Exposure to E2 and EE2 environmental concentrations affect different components of the Brain-Pituitary-Gonadal axis in pejerrey fish (Odontesthes bonariensis)

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

“…Modifications in plasma E 2 , T and 11-KT in response to EE 2 exposure in fish 12 , 43 , 44 including the gilthead seabream, depends on the reproductive stage at which it occurs 7 , 8 . The effect of EE 2 on the testis histology depended on the dose and higher doses had a more pronounced effect in common with previous reports in the gilthead seabream 8 , 35 and other teleost fish 13 , 45 . Although in our previous study we reported that 5 µg EE 2 /g food caused a reduction in the sperm concentration in gilthead seabream at the spermatogenesis stage 35 .…”

“…Although in our previous study we reported that 5 µg EE 2 /g www.nature.com/scientificreports/ food caused a reduction in the sperm concentration in gilthead seabream at the spermatogenesis stage 35 . It was not possible to obtain sperm samples from the fish fed 5 µg EE 2 /g food in the present study, although similar observations have been made in pejerrey mature males exposed to 45 ng EE 2 /L during the spawning season 13 . Less attention has been paid to the effect of EE 2 exposure on pituitary hormones 13,18,19 .…”

“…It was not possible to obtain sperm samples from the fish fed 5 µg EE 2 /g food in the present study, although similar observations have been made in pejerrey mature males exposed to 45 ng EE 2 /L during the spawning season 13 . Less attention has been paid to the effect of EE 2 exposure on pituitary hormones 13,18,19 . The doses used in this study had a variable effect on pituitary expression levels of fshb (decreased with 5 µg EE 2 /g food) and lhb (increased by 2.5 µg EE 2 /g food).…”

“…In adult Gobio cyprisrarus of both sexes, mRNA levels of fshb were not affected and lhb gene transcripts were suppressed by 1-125 ng EE 2 /L 19 . In contrast, in pejerrey (Odontesthes bonariensis) exposure of mature males to 45 ng/L of EE 2 did not affect pituitary expression levels of lhb or fshb 13 .…”

“…The expression of the gene coding for vitellogenin (Vtg, a protein normally synthesized by females during oocyte maturation) and/or plasma levels of Vtg in male fish are reference markers widely used for estrogenic disruption 6 – 8 , 12 . Alterations in reproductive endpoints such as plasma levels of steroid hormones 7 – 9 , 12 , 13 , gonad morphology 6 – 9 , 13 , 14 and the expression levels of genes coding for estrogenic receptors or for steroidogenic enzymes 8 – 10 , 13 help to assess the disruptive effects of this compound which vary according to dose, time of exposure, age and the stage in the reproductive cycle of the treated individuals 7 , 8 , 17 . However, only a few studies have dealt with the effect of EE 2 on the expression of genes coding for the β subunit of gonadotropins, luteinizing hormone ( lhb ) and follicle stimulating hormone ( fshb ) 13 , 18 , 19 , that are regulated by E 2 in some species 20 , 21 and are essential for regulation of gametogenesis and gonadal differentiation in fish.…”