title: Differences in sensitivity of murine spermatogonia and somatic cells in vivo to sister-chromatid exchange induction by nitrosoureas.
abstract: Previously published data indicate that spermatogonia (SPG) are less sensitive to a sister-chromatid exchange (SCE) induction for different mutagens. In an earlier study, we have observed that bromodeoxyuridine (BrdU) substituted murine SPG are less sensitive to SCE induction by gamma ray in cells, than bone marrow (BM) and salivary gland (SG) cells in vivo. This was interpreted to mean that SPG are more efficient in DNA repair or are less prone to SCE induction. That the lower induction of SCE could be due to a reduced accessibility of mutagens to the SPG by virtue of a physiological barrier, was discarded by using gamma radiation. The aim of the present study was to establish whether or not there are differences in SCE induction by nitrosoureas among SPG, SG and BM cells with BrdU substituted or unsubstituted DNA. It was observed that SCE induction by methylnitrosourea (MNU) or by ethylnitrosourea (ENU) in SPG was, respectively, five and two times lower than in SG, and ten and three times lower than in BM. In SPG after BrdU incorporation, there was no increase in efficiency of SCE induction; in fact, there was even a slight decrease by exposure to MNU or ENU. BM and SG cells showed an increased efficiency in SCE induction after BrdU incorporation. This implies that SPG are also less sensitive to SCE induction by nitrosoureas, which cause a different kind of damage from previously assayed mutagens.
authors.affiliation: Instituto Nacional de Investigaciones Nucleares, AP18-1027, México, D.F., Mexico. pmr@nuclear.inin.mx
authors.forename: P
authors.initials: P
authors.lastname: Morales-Ramírez
authors.forename: V
authors.initials: V
authors.lastname: Cruz-Vallejo
authors.forename: R
authors.initials: R
authors.lastname: Rodríguez-Reyes
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005038:Ethylnitrosourea / Q000633:toxicity; D008297:Male; D008770:Methylnitrosourea / Q000633:toxicity; D051379:Mice; D008807:Mice, Inbred BALB C; D009607:Nitrosourea Compounds / Q000633:toxicity*; D012469:Salivary Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012680:Sensitivity and Specificity; D012854:Sister Chromatid Exchange / Q000187:drug effects*; D013093:Spermatogonia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D009607:Nitrosourea Compounds; D008770:Methylnitrosourea; D005038:Ethylnitrosourea