The other side of the histamine H3 receptor.

Although histamine H3 receptors are predominantly known as presynaptic receptors, regulating the release of neurotransmitters such as dopamine, acetylcholine, and histamine, in the striatal complex the vast majority of these receptors are actually located on the other side, in other words postsynaptically. Given their strategic location, they can crucially affect signaling throughout the basal ganglia. We describe the anatomy and function of H3 receptors within the basal ganglia with a specific focus on their colocalization with dopamine D1 and D2 receptors. Because the basal ganglia are centrally involved in several major neurological and psychiatric disorders, we also discuss the therapeutic potential of drugs targeting H3 receptors in the treatment of Parkinson disease (PD), schizophrenia, and addiction.