title: Effect of Age, Duration of Exposure, and Dose of Atrazine on Sexual Maturation and the Luteinizing Hormone Surge in the Female Sprague-Dawley Rat.
abstract: Atrazine (ATZ) was administered daily by gavage to pregnant female Sprague Dawley rats at doses of 0, 6.25, 25 or 50 mg/kg/day, either during gestation, lactation and post-weaning (G/L/PW cohort) to F1 generation female offspring or only from postnatal day (PND 21) until five days after sexual maturation (vaginal opening) when the estrogen-primed, luteinizing hormone (LH) surge was evaluated (PW cohort). Additional subgroups of F1 females received the vehicle or ATZ from PND 21-133 or from PND 120-133. Slight reductions in fertility and the percentage of F1 generation pups surviving to PND 21 in the gestationally exposed 50 mg/kg dose group were accompanied by decreased food intake and body weight of dams and F1 generation offspring. The onset of puberty was delayed in of the F1 generation G/L/PW females at doses of 25 and 50 mg/kg/day. F1 generation females in the PW high-dose ATZ group also experienced a delay in the onset of puberty. ATZ had no effect on peak LH or LH AUC in ovariectomized rats 5 days after sexual maturation, irrespective of whether the F1 generation females were treated from gestation onward or only peripubertally. There was no effect of ATZ treatment on the estrous cycle, peak LH or LH AUC of F1 generation females exposed from gestation through to PND 133 or only for two weeks from PND 120-133. These results indicate that developing females exposed to ATZ are not more sensitive compared to animals exposed to ATZ as young adults.
authors.affiliation: Department of Toxicology and Health Sciences, Syngenta Crop Protection, LLC, Greensboro, North Carolina.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Breckenridge
authors.affiliation: WIL Research, Ashland, Ohio.
authors.forename: Pragati
authors.initials: P
authors.lastname: Sawhney Coder
authors.affiliation: Department of Toxicology and Health Sciences, Syngenta Crop Protection, LLC, Greensboro, North Carolina.
authors.forename: Merrill O
authors.initials: MO
authors.lastname: Tisdel
authors.affiliation: Department of Physiology and Pharmacology, University of West Virginia, Morgantown, West Virginia.
authors.forename: James W
authors.initials: JW
authors.lastname: Simpkins
authors.affiliation: Department of Toxicology and Health Sciences, Syngenta Crop Protection, LLC, Greensboro, North Carolina.
authors.forename: Kun Don
authors.initials: KD
authors.lastname: Yi
authors.affiliation: Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona.|Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, Alabama.
authors.forename: Chad D
authors.initials: CD
authors.lastname: Foradori
authors.affiliation: Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, Arizona.|College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Handa
mesh_terms: D000375:Aging / Q000187:drug effects*; D000818:Animals; D001280:Atrazine / Q000633:toxicity*; D001835:Body Weight / Q000187:drug effects; D003433:Crosses, Genetic; D004781:Environmental Exposure; D004958:Estradiol / Q000494:pharmacology; D030762:Estrous Cycle / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012741:Sexual Maturation / Q000187:drug effects*; D016019:Survival Analysis; D013997:Time Factors
chemical_list: D004958:Estradiol; D007986:Luteinizing Hormone; D001280:Atrazine
keywords: cyclicity; hormones; postnatal evaluation; risk assessment