Progesterone-releasing_intravaginal_device
Progesterone devices are broadly used in the control of reproductive management in livestock. They work by increasing circulating plasma progesterone levels with the following consequences:
- Progesterone suppresses the secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus. This is done via a negative feedback to the hypothalamus neuroendocrine cells, by inhibition of KiSSpeptin KiSS1-derived peptide receptor, a protein needed for the release of GnRH.
- Low levels of GnRH prevent the emergence of a dominant follicle by reducing the release of LH and FSH hormones. Current follicular waves cease and a new wave emerges 3–5 days after implant.
- A dominant follicle develops but there is no ovulation as LH release is prevented by suppression of GnRH.
- Removal of progesterone device produces a surge of GnRH, generating a pulse of LH that induces ovulation.
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