Interleukin-8 as an essential factor in the human chorionic gonadotropin-induced rabbit ovulatory process: interleukin-8 induces neutrophil accumulation and activation in ovulation

Area of Science:

• Reproductive biology
• Immunology
• Endocrinology

Background:

• Ovulation is a complex physiological process critical for reproduction.
• The role of inflammatory mediators, such as cytokines and neutrophils, in ovulation is increasingly recognized.
• Hormone-induced ovulation models are crucial for studying the underlying mechanisms.

Purpose of the Study:

• To investigate the specific involvement of interleukin-8 (IL-8) in the human chorionic gonadotropin (hCG)-induced ovulatory process in rabbits.
• To determine the relationship between IL-8 production and neutrophil activity during hCG-induced ovulation.
• To assess the impact of inhibiting IL-8 or neutrophil elastase (NE) on ovulation rates.

Main Methods:

• Rabbits were administered hCG to induce ovulation.
• Ovarian levels of IL-8, myeloperoxidase (MPO) activity (neutrophil accumulation marker), and neutrophil elastase (NE) activity (neutrophil activation marker) were measured over time.
• The effects of intravenous administration of anti-rabbit IL-8 antiserum and intraperitoneal injection of a specific NE inhibitor (ONO-5046) on MPO activity, NE activity, and ovulation rate were evaluated.

Main Results:

• IL-8 production peaked at 4 hours, preceding the peaks in MPO activity (6 hours) and NE activity (9 hours).
• Administration of anti-rabbit IL-8 antiserum significantly reduced hCG-induced MPO and NE activities and inhibited the ovulation rate.
• The NE inhibitor ONO-5046 also attenuated the hCG-induced ovulation rate.

Conclusions:

• Interleukin-8 (IL-8) is significantly involved in the hCG-induced ovulatory process in rabbits.
• IL-8 mediates ovulation through the recruitment and activation of neutrophils.
• Targeting IL-8 or neutrophil activity presents a potential strategy for modulating ovulation.