Effects of 17 beta-estradiol on neuron apoptosis after spinal cord injury in rats

Objective To investigate the effects of 17 beta-estradiol on neuron apoptosis after spinal cord injury(SCI) in rats.Methods The SD rats were randomly divided into 3 groups: sham-operated group(group A),phosphate buffer saline group(group B) and 17 beta-estradiol group(group C).Rat model of SCI was established,while animals in sham-operated group underwent a T9 laminectomy without weight-drop injury.The neurofunction of spinal cord was evaluated by modified Tarlov score and Rivlin platform test at 7 d,14 d,21 d and 28 d after injury.The animals were sacrificed at 6 h,24 h,3 d,7 d,14 d and 28 d respectively after injury.The lesion areas of the spinal cord were cut for morphological studies by hematoxylin and eosin staining.Cell apoptosis was examined using the TUNEL assay and the flow cytometry.Results Neuron apoptosis was noted by the TUNEL assay and the flow cytometry after SCI in rats,and peaked at 3 d with TUNEL after SCI,while at 7 d with the flow cytometry.Compared with group B the apoptotic rate in group C was significantly decreased at the time points of 24 h,3 d and 7 d(P0.01 or P0.05).After 14 d,the neurofunction of the spinal cord was better in group C than in group B(P0.01 or P0.05).Conclusion 17 beta-estradiol can reduce the numbers of apoptotic cells and promote the nerve function recovery after SCI.