What type of receptors does Naltrexone act on?

Naltrexone is a medication that specifically acts on opioid receptors in the brain. These receptors, which include mu, delta, and kappa subtypes, are primarily involved in the modulation of pain, reward, and addictive behaviors. Naltrexone serves as an opioid antagonist, meaning it blocks the effects of opioids at these receptors. This characteristic makes it particularly useful in the treatment of opioid dependence as it can help reduce cravings and the rewarding effects associated with opioid use.

In contrast, dopamine receptors are involved in the brain's reward system and the regulation of movement, serotonin receptors are primarily associated with mood regulation and a variety of other physiological functions, and GABA receptors play a crucial role in inhibitory neurotransmission. These receptor systems serve different functions and are not the target of Naltrexone, further underscoring why opioid receptors are the correct answer in this context.