Antagonizing Effects of Soybean Isoflavones on β-Amyloid Peptide-Induced Oxidative Damage in Neuron Mitochondria of Rats.

Soybean isoflavone ( SIF) has been demonstrated to have neuroprotective effects induced by β-amyloid peptides ( Aβ) through suppressing oxidative stress; however, the explicit mechanisms still remain uncovered. In the present study, 32 Wistar rats were randomly divided into four groups: an Aβ1-42-treated group, a SIF + Aβ1-42 group, a SIF-treated group and a control group. We measured the protein content of 8-hydroxydeoxyguanosine (8- Ohd G) and m RNA expression of 8-oxoguanine DNA glycosylase ( OGG1). The protein expression of OGG1, Bcl-xl, Bad, beta subunit of ATP synthase ( ATPB) and pyruvate dehydrogenase ( PDH) in brain was also measured. The results showed that the level of 8- OHd G in both SIF groups was significantly decreased compared to the Aβ1-42-treated group ( p < 0.05), while the m RNA and protein expression of OGG1 in the SIF + Aβ1-42 groups were up-regulated compared with the Aβ1-42-treated groups ( p < 0.05). The expression of Bcl-xl was up-regulated in the SIF-treated group compared with the Aβ1-42-treated groups ( p < 0.05), while the expression of Bad was down-regulated in the two SIF-treated groups ( p < 0.05). Aβ1-42 significantly down-regulated the expression of ATPase and PDH proteins compared with the control group ( p < 0.05). SIF reversed the down-regulation effects on the mitochondrial energy metabolic enzymes induced by Aβ1-42 ( p < 0.05) in the rats. These results suggest that SIF alleviate the oxidative stress in neurons and mitochondria of rat brains mediated by Aβ1-42, and these protective effects might be associated with the regulation of OGG1, Bad, Bcl-xl, ATPB and PDH. [ABSTRACT FROM AUTHOR]