A77636 hydrochloride is primarily used in neuroscience research as a selective dopamine D1 receptor agonist. It is employed to study dopaminergic signaling pathways in the brain, particularly in models related to movement disorders, cognition, and reward mechanisms. Due to its ability to cross the blood-brain barrier, it is valuable in in vivo studies examining the effects of D1 receptor activation on behavior and neuronal activity. Researchers also use it to investigate potential therapeutic targets for Parkinson’s disease, schizophrenia, and drug addiction, where dopamine receptor function is disrupted. Its selectivity makes it a useful tool for distinguishing D1-mediated effects from those involving other dopamine receptor subtypes.