This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Mechanism of analgesia is bya) Nociceptin stimulationb) Nocistatin stimulationc) Anandamide receptorsd) Nicotinic & cholinergic receptors \nSelect and explain. \nA. abc, B. acd, C. abd, D. bcd', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Nocistatin stimuli inhibit nociceptors and produce analgesia.\nAnandamide (a cannabinoid) produces analgesic effect by binding to CB1 receptors.\nAcetylcholine and nicotinic cholinergic receptors (subunits α4 and β 2) are involved in regulation of pain.', 'role': 'assistant'}]