Enhanced expression of tyrosine kinase receptor a in germ cells of rat testis with acute experimental testicular torsion.

Objective and Methods: To examine the involvement of neurotrophic factor receptors in the testis with acute experimental testicular torsion, the expression of tyrosine kinase receptors (trk) A and B, and p75 nerve growth factor receptor (NGFR) were studied in the rat testis with ischemia/reperfusion (I/R) injury, using Western blotting and immunohistochemistry. Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method. Results: There was a significant increase in TUNEL-positive reaction in spermatogonia in the seminiferous tubules in rat testes after testicular torsion. Western blot analysis showed that trk A expression reached a significant peak at 12 h after reperfusion (p < 0.01), as compared to sham-operated controls, whereas trk B was not increased in the testis after I/R. Constitutive expression of p75 NGFR was at or below the level detectable by Western blot analysis, and it remained unchanged in the testis after I/R. Immunohistochemistry demonstrated that after I/R trk A expression was increased in spermatocytes and spermatids in the seminiferous tubules, in contrast to the basal 1:)cation of the TUNEL-positive reaction. Immunoreactivity of trk B was seen mainly in the interstitial cells in the sham-operated testis, and its localization was not changed after I/R. Conclusion: It is postulated that trk A and B, but not p75 NGFR, are involved differently in the survival of testicular cells during acute experimental testicular torsion. In particular, increased trk A seems to be related to germ cell survival following I/R. Copyright (C) 2005 S. Karger AG, Basel.