Acute and chronic haloperidol treatments increase parkin mRNA levels in the rat brain

Mutations in the parkin gene cause autosomal recessive juvenile parkinsonism. We examined the effects of acute and chronic treatment with haloperidol on parkin mRNA expression in the rat brain by reverse transcription-polymerase chain reaction. Acute haloperidol treatment (2 mg/kg) increased parkin mRNA levels in the striatum and nucleus accumbens but not in the medial prefrontal cortex and substantia nigra. Four-week-treatment with haloperidol decanoate (25 mg eq/kg) produced a significant increase in parkin mRNA levels in the striatum without affecting to those in the medial prefrontal cortex, nucleus accumbens and substantia nigra. These results suggest that Parkin may be involved in the haloperidol-induced synaptic plasticity, since Parkin regulates the turnover of the synaptic protein, CDCrel-1.

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.