The transcription factor NGFI-B (Nur77) and retinoids play a critical role in acute neuroleptic-induced extrapyramidal effect and striatal neuropeptide gene expression

Despite extensive investigation, the cellular mechanisms responsible for neuroleptic actions remain elusive. We have previously shown that neuroleptics modulated the expression of some members of the ligand-activated transcription factors (nuclear receptors) including the nerve-growth factor inducible gene B (NGFI-B or Nur77) and retinoid X receptor (RXR) isoforms. Using genetic and pharmacological approaches, we investigated the role of NGFI-B and retinoids in acute behavioral and biochemical responses to dopamine antagonists, NGFI-B knockout (KO) mice display a profound alteration of haloperidol-induced catalepsy and striatal neuropeptide gene expression. Haloperidol-induced increase of striatal enkephalin mRNA is totally abolished in NGFI-B KO mice whereas the increase of neurotensin mRNA expression is reduced by 50%. Interestingly, catalepsy induced by raclopride, a specific dopamine D-2/D-3 antagonist is completely abolished in NGFI-B-deficient mice whereas the cataleptic response to SCH 23390, a dopamine D agonist, is preserved. Accordingly, the effects of haloperidol on striatal c-fos, Nor-1, and dynorphin mRNA expression are also preserved in NGFI-B-deficient mice. The cataleptic response and the increase of enkephalin mRNA expression induced by haloperidol can also be suppressed by administration of retinoid ligands 9-cis retinoic acid and docosahexaenoic acid. In addition, we demonstrate that haloperidol enhances colocalization of NGFI-B and RXRgamma1 isoform nnRNAs. suggesting that both NGFI-B and a RXR isoform are highly coexpressed after haloperidol administration, Our data demonstrate, for the first time, that NGFI-B and retinoids are actively involved in the molecular cascade induced by neuroleptic drugs.