2,4,6-trinitrotoluene-induced reproductive toxicity via oxidative DNA damage by its metabolite.
Several epidemiological studies and animal experiments showed that 2,4,6-trinitrotoluene (TNT), a commonly used explosive, induced reproductive toxicity. To clarify whether the toxicity results from the interference of endocrine systems or direct damage to reproductive organs, we examined the effects of TNT on the male reproductive system in Fischer 344 rats. TNT administration induced germ cell degeneration, the disappearance of spermatozoa in seminiferous tubules, and a dramatic decrease in the sperm number in both the testis and epididymis. TNT increased the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in sperm whereas plasma testosterone levels did not decrease. These results suggest that TNT-induced toxicity is derived from direct damage to spermatozoa rather than testosterone-dependent mechanisms. To determine the mechanism of 8-oxodG formation in vivo, we examined DNA damage induced by TNT and its metabolic products in vitro. 4-Hydroxylamino-2,6-dinitrotoluene, a TNT metabolite, induced Cu(II)-mediated damage to 32P-labeled DNA fragments and increased 8-oxodG formation in calf thymus DNA, although TNT itself did not. DNA damage was enhanced by NADH, suggesting that NADH-mediated redox reactions involving TNT metabolites enhanced toxicity. Catalase and bathocuproine inhibited DNA damage, indicating the involvement of H2O2 and Cu(I). These findings suggest that TNT induces reproductive toxicity through oxidative DNA damage mediated by its metabolite. We propose that oxidative DNA damage in the testis plays a role in reproductive toxicity induced by TNT and other nitroaromatic compounds.
Homma-Takeda
Shino
S
Graduate School Doctoral Program in Medical Sciences, University of Tsukuba, Ibaraki, Japan.
Hiraku
Yusuke
Y
Ohkuma
Yasuhiro
Y
Oikawa
Shinji
S
Murata
Mariko
M
Ogawa
Kazuhiko
K
Iwamuro
Taeko
T
Li
Song
S
Sun
Gui Fan
GF
Kumagai
Yoshito
Y
Shimojo
Nobuhiro
N
Kawanishi
Shosuke
S
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D002374:Catalase / Q000378:metabolism; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009243:NAD / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D010618:Phenanthrolines / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013076:Sperm Count; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism; D013737:Testis / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013739:Testosterone / Q000097:blood; D014303:Trinitrotoluene / Q000031:analogs & derivatives / Q000633:toxicity*
D010618:Phenanthrolines; D009243:NAD; D014303:Trinitrotoluene; D013739:Testosterone; D003300:Copper; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; C427203:calf thymus DNA; C002478:bathocuproine; D006861:Hydrogen Peroxide; D002374:Catalase; D003849:Deoxyguanosine