Impact of Intrafollicular Sulfated Steroids on Follicular Cells and the Oocyte's Developmental Capacity in Cattle

• Applicant: Professorin Dr. Christine Wrenzycki
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 152381467

Steroid hormones are essential in orchestrating oocyte maturation, i.e. estrogens of follicular origin support the development of the female gamete and fertilization. In this project the concentration of free and conjugated estrogens during follicular development will be analysed and compared to local concentrations in the developing follicle. Cattle are suitable animal models because of the accessibility and suitability for frequent examination and sampling. Furthermore, it has been useful for understanding several features of human reproduction including follicular dynamics, the fate of the emerging follicles is orchestrated mainly by gonadotropins and steroid hormones in a similar manner. Ovarian SULT1E1 participates locally in the regulation of follicular estrogen activity. The ESTcatalysed down-regulation of estrogen activity enables normal ovulation. Conversely, sulfoconjugated estrogens may also be precursors of the production of free estrogens depending on estrogen sulfatase (StS) acitivity. In mammals, follicular luteinisation/ovulation is triggered by a surge in LH and is characterised by numerous physical and biochemical changes, including the decreased production of estradiol (E2). This loss in E2 biosynthetic capacity has been explained by a marked decrease in the expression of key steroidogenic enzymes involved in the follicular production of active estrogens. However, little is known about the regulation of enzymes/proteins responsible for the inactivation and elimination of estrogens, as mediated for example by EST during this period.

• DFG Programme: Research Units
• Subproject of: FOR 1369: Sulfated Steroids in Reproduction
• Participating Person: Dr. Hanna Stinshoff