Hormones of the Anterior Pituitary Gland Flashcards
• Initiation and maintenance of lactation
PROLACTIN
Prolactin
• Inhibited by_____
dopamine (hypothalamus)
Prolactin
Circadian Secretion Pattern:
• Highest levels (zenith): Prolactin secretion peaks during_____, allowing for optimal conditions for lactation preparation.
• Lowest levels (nadir): Prolactin secretion reaches its lowest point between______
sleep
10 am and noon.
PROLACTIN
FUNCTION
• Stimulates milk production in the breast (casein, lactalbumin)
• Stimulates breast development (in a supportive role with estrogen)
• Inhibits ovulation by decreasing synthesis and release of gonadotropin-releasing hormone (GnRH)
• Inhibits spermatogenesis (by decreasing GnRH)
Prolactin stimulates the mammary glands to produce milk by increasing the synthesis of proteins like (2)
casein and lactalbumin
Inhibition of Ovulation: Prolactin reduces the synthesis and release of_______
This reduction lowers the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), preventing ovulation and acting as a natural contraceptive mechanism during breastfeeding.
gonadotropin-releasing hormone (GnRH)
Inhibition of Spermatogenesis: In males, high levels of prolactin decrease____, leading to lower levels of LH and FSH, which can inhibit spermatogenesis (sperm production).
GnRH
Factors that Increase Prolactin Secretion
Estrogen (pregnancy)
Breast-feeding
Sleep
Stress
TRH
Dopamine antagonists
Factors that Decrease Prolactin Secretion
Dopamine
Bromocriptine (dopamine agonist)
Somatostatin
Prolactin (by negative feedback)
PROLACTIN
DISORDERS
• results in the failure to lactate
• Due to pituitary necrosis or infarction
Prolactin Deficiency
PROLACTIN
DISORDERS
• results from hypothalamic destruction, or from prolactin-secreting tumors
(prolactinomas).
• causes galactorrhea and decreased libido.
• causes failure to ovulate and amenorrhea because it inhibits
GnRH secretion.
Prolactin Excess
• A pituitary tumor that directly secretes prolactin
• Most common type of functional pituitary tumor.
PROLACTINOMA
PROLACTIN
TESTING
• Serum half-life:______
• Laboratory
• Screening:____ specimens should be obtained at______ intervals
-_________ assay
26-47 minutes
3
20 to 30-minute
Immunometric assay
Prolactin levels are commonly measured using an________. This type of test uses antibodies to detect and quantify the amount of prolactin in the blood.
immunometric assay
Dopamine antagonists
Increase prolactin
TRH
Increase prolactin
Stress
Increase prolactin
Sleep
Increase prolactin
Breast-feeding
Increase prolactin
Estrogen (pregnancy)
Increase prolactin
Prolactin (by negative feedback)
Decrease prolactin
Somatostatin
Decrease prolactin
Bromocriptine (dopamine agonist)
Decrease prolactin
Dopamine
Decrease prolacitn