A drug that mimics a neurotransmitter at the receptor site and strengthens its effects is called:

1. Agonists are chemicals that mimic a neurotransmitter at the receptor site and thereby strengthen its effects. 2. Antagonists do the opposite, blocking or impeding the normal activity of a neurotransmitter at the receptor. 3. Both bind to receptor sites, which is what separates them from reuptake inhibitors. 4. Parkinson's disease is associated with low dopamine, so dopamine agonists are one treatment, while antipsychotics act as dopamine antagonists. _Source: OpenStax Psychology (1st ed., CC BY 4.0), Ch 3 "Biopsychology", §3.2 Cells of the Nervous System_