Sirtuin 3 (
SIRT3) mediates cellular resistance toward various forms of stress.
SIRT3 expression in the developing brain, especially its localization in various glial cell types, has not been fully explored. This study aimed to determine
SIRT3 expression in the brain of neonatal rats subjected to
hypoxia. By immunohistochemistry, immunofluorescence and Western blotting, we show here that
SIRT3 expression in the periventricular white matter was up-regulated in
hypoxia group compared with the control group at the corresponding time points. Intense
SIRT3 expression was detected in microglia at early time points after
hypoxia whose cell number was increased with reduced ramifications in
hypoxia group compared with the control group. Furthermore,
SIRT3 immunoreactivity was obviously enhanced at 24 h, 3 and 7d, but was declined at 14d after
hypoxia so that
SIRT3 expression between the two groups was comparable.
SIRT3 immunofluorescence was also localized in astrocytes labeled with GFAP which was augmented at different time points in
hypoxia group. GPAP positive astrocytes exhibited long extending processes being most pronounced at 3d.
SIRT3 was moderately expressed at 24 h, 3 and 7d, but was markedly increased at 14d after
hypoxia. Moderate
SIRT3 expression was also localized in oligodendrocytes labeled with
CNPase in the control group. The incidence of
CNPase positive oligodendrocytes showing colocalization of
SIRT3 increased significantly at 24 h, 3 and 7d after
hypoxia. In conclusion,
SIRT3 expression was differentially up-regulated in all three major glial cell types following
hypoxia. It is suggested that increased
SIRT3 expression in the respective glial cell types following
hypoxia is involved in different signaling pathways that protect against hypoxic stress in the developing brain.