Polyphenols from Toona sinensiss Seeds Alleviate Neuroinflammation Induced by 6-Hydroxydopamine Through Suppressing p38 MAPK Signaling Pathway in a Rat Model of Parkinson's Disease

Polyphenols from Toona sinensis seeds (PTSS) have demonstrated anti-inflammatory effects in various diseases, while the anti-neuroinflammatory effects still remain to be investigated. We aimed to investigate the effects of PTSS on Parkinson's disease and underlying mechanisms using a rat model. We employed 6-hydroxydopamine (6-OHDA) to male Sprague Dawley (SD) rats and PC12 cells to construct the in vivo and vitro models of PD and dopaminergic (DA) neuron injury, respectively. Cell viability was detected by cell counting kit-8 (CCK-8) assay and protein levels of inflammatory mediators and some p38 MAPK pathway molecules were investigated by immunohistochemistry and Western blot analyses. The results showed that 6-OHDA significantly increased protein levels of inflammatory mediators, such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and tumor necrosis factor α (TNF-α), which could be reversed by PTSS through suppressing the p38 MAPK pathway. The anti-inflammatory effects of PTSS were significantly enhanced by the specific p38 inhibitor of SB203580 in vitro. The present work suggests that PTSS can exert anti-inflammatory effects on PD models, which may be attributed to the suppression of p38 MAPK signaling pathway.