Bovine Reproductive Hormones
In mammals, the hormonal control of reproduction involves the complicated interplay of hormones
produced by the hypothalamic-pituitary-ovarian (HPO) axis of the endocrine system.
These hormones:
- initiate ovulation
- regulate the estrous cycle
- allow fertilization
- prepare the uterus for the fertilized ovum
- maintain pregnancy
- initiate parturition
- control lactation
The key female reproductive hormones and their actions are summarized below. Under the control of
higher centers in the brain, gonadotropin-releasing hormone (GnRH) originating in the hypothalamus
regulates release of the pituitary hormones called follicle-stimulating hormone (FSH) and luteinizing
hormone (LH). These hormones, also called gonadotropins because of their effect on the gonads, in
turn control the production of the steroids estrogen and progesterone by the ovary. These steroids
have both negative and positive feedback effects on gonadotropin secretion. (Negative feedback
inhibits secretion; positive feedback stimulates secretion.)
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Key Female Reproductive Hormones and Their Actions
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Hormone
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Produced By
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Action
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Gonadotropin-releasing hormone (GnRH)
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Hypothalamus
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Releases LH and FSH
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Follicle-stimulating hormone (FSH)
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Anterior pituitary
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Stimulates growth of ovarian follicles
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Luteinizing hormone (LH)
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Anterior pituitary
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Regulates ovulation and formation of corpus
luteum
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Estrogen
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Ovarian follicle
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Controls estrous behavior and LH surge
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Progesterone
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Corpus luteum
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Maintains pregnancy-compatible uterus
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Prostaglandin F2alpha (PGF2alpha)
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Nonpregnant uterus
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Causes regression of corpus luteum
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