Dopamine

Dopamine is an important neurotransmitter in the brain. It can also be supplied as a sympathomimetic drug, i.e. a drug which acts on the sympathetic nervous system, producing effects such as increased heart rate and blood pressure.

Shortage of dopamine has been implicated in neurological diseases such as Parkinson's disease. Overabundance of dopamine in the brain is believed to cause paranoia and hallucinations in schizophrenia and after abuse of some drugs.