Triclosan elevates estradiol levels in serum and tissues of cycling and peri-implantation female mice
Introduction
Triclosan (CAS 3380-34-5) is a synthetic biocide designed to inhibit bacterial reproduction by interacting with enoyl-acyl carrier protein reductase enzymes [1]. It is added to many consumer and household products, including soaps, dish sponges, cosmetics, deodorants, toothpastes, mouthwashes, clothing, and children’s toys [2], [3], [4]. Dermal contact with these products leads to rapid absorption of triclosan into the body through the skin [5], [6], while oral ingestion leads to uptake through the gastrointestinal tract [7]. Based on the 2003–2004 U.S. National Health and Nutrition Examination Survey (NHANES), 74.6% of the 2517 human urine samples contained detectable levels of triclosan, with concentrations ranging from 2.4 to 3790 μg/l [8]. Detection frequency of urinary triclosan in the U.S. population reached a peak between 2007 and 2008 at 80.8%, but has since fallen to 72.0% as of 2011–2012 [9]. Similarly, mean urinary triclosan concentrations in the U.S. population peaked in 2005–2006 at 18.8 μg/L but fell to 12.46 μg/l as of 2011–2012 [9]. Triclosan has also been detected in human serum [10], [11], plasma [12], breast milk [12], [13], and adipose and liver tissue [14].
Triclosan has known estrogenic effects, including stimulating breast and ovarian cancer cell growth in vitro [15], [16] and magnifying the effects of ethinyl estradiol in rodent uterotrophic assays [17], [18]. However, the mechanisms underlying these effects are not well understood. Triclosan binds to both conventional estrogen receptor (ER) subtypes, ERα and ERβ [19], [20]. Thus, exposure to triclosan may induce estrogenic effects by directly activating ER. Triclosan also potently inhibits hepatic sulfotransferase activity [21], [22], [23], thereby reducing sulfonation of endogenous estrogens such as 17β-estradiol (E2) and xenoestrogens such as bisphenol A (BPA) [23]. Thus, exposure to triclosan may potentiate in vivo estrogenic effects by preventing metabolism of estrogens to their biologically inactive forms.
Previous work in this laboratory demonstrated in vivo interactions between triclosan and BPA. When mice were given a single dose of triclosan ranging from 0.2–18 mg, greater levels of 14C-BPA were detected in serum and tissues including the heart, lung, muscle, uterus, ovaries, and epididymides, than in animals given 14C-BPA alone [24]. Other studies indicated that either triclosan or BPA can disrupt blastocyst implantation in inseminated female mice [25], [26], [27], [28], [29], and that doses of BPA or triclosan that were insufficient on their own to have effects could disrupt implantation when the two substances were given concurrently [29]. These findings are consistent with the notion that triclosan inhibits BPA conjugation [23], permitting higher levels of BPA to interact with ER in tissues such as the uterus.
Whereas BPA is a weakly estrogenic environmental chemical, E2 is the most potent natural estrogen. Any deviations from normal E2 levels might lead to adverse health effects, as estrogen levels are tightly regulated and play critical roles in development, fertility, and behavior [30]. Of especial importance to human health is the consistent finding that elevated E2, often through hormone-replacement therapy, is associated with an increased risk of breast [31], endometrial [32], and ovarian [33] cancers. Also, in inseminated females, minute elevations in estrogen activity can impede blastocyst implantation, leading to pregnancy failure [30], [34]. Given the fact that triclosan exposure is ubiquitous, its potential capacity to modulate estrogen levels or activity in vivo is worthy of investigation. Here we investigated the impact of single or repeated triclosan injections on concentrations of exogenous tritium-labeled estradiol (3H-E2) and endogenous urinary E2. We hypothesized that a single injection of triclosan would elevate 3H-E2 levels in reproductive tissues of cycling and peri-implantation female mice, and that this effect would be more pronounced with repeated triclosan injections over multiple days. We also hypothesized that triclosan administration would increase endogenous E2 concentrations as measured in urine.
