Abstract
Glial cell line-derived trophic factor (GDNF) is a peptide with pleiotropic survival and growth-promoting effects on neurons. We found that intraspinal injection of a non-replicating herpes simplex virus-based vector coding for GDNF 2 h after blunt trauma to the thoraco-lumbar spinal cord produced sustained improvement in motor behavioral outcomes up to 5 weeks following injury. The improvement in behavior correlated with an increase in synaptophysin and glutamic acid decarboxylase (GAD) in the spinal cord at the level of injury. Addition of recombinant GDNF protein to primary spinal cord neurons in-vitro resulted in enhanced neurite growth and a marked increase in protein levels of GAD65 and GAD67, synapsin I and synaptophysin. GDNF-mediated increases in GAD and the synaptic markers were blocked by the MEK inhibitor UO126, but not by the phosphoinositide 3-kinase inhibitor LY294002. These results suggest that GDNF, acting through the MEK-ERK pathway enhances axonal sprouting, synaptic connectivity, and GABAergic neurotransmission in the spinal cord, that result in improved behavioral outcomes after spinal cord contusion injury.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Analysis of Variance
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Animals
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Cells, Cultured
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Disease Models, Animal
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Embryo, Mammalian
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Female
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Genetic Therapy / methods*
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Glial Cell Line-Derived Neurotrophic Factor / genetics
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Glial Cell Line-Derived Neurotrophic Factor / metabolism*
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Glial Cell Line-Derived Neurotrophic Factor / pharmacology
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Glutamate Decarboxylase / metabolism
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Green Fluorescent Proteins / genetics
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Humans
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Microtubule-Associated Proteins / metabolism
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Motor Activity / drug effects
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Motor Activity / genetics
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Neurofilament Proteins / metabolism
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Neurons / drug effects
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Neurons / metabolism
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Psychomotor Performance / drug effects
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Psychomotor Performance / physiology
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Rats
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Rats, Sprague-Dawley
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Recovery of Function / genetics
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Recovery of Function / physiology
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Spinal Cord / cytology
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Spinal Cord Injuries / genetics
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Spinal Cord Injuries / pathology
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Spinal Cord Injuries / physiopathology*
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Spinal Cord Injuries / therapy*
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Synaptic Transmission / drug effects
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Synaptic Transmission / genetics*
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gamma-Aminobutyric Acid / metabolism*
Substances
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Glial Cell Line-Derived Neurotrophic Factor
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MAP2 protein, rat
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Microtubule-Associated Proteins
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Neurofilament Proteins
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Green Fluorescent Proteins
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gamma-Aminobutyric Acid
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Glutamate Decarboxylase
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glutamate decarboxylase 1
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glutamate decarboxylase 2