Selective, Non-nucleotidic Radiotracer for P2Y₁₂ Receptors: Design, Synthesis, Characterization, and Imaging of Brain...

Area of Science:

• Neuroscience
• Pharmacology
• Radiochemistry

Background:

• The P2Y12 receptor (P2Y12R), expressed by microglial cells, plays a role in neuroinflammation and is a potential biomarker.
• Developing selective radioligands is crucial for visualizing and targeting P2Y12R in the brain.

Purpose of the Study:

• To design and characterize a potent and selective non-nucleotidic radioligand for the P2Y12 receptor.
• To evaluate the utility of [3H]PSB-22219 as a tool for neuroinflammation research and diagnostics.

Main Methods:

• Synthesis and stability testing of the non-nucleotidic P2Y12 antagonist PSB-22219.
• Radioligand binding assays using recombinant and native P2Y12R preparations (human platelets, rat brain, mouse microglia).
• Autoradiography studies in a humanized rat model to visualize P2Y12R expression.

Main Results:

• [3H]PSB-22219 demonstrated high-affinity binding to human P2Y12R (KD = 4.57 nM) with low nonspecific binding.
• The radioligand effectively characterized native P2Y12R in human platelets, rat brain cortex, and mouse microglia, with microglia showing high expression.
• Autoradiography visualized P2Y12R overexpression in the brain of a humanized rat model.

Conclusions:

• [3H]PSB-22219 is a potent and selective radioligand for P2Y12R.
• This radioligand is a valuable tool for studying neuroinflammation and P2Y12R expression in the brain.
• The findings support the development of P2Y12R-targeting therapeutics and radiodiagnostics.