Effect of Age, Duration of Exposure, and Dose of Atrazine on Sexual Maturation and the Luteinizing Hormone Surge in the Female Sprague-Dawley Rat.

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 F-1 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 F-1 females received the vehicle or ATZ from PND 21-133 or from PND 120-133. Slight reductions in fertility and the percentage of F-1 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 F-1 generation offspring. The onset of puberty was delayed in of the F-1 generation G/L/PW females at doses of 25 and 50 mg/kg/day. F-1 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 F-1 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 F-1 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. (C) 2015 Wiley Periodicals, Inc.