Dopamine is in the brain.
Dopamine ( DA , contracted from 3,4-dihydroxyphenethylamine ) is an organic chemical of the catecholamine and phenethylamine families that plays several important roles in the brain and body . The brain includes several distinct dopamine pathways , one of which plays a major role in reward-motivated behavior . Dopamine itself is available as a manufactured medication for intravenous injection : although it can not reach the brain from the bloodstream , its peripheral effects make it useful in the treatment of heart failure or shock , especially in newborn babies .