Parkinson's disease (PD) is a debilitating disorder resulting in severe motor dysfunction caused by progressive degeneration of the substantia nigra dopaminergic neurons. L-dihydroxyphenylalanine (L-DOPA) therapy alleviates the motor symptoms, however the utility of this agent for chronic treatment is limited due to the occurrence of abnormal involuntary movements known as dyskinesia. An understanding of how L-DOPA modulates signaling pathways in the striatum of PD is important in devising an effective treatment for L-DOPA induced dyskinesia (LID). Among the signaling molecules associated with LID is extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK) whose activation in medium spiny neurons has been associated with induction of LID. Preliminary results from our laboratory have shown that ERK is mainly activated in striatal cholinergic neurons with long-term administration of L-DOPA and is correlated with expression of LID. The objective of the proposed studies is to determine the functional significance of ERK activation in striatal cholinergic neurons with respect to the expression of LID. We will examine this issue in aphakia mice, a genetic model of nigrostriatal degeneration that expresses LID, as well as in established unilateral neurotoxin- lesion based models. The proposed experiments are focused on the following objectives: 1) Correlation of the temporal expression of dyskinesia with ERK activation in striatal cholinergic neurons;2) Characterization of the DA receptor subtype and intracellular signaling pathways linked to L-DOPA-induced ERK activation in striatal cholinergic neurons and medium spiny neurons;and 3) Determining the functional outcome of ERK activation in cholinergic neurons with respect to neuronal excitability and cholinergic phenotypic expression. A better understanding of cell signaling mechanisms involved in LID will facilitate identification of potential targets for the treatment of PD.

Public Health Relevance

L-DOPA is the most efficacious drug therapy for Parkinson's disease (PD), but chronic administration of this drug leads to debilitating abnormal involuntary movements known as dyskinesia. Establishment of experimental models which can mimic the cellular and behavioral processes underlying PD and the development of L-DOPA-induced dyskinesia are important for developing alternative efficacious therapies without unwanted dyskinetic side effects. The research proposed here will provide insight with respect to cell signaling mechanisms involved in dyskinesia behavior and will facilitate identification of potential targets for the treatment of PD.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS064865-02
Application #
7825453
Study Section
Special Emphasis Panel (ZRG1-BDCN-J (03))
Program Officer
Sieber, Beth-Anne
Project Start
2009-05-15
Project End
2014-04-30
Budget Start
2010-05-01
Budget End
2011-04-30
Support Year
2
Fiscal Year
2010
Total Cost
$337,838
Indirect Cost
Name
University of Chicago
Department
Neurology
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
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