© Daniel A. Anderson/UCI
The researchers report that antipsychotics side-effects are due to blockade of the dopamine D2 receptor in a specialized type of neurons in the striatum, called interneurons. Blockade of D2 receptor in these neurons increases neurotransmitter signaling (acetylcholine) above threshold on neighbor neurons leading to motor abnormalities in rodents (catalepsy) which correspond to parkinsonism in humans. Catalepsy is marked by severe muscular rigidity and fixity of posture regardless of external stimuli. Indeed, in mouse studies, the Borrelli team discovered that removing D2 receptors in nerve cells (cholinergic interneurons) did not result in catalepsy in the mice upon antipsychotic treatment.
Borrelli said the importance of this study is twofold.