Neurobiology

Cocaine works by inhibiting the reuptake of dopamine in the brain. Normally, dopamine is released into the synaptic gap and then reabsorbed into the nerve cells, but cocaine blocks this reuptake process. This results in an accumulation of dopamine in the synaptic cleft, which leads to prolonged stimulation of the post-synaptic neurons. The effect is associated with intense feelings of euphoria and stimulation.
Therefore, cocaine interferes with the normal transport and regulation of dopamine, contributing to its addictive and harmful effects.
Final Answer:
Cocaine.