In response to hypoxic-ischemic brain damage (HIBD), microglia activation and its mediated
inflammation contribute to neuronal damage. Inhibition of over-activated microglia is deemed to be a potential therapeutic strategy. Our previous studies showed that
gastrodin efficiently depressed the
neuroinflammation mediated by activated microglia in HIBD neonatal rats. The underlying mechanisms through which
gastrodin acts on activated microglia have not been fully elucidated. This study is designed to determine whether
gastrodin would regulate the Notch signaling pathway and Sirtuin3 (
Sirt3), which are implicated in regulating microglia activation. The present results showed that
gastrodin markedly suppressed the expression of members of Notch signaling pathway (Notch-1, NICD, RBP-JK and Hes-1) in activated microglia both in vivo and in vitro. Conversely,
Sirt3 expression was enhanced. In BV-2 microglia treated with a γ-
secretase inhibitor of Notch pathway-
DAPT, the expression of RBP-JK, Hes-1, and NICD was suppressed in activated microglia. Treatment with
DAPT and
gastrodin further decreased NICD and Hes-1 expression.
Sirt3 expression was also decreased after
DAPT treatment. However,
Sirt3 expression in activated BV-2 microglia given a combined
DAPT and
gastrodin treatment was not further increased. In addition, combination of
DAPT and
Gastrodin cumulatively decreased
tumor necrosis factor-α (TNF-α) expression. The results suggest that
gastrodin regulates microglia activation via the Notch signaling pathway and
Sirt3. More importantly, interference of the Notch signaling pathway inhibited
Sirt3 expression, indicating that
Sirt3 is a downstream gene of the Notch signaling pathway. It is suggested that Notch and
Sirt3 synergistically regulate microglia activation such as in TNF-α production.