Induction of
motor disorders is considered the clinical landmark differentiating typical from atypical
antipsychotics, and has been mainly correlated to
dopamine D2 receptors blockade in striatum. This view is challenged by
benzamides, such as
amisulpride, which display low liability for motor side effects despite being D2/D3 receptors high-affinity blocking agents. These effects have been explained with the prominent presynaptic action of
amisulpride or with the fast dissociation at D2 receptors, but there is scarce information on the effects of
amisulpride on postsynaptic signaling. We carried out a molecular imaging study of gene expression after acute administration of
haloperidol (0.8 mg/kg),
amisulpride (10 or 35 mg/kg), or vehicle, focusing on postsynaptic genes that are key regulators of synaptic plasticity, such as
Arc, c-fos, Zif-268,
Norbin, Homer. The last one has been associated to
schizophrenia both in clinical and preclinical studies, and is differentially induced by
antipsychotics with different D2 receptors affinity. Topography of gene expression revealed that
amisulpride, unlike
haloperidol, triggers transcripts expression peak in medial striatal regions. Correlation analysis of gene expression revealed a prevalent correlated gene induction within motor corticostriatal regions by
haloperidol and a more balanced gene induction within limbic and motor corticostriatal regions by
amisulpride. Despite the selective dopaminergic profile of both compounds, our results demonstrated a differential modulation of postsynaptic molecules by
amisulpride and
haloperidol, the former impacting preferentially medial regions of striatum whereas the latter inducing strong gene expression in lateral regions. Thus, we provided a possible molecular profile of
amisulpride, putatively explaining its "atypical atypicality".