[Endocrine disruptors and brain estrogen receptors: the current state of behavioral, neurochemical, and molecular biological studies].

Based on epidemiological studies and animal studies, endocrine disrupters have received considerable attention as exerting disrupting actions on the developing brain. On the other hand, there has been increasing evidence that sex hormones and thyroid hormones play important roles in the development of the brain, including sexual dimorphism during the perinatal stage. Thus it seems probable that perinatal exposure to endocrine disruptors, which may have an affect on biosynthesis, transport, action, and metabolism of the hormones, may disrupt brain development enough to impair the brain functions. In this review, we introduce the current state of studies on brain disrupting actions of endocrine disruptors, addressing their actions on the estrogen system, including our own findings. The outline of the findings thus far reported are as follows: (1) Perinatal exposure to relatively low concentrations of endocrine disrupters may cause an impairment of higher brain functions, such as sexual behavior and learning behavior, (2) There seems to be sexual difference about the impairment described above, (3) Endocrine disruptors may cause an increase in volume of some nuclei, such as the sexual dimorphic nucleus of the preoptic area and locus coeruleus of the brain, (4) The disruptor might change the level of some substances that are considered to be involved in synaptic functions. Much remained to be studied about how does each finding reported link the others, and about detailed mechanisms of the disrupting actions of endocrine disruptors on the developing brain.