Protection by genistein on cortical neurons against oxidative stress injury via inhibition of NF-kappaB, JNK and ERK signaling pathway

Abstract

Context: Genistein, one of the isoflavones derived from soybean seeds, has been reported to exert multiple bioactivities. However, the mechanism of its action on the central nervous system is not fully understood.Objective: To investigate the cytoprotection of genistein and its molecular mechanism against H2O2-induced cell death in primary rat cortical neurons.Materials and methods: Genistein (0.01, 0.1, and 1 μM) were added into the primary rat neurons 24 h before and co-cultured with 500 μM H2O2 for 1 h. Neuronal injury was assessed by MTT, lactate dehydrogenase (LDH) assay, and Hoechst33258 staining. Intracellular reactive oxygen species (ROS) generation induced by H2O2 was determined. Neuronal apoptosis was evaluated by Bcl-2/Bax ratio as well as by caspase-9 and caspase-3 activities. The protein levels and phosphorylation of NF-κB/p65, IκB, JNK, and ERK were detected by western blots.Results: Genistein pretreatment attenuated H2O2-mediated neuronal viability loss, nuclear condensation, and ROS generation in a concentration-dependent manner. Genistein exerted anti-apoptotic effects by reversing the apoptotic factors Bcl-2 and Bax ratio, along with the suppression of caspase-9 and caspase-3 activities. In addition, genistein down-regulated the expression of NF-κB/p65, and suppressed the phosphorylation of p65 and IκB. Genistein also inhibited H2O2-induced activation of the MAPK-signaling pathway including JNK and ERK.Discussion and conclusion: The results indicated that genistein effectively protects cortical neurons against oxidative stress at least partly via inactivation of NF-κB as well as MAPK-signaling pathways, and suggested the possibility of this antioxidant for the prevention and treatment of stroke.