply maintains the oxygen availability in cerebral tissue, despite decreased tissue pO 2 next to arterioles. After middle-age, due to decreased hematocrit, reduced capillary density and higher capillary transit time heterogeneity, the capillary network fails to compensate for larger decreases in arterial pO 2 . The substantial decrease in brain tissue pO 2 , and the presence of hypoxic micro-pockets after middle-age are of significant importance, as these factors may be related to cognitive decline in elderly people.