Abstract: Objective To study the molecular mechanism of protective effects of soybean isoflavones (SI) on cerebral ischemia-reperfusion (I/R) injury in rats. Methods Rats were randomly divided into sham operation group (sham), ischemia-reperfusion group (I/R), soybean isoflavones (SI) intervention group(50, 100 and 200 mg/kg) . 2,3,5-triphenylte-trazolium chloride (TTC) staining method was used to detect the cerebral infarction volume. HE staining was used to detect the pathological changes of brain tissues. The activity of superoxide dismutase SOD and the contents of IL-6, TNF-α, cAMP were measured by ELISA. Western blot was used to detect the level of p-ERK1/2. Results The I/R group had obvious infarct foci compared with the sham group (p<0.05), but the cerebral infarct volume significantly decreased after SI intervention(100 and 200 mg/kg) (p<0.05), respectively. In model group, cell gap was widened and nucleus became pyknosis. After the intervention of SI group, the pathological changes of cells were improved. Compared with the sham group, the activity of SOD and the content of cAMP in I/R group were significantly reduced, but after SI intervention (100 and 200 mg/kg), the activity of SOD and the content of cAMP were increased ( p<0.05). Compared with the sham group, the content of IL-6 and TNF-α in I/R group increased, but they were decreased after intervented with SI (100 and 200 mg/kg) ( p<0.05). Compared with the sham group, the expression of p-ERK1/2 in the model group was increased, and the expression of p-ERK1/2 was decreased after SI intervention (100 and 200 mg/kg) (p< 0.01). Conclusion SI can effectively improve oxidative stress and inflammatory response induced by I/R in rats. It is suggested that the protective mechanism of SI on cerebral I/R in rats may be related to the antioxidant and inflammatory reaction of SI.

Key words: cerebral ischemia-reperfusion injury, soybean isoflavones, oxidative stress, inflammatory response