Age-related changes in rat brain capillaries

We have measured several morphological parameters by electron microscopy of frontal cortex (FC) and hippocampal CA1 (HC) capillaries in male Fischer 344 rat 3-, 9- and 24-months old. The results indicate that with increasing age there is an increase in the cross-sectional area of the basement membrane, increase in the friction of endothelial cell and pericyte cytoplasmic area occupied by mitochondria in the FC, increase in the size of the pericyte mitochondria in both the FC and HC, increased capillary lumen area in the FC and decreased capillary lumen area in the HC. Also, the cytoplasmic area occupied by mitochondria in capillary pericytes is larger than in the endothelial cells of both FC and HC. These results suggest that there is regional variation in the age-associated changes in capillary morphometrics.