Isoflavone Attenuates the Nuclear Transcription Factor Kappa B (NF-<i>κ</i>B) Activation on MPP⁺-Induced Apoptosis of PC12 Cells

Abstract

Objective: To explore the underlying molecular mechanisms of cellular response to the challenge by 1-methyl-4-phenylpyridinium (MPP ⁺ )-induced apoptosis of PC12 cells, an in vitro cell model for Parkinson’s disease, and the effect of NF- κ B activation on the protection of Parkinson’s disease by Isoflavone (I). Methods: PC12 cells were used to establish the cell model of Parkinson’s disease, and are divided into five groups: control group; MPP ⁺ group; I (Isoflavone) + MPP ⁺ group; I group; SN-50 + MPP ⁺ group. The content of NF- κ B in PC12 cells was determined by immunocytochemistry; The viability of PC12 cells after treated with cell-permeable NF- κ B inhibitor SN-50 and cell viability were measured by MTT assay; the expression levels of NF- κ B p65 in cytoplasm and nuclear fractions were evaluated by western blot analysis; the mRNA expression of NF- κ B p65 was analyzed by in situ hybridization (ISH). Results: Compared with the control group, the protein of NF- κ B p65 both in cytoplasm and in nuclei was significantly higher than in I + MPP ⁺ and MPP ⁺ groups; similarly, the mRNA expression level of NF- κ B p65 gene was also significantly higher; moreover, the protein expression of NF- κ B p65 was much lower in I group ( P < 0.05). In addition, compared with the MPP ⁺ group, the protein of NF- κ B p65 was significantly lower in I + MPP ⁺ group, the mRNA expression level of NF- κ B p65 gene was also significantly lower, and the protein expression level of NF- κ B p65 was much lower in I + MPP ⁺ group ( P < 0.05); however, there was no significant difference between control group and I + MPP ⁺ group ( P > 0.05). Conclusion: NF- κ B activation is essential to MPP ⁺ -induced apoptosis in PC12 cells; but Isoflavone can inhibit the cell damage to some extent to execute its protective function, which may be involved in nigral neurodegeneration in patients with Parkinson’s disease.