Exam 1 - Prolactin Releasing Hormone

prolactin releasing hormone stimulates what tropic cells? what kind of hormone is this? what mechanism is used?

lactotrophs

peptide

phospholipase c

dopamine and PIH inhibit lactotrophs through which mechanism? what kind of hormone are they?

inhibition of adenylyl cyclase

amine

lactotrophs will release prolactin when stimulated, what kind of protein is this? What mechanism does it use

peptide

tyrosine kinase

when do levels of prolactin in the blood increase

during pregnancy

what is the major action of prolactin

stimulation of milk production and secretion in response to suckling

prolactin stimulates milk production by inducing synthesis of what components of milk in the mammary glands

lactose, casein, lipids

why does lactation not occur during pregnancy even though prolactin levels are high

higher levels of estrogen and progesterone down regulate prolactin receptors

prolactin uses a ____ feedback loop

positive

hypopituitarism caused by abnormal pressure on the pituitary gland or damage to it causes destruction to the anterior lobe resulting in ___ deficiency

prolactin - failure to lactate after giving birth

what is the most common cause of prolactin deficiency

Sheehan Syndrome

what is Sheehan syndrome characterized by?

postpartum pituitary necrosis due to excessive blood loss during or after childbirth

what nucleus of the hypothalamus makes dopamine? if this is damaged, what can result?

arcuate

less dopamine produces = interrupt hypothalamic-hypophyseal tract of dopamine = increase prolactin secretion

which nucleus of the hypothalamus can become over active and cause excess secretion of prolactin

paraventricular

if TRH increase, what happens to prolactin levels

increase

what are the major symptoms of excess prolactin

galactorrhea and infertility

why is infertility of women a symptom of excess prolactin

- high prolactin levels = inhibit GnRH = inhibits ovulation by decreasing FSH and LH

why is infertility of men a symptom of excess prolactin

inhibition of GnRH = decrease spermatogenesis

how can excess prolactin levels be treated

bromocriptine which is a dopamine agonist