Long-term treatment with haloperidol decreases the mRNA levels of complexin I, but not complexin II, in rat prefrontal cortex, nucleus accumbens and ventral tegmental area.

The effect of long-term treatment with haloperidol on gene expression of the presynaptic protein complexins was investigated in the discrete brain regions of rats, using reverse transcription-polymerase chain reaction. Four-week-treatment with haloperidol decanoate (25 mg eq/kg) produced a significant decrease in the mRNA levels of complexin I in the medial prefrontal cortex, nucleus accumbens and ventral tegmental area, but not in the striatum and substantia nigra. No significant changes in complexin II mRNA levels were observed in any brain region examined here. The reduced expression of complexin I may be associated with the haloperidol-induced depolarization block of mesocorticolimbic dopamine neurons.