Bioactivity of gonadotropins.

Area of Science:

• Endocrinology
• Reproductive Biology
• Molecular Endocrinology

Background:

• Gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), are crucial for reproductive function.
• These hormones circulate as heterogeneous isoforms with distinct bioactive to immunoreactive potentials.
• Understanding isoform variations is key to comprehending reproductive development.

Purpose of the Study:

• To differentiate the roles of bioactive versus immunoreactive gonadotropin isoforms.
• To highlight the significance of bioactivity measurements in understanding human puberty.
• To review methodological advances in gonadotropin isoform analysis.

Main Methods:

• In vitro bioactivity assays defining LH's T production and FSH's E2 production.
• Measurement of immunologic potencies using specific antibodies.
• Comparison of bioactivity and immunoreactivity results, especially for FSH.

Main Results:

• Bioactivity measurements revealed greater functional excursions than immunologic potencies, particularly for FSH.
• Gonadotropin isoforms stimulate postreceptor binding functions, influencing G-protein activation.
• Current isoform separation methods lack the precision to distinguish all functional variants.

Conclusions:

• Bioactivity measurements provide a more comprehensive assessment of gonadotropin function than immunoreactivity alone.
• Understanding gonadotropin isoform heterogeneity is vital for studying human puberty.
• Methodological advancements in bioactivity assays enhance our comprehension of reproductive endocrinology.