5 OH DPAT

5-OH-DPAT is a synthetic compound that acts as a dopamine receptor agonist with selectivity for the D₂ receptor and D₃ receptor subtypes. Only the (S)-enantiomer is active as an agonist, with the (R)-enantiomer being a weak antagonist at D₂ receptors. Radiolabelled ¹¹C-5-OH-DPAT is used as an agonist radioligand for mapping the distribution and function of D₂ and D₃ receptors in the brain, and the drug is also being studied in the treatment of Parkinson's disease.