Drugs Effects on the Extracellular Presence of Dopamine
Normally:Dopamine is released in response to an action as a reward. Dopamine is then reabsorbed into the presynaptic neuron or is broken down.
Cocaine: Dopamine is released in response to the drug's presence, but reabsorbtion of dopamine is blocked. Thus, dopamine accumulates in the synapse and stimulates the reciever cell.
Amphetamines: Dopamine is released in large quantities in response to the drug's presence. The amount of dopamine in the synapse overwhelms the process of re-uptake and breakdown.
Nicotine: Nicotine stimulates the release of dopamine while a second substance in cigarettes blocks the chemical MAO which would normally breakdown dopamine in the synapse.
*Adapted from Time article "Addicted"
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