Comparison of Germ Cell Mutagenicity in Male CYP2E1-Null and Wild-Type Mice Treated with Acrylamide: Evidence Supporting a Glycidamide-Mediated Effect

Abstract

Acrylamide is an animal carcinogen and probable human carcinogen present in appreciable amounts in heated carbohydrate-rich foodstuffs. It is also a germ cell mutagen, inducing dominant lethal mutations and heritable chromosomal translocations in postmeiotic sperm of treated mice. Acrylamide's affinity for male germ cells has sometimes been overlooked in assessing its toxicity and defining human health risks. Previous investigations of acrylamide's germ cell activity in mice showed stronger effects after repeated administration of low doses compared with a single high dose, suggesting the possible involvement of a stable metabolite. A key oxidative metabolite of acrylamide is the epoxide glycidamide, generated by cytochrome P4502E1 (CYP2E1). To explore the role of CYP2E1 metabolism in the germ cell mutagenicity of acrylamide, CYP2E1-null and wild-type male mice were treated by intraperitoneal injection with 0, 12.5, 25, or 50 mg acrylamide (5 ml saline)(-1) kg(-1) day(-1) for 5 consecutive days. At defined times after exposure, males were mated to untreated B6C3F1 females. Females were killed in late gestation and uterine contents were examined. Dose-related increases in resorption moles (chromosomally aberrant embryos) and decreases in the numbers of pregnant females and the proportion of living fetuses were seen in females mated to acrylamide-treated wild-type mice. No changes in any fertility parameters were seen in females mated to acrylamide-treated CYP2E1-null mice. Our results constitute the first unequivocal demonstration that acrylamide-induced germ cell mutations in male mice require CYP2E1-mediated epoxidation of acrylamide. Thus, CYP2E1 polymorphisms in human populations, resulting in variable enzyme metabolic activities, may produce differential susceptibilities to acrylamide toxicities.

Assessing human germ‐cell mutagenesis in the Postgenome Era: A celebration of the legacy of William Lawson (Bill) Russell

“…However, these results are based on the analyses of a very small number of genotypes, and it is well known that genetic variation among strains of mice affects their susceptibility to toxicants. Thus, genotype differences are expected to affect the susceptibility to germ-cell mutagenicity, as was recently reported for the model germ-cell mutagen acrylamide [Ghanayem et al, 2005;Manson et al, 2005]. Most germ-cell mutagens in rodents induce mutations in postmeiotic stages of spermatogenesis but not in premeiotic stages of spermatogenesis or in oocytes.…”

Pathological assessment of the nervous and male reproductive systems of rat offspring exposed maternally to acrylamide during the gestation and lactation periods - a preliminary study

“…Additionally, ACR has carcinogenic potential (Dearfield et al, 1988;IARC, 1994), and exerts adverse effects on male reproduction, including dominant lethality, degeneration of testicular epithelial tissue, and impaired fertilization (Sakamoto et al, 1988;Adler et al, 2000;Tyl and Friedman, 2003). It has been demonstrated that reproductive toxicity is not only induced by ACR, but also by glycidamide (GA), an oxidized metabolite of ACR generated by CYP2E1, which exerts clastogenic effects on spermatids (Adler et al, 2000;Costa Correspondence: Makoto Shibutani (E-mail: shibutan@nihs.go.jp) et al, 1992;Ghanayem et al, 2005).…”

Effect of Dose Volume on the Toxicokinetics of Acrylamide and Its Metabolites and 2-Deoxy-d-glucose

“…administration of the same AA dose to male mice followed by mating with untreated female mice caused greater reduction in the pregnancy rate (4.69% compared with 62% in vehicle-treated mice) (Ghanayem et al, 2005a) in comparison to the Alder studies (2004). A close comparison of the two studies revealed that, in addition to the difference in the mouse strain used, the dose volume used in the Alder et al (2004) studies was 10 ml/kg compared with 5 ml/kg in the Ghanayem et al (2005a) study. In another dominant lethal mutations study, AA was administered in a dose volume of 100 ml/kg (Adler et al, 2000).…”

“…1B). This may explain the greater genotoxicity of 50 mg AA/kg when administered at a high versus low concentration, because GA is considered to be the ultimate genotoxic metabolite of AA (Ghanayem et al, 2005a).…”