Long-term sex selective hormonal and behavior alterations in mice exposed to low doses of chlorpyrifos in utero

Reprod Toxicol. 2010 Jan;29(1):74-9. doi: 10.1016/j.reprotox.2009.10.008. Epub 2009 Oct 29.


Chlorpyrifos, O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate, is an organophosphate insecticide known to be present in human urine. In utero exposure to chlorpyrifos may cause long-term hormonal and behavior alterations. In this study mice were exposed to 0, 1 or 5mg/kg chlorpyrifos on gestational days 17-20. In utero exposed mice were then tested in a novel foraging behavior maze and assayed for thyroid hormones. Free Thyroxine Index increased significantly in females, but not males. Learning latency and reduced learning ability was evident during training sessions 5-9 in female mice exposed to 1 or 5mg/kg chlorpyrifos. No learning deficiencies were observed in male mice. No differences were seen in behavior when using a standard radial arm maze during the nine training sessions. These data suggest that mice are susceptible to neuro-endocrine reprogramming by chlorpyrifos, and demonstrate the efficacy of the novel foraging maze as an efficient behavior assay tool.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Behavior, Animal / drug effects*
  • Chlorpyrifos / administration & dosage*
  • Chlorpyrifos / toxicity*
  • Female
  • Gestational Age
  • Insecticides
  • Male
  • Mice
  • Pregnancy
  • Prenatal Exposure Delayed Effects*
  • Sex Factors*
  • Thyroid Hormones / blood*
  • Thyroxine / blood
  • Triiodothyronine / blood


  • Insecticides
  • Thyroid Hormones
  • Triiodothyronine
  • Chlorpyrifos
  • Thyroxine