1. The long-term delivery of
neurotrophic factors to specific regions of the central nervous system via gene therapy offers a new strategy for the treatment of
neurodegenerative disorders. 2. The neurotrophic factor
glial cell line-derived neurotrophic factor (
GDNF) is a potent dopaminergic (DA) trophic factor that ameliorates the behavioural and histological consequences of lesioning DA neurons in rodent and primate models of
Parkinson's disease. 3.
Glial cell line-derived neurotrophic factor gene therapy may have a potential use in the clinical treatment of
Parkinson's disease. 4. We examined whether injection of an adenoviral vector encoding human
GDNF preproprotein (Ad
GDNF) could protect the rat nigrostriatal DA system from progressive neuronal degeneration. Because
Parkinson's disease occurs primarily in the elderly population, we studied the effect of
GDNF gene delivery in an aged rat model of
Parkinson's disease. 5. In the aged (20 month) Fischer 344 rat, Ad
GDNF was injected either near DA cell bodies in the substantia nigra (SN) or at the DA terminals in the striatum. One week following gene delivery, the neurotoxin
6-hydroxydopamine (6-OHDA) was injected unilaterally into the striatum to cause progressive degeneration of the DA neurons. 6. Injection of
GDNF vector into either the striatum or the SN provided significant cell protection against
6-OHDA. However, only striatal injection of Ad
GDNF protected against the development of behavioural and neurochemical changes that occur in the DA-depleted brain. 7. The results of this study are reviewed here and the behavioural and cellular effects of
GDNF gene delivery into striatal versus mesencephalic sites are discussed.