Section snippets
Animals and housing
Female mice aged 3–5 months were of CF–1 strain and obtained from Charles River (Kingston, NY). Animals were housed in standard polypropylene cages measuring 28 × 16 × 11 (l × w × h) cm with wire tops allowing ad libitum access to food (8640 Teklad Certified Rodent Chow; Harlan Teklad, Madison, WI) and water, except where otherwise stated. The colony was maintained at 21 °C with a reversed 14 h light:10 h darkness cycle. All procedures adhered to the standards of the Canadian Council on Animal Care and
Experiment 1: measurement of 3H-E2 in cycling females after repeated triclosan doses
Radioactivity was measured in the peripheral tissues of cycling females that received daily sc injections of triclosan followed by an ip injection of 1 μCi 3H-E2 (Fig. 1). The impact of triclosan on 3H-E2 concentrations was most prominent in the reproductive tissues of females; mice given 2 mg triclosan had mean radioactivity levels that were 5.4 and 2.9 times higher than those of controls in the uterus and ovaries respectively. Statistical comparisons were made among the three treatments for
Discussion
To the best of our knowledge, these data are the first to show that triclosan modulates the concentrations of exogenous and endogenous E2 in vivo. We have shown this using two strategies. First, we found enhanced uptake of 3H-E2 in the uterus and other tissues of female mice that received triclosan. Second, after triclosan administration, we observed an elevation in endogenous E2 as reflected in urinary measures. We measured urinary E2 given evidence that enzyme immunoassay cannot reliably
Acknowledgements
This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada awarded to D. deCatanzaro (RGPIN/1199-2010, EQPEQ/390407-2010). We greatly appreciate the assistance of Edwin Wong, Leanna Mantella, and Tharshni Velauthapillai with experimental procedures.
References (58)
- et al.
Mechanism of triclosan inhibition of bacterial fatty acid synthesis
J. Biol. Chem.
(1999) - et al.
National and regional assessment of the antibacterial soap market: a step toward determining the impact of prevalent antibacterial soaps
Am. J. Infect. Control
(2001) - et al.
Percutaneous penetration and dermal metabolism of triclosan (2 4,4′-trichloro-2′-hydroxydiphenyl ether)
Food Chem. Toxicol.
(2000) - et al.
Ten-year trends in urinary concentrations of triclosan and benzophenone-3 in the general U.S. population from 2003 to 2012
Environ. Pollut.
(2016) - et al.
The influence of age and gender on triclosan concentrations in Australian human blood serum
Sci. Total Environ.
(2008) - et al.
Sensitive and selective method for the determination of bisphenol-A and triclosan in serum and urine as pentafluorobenzoate-derivatives using GC–ECNI/MS
J. Chromatogr. B
(2009) - et al.
Triclosan in plasma and milk from Swedish nursing mothers and their exposure via personal care products
Sci. Total Environ.
(2006) - et al.
Triclosan in individual human milk samples from Australia
Chemosphere
(2011) - et al.
Distribution of bisphenol-A, triclosan and n-nonylphenol in human adipose tissue, liver and brain
Chemosphere
(2012) - et al.
Methoxychlor and triclosan stimulates ovarian cancer growth by regulating cell cycle- and apoptosis-related genes via an estrogen receptor-dependent pathway
Environ. Toxicol. Pharmacol.
(2014)
The effect of triclosan on the uterotrophic response to extended doses of ethinyl estradiol in the weanling rat
Reprod. Toxicol.
Triclosan is a potent inhibitor of estradiol and estrone sulfonation in sheep placenta
Environ. Int.
Triclosan exacerbates the presence of 14C-bisphenol A in tissues of female and male mice
Toxicol. Appl. Pharmacol.
Bisphenol-A exposure during the period of blastocyst implantation alters uterine morphology and perturbs measures of estrogen and progesterone receptor expression in mice
Reprod. Toxicol.
