title: Increased sensitivity to testicular toxicity of transplacental benzo[a]pyrene exposure in male glutamate cysteine ligase modifier subunit knockout (Gclm-/-) mice.
abstract: Polycyclic aromatic hydrocarbons (PAHs), like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants formed by the incomplete combustion of organic materials. The tripeptide glutathione (GSH) is a major antioxidant and is important in detoxification of PAH metabolites. Mice null for the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH concentrations. We investigated the effects of Gclm deletion alone on male fertility and spermatogenesis and its effect on the sensitivity of male embryos to the transplacental testicular toxicity of BaP. Gclm-/- males had dramatically decreased testicular and epididymal GCL enzymatic activity and total GSH concentrations compared with Gclm+/+ littermates. Ratios of reduced to oxidized GSH were significantly increased in Gclm-/- testes. GSH reductase enzymatic activity was increased in Gclm-/- epididymides. We observed no changes in fertility, testicular weights, testicular sperm head counts, or testicular histology and subtle changes in cauda epididymal sperm counts, motility, and morphology in Gclm-/- compared with Gclm+/+ males. Prenatal exposure to BaP from gestational day 7 to 16 was dose dependently associated with significantly decreased testicular and epididymal weights, testicular and epididymal sperm counts, and with vacuolated seminiferous tubules at 10 weeks of age. Gclm-/- males exposed prenatally to BaP had greater decreases in testicular weights, testicular sperm head counts, epididymal sperm counts, and epididymal sperm motility than Gclm+/+ littermates. These results show no effects of Gclm deletion alone on male fertility and testicular spermatogenesis and subtle epididymal effects but support increased sensitivity of Gclm-/- males to the transplacental testicular toxicity of BaP.
authors.affiliation: Department of Medicine, University of California-Irvine, Irvine, California 92617, USA.
authors.forename: Brooke N
authors.initials: BN
authors.lastname: Nakamura
authors.forename: Isaac
authors.initials: I
authors.lastname: Mohar
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Lawson
authors.forename: Mabel M
authors.initials: MM
authors.lastname: Cortés
authors.forename: Yvonne D
authors.initials: YD
authors.lastname: Hoang
authors.forename: Laura
authors.initials: L
authors.lastname: Ortiz
authors.forename: Reshma
authors.initials: R
authors.lastname: Patel
authors.forename: Bogdan A
authors.initials: BA
authors.lastname: Rau
authors.forename: Lisa A
authors.initials: LA
authors.lastname: McConnachie
authors.forename: Terrance J
authors.initials: TJ
authors.lastname: Kavanagh
authors.forename: Ulrike
authors.initials: U
authors.lastname: Luderer
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000008:administration & dosage / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005260:Female; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009929:Organ Size / Q000187:drug effects; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D013091:Spermatogenesis / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects / Q000473:pathology; D013737:Testis / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
chemical_list: D004785:Environmental Pollutants; D001564:Benzo(a)pyrene; D005980:Glutathione Reductase; C560749:GCLM protein, mouse; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione