每日一题_2023.06.14

A woman with a 2-year-old son comes to her physician because she has been unable to conceive a second child for more than a year. The woman is currently breastfeeding her son. Which of the following best explains the physiologic mechanism currently preventing her from getting pregnant?

一名妇女带着两岁的儿子来找她的医生，因为她已经一年多没能怀上第二个孩子了。这名妇女目前正在给她的儿子哺乳。下列哪一项能最好地解释目前阻止她怀孕的生理机制?

(A) Prolactin inhibits secretion of estrogen from the ovaries 催乳素抑制卵巢分泌雌激素

(B) Prolactin inhibits secretion of folliclestimulating hormone from the anterior pituitary gland 泌乳素抑制垂体前叶促卵泡激素的分泌

(C) Prolactin inhibits secretion of gonadotropin-releasing hormone from the hypothalamus 泌乳素抑制下丘脑分泌促性腺激素释放激素

(D) Prolactin inhibits secretion of luteinizing hormone from the anterior pituitary gland 泌乳素抑制垂体前叶的黄体生成素分泌

(E) Prolactin inhibits secretion of progesterone from the corpus luteum 催乳素抑制黄体分泌孕酮

答案解析：

由垂体前叶分泌的催乳素维持泌乳。催乳素通过抑制下丘脑分泌促性腺激素释放激素(GnRH)来阻止排卵。GnRH的减少导致垂体前叶分泌的黄体生成素(LH)和卵泡刺激素(FSH)减少，而这些激素会阻止排卵。如果这名妇女停止给她的儿子哺乳，她可能会有更好的机会怀孕。

正确答案：C