Final answer:
Naloxone is the opiate antagonist that reduces the analgesic effects of morphine and acupuncture, acting by blocking opioid receptors to reverse the effects of opioids like morphine.
Step-by-step explanation:
The opiate antagonist that reduces the analgesic effects of morphine and acupuncture is Naloxone. Naloxone is a medication designed to rapidly reverse opioid overdose; it binds to opioid receptors and can block the effects of opioids, essentially reversing the depressant effects including analgesia. Unlike other options such as morphine, acetaminophen, or ibuprofen which are analgesics with varying mechanisms of action, Naloxone acts specifically as an opioid antagonist. It is particularly useful in emergency situations where opioid intoxication has caused life-threatening respiratory depression. It differs from naltrexone, which is another opiate antagonist, because it is not well absorbed orally and has a shorter duration of action, but is impactful in immediate overdose interventions.