Daily rhythms count for female fertility

Area of Science:

• Neuroendocrinology
• Reproductive Biology
• Chronobiology

Background:

• Female ovulation is triggered by a luteinizing hormone (LH) surge, requiring high estradiol levels.
• The timing of this surge is influenced by both estradiol feedback and the body's master circadian clock, located in the suprachiasmatic nuclei.

Purpose of the Study:

• To review the mechanisms by which daily time cues regulate the pre-ovulatory LH surge in females.
• To explore the role of the suprachiasmatic nuclei in timing reproductive events.

Main Methods:

• This review synthesizes existing research on the neuroendocrine pathways involved in ovulation timing.
• Focuses on the communication between the suprachiasmatic nuclei and reproductive hypothalamic neurons.

Main Results:

• The suprachiasmatic nuclei convey daily time cues to reproductive neurons.
• In female rodents, specific neurotransmitters from the suprachiasmatic nuclei activate kisspeptin neurons and inhibit RFRP neurons in the late afternoon of proestrus, facilitating the LH surge.

Conclusions:

• Daily time cues are critical for precisely timing the pre-ovulatory LH surge.
• Circadian disruptions, such as those from shift work, warrant investigation for their impact on female fertility and reproductive performance in humans and animal models.