Morphine's receptor target is which receptor?

Morphine's receptor target is which receptor?

• A. Kappa
• B. Delta
• C. Mu receptor
• D. NMDA

Answer: (C)

Morphine binds primarily to mu opioid receptors, a type of G-protein–coupled receptor. When mu receptors are activated, they inhibit adenylate cyclase, reduce cAMP, and promote opening of potassium channels while closing calcium channels. This leads to hyperpolarization of neurons and decreased neurotransmitter release in pain pathways, producing strong analgesia. The mu receptor is also responsible for many characteristic opioid effects, such as respiratory depression and euphoria. There are other opioid receptors, like kappa and delta, that can contribute to analgesia and have different side-effect profiles, but morphine has its highest affinity for the mu receptor, making it the main target. NMDA receptors are a separate glutamate receptor and not the primary target of morphine; NMDA involvement is more about modulation of opioid tolerance and pain signaling, not the direct receptor that morphine activates.

Morphine binds primarily to mu opioid receptors, a type of G-protein–coupled receptor. When mu receptors are activated, they inhibit adenylate cyclase, reduce cAMP, and promote opening of potassium channels while closing calcium channels. This leads to hyperpolarization of neurons and decreased neurotransmitter release in pain pathways, producing strong analgesia. The mu receptor is also responsible for many characteristic opioid effects, such as respiratory depression and euphoria. There are other opioid receptors, like kappa and delta, that can contribute to analgesia and have different side-effect profiles, but morphine has its highest affinity for the mu receptor, making it the main target. NMDA receptors are a separate glutamate receptor and not the primary target of morphine; NMDA involvement is more about modulation of opioid tolerance and pain signaling, not the direct receptor that morphine activates.