Vasectomy impairs spermatogenesis through germ cell apoptosis mediated by the p53-Bax pathway in rats.
OBJECTIVE
The pathophysiology of impaired spermatogenesis after vasectomy has not been completely investigated. We examined the role of p53 protein in cell cycle arrest and apoptosis of germ cells after vasectomy in the rat.


METHODS
Eight-week old rats underwent bilateral vasectomy and the testes were harvested 1, 4, 8, 12 and 24 weeks after surgery. Germ cell apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) and electrophoresis assay of DNA fragmentation. Western blot analysis and immunohistochemistry were performed to examine the expression of p53, proliferating cell nuclear antigen, Bax, Bcl-2, p21WAF1/Cip1 and Gadd45. To evaluate spermatogenesis, testicular weight and percent of haploid cells flow cytometry was done.


RESULTS
Spermatogenesis impairment was associated with increased p53 and decreased proliferating cell nuclear antigen expression at the delayed phase more than 8 weeks after vasectomy. The number of TUNEL positive germ cells was increased at the early 1-week and delayed phases after vasectomy. Bax but not p21WAF1/Cip1 or Gadd45 expression was increased. p53, Bax and TUNEL positive cells were co-localized in the seminiferous tubules.


CONCLUSIONS
Spermatogenesis was impaired after vasectomy by apoptosis but not by cell cycle arrest. The p53-Bax pathway effects apoptosis in the delayed phase after vasectomy in some seminiferous tubules.
Shiraishi
K
K
Department of Urology, Yamaguchi University School of Medicine, Yamaguchi, Japan.
Naito
K
K
Yoshida
K
K
D000818:Animals; D017209:Apoptosis; D020287:In Situ Nick-End Labeling; D008297:Male; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*; D014659:Vasectomy / Q000009:adverse effects*; D051028:bcl-2-Associated X Protein
C494828:Bax protein, rat; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein