Perinatal exposure to chemical agents: delayed effects by the mechanism of imprinting (cell programming)

RESUMO

The early reports linking the development of clear cell cervicovaginal adenocarcinoma in young women with diethylstilbestrol treatment of their mothers during pregnancy were the first evidence that perinatal exposure to several substances may induce irreversible alterationsthat can be detected at older ages. Current evidence suggests that these substances induce, by the mechanism of imprinting, alterations of the differentiation or programming of several cell-types that last for life and that may further result in the development of disease. The first evidence for the induction of the imprinting mechanism was obtained by prenatal or early postnatal exposure to abnormal hormone levels or to synthetichormonal compounds. Today it is known that several non-hormonal compounds such as heavy metals, pesticides, other pollutants, pharmaceuticals, drugs of abuse, food additives and even normal constituents present in food may induce this mechanism. The present review describes most relevant delayed effects of perinatal exposure to hormones displaying sex hormone action, several pollutants (lead, benzopyrenes, ozone, nitrogen dioxide, carbon monoxide, chlorinated organic persistent compounds, polychlorobiphenyls (PCBs), dioxins and several pesticides), maternal tobacco smoking, and illicit (tetrahydrocannabinol, cocaine, opiates, ketamine, toluene) and licit (nicotine, caffeine and ethyl alcohol) drugs of abuse. It is concluded that perinatal exposure to several agents causes irreversible changes that determine health conditions during adulthood. Several diseases developing during adulthood probably were determined during early stages of life, under the effect of exposure or preferential mothers diet during pregnancy. Regulations to avoid these early exposures may contribute to an important improvement of health conditions of humankind