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BACKGROUND: Nerve growth factor (NGF) attenuates glutamate-induced injury to hippocampal neurons, and the human tumor suppressor gene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) promotes neuronal apoptosis. However, effects of PTEN in NGF-mediated neuroprotection against glutamate excitotoxicity remain poorly understood. OBJECTIVE: To investigate the relationship between NGF inhibition of glutamate-induced injury and PTEN. DESIGN, TIME AND SETTING: The randomized, controlled, in vitro study was performed at the Department of Pathophysiology, Medical School of Nantong University, China from October 2007 to March 2008. MATERIALS: Glutamate, NGF, 4, 6-diamidino-2-phenyl-indolediacetate, 3-[4, 5-dimethylthiazol-2-yl]- 2, 5-diphenyl tetrazoliumbromide (MTT), and lactate dehydrogenase kit (Sigma, USA), fluorescence microscope and inverted phase contrast microscope (Olympus, Japan) were used in this study. METHODS: Hippocampal neurons were obtained from newborn (< 24 hours) Sprague Dawley rats and cultured for 7 days. The control group was not treated with any intervention factor, the glutamate group was treated with glutamate (0.2 mmol/L), and NGF groups were treated with NGF (10, 50, 100, and 200 μg/L, respectively) prior to glutamate treatment. MAIN OUTCOME MEASURES: The MTT and lactate dehydrogenase assays were applied to evaluate viability of hippocampal neurons. Morphological changes in hippocampal neurons were observed using an inverted phase-contrast microscope, and neuronal apoptosis was detected by 4, 6-diamidino-2-phenyl-indolediacetate staining. PTEN mRNA and protein expression were measured by reverse transcription-polymerase chain reaction and Western blot analysis, respectively. RESULTS: Glutamate (0.2 mmol/L) induced significantly decreased neuronal viability and greater lactate dehydrogenase efflux compared with the control group (P < 0.01). However, compared with the glutamate group, cell viability significantly increased and lactate dehydrogenase efflux decreased in the NGF group with increasing NGF concentrations (P < 0.05 or P < 0.01). The apoptotic ratio and PTEN mRNA and protein expression decreased in the NGF group compared with the glutamate group (P < 0.01). CONCLUSION: Pretreatment with NGF exerted neuroprotective effects against glutamate-induced injury, partially through inhibition of PTEN expression and neuronal apoptosis.
BACKGROUND: Nerve growth factor (NGF) attenuates glutamate-induced injury to hippocampal neurons, and the human tumor suppressor gene phosphatase and tensin homolog deleted deleted on chromosome 10 (PTEN) promotes neuronal apoptosis. However, effects of PTEN in NGF-mediated neuroprotection against glutamate OBJECTIVE: To investigate the relationship between NGF inhibition of glutamate-induced injury and PTEN. DESIGN, TIME AND SETTING: The randomized, controlled, in vitro study was performed at the Department of Pathophysiology, Medical School of Nantong University, China from October 2007 to March 2008. MATERIALS: Glutamate, NGF, 4, 6-diamidino-2-phenyl- indolediacetate, 3- [4,5-dimethylthiazol-2-yl] METHODS: Hippocampal neurons were obtained from newborn (<24 hour s) Sprague Dawley rats and cultured for 7 days. The control group was not treated with any intervention factor, the glutamate group was treated with glutamate (0.2 mmol / L), and NGF groups were treated with NGF (10, 50, 100, and 200 μg / L, respectively) prior to glutamate treatment. MAIN OUTCOME MEASURES: The MTT and lactate dehydrogenase assays were applied to evaluate viability of hippocampal neurons. Morphological changes in hippocampal neurons were observed using an inverted phase-contrast microscope, and neuronal apoptosis was detected by 4, 6-diamidino-2-phenyl-indolediacetate staining. PTEN mRNA and protein expression were measured by reverse transcription-polymerase chain reaction and Western blot analysis respectively. RESULTS: Glutamate (0.2 mmol / L) viability and greater lactate dehydrogenase efflux compared with the control group (P <0.01). However, compared with the glutamate group, cell viability significantly increased and lactate(P <0.05 or P <0.01). The apoptotic ratio and PTEN mRNA and protein expression decreased in the NGF group compared with the glutamate group (P <0.01). CONCLUSION: Pretreatment with NGF exerted neuroprotective effects against glutamate-induced injury, partially through inhibition of PTEN expression and neuronal apoptosis.