Localization of serotonin 5‐HT2 receptors in living human brain by positron emission tomography using N1‐([11C]‐methyl)‐2‐BR‐LSD

Abstract

N1‐([11C]‐Methyl)‐2‐Br‐LSD ([11C]‐MBL) has been developed as a positron emission tomography (PET) imaging agent for serotonin 5‐HT2 receptors. In vitro receptor binding assays with nonradioactive MBL show high‐affinity binding to serotonin 5‐HT2 receptors (Ki = 0.5 nM), a secondary interaction of 8‐fold lower affinity with dopamine D2 receptors, and low‐affinity interactions with α1‐adrenergic as well as serotonin 5‐HT1 receptors. Intravenous injection of [11C]‐MBL in a baboon led to selective labeling of cortical regions that was markedly blocked by prior administration of ketanserin, a selective 5‐HT2 receptor antagonist. Clinical trials with [11C]‐MBL have been conducted in seven normal h..