Maslinic acid promotes synaptogenesis and axon growth via Akt/GSK-3ß activation in cerebral ischemia model.

Maslinic acid, a natural pentacyclic triterpene from Olea europaea plants, possesses neuroprotective effects both in vivo and in vitro. However, the mechanism of its action is not well understood. In this study, we investigated the potential effects of maslinic acid on synaptogenesis and axonal regeneration, as well as the possible signal pathway involved in a cerebral ischemia mouse model. Adult male C57BL/6J mice were subjected to 1h of cerebral ischemia by middle cerebral artery occlusion (MCAO). Maslinic acid (0.1, 1 and 10mg/kg) was administered intragastrically 24h after MCAO once daily for 7 consecutive days. Axonal loss and synaptophysin expression in the ischemic boundary area was evaluated by histological assay. The Akt/GSK-3ß signal pathway was determined by western blot analysis. Two Akt inhibitors, LY294002 and MK2206, were used to verify the involvement of Akt/GSK-3ß pathway in maslinic acid-mediated neuroprotection. Maslinic acid significantly prevented axonal damage, promoted axonal regeneration and increased synaptophysin expression 7 days after ischemia. In addition, maslinic acid treatment was shown to enhance Akt activity and promote GSK-3ß phorsphorylation in stoke mice. The increased neurite outgrowth and synaptophysin expression by maslinic acid treatment was blocked by the Akt inhibitors both in vivo and in vitro.. These findings suggested that maslinic acid promotes synaptogenesis and axonal regeneration by regulating Akt/GSK-3ß signaling pathway, which may, in turn, provide neuroprotection.

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

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.

Neuroprotection by the soy isoflavone, genistein, via inhibition of mitochondria-dependent apoptosis pathways and reactive oxygen induced-NF-κB activation in a cerebral ischemia mouse model.

Recently, the treatment of stroke has focused on antioxidant therapies, where oxidative stress is implicated. The preventive and therapeutic potential of plant compounds on ischemic stroke has been intensively studied because many of them contain antioxidant properties. Genistein, one of the active ingredients in soybean, possesses many bioactivities. In this study, we investigated the potential neuroprotective effects of genistein and its possible mechanism of action in a cerebral ischemia mouse model. Mice were pretreated with genistein (2.5, 5, and 10mg/kg) or vehicle orally once daily for 14 consecutive days before transient middle cerebral artery occlusion was performed. Genistein at doses of 2.5-10mg/kg significantly reduced the infarct volume, improved the neurological deficit and prevented cell apoptosis after ischemia. In addition, genistein pretreatment was shown to inhibit the ischemia-induced reactive oxygen species (ROS) production, enhance the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), and decrease levels of malondialdehyde (MDA) in stroke mice. Moreover, genistein reversed the mitochondria dysfunction after ischemia, as evidenced by decreasing mitochondria ROS levels, preventing cytochrome C release to the cytoplasm and inhibiting caspase-3 activation. Western blotting showed ischemia activated the ROS-dependent nuclear factor-κB (NF-κB) signaling pathway, and genistein suppressed phosphorylation and activation of the NF-κB p65 subunit, as well as the phosphorylation and degradation of the inhibitor protein of κBα (IκBα). Our findings suggested that genistein has a neuroprotective effect in transient focal ischemia, which may involve regulation of mitochondria-dependent apoptosis pathways and suppression of ROS-induced NF-κB activation.