Breat anatomy and Prolactin

How many lobes does each breast have?

15-20 lobes

What are the septae between the lobes called?

Cooper’s ligaments

What is the functional unit of the breast?

Alveoli

What is an aka for the alveoli?

Acinus (acini)

What two cell types make up the aveoli of the breast?

Epithelial cells that are milk producing

Myoepithelial cells- surround epithelia cells and contract

Myoepithelial cells have receptors for which hormone?

Oxytocin

Lactotroph cells have receptors for which hormone and what is the affect?

Prolactin - begin producing milk

What did the lactiferous ducts connect to?

Nipple

What cells respond to prolactin and where are they?

Alveolar cells in the epithelial tissue of the breast

What and where are the cells that release prolactin?

Lactotoph cells in the anterior pituitary

What growth does prolactin stimulate?

Mammogenesis- growth of breast tissue

Can prolactin help with parent-infant bonding?

YES

What does abnormally high levels of prolactin in the first trimester lead to?

Increased risk of gestational diabetes

What hormones inhibit prolactin during pregnancy?

Estrogen and progesterone

Where does the estrogen and progesterone come from during pregnancy early and later on?

Early: corpus luteum

Later: placenta

What causes prolactin to be released?

Positive feedback to suckling - sensory neuron

Estrogen and progesterone inhibit what genetic expression of the alveoli?

Alveolar receptors for prolactin

What makes dopamine? Where are those neurons?

TIDA- tuberoinfundibular dopamine neurons In the Arcuate Nucleus of hypothalamus

What hormone binds to the lactotroph cells to inhibit prolactin production?

Dopamine binds to D2 receptors

What receptor does dopamine bind to inhibit prolactin production?

D2 receptor on lactotrophs of anterior pituitary

What inhibits dopamine release stopping it’s inhibition on prolactin production?

Baby suckling inhibits TIDA which inhibits dopamine

Do lactotrophs have a releasing factor?

No as of yet discovered

How does suckling/nipple stimulation cause the release of Thyrotropin releasing hormone (TRH)?

Suckling sends signals to hypothalamus, specifically the parvocellular neurons of the paraventricular nucleus, which stimulates the release of TRH from anterior pituitary

What does thyroid releasing hormone (TRH) normally do?

Normally stimulates the release of thyroid stimulating hormone from thyrotrpes in the ant pit which stimulate the thyroid gland to make T3 and T4

What hormone acts as a “pseudo- prolactin releasing hormone”?

Thyroid Release Hormone - binds to lactotrophs

What is the most common type of pituitary tumor?

Prolactinoma

What is Prolactinoma?

Neuroendocrine tumor of the anterior ptiuitary gland made of mutated lactotroph cells that overproduce prolactin

Overproduction of prolactin leads to?

Hyperprolactinemia

What do high levels of prolactin inhibit?

Hypothalamic secretion of gonadotropin-releasing hormone (GnRH) from arcuate nucleus

What are gonadotropic hormones?

Luteinizing hormone (LH)

Follicle-stimulating Hormone (FSH)

What stimulates LH and FSH release?

Gonadotropins (GnRH)

What does hyperprolactinemia cause?

Inhibition of GnRH from arcuate nucleus of hypothalamus

What are the effects of not enough GnRH secretion?

Not enough testosterone or estrogen will be produced causing hypogonadism

Symptoms of hypogonadism?

Dys/amenorrhea

Decreased sex drive

Disrupted spermatogenesis (inferitility)

Breast lactation is fairly rare

What is the most common clinical finding of a Prolactinoma?

Loss of peripheral vision = tunnel vision

What is the Prolactinoma pressing on when there’s tunnel vision?

Center of optic chiasm

What type of headache is associated with Prolactinoma?

Frontal headed

A tumor in the sella trucica takes out which field of vision and which nerve pathway?

Takes out both nasal retina which presents as temporal field visual loss