Diosgenin Attenuates Lipopolysaccharide-Induced Parkinson's Disease by Inhibiting the TLR/NF-kappa B Pathway

Background: Parkinson's disease (PD) is a neurodegenerative disease characterized by loss of dopaminergic neurons in the substantia nigra. Diosgenin is a natural steroid saponin which was shown to play a beneficial role in Alzheimer's disease. Objective: This study sought to investigate the potential effect of diosgenin on a rat model of PD. Methods: Sprague Dawley rats were subjected to intra-striatal injection of lipopolysaccharide (LPS) and treated with diosgenin. Stepping, Whisker, and Cylinder tests were carried out to determine the motor function, and the expression of tyrosine hydroxylase was detected by immunohistochemistry. The levels of multiple proinflammatory cytokines, oxidative stress related factors and proteins involved in Toll-like receptor (TLR)/nuclear factor kappa B (NF-kappa B) pathway were measured. The synergistic effect of environment enrichment on diosgenin was also investigated. Results: Intra-striatal injection of LPS caused motor deficits in rats, induced inflammatory response and oxidative stress response, and activated the TLR/NF-kappa B pathway both in vivo and in vitro. Diosgenin could attenuate the LPS-induced alterations. Enriched environment enhanced the effect of diosgenin to ameliorate the LPS-induced motor deficits in rats and decreased the protein levels of TLR2, TLR4, and nuclear NF-kappa B in diosgenin treated PD rats. Conclusion: Diosgenin had a beneficial effect in LPS-induced rat PD models, by suppressing the TLR/NF-kappa B signaling pathway. Environmental enrichment could play a synergistic effect with diosgenin, by enhancing the inhibitory effect of diosgenin on the TLR/ NF-kappa B signaling pathway.