system
Given the following post, respond as if you're commenting on Reddit:
human
Is it true that the brain can run out of dopamine?

My friend and I were in psychology class and that class, we were studying the affects of drugs on the brain, and he told me that the brain can eventually run out of dopamine, so if you do too many drugs, you'll never be able to feel happy again.

Is this true? It seems doubtful.
gpt
No, not true unless of course you kill off your dopamine-producing neurons (such as in Parkinson's, though that's a different pathway than the reward circuitry in your brain). What happens during prolonged drug usage is your neurons lose sensitivity to dopamine (DA) through decreased production of DA and decreased amounts of DA receptors among other things, but you don't "run out". Your brain is just trying to maintain status quo, so when you artificially increase the amounts of DA that are released your brain actively tries to counteract this by producing less of these things. So, it's an active and deliberate process whereby your neurons decrease production of DA, not a passive running out.