MPEP Hydrochloride is primarily used in neuroscience research as a selective antagonist for the metabotropic glutamate receptor subtype 5 (mGluR5). It is widely applied in studies investigating the role of mGluR5 in various neurological and psychiatric disorders, such as anxiety, depression, and Parkinson's disease. Researchers utilize it to understand the receptor's involvement in synaptic plasticity, learning, and memory processes. Additionally, it is employed in preclinical models to explore potential therapeutic strategies for conditions like fragile X syndrome and addiction, where mGluR5 signaling is implicated. Its ability to modulate glutamate signaling makes it a valuable tool for dissecting the complex mechanisms underlying brain function and disease.