Endocrine disruption by pollutants and effects on progeny

Abstract

As mentioned in Chapter 10, hormonally-regulated functions of crustaceans have been reviewed during the last years by several authors. Main endocrine-regulated processes of crustaceans involve moulting, reproduction, glycemia levels, and pigment migration, among others. Several pollutants, such as pesticides, alkylphenols, polychlorinated biphenyls, hydrocarbons, and heavy metals, can interfere with these processes, therefore acting as endocrine-disrupting compounds (ECDs) on crustaceans, as reviewed by several authors (LeBlanc 2007, Rodríguez et al. 2007, deFur et al. 1999). The hyperglycemic crustacean hormone (CHH) belongs to a highly diversified family of peptide hormones, secreted by the sinus gland at the eyestalks (Nagaraju 2011, Fingerman 1997). This hormone has been considered as the “stress hormone” of crustaceans (Chang et al. 1999). In some cases, a hyperglycemic response has been observed following exposure to cadmium (Reddy et al. 2009), but an eventual inhibition of the CHH synthesis has also been reported (Reddy et al. 1996). Hyperglycemia caused by heavy metals in shrimps also showed dependence on both the time of exposure and concentration (Lorenzon et al. 2000). An inhibition of moulting by several estrogenic compounds, as well as by testosterone, antiandrogens, antiestrogens, and some pesticides, has been reported in daphnids and copepods (LeBlanc 2007, Andersen et al. 2001, Zou and Fingerman 1997). Besides, evidence about a possible antagonism of these compounds with the transductional pathway of ecdysone at target tissues has been provided (Mu and LeBlanc 2002a). Juvenoid compounds, such as methoprene and JHIII have also inhibited moulting, perhaps interfering with the stimulating effect of the juvenoid hormone methyl farnesoate (Olmstead and LeBlanc 2001). Regarding reproduction, several estrogenic compounds, both natural and synthetic, as well as some juvenoids and ecdysteroids, have shown to exert an abnormal stimulation on several aspects of crustacean reproduction. Observed effects were mainly the abnormal development of secondary sexual characters in both sexes, and a shift to all-female or allmale broods. These effects were observed in daphnids (Dodson et al. 1999, Olmstead and LeBlanc 2000), copepods (Andersen et al. 1999), and amphipods (Brown et al. 1999, Watts et al. 2002).