The Neuroprotective Effect Of Z-ligustilide Against Oxidative Stress Induced By D-galactose And Hydrogen Peroxide

Objective To observe the protection of Z-ligustilide against aging mice induced by D-galactose(D-gal) and explore the possible mechanisms from the point of oxidative stress.Methods The aging mice were induced by subcutaneous injection of D-gal (150 mg/kg) once daily for 8 weeks. At the same time, Z-ligustilide (Lig, 80mg/kg) and vitamin E (100mg/kg, positive control) were administered intragastrically once daily for 8 weeks. Morris water maze and Y-maze were used to test the space learning and memory impairment, meanwhile the content of malondialdehyde (MDA) and the activity of Na+-K+-ATPase in cortex were detected using commercially available kits. The expression of MAP-2, GAP-43, GFAP and Caspase-3 in the cortex and hippocampus were measured by immunefluorescent. Furthermore, the effects of pre-treatment of Lig on SH-SY5Y cell line against hydrogen peroxide-mediated oxidative stress were also investigated through the observation of apoptotic cell nuclei by fluorescence microscopy with dye Hoechst 33342. Cell viabilities were analyzed by use of MTT assays, and the expression of Bcl-2, Bax and Caspase-3 were measured by Western blot analysis.Results⑴The escape latency and swimming pathway in the Morris water maze increased and the correct reaction rate in Y-maze decreased after subcutaneous injection of D-gal for 8 weeks, which was improved by the treatment of Lig and Vit E, respectively.⑵The content of MDA increased and the activity of Na+-K+-ATPase decreased in cortex after exposure to D-gal for 8 weeks, which was reversed by the treatment of Lig and Vit E, respectively.⑶The expression of MAP-2, GAP-43 reduced and the expression of GFAP, Caspase-3 rised after received D-gal for 8 weeks, which was prevented by the treatment of Lig and Vit E, respectively.⑷After exposure to H₂O₂ (100?M) for 4h, SH-SY5Y acquired a cytotoxicity such as cell bodies began to shrink, cell viabilities descended in dose-dependent manner, fragmented and apoptotic nuclei obviously formated stained by Hoechst 33342, expression of Bcl-2 down-regulated, and expression of Bax, Caspase-3 up-regulated.⑸Pre-incubated with 8M Lig before H2O2 indury, cell viabilities increased, fragmented and apoptotic cells were seldomly found, the expression of Bcl-2 up-regulated and the expression of Bax, Caspase-3 down-regulated.Conclusions Lig markedly reversed the D-gal induced space learning and memory impairment, showing obvious improvements in cognition impairment. The neuroprotective effect of Lig against aging might be caused by the reduction of membrane lipid peroxidation, inhibition of apoptosis in neurons, depression of reactive hyperplasia of ascrocytes.