Biochanin A Protects Against Lipopolysaccharide-Induced Damage of Dopaminergic Neurons Both In Vivo and In Vitro via Inhibition of Microglial Activation

Neuroinflammation has been reported to be involved in the pathogenesis of Parkinson's disease (PD). Inhibition of microglia-mediated neuroinflammation might be a potential strategy for PD treatment. Biochanin A, is an O-methylated isoflavone, classified as a kind of phytoestrogens due to its chemical structure that is similar to mammalian estrogens. It has been found to possess antifibrotic, antiapoptotic, and antioxidant effects. In the present study, we investigated the neuroprotective effects of biochanin A on lipopolysaccharide (LPS)-induced dopaminergic neurons damage both in vivo and in vitro and the related molecular mechanisms. The results showed that biochanin A treatment for 21 days significantly attenuated the behavioral dysfunction of PD rats, prevented dopaminergic neurons damage, and inhibited activation of microglia in the LPS-induced PD rats. Furthermore, biochanin A decreased the levels of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in the serum, and inhibited the phosphorylation of ERK, JNK, p38 in the substantia nigra of PD rats. In vitro test, biochanin A also inhibited primary microglial activation and protected dopaminergic neurons, decreased the content of nitric oxide, IL-1 beta, and TNF-alpha in supernatants, and inhibited the reactive oxygen species production. Taken together, these results suggest that biochanin A exerts protective effects on LPS-induced PD rats, and the mechanisms may be associated with the inhibition of inflammatory response and the MAPK signaling pathway.