Tamoxifen disrupts the reproductive process in gilthead seabream males and modulates the effects promoted by 17alpha-ethynylestradiol

17α-ethynylestradiol (EE2), which is used in oral contraceptives and hormone replacement therapy, is a well documented estrogenic endocrine disruptor and an aquatic contaminant. In the present study, adult male specimens of the marine hermaphrodite teleost gilthead (Sparus aurata L.) were fed a diet containing tamoxifen (Tmx), an estrogen receptor ligand used in cancer therapy, alone or combined with EE2, for 25 days and then fed a commercial diet for a further 25 days (recovery period). The effects of short (5 days) and long (25 days) treatments on several reproductive and gonad immune parameters and the reversibility of the disruptive effects after the recovery period were examined. Our data showed that Tmx acted as an estrogenic endocrine disruptor as revealed by the increase in the hepatic transcription of the vitellogenin gene in males, the serum levels of 17β-estradiol and the gonad expression levels of the estrogen receptor α and G protein-coupled estrogen receptor genes, and the recruitment of leukocytes into the gonad, a well known estrogenic-dependent process in gilthead seabream males. On the other hand, Tmx also increased sperm concentration and motility as well as the serum levels of androgens and the expression levels of genes that codify for androgenic enzymes, while decreasing the expression levels of the gene that code for gonadal aromatase. When applied simultaneously, Tmx and EE2 could act in synergy or counteract, each other, depending on the parameter measured. The disruptive effect of EE2 and/or Tmx was not reversible after a 25 day recovery period.Postprin

17α‑ethynylestradiol prevents the natural male‑to‑female sex change in gilthead seabream (Sparus aurata L.)

Exposure to 17α-ethynylestradiol (EE2, 5 μg/g food) impairs some reproductive events in the protandrous gilthead seabream and a short recovery period does not allow full recovery. In this study, spermiating seabream males in the second reproductive cycle (RC) were fed a diet containing 5 or 2.5 μg EE2/g food for 28 days and then a commercial diet without EE2 for the remaining RC. Individuals were sampled at the end of the EE2 treatment and then at the end of the RC and at the beginning of the third RC, 146 and 333 days after the cessation of treatment, respectively. Increased hepatic transcript levels of the gene coding for vitellogenin (vtg) and plasma levels of Vtg indicated both concentrations of EE2 caused endocrine disruption. Modifications in the histological organization of the testis, germ cell proliferation, plasma levels of the sex steroids and pituitary expression levels of the genes coding for the gonadotropin β-subunits, fshβ and lhβ were detected. The plasma levels of Vtg and most of the reproductive parameters were restored 146 days after treatments. However, although 50% of the control fish underwent sex reversal as expected at the third RC, male-to female sex change was prevented by both EE2 concentrations.Ministerio de Ciencia e Innovación and FEDER (AGL2014-53167-C3-1R, -2-R; AGL2017-85978-C2-1-R; RTI2018-096625-B-C33) and the Fundación Séneca (CARM) (19883/GERM/15).Versión del editor2,92

Endocrine disrupter chemicals affect the humoral antimicrobial activities of gilthead seabream males even upon the cease of the exposure

17α-ethynilestradiol (EE2) and tamoxifen (Tmx) are pollutants world-wide distributed in aquatic environments. Gilthead seabream, Sparus aurata L., is highlighted as a species model of intensively culture in anthropogenic disturbed environments. The effects of these pollutants on gilthead seabream reproduction and some immune responses have been described but, the humoral innate antimicrobial activities have never received attention. In this work we analysed the latest in the plasma of gilthead seabream males of different ages and reproductive stages treated with 0, 2.5, 5 or 50 μg EE2 or 100 μg Tmx g−1 food during different times of exposure and of reverting to commercial diet (recovery). The peroxidase and protease activities decreased as the spermatogenesis of the first reproductive cycle (RC) proceeded in control fish. However, only protease and antiprotease activities showed different level at different stages of the second RC in control fish, but showed scarce disruption in fish treated with EE2 or Tmx. Peroxidase and bactericide activities are more sensitive to EE2, than to Tmx. The effects induced by EE2 varied depending on the activity analyzed, the dose and the time of exposure and the reproductive stage and the age of the specimens.Versión del editor2,92

Effect of 17alpha-ethynylestradiol on steroidogenesis and gonadogenesis in wean gilthead seabream larvae

A wide variety of chemicals discharged from industrial and municipal sources have been reported to disrupt the endocrine system of animals, which may be exposed via the food chain and contaminated water. 17α-ethinylestradiol (EE2), a drug used in oral contraceptives and hormone replacement therapy, has a widespread presence in the aquatic environment. Current knowledge on the sensitivity of marine fish reproductive system to estrogenic environmental chemicals is limited. Interestingly, the resistance of EE2 to degradation should not be underestimated and for instance, determining the impact of the intake of low levels of EE2 with the food on fish reproduction is mandatory. We report here the effects of dietary intake of EE2 on gilthead seabream recently weaned larvae (50 days post-hatching, dph) during 100 days of exposure (150 dph) on the gene expression profile of several steroidogenic-relevant genes and T, E2 and 11KT larvae levels in order to asses the degree of endocrine disruption induced by the treatment and secondly, we have analyzed the gonadogenesis of these treated specimens after 100 days of exposure (150 dph) and after a recovery period of 50 days (200 dph) in order to determine the sensibility of the gonadogenesis process to endocrine disrupted chemicals