Head and spinal cord injury are major health care issues, causing immense hardships to the victims and their families. The initial trauma is worsened by secondary destructive processes, including lipid peroxidation. Better understanding the mechanisms of secondary damage accompanying central nervous system trauma should pave the way to developing improved pharmacological methods of disrupting the cascade of processes contributing to secondary damage. It has been hypothesized that free radicals attack polyunsaturated fatty acids in cell membranes, triggering free radical chain reactions that destroy membrane phospholipids. Although a variety of free radical species may be involved in peroxidative damage hydroxyl radical is the most destructive of these. Two major pathways for generating hydroxyl radical in vivo have been proposed. One is the iron-catalyzed Haber-Weiss reaction. Another is NO-medicated OH generation. This project is to unequivocally determine whether free radicals in these two pathways contribute to secondary injury through peroxidative degradation of membrane phospholipids and to provide information of the roles of these free radicals in spinal cord injury.
The specific aims are: 1. To obtain time courses of superoxide, hydroxyl radical, nitric oxide and peroxynitrite release following in vivo impact injury to the rat spinal cord. 2. To generate the free radicals involved in the two pathways in vivo in the rat spinal cord at the concentration and duration that mimic release upon trauma and characterize the damage they cause neurochemically and histologically. A model well established in the P.I.'s laboratory will be used.
for Aim 1, a microdialysis fiber or a push-pull cannula will be inserted laterally into the spinal cord, and released species will be analyzed by measuring products of reactions of free radicals in microdialysates or perfusates. The measurements will be made specific by administering free radical scavengers or inhibitors through the dialysis fiber or cannula. The results will provide sound in vivo tests of whether these free radicals are indeed released following trauma.
For Aim 2, microdialysis and a push-pull cannula will be used to apply free radical precursors and pertinent enzymes into the spinal cord to generate free radicals, and to sample released substances. As a marker of peroxidation, malonyldialdehyde (MDA) will be measured from microdialysates during application of the free radicals to correlate free radical production and peroxidative damage in in vivo experiments. The other radicals measured from microdialysates during one radical generation will also provide information on the pathways of hydroxyl radical generation. Histological examination will reveal whether these free radicals damage neurons.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29NS034048-02
Application #
2379729
Study Section
Neurology B Subcommittee 2 (NEUB)
Program Officer
Cheung, Mary Ellen
Project Start
1996-03-01
Project End
2001-02-28
Budget Start
1997-03-01
Budget End
1998-02-28
Support Year
2
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Biochemistry
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555