Originally Posted by VegasGirl1

Dopamine is commonly associated with the pleasure system of the brain, providing feelings of enjoyment and reinforcement to motivate us to do certain activities. Dopamine is released (particularly in areas such as the nucleus accumbens and striatum) by naturally-rewarding experiences such as food, sex, use of certain drugs and neutral stimuli that become associated with them. This theory is often discussed in terms of drugs (such as cocaine and amphetamines), which seem to be directly or indirectly related to the increase of dopamine in these areas, and in relation to neurobiological theories of chemical addiction, which argue that these dopamine pathways are pathologically altered in addicted persons. However, cocaine and amphetamine have different mechanisms of action. Cocaine is a dopamine transporter blocker: it competitively inhibits dopamine uptake to increase the lifetime of dopamine. On the other hand, amphetamines act as dopamine transporter substrates to competitively inhibit dopamine uptake and increase dopamine efflux via a dopamine transporter.