BACKGROUND: It has been previously reported that soybean phosphatide could reduce the cerebral ischemia damage obviously. Whether soybean phospholipid liposome (SPL) can protect cerebral cortical neurons cultured in vitro from glutamate (Glu)-induced neurotoxicity, particularly nerve cell membrane damage has not been fully investigated.OBJECTIVE: To study the protective effects of SPL on Glu-induced neurotoxicity of neurons in culture,and to discuss the possible mechanisms of neuroprotection.DESIGN: Randomized controlled trial.SETTING: Department of Biochemistry, Liaoning Medical University.MATERIALS: Twelve Sprague-Dawley rats, of either gender, aged 0 to 1 day, were involved in this study.Drugs and reagents: poly-L-lysine and L-glutamate were purchased from Sigma company (USA).METHODS: The study was carried out in the Department of Biochemistry of Jinzhou Medical University from November 2004 to June 2005. Glu(1×10-4 mol/L) was added to cortical neurons in injury group for 3 hours, while different concentrations of SPL (0.2, 0.4, 0.8, 1.6 g/L) were added at the same time in the SPL groups. Neurons in the normal control group were untouched.MAIN OUTCOME MEASURES: According to the instruction of reagent kit, lactate dehydrogenase(LDH) activity and nitric oxide(NO) content in the supematant fluid of the culture medium were assayed, and the activity of nitric oxide synthase (NOS) and superoxide dismutase(SOD),malonaldehyde (MDA) content in the neurocytes were also determined.RESULTS: ①Activities of LDH and NOS, as well as NO content in the supernatant fluid of injury group were significantly higher than those of normal control group (P ＜ 0.01). Activities of LDH and NOS, and NO content in the supematant fluid of SPL groups were significantly lower than those of injury group (P ＜ 0.01).②MDA content of the SPL groups was significantly lower than that of injury group (P ＜ 0.01); SOD activity of neurons in the injury group was significantly lower than that in the normal control group (P＜0.01), but was significantly higher than that in the injury group (P ＜ 0.01). ③ The protective effect of SPL increased with increasing concentration (0.2 - 0.8 g/L), and plateaus at around 1.6 g/L.CONCLUSION: SPL can protect rat cerebral cortical neurons from Glu-induced neurotoxicity in a dose-dependent manner. This protection is possibly related to SPLs effect against damages associated with lipid peroxidation.