Reproductive Toxicology 22 (2006) 449–454 Effects of nonylphenol on juveniles and adults in the grey mullet, Liza aurata Cristina Cionna, Francesca Maradonna, Ike Olivotto, Gianluca Pizzonia, Oliana Carnevali ∗ Dipartimento di Scienze del Mare, Universit` a Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy Received 6 October 2004; received in revised form 29 March 2006; accepted 5 April 2006 Available online 13 June 2006 Abstract The aim of this study was to investigate the effects of nonylphenol (NP), an environmental pollutant known to have estrogenic activity, on grey mullets. Juvenile and adult physiology was monitored by the expression of vitellogenin (VTG), which is commonly induced by estrogenic pollutants, and cytochrome P4501A1(CYP1A1) as a first signal of detoxification. The dose–response estrogenic effects of NP (25, 100, 1000 g/l) on hepatic VTG transcript and plasma protein levels, as well as on CYP1A1 transcription and its associated ethoxyresorufin O-deethylase (EROD) activity, were assessed in juvenile Liza aurata; 17-estradiol (E2; 2 g/l) treatment for 1 week served as positive control. In addition, we investigated VTG and CYP1A1 expression in adult males injected with two NP at 0.25 or 250 mg/kg body weight relative to 0.07 mg/kg of E2 as a positive control. Juvenile exposure to NP failed to induce a measurable VTG response. In the adult fish, NP exerted estrogenic effects only at the highest dose injected. E2 treatment elicited VTG induction only in adults in a time-related manner. In contrast, NP treatment induced a dose-dependent decrease in CYP1A1 response in both juveniles and adults. An inhibitory effect of E2 on CYP1A1 was evident in all treatment groups as well. These data suggest that, in biomonitoring studies, testing the expression of different biomarkers may provide a more realistic picture of the environmental conditions. © 2006 Elsevier Inc. All rights reserved. Keywords: Fish; EROD; Estrogens; Liver; Reproduction; Xenobiotics; Pollutants; Detoxification; VTG and CYP1A1 1. Introduction 17-Estradiol and xenoestrogenic compounds such as nonylphenol (NP) induce physiological changes by binding to the estrogen receptor (ER) and subsequent transactivation of downstream genes via estrogen responsive elements (ERE) [1]. Many xenobiotic compounds classified as endocrine disrupters (EDCs) may bind to ER and cause direct adverse effects on reproduction or affect the progeny of various species. NP is considered one of the most critical metabolites of alkylphenol polyethoxylates (APEs) due to enhanced resistance towards biodegradation and toxicity, together with its ability to bioaccumulate in aquatic organisms [2–4]. Recently, estrogenic activity of NP has been documented in a number of in vivo and in vitro studies [2,5,6]. NP exposure has been shown to induce plasma vitellogenin (VTG) and high levels of eggshell zona radi- ∗ Corresponding author. Tel.: +39 071 2204990; fax: +39 071 2204650. E-mail address: o.carnevali@univpm.it (O. Carnevali). ata proteins in juvenile Atlantic salmon (Salmo salar) [7–9]. In medaka, 50% of fish exposed to 50 g/l NP, and 86% of those exposed to 100 g/l NP, displayed an intersex phenotype [10]. Cytochrome P4501A1 (CYP1A1) expression and activity [11] were analyzed by Southern blot and enzymatic assay in light of recent findings in the marine teleost G. niger [12] that showed CYP1A1 is differently modulated by estrogenic and dioxin-like compounds. Specifically, compounds with estrogenic potency were able to inactivate the CYP1A1 detoxification system. It is well known that CYP1A1 detoxification is stimulated via the aryl hydrocarbon receptor (AhR). In fact, CYP1A1 inducers initially bind to cytosolic AhR [13]. Upon ligand binding, AhR dimerizes with the aryl hydrocarbon receptor nuclear translo- cator (ARNT) protein [14] and the heterodimer can transacti- vate genes with a xenobiotic response element (XRE), includ- ing CYP1A1. This is an important system for detoxification through which apolar xenobiotics are converted into water- soluble derivatives. The present study monitored VTG and CYP1A1 as bioindica- tors of fish exposure to environmentally relevant concentrations 0890-6238/$ – see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.reprotox.2006.04.025