The Expression Of PTEN Protein In The Abdominal Aorta Of Rats After Balloon Injury

Objective To investigate the dynamic change of PTEN protein in the abdominal aorta of rats after balloon injury and its effect on intimal hyperplasia. To evaluate the effect of PTEN protein on intimal hyperplasia after balloon injury.Methods The 56 male SD rats were randomized into two groups: sham operated group(n=8),ballon-injured group(n=48, including: 1,4,7,14,21,28-day subgroup).The balloon-injury model of rat abdominal aorta was established. The vascular tissues were harvested on the 28th day,1st day,4th day,7th day,14th day,21st day and 28th day after harvested as the operation respectively.(1)Histomorphology: The specimens were stained by the metheods of HE and Verhoeff. Morphology of tissue was observed in optics microscope. The intima thickness was measured by computer graph analysis system. (2)Immunohistochemistry :The expression level of PTEN and PCNA were examined with the method of immunohistochemistry(SABC and SP method). The slides were observed in 400 optics microscope and calculated the postitive cells of PTEN and PCNA respectively. (3)Western blotting: The frozen specimens from different phases were treated by SDS-acrylamide gel electrophoresis(SDS-PAGE), then immune reaction and result analysis , to get the level of PTEN protein.Statistical analysis:The result was analyzed with computer using one-way ANOVA by SPSS12.0.1,statistical significance was defined at P<0.05.Results The vessel wall of normal arteries could be found thinner. After the operation, intima and tunica media of injuried arteries were thickening the intima-media ratio was found reaching the peak(2.26±0.38 vs control 0.02±0.005 ,P < 0.01)at 28th day. The PTEN protein positive cells were cytoplasma stained. In normal arteries it had a high expression. It decreased significantly after balloon injury,and increased again in 1 week gradually.The amount of positive cells increased to the top on the 14th day which was twice of normal level or so. It maintained a higher level on the 21th day and a lower level on the 28th day. The PCNA positive cells were nucleus stained. The day after balloon injury PCNA positive cells were detected。The amount of positive cells increased and reached the top on the 7th day,then gradually decreased. The amount of posifive cells were less on the 28th day. The western blotting detection of PTEN protein has the tendency that is similar to the immunohistochemistry. Compared with the expression of PTEN and PCNA,PCNA was higher when intimal hyperplasia was serious and at the same time the expression of PTEN was lower. Intimal hyperplasia was inhibited when the expression of PTEN reached to higher level and the expression of PCNA was restrained.Conclusion The intima hyperplasia of abdominal aorta of rats after balloon injury occured as soon as after operation. The proliferation reached the highest point on the 14th day and then came to a lower speed. The PTEN protein had a high expression in normal arteries,almost no expression from the 1st day to the 4th day after balloon injury. The expression reached the top in the 14th～21th days. The variation of PTEN protein expression concerned with VSMC proliferation and migration,intima hyperplasia. PTEN should be considered to play a important role in preventing and curing restenosis after balloon injury.