GDNF, a “growth factor” capable of promoting the survival of dopamine neurons, has great potential as a treatment for Parkinson’s disease. However, getting GDNF into the brain has proven to be an insurmountable obstacle. Studies conducted in our lab have shown that when administered to a pre-clinical model by the nasal route, GDNF reaches affected areas of the brain and protects dopamine neurons in a standard pre-clinical model of Parkinson’s disease. We will now determine if the beneficial effect extends to a more refined model of the disease, the next critical step in pre-clinical development.
We will conduct a “neuroprotection study” designed to assess whether intranasal GDNF reduces the Parkinson’s symptoms and dopamine cell loss caused by the neurotoxin, MPTP. GNDF will be given intranasally to a pre-clinical model just before MPTP. This timing should insure that GDNF is present in the target brain areas at the same time that MPTP is active. Controls will receive intranasal saline prior to MPTP. We will follow all for 8 weeks, the time necessary for the neurotoxin effect to stabilize and the effectiveness of the GDNF treatments to be revealed. The degree of neuroprotection will be assessed by daily behavioral tests to detect Parkinson’s-like symptoms, and by counting the number of surviving dopamine neurons present in the models at the end of the study.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
GDNF cannot enter the brain after systemic administration, and the surgery to inject it directly into brain is too invasive for many patients. Intranasal administration is a novel delivery approach that may bypass these problems allowing enough GDNF to reach the brain to stop Parkinson’s disease progression in its early stages. If this route of administration proves effective in a pre-clinical model of Parkinson’s disease, it moves one step closer to being developed as a therapy for patients.
Our project is a “proof-of-concept” study that will tell us whether intranasal delivery of GDNF should be pursued as a therapy for humans. If we learn that the approach is successful in the pre-clinical MPTP model, the next goal would be to test intranasal GNDF in a human clinical trial. Ultimately, intranasal GDNF may become an effective, non-surgical means of harnessing the therapeutic effects of GDNF for patients with Parkinson’s disease
Our study to assess the neuroprotective efficacy of intranasal GDNF in a pre-clinical model of Parkinson’s disease has reached completion. Analysis of the data is on-going and final results are not yet available. An interim analysis of the data suggests that intranasal administration of GDNF protects dopamine nerve terminals in the caudate and putamen of pre-clinical models. If confirmed, this result would be consistent with a neuroprotective effect in a pre-clinical model of Parkinson’s disease. Intranasal delivery has potential to provide a non-invasive means of delivering GDNF to the brain as a therapeutic strategy for arresting disease progression.