Office Hours
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Questions can be directed to the Office Manager of the Fertility Center between 8:00
a.m. to 4:00 p.m. I will try to respond to all questions within 24 hours except on
weekends.
E-Mail: esther.pherrin@hsc.utah.edu
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Oxytocin means quick birth. In 1906, Sir Henry Dale discovered uterotonic bioactivity
in extracts of the posterior pituitary. Oxytocin is a nonapeptide synthesized in the
magnocellular neurons of the supraoptic and paraventricular neurons. Oxytocin
prohormone is transported with a carrier protein, neurophysin, along the axons to the
neural lobe of the posterior pituitary and membrane-bound vesicles for storage and
later release. Progesterone acts to prevent lactogenesis itself, but with progesterone
withdrawal after the placenta delivers, lactogenesis begins. Suckling on the breasts by
the newborn induces episodic secretion of oxytocin from the maternal
neurohypophysis. Oxytocin acts on the myoepithelial cells of the breast ducts to cause
milk let-down.
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Males with decreased libido may have low testosterone levels secondary to
hyperprolactinemia. Hyperprolactinemia may act to suppress pulsatile GnRH release.
Hyperprolactinemia should be considered as a potential cause of hypoandrogenism and
subsequent decreased libido.
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Dopamine is the predominant physiologic prolactin inhibitory factor. The axon's
response will further release dopamine into the median eminence originate in the
perykaryons in the arcuate ventral medial nucleus of the hypothalamus. Other
inhibitory factors include gonadotropin-associated peptide (GAP), gamma
aminobutyric acid, histidyl-proline, diketopiperazine, pyroglutamic acid, and
somatostatin.
Renal Failure and Hyperprolactinemia
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Hyperprolactinemia occurs in 73% to 91% of women and 25% to 57% of men with end-
stage renal disease. Prolactin metabolism is delayed in renal failure, and there is also
increased production. Correction of renal failure with transplantation causes a return
of prolactin levels to normal. Hyperprolactinemia may play a role in the hypogonadism
found in many patients with chronic renal failure.
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It appears that approximately 28% of women with galactorrhea and normal menses
have elevated prolactin levels. One-third of women with hyperprolactinemia have
pituitary adenomas. Two-thirds of women with galactorrhea and amenorrhea have
hyperprolactinemia.
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Increased vascularity results in a characteristic violet color of the vagina during pregnancy.
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Compressibility and softening of the cervical isthmus (the portion of the cervix between the uterus and the vaginal portion of the cervix).
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Significant softening of the vaginal portion of the cervix.