Gastrodin Attenuates Lipopolysaccharide-Induced Inflammatory Response and Migration via the Notch-1 Signaling Pathway in Activated Microglia

Microglia-mediated neuroinflammation is known to play a pivotal role in the pathogenesis of different neurological diseases. Gastrodin, a phenolic glucoside, has been reported to exert anti-inflammatory effects in activated microglia challenged with lipopolysaccharide (LPS); however, the underlying mechanism has remained obscure. The present study aimed to ascertain if Gastrodin would regulate the Notch signaling pathway involved in microglia activation. We show here that LPS increased the expression of various members of the Notch-1 pathway, including intracellular Notch receptor domain (NICD), recombining binding protein suppressor of hairless (RBP-Jκ) and transcription factor hairy and enhancer of split-1 (Hes-1) in microglia in postnatal rat brain and in BV-2 microglia. Remarkably, Gastrodin was found to markedly attenuate the expression of the above various biomarkers both in vivo and in vitro. Moreover, increased phosphorylation level of ERK, JNK and P38 induced by LPS was attenuated with pretreatment of Notch-1 signaling inhibitor, N-[N-(3,5-difluorophenacetyl)-1-alany1-Sphenyglycinet-butylester (DAPT) as well as Gastrodin. Gastrodin mimicked the effects of DAPT by inhibiting the LPS-induced expression of IL-1β, IL-6, IL-23, TNF-α and NO. Moreover, lentivirus transfection mediated NICD overexpression inhibited the anti-inflammatory effects of Gastrodin. Furthermore, the activation of Notch-1 signaling promoted microglia migration and Gastrodin could inhibit the migration of activated BV-2 microglia by regulating the Notch-1 signaling pathway. In light of the above, our results indicate that Notch-1 signaling pathway is involved in the anti-inflammatory effects of Gastrodin against LPS-induced microglia activation. These findings provide a new biological target of Gastrodin for the treatment of neuroinflammatory disorders.