DNA double-strand damage and repair following γ-irradiation in isolated spermatogenic cells

Various cell types in spermatogenesis exhibit differential sensitivity to radiation-induced DNA damage. The investigation of DNA radiosensitivity in vitro is complicated by the heterogeneous population of male germ cells (MGC) present in isolated single-cell suspensions. In the present investigation, the neutral elution technique was used to assess γ-irradiation-induced DNA double-strand damage (DSD) in spermatogonia and preleptotene spermatocytes (SG/PL), pachytene spermatocytes and spermatid spermatocytes, as well as in MGC. In addition, the capability of these cell types to repair DNA double-strand damage was investigated. DSD was induced in a dose-dependent manner in the heterogeneous population as well as in the labeled cell populations. SG/PL were more sensitive to γ-irradiation-induced DSD than either the heterogeneous MGC population, pachytene or spermatid spermatocytes. Each cell type exhibited a similar capability to repair DSD following exposure to 3000 rad. Only pachytene spermatocytes exhibited significant repair following exposure to 6000 ras. Since a difference in sensitivity to radiation-induced DSD was demonstrated, the capability of each cell type to repair a similar initial frequency of strand damage. (author). 33 refs.; 5 figs