Endogenous opioids have what effect on pain and mood?

• A. Increase pain and decrease mood
• B. Reduce pain and increase euphoria
• C. Have no effect on pain
• D. Increase pain and increase anxiety

Answer: (B)

Endogenous opioids modulate both pain and mood by activating opioid receptors in the central nervous system. When these natural opioids (endorphins, enkephalins, and dynorphins) bind to mu, delta, and kappa receptors, they dampen the transmission of pain signals and also engage reward/mood pathways, producing analgesia and a sense of well-being or euphoria.

That combination—lowered pain perception and increased mood—is why the option describing reduced pain and increased euphoria is the best fit. They don’t typically increase pain or anxiety, and they do have a real, not absent, effect on pain and mood.