Fig. 3. Gliovascular structural plasticity remains intact at all levels of the vascular tree in aging.
In order to determine if gliovascular structural plasticity remained intact in aging, we ablated astrocytes in 12-month-old Aldh1l1-eGFP mice making contact with Alexa 633 hydrazide positive penetrating arterioles, capillaries, and venules. We further compared the extent of replacement in old versus young mice as well. In all images, asterisks indicate the ablated astrocyte(s) (shown in gray, blood vessels are in red), arrow heads indicate the eventual replacement astrocyte, and arrows demarcate replacement processes. Volumetric reconstruction showing astrocyte associations with a penetrating arteriole at dpa0 (left) and dpa6 (right), from a a dorsal perspective and b a dorsolateral perspective. Scale bar = 25 µm. n = 40 astrocytes across 6 mice. c and d Volumetric reconstruction showing astrocytes and their association with a capillary at dpa0 (left) and dpa6 (right) from c a dorsal view and d a dorsolateral view. Scale bar = 10 µm. n = 40 astrocytes over 4 mice. Volumetric reconstruction showing an ascending venule and astrocyte interactions with it at dpa0 (left) and dpa7 (right), from e a dorsal view and f a dorsolateral view. Scale bar = 20 µm. n = 40 astrocytes across 5 mice. g Average number of replacement astrocytes (the number of cells extending processes to vascular vacancies) in 4- versus 12-month old mice at arterioles, Two-tailed Mann–Whitney test, p = 0.9465, n = 40 cells examined over 7 mice for 4-month data, n = 40 cells examined over 6 mice for 12-month data. h Average number of replacement astrocytes in 4-versus 12-month old mice at capillaries, Two-tailed Mann–Whitney test, p = 0.6853, n = 40 cells examined over 4 mice for both 4- and 12-month old mice. i Average number of replacement astrocytes in 4-versus 12-month old mice at venules, Two-tailed Mann–Whitney test, p = 0.3060, n = 40 cells examined over 7 mice for 4-month old data, n = 40 cells examined over 5 mice for 12-month old data. Data are presented as mean values ± SEM. LUTs have been adjusted to emphasize the replacement astrocytes and associated processes.