Impact of acute bisphenol-A exposure upon intrauterine implantation of fertilized ova and urinary levels of progesterone and 17β-estradiol
Reprod. Toxicol.
Influence of oral and subcutaneous bisphenol-A on intrauterine implantation of fertilized ova in inseminated female mice
Reprod. Toxicol.
Stress lowers the threshold dose at which bisphenol A disrupts blastocyst implantation, in conjunction with decreased uterine closure and e-cadherin
Chem. Biol. Interact.
Disruption of blastocyst implantation by triclosan in mice: impacts of repeated and acute doses and combination with bisphenol-A
Reprod. Toxicol.
Sex steroids as pheromones in mammals: the exceptional role of estradiol
Horm. Behav.
Ovarian cancer and hormone replacement therapy in the Million Women Study
Lancet
Presence and bioavailability of bisphenol A in the uterus of rats and mice following single and repeated dietary administration at low doses
Reprod. Toxicol.
Non-invasive repeated measurement of urinary progesterone 17β-estradiol, and testosterone in developing, cycling, pregnant, and postpartum female mice
Steroids
Estrogen–progesterone balance in the context of blastocyst implantation failure induced by predator stress
Psychoneuroendocrinology
Comparison of ethinylestradiol pharmacokinetics in three hormonal contraceptive formulations: the vaginal ring, the transdermal patch and an oral contraceptive
Contraception
Potential estrogenic activity of triclosan in the uterus of immature rats and rat pituitary GH3 cells
Toxicol. Lett.
Sulfonation of 17β-estradiol and inhibition of sulfotransferase activity by polychlorobiphenylols and celecoxib in channel catfish, Ictalurus punctatus
Aquat. Toxicol.
Parabens inhibit human skin estrogen sulfotransferase activity: possible link to paraben estrogenic effects
Toxicology
Occurrence, efficacy, metabolism, and toxicity of triclosan
J. Environ. Sci. Health C
Triclosan: a critical review of the experimental data and development of margins of safety for consumer products
Crit. Rev. Toxicol.
Cited by (26)
Triclosan induces earlier puberty onset in female mice via interfering with L-type calcium channels and activating Pik3cd
2024, Ecotoxicology and Environmental SafetyInvolvement of sirtuins (Sirt1 and Sirt3) and aryl hydrocarbon receptor (AhR) in the effects of triclosan (TCS) on production of neurosteroids in primary mouse cortical neurons cultures
2022, Pesticide Biochemistry and PhysiologyCitation Excerpt :In addition, it has been evidenced that TCS can cause genotoxic, hepatotoxic, immunotoxic, neurotoxic, and cardiotoxic effects and interfere with the reproductive function and development of organisms (Ashley-Martin et al., 2016; Du et al., 2018; Huang et al., 2020; Parenti et al., 2019; Szychowski et al., 2020, 2019, 2015). There is also an increasing number of publications describing the role of TCS as an endocrine disruptor (Farmer et al., 2018; Ha et al., 2018; Honkisz et al., 2012; Kumar et al., 2009, 2008; Pollock et al., 2016). TCS has been shown to interfere with the synthesis and/or secretion of progesterone (P4), testosterone (T), and estradiol (E2); moreover, these effects were dependent on the time, dose, sex, and even the physiological state of the body (Farmer et al., 2018; Ha et al., 2018; Honkisz et al., 2012; Kumar et al., 2009, 2008; Pollock et al., 2016).
The triclosan-induced shift from aerobic to anaerobic metabolism link to increased steroidogenesis in human ovarian granulosa cells
2021, Ecotoxicology and Environmental SafetySeasonal transfer and quantification of urinary estradiol in the big brown bat (Eptesicus fuscus)
2020, General and Comparative EndocrinologyTriclosan exposure and ovarian reserve
2019, Reproductive Toxicology