Tamoxifen as an emerging endocrine disruptor. effects on fish reproduction and detoxification target genes

The effect of tamoxifen (TAM) on the black goby Gobius niger exposed to different contaminants was analyzed by investigating the response of a set of biomarkers involved in reproduction and cell recovery. While the effects of TAM are well known in mammalian breast and endometrial cells (with severe consequences on physiology), few contrasting data are available for fish. In this work the expression of vitellogenin (vtg), estrogen receptor alpha (ERalpha), cytochrome P4501A1 (CYP1A1), and heat shock protein 70 (HSP70) genes was evaluated in fish treated with TAM alone or co-injected with nonylphenol, estradiol, and beta-naphtoflavone. The induction of vtg observed in male fish treated with estrogens was significantly lowered by the co-injection of TAM. ERalpha and HSP70 gene expressions were significantly upregulated in all experimental groups; however, TAM treatment did not change CYP1A1 gene expression. Together these data confirm the mixed estrogenic/anti-estrogenic action of TAM, indicating its interference in fish reproduction and physiology.