Etoposide is a podophyllotoxin semiderivative that is used in a variety of chemotherapy treatments, including therapy for children tumors. This drug promotes the formation of a ternary DNA-topoisomerase II-etoposide complex that triggers apoptosis. The purpose of this work was to analyze the occurrence of apoptosis in the seminiferous epithelium of prepubertal, pubertal, and adult rats treated with 10, 20, and 40 mg/Kg of etoposide during the prepubertal phase, as well as the role of apoptosis in etoposide-induced testicular damage. The rat testes were fixed in Bouin's liquid, and the apoptotic cells were quantified by means of the hematoxylin and eosin (H&E) technique (all groups) and the terminal dUTP nick end labeling (TUNEL) method (prepubertal groups only). The results obtained from both the H&E and TUNEL methods showed an increased frequency of apoptosis in the seminiferous epithelium of treated animals, except for the subgroup that received the 10-mg/Kg dose and was sacrificed 12 hr after the treatment and for the etoposide-treated pubertal group, that did not show cells suggesting apoptosis during H&E analysis. The labeled cells were mainly primary spermatocytes and differentiated spermatogonia. The prepubertal rats showed an etoposide-dose-dependent diminution of differentiated spermatogonia. Etoposide treatment during the prepubertal phase increases the frequency of apoptosis in the seminiferous epithelium, and causes serious harm to male fertility. © 2004 Wiley-Liss, Inc.
Key words: testis; etoposide; apoptosis; rat; spermatogenesisEtoposide is a podophyllotoxin semiderivative agent that has been used in a variety of chemotherapeutic treatments, including therapy for pediatric tumors. Previous reports have proposed that etoposide antimitotic activity is mediated by its interaction with topoisomerase II, an ATP-dependent nuclear enzyme that regulates DNA topology by transiently breaking and uniting doublestranded DNA (Arnold, 1979;Hande, 1998). Topoisomerase II is essential for DNA replication, transcription, recombination, and chromosomal segregation. Etoposide promotes the formation of a ternary DNA-topoisomeraseetoposide complex; thus, topoisomerase II is not allowed to rejoin the DNA fragment that is produced during the cell cycle (Creaven and Allen, 1975). This action converts topoisomerase II into physiological toxins that induce irreversible damage to DNA by generating insertions, deletions, chromosomal aberrations, and translocations. When a sufficient concentration of permanent DNA breaks is present in the cells, a series of events occurs that culminates in apoptosis (Creaven and Allen, 1975;Russell et al., 1998).Apoptosis is a common physiological phenomenon that occurs in proliferating and constantly renewing tissues, including the seminiferous epithelium (Russell et al., 1987;Kerr, 1992;Brinkworth et al., 1995; Blanco-Rodrí-guez and Martínez-Garcia, 1996). Spontaneous cell death during spermatogenesis is an essential means of maintaining homeostasis in the testis, and is responsible...