Methoxychlor given in the periimplantation period blocks sexual arousal in male mice

Abstract To determine whether pesticide methoxychlor (MXC) alters sexual arousal in male offspring, pregnant ICR mice remained untreated or received daily subcutaneous injections (s.c.) of olive oil, 33.0 mg/kg bw purified (95%) MXC, or 0.33 mg/kg bw estradiol-17β in vehicle on Days 5 to 7 of pregnancy. Live births were recorded in all groups except the estradiol group. At 4 months, untreated or olive oil-treated male offspring exhibited normal sexual arousal. When placed near a plastic partition with an estrus female behind it, these males spent significantly more time near the partition than near a vacant half of the cage and exhibited a sharp increase in plasma testosterone. MXC-exposed males showed no sexual arousal, spent much less time near the partition with an estrus female, and exhibited significantly lower plasma testosterone levels. Exposure to purified MXC close to implantation alters the function of the hypothalamic–pituitary–testicular axis and compromises male sexual behavior in offspring.