Physiology disruptors

As an example of suspected endocrine disruptors (EDs), studies of the estrogenic action of bisphenol A (BPA) have been in progress in medical, physiological, and biological fields. In this situation, physicochemical approaches are required to get the structural information of BPA trapped in biomembranes. Most recently, we have determined the site and the orientation of BPA trapped in phospholipid vesicles by NMR, using the HCS rule [47]. In particular, we have succeeded in monitoring the NMR spectral changes of phospholipid vesicles, which are induced by the BPA delivery. 

Figure 7 shows the effect of ectopic administration of T3 to the developing zebrafish embryo. At nontoxic concentration (50 nM), only a moderate fraction (less than 5%) of the zebrafish transcriptome shows significant changes. Ossification, visual processes, and the hematopoietic system were the physiological processes most affected by the treatment, in a pattern consistent with an advancement of the development in these particular functions (Fig. 7b). Genes involved in these three processes are known targets for TDCs during metamorphosis in amphibians, teleost fishes, and lampreys [54—60], and constitute molecular counterparts of different endpoints used to test for TDC in amphibians [56, 58]. Therefore, they are excellent candidates for markers of thyroid disruptors in zebrafish at early developmental stages. Chapter 14 provides a more in-deep description of the developmental effects of thyroid disruption in zebrafish embryos.

Choi KC, Leung PC, Jeung EB. 2005. Biology and physiology of Calbindin-D9k in female reproductive tissues involvement of steroids and endocrine disruptors. Reprod Biol Endocrinol 3 66. 

Endocrine disruption is a newly discovered mode of action and has encouraged a great deal of research. Compared to some of the other mechanisms described in this chapter, endocrine disruption is more subtle with alterations in reproductive physiology and morphology often being the effects, instead of death. Because of the hormone-like activity, these compounds can have identifiable effects at very low concentrations. It is not yet clear what the overall importance of endocrine disruptors are in creating environmental impacts compared to other modes of action. 

Endocrine disruptors are exogenous chemicals (for example, PCBs) that enter the body and act like hormones. They can dismpt physiology, sometimes with devastating consequences. Startling evidence from animal studies shows that male fish in detergent-contaminated water express female characteristics, turtles are sex-reversed by PCBs, male frogs exposed to a common herbicide form multiple ovaries, pseudohermaphroditic offspring are produced by polar bears found in contaminated waters, and seals in contaminated water have an excess of uterine fibroids.46... 

Can we expect environmental endocrine disruptors to affect the sexual development of the human fetus In my opinion, the answer is an absolute yes, if only because we know that endocrine disruptors act like foreign hormones and thereby disrupt natural hormone physiology. Hormones are critical in fetal sexual and brain development. Exposure of the fetus to hormones can produce profound changes in development. In the case of androgenic hormones, for example, exposure diverts a genetic female to take on the phenotypic appearance of a male, and these hormones change the areas of the brain that ordinarily differ between the sexes (sexually dimorphic areas). 

Palanza P, Morellini F, Parmigiani S et al (1999) Prenatal exposure to endocrine disrupting chemicals effects on behavioral development. Neurosci Biobehav Rev 23(7) 1011-1027 Patisaul HB, Adewale HB (2009) Long-term effects of environmental endocrine disruptors on reproductive physiology and behavior. Front Behav Neurosci 3 1-10... 

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