摘要
BACKGROUND:Folic acid is essential for normal functioning of the nervous system.Previous studies have focused on the effects of folic acid on astrocyte proliferation.OBJECTIVE:To explore the effects of folic acid on astrocyte differentiation of neural stem cells(NSCs)and the related mechanisms in vitro.DESIGN,TIME AND SETTING:A randomized,controlled,grouping experiment was performed in Tianjin Medical University between August 2007 and October 2008.MATERIALS:Folic acid and 5-bromo-2-deoxyuridine(BrdU)were obtained from Sigma,MO,USA.Primary antibodies[rabbit anti-rat nestin,β-tubulin-Ⅲ,glial fibrillary acidic protein,and neurogeninl(Ngnl);mouse anti-rat BrdU andβ-actin monoclonal antibodies]were purchased from Santa Cruz Biotechnology,USA.METHODS:At 6 days of NSC proliferation from 24-hour-old neonatal rats,BrdU incorporation assay was performed.Seven days after primary culture,NSCs were induced to differentiate with medium containing 5%fetal bovine serum.Cultured NSCs were assigned to three groups:control,low-dose(liquid media with 8 mg/L folic acid),and high-dose folic acid(liquid media with 44 mg/L folic acid).MAIN OUTCOME MEASURES:At day 7 after primary culture,the cells were identified as NSCs by immunocytochemical methods.Double-label immunofluorescence technique for glial fibrillary acidic protein/BrdU detected differentiated cells 7 days after induction.Western blot was used to analyze expression of Ngnl protein in NSCs.RESULTS:In serum-free suspension medium,neurospheres comprised a large number of Nestin-,glial fibrillary acidic protein-,β-tubulin-Ⅲ-,and BrdU-positive cells.Compared with the control group,high-dose folic acid supplementation led to an marked increase in the percentage of glial fibrillary acidic protein/BrdU-positive cells(P〈0.05),and significantly decreased Ngnl protein expression(P〈0.05).CONCLUSION:Folic acid promotes astrocytic differentiation of NSCs,which might be related to downregulation of Ngnl protein expression.
基金
the National Natural Science Foundation of China,No.30571563,30771797
the grant from Tianjin Education Commission,China,No.20070208
