Gonadotrophin control of follicular function

Area of Science:

• Reproductive Endocrinology
• Molecular Endocrinology
• Ovarian Physiology

Background:

• Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are crucial for follicular development and estradiol synthesis.
• Previous studies lacked pure FSH and LH preparations, hindering definitive understanding of their individual roles.
• The availability of recombinant human FSH (rec-FSH) and LH (rec-LH) enables precise investigation of their functions.

Purpose of the Study:

• To elucidate the specific contributions of rec-FSH and rec-LH in regulating ovarian function.
• To investigate the role of LH in optimizing ovarian responsiveness to FSH.
• To provide insights into the clinical interpretation of 'pure' FSH preparations in therapeutic regimens.

Main Methods:

• Hypophysectomized immature female rats were treated with varying doses of rec-FSH and/or rec-LH.
• Ovarian responsiveness was assessed by measuring steroidogenesis in isolated granulosa and thecal cells.
• Gene expression analysis (Northern blot, in situ hybridization) of cytochrome P-450c17 (P-450C17) was performed.

Main Results:

• Recombinant FSH demonstrated the capacity to influence LH-responsive androgen synthesis.
• A paracrine mechanism involving the upregulation of thecal P-450C17 mRNA was identified.
• These findings highlight the intricate interplay between FSH and LH in ovarian steroidogenesis.

Conclusions:

• Pure rec-FSH can modulate LH-dependent androgen production, suggesting a significant role beyond direct follicular stimulation.
• The study clarifies the distinct yet cooperative roles of FSH and LH in ovarian function.
• Results have implications for understanding and optimizing assisted reproductive technologies.