The effects of selected Endocrine disruption on reproductive physiology in fish

MSc. Azadeh HATEF

Doctoral thesis

Abstract:

In the present study, both in vitro and in vivo experiments were performed to investigate modes of action of selected EDCs including mercury chloride (HgCl2), bisphenol A (BPA), vinclozolin (VZ) and Di-(2-ethylhexyl)-phthalate (DEHP) on male reproductive physiology in fish. Results obtained from in vitro studies showed that EDCs decrease sperm motility via disruption in energetics and damage to spermatozoa; however the effective doses are higher than reported in the environmentally relevant concentrations. In contrast, in vivo studies showed adverse effects of BPA, VZ, and DEHP on sperm quality at environmentally relevant concentrations. Decrease in sperm quality is associated with disruption in testicular steroidogenesis, particularly inhibition of androgens. Only BPA induced vitellogenin production, associated with increase in transcripts of estrogen receptor, androgen receptor and cytochrome P450 mRNA at the high dose approaching environmental level. Inhibition of androgen production is due to disruption in transfer of cholesterol into the steroidogenesis pathway, because transcript of steroidogenic acute regulatory protein mRNA was decreased. In addition, BPA acts through sex steroid-mediated mechanism while DEHP mode of action is sex-steroid independent mechanism.

Abstract:

In the present study, both in vitro and in vivo experiments were performed to investigate modes of action of selected EDCs including mercury chloride (HgCl2), bisphenol A (BPA), vinclozolin (VZ) and Di-(2-ethylhexyl)-phthalate (DEHP) on male reproductive physiology in fish. Results obtained from in vitro studies showed that EDCs decrease sperm motility via disruption in energetics and damage to spermatozoa; however the effective doses are higher than reported in the environmentally relevant concentrations. In contrast, in vivo studies showed adverse effects of BPA, VZ, and DEHP on sperm quality at environmentally relevant concentrations. Decrease in sperm quality is associated with disruption in testicular steroidogenesis, particularly inhibition of androgens. Only BPA induced vitellogenin production, associated with increase in transcripts of estrogen receptor, androgen receptor and cytochrome P450 mRNA at the high dose approaching environmental level. Inhibition of androgen production is due to disruption in transfer of cholesterol into the steroidogenesis pathway, because transcript of steroidogenic acute regulatory protein mRNA was decreased. In addition, BPA acts through sex steroid-mediated mechanism while DEHP mode of action is sex-steroid independent mechanism.

Keywords

bisphenol A, Di-(2-ethylhexyl)-phthalate, mercury chloride, sperm quality, steroids, vinclozolin, vitellogenin

Language used: English

Date on which the thesis was submitted / produced: 27. 4. 2012

Accessible from:: 27. 4. 2012

Thesis defence

• Date of defence: 12. 9. 2012

UNIVERSITY OF SOUTH BOHEMIA IN ČESKÉ BUDĚJOVICE

Faculty of Fisheries and Protection of Waters

Doctoral programme / field:
Zootechnics / Fishery