[Kaempferol attenuates 6-OHDA-induced inflammatory damage in PC12 cells via inhibting p38 MAPK signaling pathway]

Objective To investigate the protective effects of kaempferol (KAE) on PC12 cells against neurotoxin 6-hydroxydopamine (6-OHDA)-induced inflammatory damage and explore whether it is related to the inhibition of the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway. Methods After being cultured for 24 hours, PC12 cells were divided into 4 groups: control, 6-OHDA (100 μmol/L), 6-OHDA combined with (20, 40, 60, 80, 100) μmol/L KAE and KAE groups. The morphological features of PC12 cells were observed under an inverted microscope, and the cell viability was detected by CCK-8 assay. In the case of the optimal effective dose of KAE, the expression of cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), nuclear factors (NF)-κB were evaluated by immunocytochemical staining and Western blot analysis. To explore the mechanism underlying the protective role of KAE, KAE and SB203580 (p38 MAPK pathway inhibitor) (10 μmol/L) were separately added into 6-OHDA culture medium of PC12 cells. The protein levels of iNOS, COX2, NF-κB, p38 MAPK and p-p38 MAPK were tested by Western blotting. Results Compared with the control group, the number of cells in the 6-OHDA group was significantly reduced, with most cell bodies shrunk and aggregated into clumps. Compared with the 6-OHDA group, the number of cells increased and the morphology was effectively improved in the 6-OHDA combined with KAE (20, 40, 60, 80, and 100 μmol/L) group. KAE at 80 μmol/L was demonstrated the best protective effects in the present work. In the 6-OHDA group, the expression of COX2, iNOS, NF-κB significantly increased. Compared with the 6-OHDA group, the expression of the above molecules decreased markedly in the 6-OHDA combined with 80 μmol/L KAE group. The protein expression levels of COX2, iNOS, NF-κB, p38 MAPK and p-p38 MAPK went up significantly in the 6-OHDA group as compared with the control group, while they were down-regulated obviously by both KAE and SB203580. Conclusion KAE exerts neuroprotective effects on PC12 cells against the damage induced by 6-OHDA probably through the p38 MAPK signaling pathway.