ACUTE TESTICULAR ISCHEMIA RESULTS IN GERM CELL-SPECIFIC APOPTOSIS IN THE RAT

Testis torsion-induced aspermatogenesis is not necessarily due to perm anent loss of blood flow nor to dysfunctional Leydig cells or Sertoli cells. This investigation was undertaken to gain further insight into the mechanism underlying torsion-induced germ cell loss. Male rats wer e subjected to 1-h or 2-h ischemia-inducing torsion, and testes were e xamined at either 1, 2, 4, 24, or 48 h after torsion, depending on the study. Testes were examined for evidence of 1) in situ apoptosis by t he terminal deoxynucleotidyl transferase-mediated deoxyuridine triphos phate (dUTP)-biotin nick-end labeling (TUNEL) technique, 2) apoptosis by the DNA ''laddering'' technique, 3) leukocyte margination and diape desis in testicular vessels by immunocytochemical and histological tec hniques, and 4) testicular lipid peroxidation by the thiobarbituric ac id reactive substances assay. The first TUNEL evidence for torsion-ind uced apoptosis was at 4 h after repair of 1-h torsion. Induction of ap optosis was confirmed by the electrophoretic laddering of DNA fragment s. It was hypothesized that apoptosis was induced by reactive oxygen s pecies arising from reperfusing leukocytes. A significant increase in both leukocyte margination and diapedesis occurred 4 h after torsion r epair as did a significant increase in intratesticular lipid peroxidat ion products. These events were contemporaneous with the first appeara nce of apoptosis and consistent with the hypothesis that post-torsion, germ cell-specific apoptosis is induced by reactive oxygen species.