Restoration of spermatogenesis after scrotal replacement of experimentallycryptorchid rat testis: Assessment of germ cell apoptosis and eNOS expression

Objectives. Cryptorchidism has been shown to induce germ cell apoptosis. Ni tric oxide (NO), a ubiquitous free radical produced by the nitric oxide syn thases (NOSs), has been associated with apoptosis in a number of cell types . We examined the effect of experimental cryptorchidism and subsequent orch idopexy on germ cell apoptosis and endothelial NOS (eNOS) expression. Methods. Prepubertal rats were rendered unilaterally cryptorchid, and 14 da ys later, orchidopexy was performed on a subset of these rats. Forty days a fter the initial procedure, testes were harvested from experimental and sha m-operated rats for immunohistochemical studies. Apoptosis was detected by in situ 3'-end-labeling of DNA with digoxigenin-ddUTP, and eNOS protein was detected using an eNOS monoclonal antibody. Results. Cryptorchid testes were characterized by diffuse hypospermatogenes is and had a 25-fold increase in apoptotic germ cells per cross-sectional a rea compared with sham-operated testes (P < 0.05). By contrast, the number of apoptotic germ cells per cross-sectional area in orchidopexied testes wa s not significantly different from that of sham-operated testes. In additio n to its known expression in Leydig, Sertoli, and vascular endothelial cell s, eNOS was detected in the cytoplasm of degenerating germ cells. Consecuti ve testis sections stained for eNOS and cellular DNA fragmentation demonstr ated co-localization of eNOS protein and germ cell apoptosis. Conclusions. In our experimental model, cryptorchidism induced germ cell ap optosis, and orchidopexy lowered the levels of germ cell apoptosis. Our dat a also support a role of eNOS in germ cell degeneration. UROLOGY 53: 223-22 7, 1999. (C) 1999, Elsevier Science Inc. All rights reserved.