All dopaminergic neurons have both of these enzymes and can therefore make dopamine . Cells that make norepinephrine and epinephrine also produce these two enzymes. But they don't release dopamine. In the CNS and PNS that's the end of story, but to be complete, the adrenal glands have these three enzymes and another, let's just call it enzyme number 4, which converts the norepinephrine into epinephrine before it is released. Certainly there must be agonist and antagonists for the family.
Antagonists Let's do dopamine first.
Dopamine does have several different receptor types. They are called D1, D2, D3, etc. receptors. Sounds like chemists named them to me. It is used to treat diseases like Parkinson's disease because, unlike dopamine, L-dopa crosses the blood brain barrier. Giving L-Dopa to Parkinson's disease patients works as long as neurons with amino acid decarboxylase are still functioning in the brain.