Prenatal exposure to endocrine disrupting chemicals: effects on behavioraldevelopment

Numerous chemicals released into the environment by man are able to disrupt the functioning of the endocrine system by binding to hormonal receptors. Exposure to estrogenic endocrine disrupters during critical periods in feta l life can alter the development of reproductive organs, the neuroendocrine system and subsequent behavior. We present a series of studies on the effe cts of exposure during fetal life to low, environmentally relevant doses of two pesticides, o, p ' DDT and methoxychlor, and of low doses of the synth etic estrogen, diethylstilbestrol on subsequent neuro-behavioral developmen t in house mice. The main findings can be summarized as follows: (1) Mice p renatally exposed to methoxychlor showed changes in reflex development. Exp osure to a very low dose of methoxychlor appeared to produce an increased r eactivity during early postnatal life. (2) Methoxychlor exposed periadolesc ent mice showed a decreased reaction time exploring both a novel environmen t and a novel object. (3) The onset of male intrasex aggression appeared to be delayed in males prenatally exposed to low doses of methoxychlor, since exposed males showed low levels of aggressive interactions during early ad olescence but not after they reached adulthood. (4) The rate of depositing urine marks in a novel environment was increased in males prenatally expose d to DES, and also to o, p ' DDT and methoxychlor. (5) The proportion of bo th males and females attacking a same-sex conspecific was increased in mice prenatally exposed to low doses of DES and, marginally, to o, p ' DDT. Thi s effect appeared to be related to a decreased latency to attack. However, males prenatally exposed to o, p ' DDT displayed a decreased intensity of a ggression. The possible implications of perturbing the hormonal milieu duri ng fetal development on the modulation of developmental turnpoints and futu re behavioral responses are discussed. (C) 1999 Elsevier Science Ltd. All r ights reserved.