Pramipexole induced place preference after L-dopa therapy and nigral dopaminergic loss: linking behavior to transcriptional modifications.

ABSTRACT

RATIONALE Impulsive-compulsive disorders (ICD) in patients with Parkinson's disease (PD) have been described as behavioral or substance addictions including hypersexuality, gambling, or compulsive medication use of the dopamine replacement therapy (DRT). OBJECTIVES: A remaining challenge is to understand the neuroadaptations leading to reward bias in PD patients under DRT. METHODS: To this end, the appetitive effect of the D2/D3 agonist pramipexole was assessed after chronic exposure to L-dopa in an alpha-synuclein PD rat model. RESULTS: Association of progressive nigral loss and chronic L-dopa was required to observe a pramipexole-induced place preference. This behavioral outcome was inhibited by metabotropic glutamate receptor 5 (mGluR5) antagonism while transcriptional profiling highlighted regulations potentially related to the context of psychostimulant addiction. CONCLUSION: This study provides evidences strongly suggesting that PD-like lesion and L-dopa therapy were concomitant factors involved in striatal remodeling underlying the pramipexole-induced place preference. Molecular and pharmacological data suggest a key involvement of the glutamatergic pathway in this behavioral outcome.