title: The stage-specific testicular germ cell apoptotic response to low-dose radiation and 2,5-hexanedione combined exposure. II: qRT-PCR array analysis reveals dose dependent adaptive alterations in the apoptotic pathway.
abstract: Testicular effects of chemical mixtures may differ from those of the individual chemical constituents. This study assessed the co-exposure effects of the model germ cell- and Sertoli cell-specific toxicants, X-irradiation (x-ray), and 2,5-hexanedione (HD), respectively. In high-dose studies, HD has been shown to attenuate x-ray-induced germ cell apoptosis. Adult rats were exposed to different levels of x-ray (0.5 Gy, 1 Gy, and 2 Gy) or HD (0.33%), either alone or in combination. To assess cell type-specific attenuation of x-ray effects with HD co-exposure, we used laser capture microdissection (LCM) to enrich the targeted cell population and examine a panel of apoptosis-related transcripts using PCR arrays. The apoptosis PCR arrays identified significant dose-dependent treatment effects on several genes, with downregulation of death receptor 5 (DR5), Naip2, Sphk2, Casp7, Aven, Birc3, and upregulation of Fas. The greatest difference in transcript response to exposure was seen with 0.5 Gy x-ray exposure, and the attenuation effect seen with the combined high-dose x-ray and HD did not persist into the low-dose range. Examination of protein levels in staged tubules revealed a significant upregulation in DR5, following high-dose co-exposure. These results provide insight into the testis cell-specific apoptotic response to low-dose co-exposures of model testicular toxicants.
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA.
authors.forename: Natasha R
authors.initials: NR
authors.lastname: Catlin
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Huse
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island, USA kim_boekelheide@brown.edu.
authors.forename: Kim
authors.initials: K
authors.lastname: Boekelheide
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling / Q000379:methods*; D006588:Hexanones / Q000633:toxicity*; D061346:Laser Capture Microdissection; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D013091:Spermatogenesis / Q000187:drug effects / Q000528:radiation effects; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D014965:X-Rays
chemical_list: D006588:Hexanones; C011269:2,5-hexanedione
keywords: 2,5-hexanedione; PCR array; adaptive.; apoptosis; laser capture microdissection; testis; x-irradiation