Objective　To　investigate　the　controlled　expression　of　neuroiropliin-3　(NT-3)　by　HRE　under　hypoxic　conditions　and　determine　the　protective　effects　of　conditionally　expressed　NT-3　on　hypoxia-induced　spnptosis　in　PCI2　celk.　Methods　Five　copies　of　the　HRE　(5HRE)　and　NT-3　were　employed　to　construct　a　therapeutic　vector,　and　transferred　into　PCL2　cells.　Expression　and　secretion　of　NT-3　were　detected　by　ELISA.　Apoptosis　of　PCL2　cells　induccd　by　hypoxia　was　assayed　by　TUNEL.　Activation　of　p-38　and　Caspase-3　was　detected　by　Western　blotting.　Results　The　retroviral　vectors　were　successfully　constructed　and　transfecied　into　PCI2　cells　to　produce　gene　transferred　cells,　PCI2-NT3-EGFP,　PC12-5HRE-NT3-EGFP　and　PCI2-5HRE-EGFP.　Compared　with　normal　conditions,　in　which　NT-3　was　expressed　at　low　levels,　the　expression　of　NT-3　significantly　increased　under　hypasic　conditions　in　PCI2-5HRE-NT3-F.GFP　(a　=　3,　P　＜　0.　05).　The　conditional　adjustment　of　NT-3　expression　by　514RE　significantly　reduced　apoptosis　induced　by　hypoxia　in　PC12-5HFIE-NT3-EGFP　(a　.3.　P＜0.05).　In　addition,　the　hypoxia-induced　phosphorylation　of　both　p38　and　Caspasc-3　activities　was　decreased　in　PCI2-5HRE-NT3.EGFP　under　hypoxic　conditions　(n　=　3,　P　＜　0.05).　Conclusion　Up-　regulated　expression　of　NT-3　mediated　by　hypoxia　response　element　in　response　to　hypoxia　in　PCI2　cells　can　protect　PCI2　cells　against　hypoxia-induced　apoptosia.