Pramipexole induced place preference promoted after L-dopa therapy and nigral dopaminergic loss: linking behavior to transcriptional modifications
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ABSTRACT: Symptoms of the dopamine dysregulation syndrome in patients with Parkinsonâs disease (PD) are close to those observed in psychostimulant addiction. This suggests that dopamine replacement therapy shares some properties with potentially addictive drugs. A remaining challenge is to understand the neuroadaptations leading to compulsive dopaminergic medication use. To this end, the reinforcing properties of the D2/D3 agonist pramipexole (PPX) were assessed after chronic exposure to L-dopa in an alpha-synuclein PD rat model. Individual male rats underwent a bilateral nigral loss induced by AAV-mediated alpha-synuclein overexpression. Control sham animals received stereotaxic injection of the same AAV vector enabeling expresion of the GFP. Five weeks after lesion induction, animals received a subcutaneous daily administration of L-dopa methyl-ester (50mg/kg) plus benserazide (12,5mg/kg) or a saline solution. Following this 3 weeks period of chronic treatment, the reinforcing properties of the D2/D3 agonist pramipexole were assessed using a place conditioning paradigm. This procedure consists in pairing a drug with a specific environment and vehicle with another environment during a conditioning period. The first day, animals received an intraperitoneal injection of saline solution before a 20min habituation period that allowed exploration of the apparatus (pre-test). Time spent in each chamber was analyzed. The compartment less occupied by the animal was determined as the drug paired side. The following days, animals received either pramipexole 2mg/kg on days 1, 3, 5 and 7 or vehicle on days 2, 4, 6 and 8 and were placed in the paired-chamber for 40 minutes. Controls groups received saline solution during all conditioning sessions. The day following the last conditioning session, a probe test (post test) was performed with 20min free access to the apparatus after an ip injection of saline solution. Place preference scores were calculated as the difference in time spent in the drug-paired chamber between post-test and pre-test.
ORGANISM(S): Rattus norvegicus
SUBMITTER: Simon Loiodice
PROVIDER: E-GEOD-74382 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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