Protective effect of hydroxysafflor yellow A on dopaminergic neurons against 6-hydroxydopamine, activating anti-apoptotic and anti-neuroinflammatory pathways

Context: Hydroxysafflor yellow A (HSYA) has been shown to have neuroprotective effects in cerebral infarction. However, its underlying roles in apoptosis and inflammation in Parkinson's disease (PD) are unknown.

Objective: The present study investigates the effects and underlying mechanisms of HSYA on dopaminergic (DA) neurodegeneration, inflammation, and apoptosis.

Materials and methods: The PD model was established by 2 μL of 6-hyroxydopamine (6-OHDA) (3 μg/μL) striatal injection in C57BL/6J mice with different doses of HSYA (2, 4, or 8 mg/kg). In vitro, after being treated with HSYA for 1 h, SH-SY5Y cells were exposed to 6-OHDA for 24 h before analysis. Expression of tyrosine hydroxylase (TH) in substantia nigra (SN) and corpus striatum (STR) was evaluated by immunohistochemistry (IHC) and western blot. In addition, apoptosis-related and inflammatory proteins were examined by western blot.

Results: Administration of HSYA significantly reduced the Apomorphine (APO)-induced rotation, decreased from 122.5 ± 15.1 (6-OHDA group) to 47.2 ± 14.3 (8 mg/kg HSYA group). HSYA partially restored a deficit in the SN and STR of PD mice brains in TH. Furthermore, western blot analysis revealed that HSYA reduced inflammatory proteins, including iNOS, COX-2 and NF-κB and attenuated the elevation of DA neuronal apoptosis observed in PD. In vitro assays showed that HSYA reduced the levels of p-p38 and p-JNK and increased that of p-ERK in 6-OHDA-leisoned SH-SY5Y cells.

Conclusions: These findings indicate that HSYA protects against 6-OHDA induced DA neurodegeneration partly by regulating the MAPK inflammatory signalling pathway and apoptosis which highlight its therapeutic potential in the treatment of PD.

Keywords: Parkinson’s disease; apoptosis; p38 MAPK pathway.