The principal mechanism by which narcotics yield euphoria involves interaction with which of the following?

The principal mechanism by which narcotics yield euphoria involves interaction with which of the following?

• A. Endorphin receptors
• B. Dopamine transporters
• C. NMDA receptors
• D. Serotonin reuptake

Answer: (A)

Opioids produce euphoria by activating the brain’s endogenous opioid system, specifically endorphin receptors (mu-opioid receptors). When these receptors are engaged in reward-related circuits, they inhibit local GABAergic neurons, which normally dampen dopamine signaling. With the brake lifted, dopamine release in the nucleus accumbens increases, producing the felt euphoria. The other systems listed play roles in different drugs or processes (dopamine transporters relate to stimulant effects, NMDA receptors to glutamate signaling and plasticity, serotonin reuptake to serotonin is a separate pathway). But for narcotics, the key action is binding to endorphin receptors and triggering the dopamine-driven reward response.

Opioids produce euphoria by activating the brain’s endogenous opioid system, specifically endorphin receptors (mu-opioid receptors). When these receptors are engaged in reward-related circuits, they inhibit local GABAergic neurons, which normally dampen dopamine signaling. With the brake lifted, dopamine release in the nucleus accumbens increases, producing the felt euphoria.

The other systems listed play roles in different drugs or processes (dopamine transporters relate to stimulant effects, NMDA receptors to glutamate signaling and plasticity, serotonin reuptake to serotonin is a separate pathway). But for narcotics, the key action is binding to endorphin receptors and triggering the dopamine-driven reward response.