Objective: To investigate the changes of nuclear factor-kappa gene binding (NF-kappaB) expression in and apoptosis of spermatogenic epithelial cells in the restored testis after torsion and analyze the relationship between them.
Methods: Sixteen male SD rats underwent torsion of the left testis clockwise at an angle of 720 degrees for 2 hours and then the testis was restored to the original position and fixed. Then the 16 rats were randomly divided into 2 equal group: Group I in which salicylazosulfapyridium (SASP) suspension was infused intra-gastrically 5 h after operation and then once a day for 4 times, and Group II in which normal saline (NS) was infused in the same manner. Eight rats (Group III) underwent sham operation and then infused with NS in the same manner as that of Group II. Three days after operation the rats were killed and the samples of the testes at the torsion side were taken out and the seminiferous tubules were isolated. Western blotting was used to detect the NF-kappaB expression in the cytoplasm and nucleus of spermatogenic epithelial cells. Immunohistochemistry was used to detect the in situ expression of NF-kappaB. The apoptosis of the spermatogenic epithelial cells was examined by TUNEL method.
Results: Western blotting showed that the NF-kappaB expression in the cytoplasm of spermatogenic epithelial cells of Group II was 9.4 +/- 2.68, somewhat lower, but not significantly, than those of Group I and III (12 +/- 2.2 and 11.1 +/- 3 respectively, both P > 0.05). The NF-kappaB expression in the nucleus of spermatogenic epithelial cells of Group II was 21.1 +/- 3.6, significantly higher than those of Group I and III (8.4 +/- 3.1 and 6.0 +/- 2.3 respectively, both P < 0.05). However, there were no significant differences in the NF-kappaB expression in the cytoplasm and nucleus of spermatogenic epithelial cells between Groups I and III. The NF-kappaB activity coefficient of spermatogenic epithelial cells of Group II was 2.32 +/- 0.4, significantly higher than those of Groups I and III (0.68 +/- 0.3 and 0.52 +/- 0.1 respectively, both P < 0.01). However, there was no significant difference in the NF-kappaB activity coefficient of spermatogenic epithelial cells between Groups I and III (P > 0.05). The NF-kappaB positive cell rate of Group II was 66.1% +/- 3.8%, significantly higher than those of Groups I and III (15.6% +/- 2.6% and 10.8% +/- 2.7%, both P < 0.01). The apoptotic cell rate of Group II was 37.2% +/- 3.3%, significantly higher than those of Groups I and III (7.7% +/- 2.0% and 5.9% +/- 1.7%, both P < 0.01).
Conclusion: After the torsion of testis, NF-kappaB was activated and released from the nucleus into the cytoplasm, thus initiating the apoptosis of spermatogenic epithelial cells.