Endocrine System MCAT Practice Question
A patient with a pituitary adenoma shows elevated prolactin levels (180 ng/mL, normal <25 ng/mL) and reports amenorrhea. When dopamine agonist bromocriptine is administered, prolactin levels normalize within one week. Which of the following best explains the mechanism by which bromocriptine restores reproductive function?
Answer choices
- ABromocriptine directly stimulates GnRH secretion from the hypothalamus
- BBromocriptine inhibits dopamine receptors on lactotroph cells, suppressing prolactin synthesis and secretion
- CBromocriptine mimics dopamine's inhibitory effect on prolactin, allowing GnRH-mediated LH and FSH restorationCorrect answer
- DBromocriptine increases estrogen synthesis in ovarian granulosa cells through direct enzyme upregulation
- EBromocriptine directly stimulates FSH release from gonadotroph cells in the anterior pituitary
- FBromocriptine blocks prolactin receptors on the hypothalamus, thereby removing prolactin's inhibitory feedback on GnRH neurons
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