Cellular and biochemical mechanisms by which environmental oestrogens influence reproductive function

Abstract

The biology and physiology of the male as well as female reproductive system is hormonally regulated. Abnormalities in the dynamics of hormone production, metabolism and elimination, as well as their binding to certain target tissues, has been associated with pathophysiological conditions of the reproductive system. Although oestrogens are known to be one of the major hormone groups in regulating the reproductive function and the fertilization process, the cellular and biochemical mechanism or mechanism(s) via which oestrogens induce their effects are still not fully defined. Moreover, in a modern environment we are also exposed to a wide battery of environmental agents which are structurally similar to oestrogens, and termed 'environmental oestrogens'. Because environmental oestrogens have been shown to mimic some of the effects of oestradiol, it has been postulated that these exogenous chemicals may influence or interfere with the oestrogen-dependent reproductive processes, and may be associated with beneficial as well as deleterious effects on the reproductive system. In this regard, two classes of environmental oestrogens have been widely studied, i.e. phyto-oestrogens (plant-derived dietary oestrogens) and xeno-oestrogens (industrial chemicals, including polychlorinated biphenyls, DDT, TCDD, dioxins, etc.). The main focus of this review is to provide an overview on the cellular and biochemical mechanism(s) by which xeno-oestrogens and phyto-oestrogens influence the oestrogen-dependent reproductive functions and induce their deleterious or protective effects on the reproductive system.

Concentrations of Isoflavones and Their Metabolites in the Blood of Pregnant and Non-pregnant Heifers Fed Soy Bean

“…In particular, the increases in the concentrations of active phytoestrogen metabolites in the blood plasma of the early-pregnant heifers may enable these substances to influence the secretory functions of the reproductive system. Our previous studies and those of other authors have shown studies that not only high, but also low concentrations of phytoestrogens are widespread, have substantial deleterious effects on the reproductive processes and may cause severe disorders during the estrous cycle and development of early pregnancy in many animal species [5,6,[23][24][25][26]. In particular, the problem of estrogen-dependent infertility has been studied extensively in ewes [5].…”

Phytoestrogens and Their Metabolites Inhibit the Sensitivity of the Bovine Corpus Luteum to Luteotropic Factors

“…As agonists and/or antagonists of endogenous estrogens, phytoestrogens may induce various pathologies in the female reproductive tract including disorders in the function of the ovary, oviduct, and uterus [14]. We recently showed that phytoestrogens present in soy beans (genistein and daidzein) and their active metabolites (equol and para-ethyl-phenol; respectively) decrease fertility in cows [15].…”

Fitoestrogênios: posicionamento do Departamento de Endocrinologia Feminina da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM)

“…A presença dos xenormônios no ambiente tem causado preocupações sobre o impacto destas substâncias na saúde humana (103). A exposição se dá principalmente pela alimentação e as suas conseqüências estão longe de serem conhecidas, quer durante a vida intra-uterina, quer no desenvolvimento e suas repercussões na reprodução.…”