This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Puerperium, Subject name: Gynaecology & Obstetrics
[{'content': 'In the mother, suckling leads to which of the following responses? \nSelect and explain. \nA. Decrease of oxytocin, B. Increase of prolactin-inhibiting factor, C. Increase of hypothalamic dopamine, D. Increase of hypothalamic prolactin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The normal sequence of events triggered by suckling is as follows: through a response of the central nervous system, dopamine is decreased in the hypothalamus. Dopamine suppression decreases production of prolactin-inhibiting factor (PIF), which normally travels through a portal system to the pituitary gland; because PIF production is decreased, production of prolactin by the pituitary is increased. At this time, the pituitary also releases oxytocin, which causes milk to be expressed from the alveoli into the lactiferous ducts. Suckling suppresses the production of luteinizing hormone-releasing factor and, as a result, acts as a mild contraceptive (because the midcycle surge of luteinizing hormone does not occur).', 'role': 'assistant'}]