Differential Binding of Endogenous Steroids and Chemicals to Androgen Receptors in Rainbow Trout and Goldfish

Abstract

Abstract-Androgen receptors (ARs) from fish were characterized in order to evaluate differences in the binding affinities of steroids and environmental chemicals between mammals and fish, among species of fish, and among target tissues within a species of fish. High-affinity, low-capacity ARs were identified in cytosolic fractions of rainbow trout brains (Oncorhynchus mykiss) and the brains, ovaries, and testes of goldfish (Carassius auratus) using [ 3 H]testosterone. The binding specificities of endogenous steroids to the ARs did not differ between goldfish tissues but did differ between goldfish and rainbow trout. Interspecies differences in binding specificities were also seen using cyproterone acetate, which bound to the ARs in the goldfish tissues, but not in the rainbow trout brains. The mammalian antiandrogens flutamide, vinclozolin and its metabolites 2-(((3,5)-dichlorophenyl-carbamoyl)oxy)-2-methyl-3-butenoic acid and 3Ј,5Ј-dichloro-2-hydroxy-2-methylbut-3-enanilide, along with procymidone did not bind to the ARs in any of the fish tissues tested. However, other mammalian antiandrogens including methoxychlor and its metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane, o,pЈ-DDT, o,pЈ-dichlorodiphenyldichloroethylene (DDE) and p,pЈ-DDE did bind to the fish ARs, but only in the goldfish testes, demonstrating tissue differences in AR binding specificities of environmental chemicals. These results may be due to the presence of multiple AR isoforms in the different fish species and tissues. This study supports the growing evidence of species differences in the potency and actions of endocrine-disrupting chemicals and suggests that multiple species need to be tested when screening the receptor binding ability of potential endocrine-disrupting chemicals.

In ovo exposure to o,p -DDE affects sexual development but not sexual differentiation in Japanese medaka (Oryzias latipes).

“…Although estrogens at this concentration can cause sex reversal (Papoulias et al 1999), the comparatively lower affinity of o,p´-DDE and o,p´-DDT for the ER (Nimrod and Benson 1997) suggests that higher exposures of these compounds are required for sex reversal to occur. Nevertheless, o,p´-DDT and o,p´-DDE at low concentrations may interfere with the binding of natural ligands to a variety of steroid binding moieties (e.g., receptors and binding proteins) (Danzo 1997;Donohoe and Curtis 1996;Gaido et al 1997;Kupfer and Bulger 1976;Lundholm 1998;Mason and Schulte 1980;Nimrod and Benson 1997;Shilling and Williams 2000;Wells and Van Der Kraak 2000), thereby allowing for endocrine-disrupting effects.…”

“…However, like o,p´-DDT, o,p´-DDE is believed to work through the ER and to have a similar ER agonist potency (Donohoe and Curtis 1996), and exposure to o,p´-DDE has been associated with decreased fecundity and fertility and increased early oocyte atresia (Hose et al 1989). Recently, Wells and Van Der Kraak (2000) showed that o,p´-DDE and o,p´-DDT will also bind to the androgen receptor in goldfish (Carassius auratus) but not rainbow trout (Oncorhynchus mykiss) testes at approximately half the affinity of p,p´-DDE. o,p´-DDE has even been shown to bind to the progesterone receptor in the eggshell gland mucosa of egg-laying ducks and domestic fowl and to the endometrium of the rabbit uterus (Lundholm 1988).…”

Rapid, Hierarchical Modulation of Vocal Patterning by Steroid Hormones

“…To directly investigate the possibility of steroid specificity, we used two steroid receptor antagonists, cyproterone acetate (CA; an anti-androgen) and mifepristone (RU486; an antiglucocorticoid). CA selectively interferes with androgens binding to the androgen receptor in goldfish brain (Wells and Van Der Kraak, 2000) and has been shown to be an effective androgen antagonist in many fish species (Billard, 1982;Kindler et al, 1991;Singh and Joy, 1998;Kiparissis et al, 2003). A more recently developed androgen receptor antagonist, flutamide, does not bind to androgen receptors in teleost brain (Wells and Van Der Kraak, 2000), necessitating the use of CA.…”

“…CA selectively interferes with androgens binding to the androgen receptor in goldfish brain (Wells and Van Der Kraak, 2000) and has been shown to be an effective androgen antagonist in many fish species (Billard, 1982;Kindler et al, 1991;Singh and Joy, 1998;Kiparissis et al, 2003). A more recently developed androgen receptor antagonist, flutamide, does not bind to androgen receptors in teleost brain (Wells and Van Der Kraak, 2000), necessitating the use of CA. RU486 is a commonly used glucocorticoid receptor antagonist (it is also an antiprogesterone) and has been shown to interfere with rapid, nongenomic effects of glucocorticoids in other systems (Liu et al, 1995;Roozendaal et al, 2002;He et al, 2003).…”

Screening of multiple hormonal activities in surface water and sediment from the Pearl River system, South China, using effect‐directed in vitro bioassays

“…Several contaminants have been shown to have the ability to bind to estrogen receptors or androgen receptors, thus disrupting the normal endocrine functions in organisms [1,2]. These endocrine-disrupting chemicals (EDCs) are derived from natural or anthropogenic sources and have been widely detected in sewage treatment plant (STP) effluents [3,4], treated industrial wastewater [5], river surface water [6], and river sediment [7].…”