Baicalein exerts anti-neuroinflammatory effects to protect against rotenone-induced brain injury in rats

Baicalein, a major bioactive flavone constituent isolated from Scutellaria baicalensis Georgi, has been shown to be neuroprotective in several Parkinson's disease (PD) animal models. Since neuroinflammation has been known to play a critical role in the pathogenesis of PD, potential explanation for the neuroprotective action of anti-PD compounds involves among others reduced inflammation. Our study investigated that one of the mechanisms of protection afforded by baicalein in rotenone-induced parkinsonian rats was associated with anti-inflammatory action and explored its underlying mechanism in vivo and in vitro. The results showed that baicalein treatment improved motor impairments, attenuated brain damage, suppressed the production of proinflammatory cyto-kines (tumor necrosis factor a (TNF-alpha), and interleukin 6 (IL-6)), modulated the astrocytes and microglia activation, and blocked the activation of nuclear factor-kappa B (NF-kappa B) and mitogen-activated protein kinase (MAPK) signals in rotenone-induced rats of PD. Furthermore, treatment of baicalein prominently suppressed the generation of nitric oxide (NO) and the expression of inducible NO synthase (iNOS) protein by blocking LPS-induced I kappa B alpha phosphorylation and NF-kappa B translocation, and downregulated the Toll-like receptor 4 (TLR4) which functions in the upstream of NF-kappa B signal in the activated BV2 microglia. In conclusion, our studies suggest that baicalein may be effective in the treatment of PD through anti-neuroinflammation.