Effects of Nonylphenol and Triclosan on Production of Plasma Vitellogenin and Testosterone in Male South African Clawed Frogs (Xenopus laevis)

Abstract

Recently, a number of studies have been performed worldwide to examine endocrine-disrupting chemicals (EDCs) and their interactions with the development and function of various systems in animals and humans.1-3) Among these EDCs, alkylphenol polyethoxylate non-ionic surfactants are used in the manufacture of cleaning agents, cosmetics and food products, as well as in plastic polymerization processes. Nonylphenol ethoxylates have predominantly been used, amounting to about 80% of the production of alkylphenol surfactants. In a recent study, nonylphenol (NP) had significant effects on the reproductive potential of medaka (Oryzias latipes) at concentrations as low as 17.7 mg/l, 4) and 50% of the male fish in the 50 mg/l treatment and 86% of the males in the 100 mg/l treatment developed testis-ova, an intersex condition characterized by both testicular and ovarian tissue in the gonad. 5) On the other hand, triclosan (TCS, 2,4,4Ј-trichloro-2Ј-hydroxydiphenyl ether) is widely used as an antibacterial agent in liquid toothpaste, soap, shampoo, and cosmetics, and is frequency found in wastewater effluent. Water samples collected near the outfall of a wastewater treatment plant in Rhode Island, U.S.A., showed 10-20 mg/l of TCS in the effluent and 80-100 mg/g of TCS in the sediment.6,7) Our previous study suggests that TCS has high toxicity on the early life stages of medaka, and that the metabolite of TCS may be a weak estrogenic compound in male medaka but with no adverse effect on reproductive success (such as fecundity and fertility) and offspring. 8) Moreover, Hanioka et al. 9,10) reported that 7-benzyloxyresorufin Odebenzylase (BROD) and 7-pentoxyresorufin O-depentylase (PROD) activities, which are associated with CYP2B1 activity, were remarkably induced by all doses of TCS in rats. Their results suggested that TCS induces the P450 isoforms of the CYP2B subfamily in the rat liver, and that the induced P450 isozymes were closely related to the toxicity of TCS or its chlorinated derivatives. However, there is no information about the effects of these chemicals on the hormonally responses of amphibian. 11)The South African clawed frog (Xenopus laevis) is sensitive to environmental chemicals as it spends all the life stages (egg, larva, and adulthood) in water. Hayes et al. 12) examined the effects of atrazine on sexual development in X. laevis, and reported that atrazine (Ͼ or ϭ0.1 mg/l) induced hermaphroditism and demasculinized the larynx of exposed males (Ͼ or ϭ1.0 mg/l), and male X. laevis suffered a 10-fold decrease in testosterone levels when exposed to 25 mg/l atrazine. Therefore, in the present study, we used X. laevis as a test organism, and investigated the effects of NP and TCS on production of plasma vitellogenin (Vg, egg yolk protein precursor), steroid hormone testosterone (T) synthesis, and hepatic CYP1A and CYP2B, as measured by the ethoxyresorufin O-deethylase (EROD) or PROD activities in male X. laevis. To our knowledge, this is first study on the effect of TCS in male X. laevis. MATERIALS AND MET...

Reproductive endocrine-disrupting effects of triclosan: Population exposure, present evidence and potential mechanisms

“…No obvious changes in the sex ratio or sexually dimorphic fin traits were found in the TCS-treated group, although the lack of estrogenic effects in this study was possibly due to a relatively lower dosage (Foran et al, 2000). However, in another study on male Xenopus laevis, exposure to TCS (4e400 mg/g body weight, 14 days) lowered the plasma Vtg and testosterone levels, indicating antiestrogenic effects (Matsumura et al, 2005).…”

Distinct expression and activity profiles of largemouth bass (Micropterus salmoides) estrogen receptors in response to estradiol and nonylphenol

“…This level of induction (1 ng/ml) is similar to physiological levels seen in female LMB during active reproduction and corresponds to peak levels observed in this species during the annual reproductive cycle. Although NP has been shown to interact directly with the ERs of numerous species (White et al 1994, Kuiper et al 1998, Balaguer et al 1999, Nishikawa et al 1999, Gale et al 2004), a few reports have suggested that the estrogenic effects of NP in vivo are the result from altered levels of endogenous steroids (Acevedo et al 2005, Matsumura et al 2005, Soverchia et al 2005. Exposure of fathead minnows to NP also resulted in increased levels of plasma E 2 with a concomitant decrease in testosterone (Soverchia et al 2005).…”

Effects of Triclosan and Triclocarban, Two Ubiquitous Environmental Contaminants, on Anatomy, Physiology, and Behavior of the Fathead Minnow (Pimephales promelas)

“…Further studies demonstrated that TCS might exhibit weak estrogenic activity because concentrations of hepatic vitellogenin were increased in male medaka fry exposed to 20 lg/l and 100 lg/l TCS (Ishibashi et al 2004) and in mature male western mosquitofish (Gambusia affinis) treated with TCS at 101.3 lg/l TCS in laboratory exposure experiments (Raut and Angus 2010). However, male South African clawed frogs (Xenopus laevis) injected with 4, 40, or 400 lg/g TCS (per body weight) exhibited decreased plasma vitellogenin and testosterone levels, suggesting that TCS may possess estrogen-antagonist activity (Matsumura et al 2005). In vitro studies also confirmed that TCS possesses both estrogenic and androgenic activity in assays with breast cancer cells ) and receptor-based bioassay screens (Ahn et al 2008).…”